Rajita Sinha: The Stressed Brain: Hijacking Cognition, Emotion, Behavior, and Health

The video below showed up in my feed a couple of days before the article I'm sharing on how stress generates enzymes that attack the brain. Together, this information highlights how destructive stress can be on our brains and our cognitive function.

How stress tears us apart: Enzyme attacks synaptic molecule, leading to cognitive impairment

Date: September 18, 2014
Source: Ecole Polytechnique Fédérale de Lausanne

Summary:
Why is it that when people are too stressed they are often grouchy, grumpy, nasty, distracted or forgetful? Researchers have just highlighted a fundamental synaptic mechanism that explains the relationship between chronic stress and the loss of social skills and cognitive impairment. When triggered by stress, an enzyme attacks a synaptic regulatory molecule in the brain, leading to these problems.

Carmen Sandi's team at EPFL discovered an important synaptic mechanism in the effects of chronic stress. It causes the massive release of glutamate which acts on NMDA receptors, essential for synaptic plasticity. These receptors activate MMP-9 enzymes which, like scissors, cut the nectin-3 cell adhesion proteins. This prevents them from playing their regulatory role, making subjects less sociable and causing cognitive impairment. Credit: EPFL  

Why is it that when people are too stressed they are often grouchy, grumpy, nasty, distracted or forgetful? Researchers from the Brain Mind Institute (BMI) at EPFL have just highlighted a fundamental synaptic mechanism that explains the relationship between chronic stress and the loss of social skills and cognitive impairment. When triggered by stress, an enzyme attacks a synaptic regulatory molecule in the brain. This was revealed by a work published in Nature Communications.

Carmen Sandi's team went to look for answers in a region of the hippocampus known for its involvement in behavior and cognitive skills. In there, scientists were interested in a molecule, the nectin-3 cell adhesion protein, whose role is to ensure adherence, at the synaptic level, between two neurons. Positioned in the postsynaptic part, these proteins bind to the molecules of the presynaptic portion, thus ensuring the synaptic function. However, the researchers found that on rat models affected by chronic stress, nectin-3 molecules were significantly reduced in number.

The investigations conducted by the researchers led them to an enzyme involved in the process of protein degradation: MMP-9. It was already known that chronic stress causes a massive release of glutamate, a molecule that acts on NMDA receptors, which are essential for synaptic plasticity and thus for memory. What these researchers found now is that these receptors activated the MMP-9 enzymes which, like scissors, literally cut the nectin-3 cell adhesion proteins. "When this happens, nectin-3 becomes unable to perform its role as a modulator of synaptic plasticity" explained Carmen Sandi. In turn, these effects lead subjects to lose their sociability, avoid interactions with their peers and have impaired memory or understanding.

The researchers, in conjunction with Polish neuroscientists, were able to confirm this mechanism in rodents both in vitro and in vivo. By means of external treatments that either activated nectin-3 or inhibited MMP-9, they showed that stressed subjectscould regain their sociability and normal cognitive skills. "The identification of this mechanism is important because it suggests potential treatments for neuropsychiatric disorders related to chronic stress, particularly depression," said Carmen Sandi, member of the NCCR-Synapsy, which studies the neurobiological roots of psychiatric disorders.

Interestingly, MMP-9 expression is also involved in other pathologies, such as neurodegenerative diseases, including ALS or epilepsy. "This result opens new research avenues on the still unknown consequences of chronic stress," concluded Carmen Sandi, the BMI's director.

Story Source:
The above story is based on materials provided by Ecole Polytechnique Fédérale de Lausanne. Note: Materials may be edited for content and length.

Journal Reference:
Michael A. van der Kooij, Martina Fantin, Emilia Rejmak, Jocelyn Grosse, Olivia Zanoletti, Celine Fournier, Krishnendu Ganguly, Katarzyna Kalita, Leszek Kaczmarek, Carmen Sandi. (2014). Role for MMP-9 in stress-induced downregulation of nectin-3 in hippocampal CA1 and associated behavioural alterations. Nature Communications; 5: 4995 DOI: 10.1038/ncomms5995

The article referenced here is open access, but it is highly technical. For those who want to read more, I am including the Discussion section below the video (at the bottom of the page).

* * * * *

Rajita Sinha: The Stressed Brain

Published on Sep 16, 2014


A Stockholm Psychiatry Lecture given by Professor Rajita Sinha, Yale University, at Karolinska Institutet Aug 27 2014. Title of the lecture: The stressed brain: hijacking cognition, emotion, behavior and health.

* * * * *

Here is the discussion section of the article summarized above.

Discussion

We tested the hypothesis that MMP gelatinase activity is involved in key proteolytic processing events induced by chronic stress in a hippocampal subfield-dependent manner and in connection with behavioural changes. We show that chronic stress leads to a CA1-specific reduction in the perisynaptic expression of ​nectin-3 and found that this reduction is critically involved in the stress-induced deficits in social exploration, social recognition and CA1-dependent cognition. Interestingly, we found increased ​MMP-9-related gelatinase activity in the hippocampal CA1 in chronically stressed animals and could show that ​MMP-9 itself cleaves recombinant ​nectin-3, a process mediated via the NMDA-receptor. Consistently, intra-CA1 administration of either an ​MMP-9 inhibitor or an NMDA receptor antagonist during stress exposure prevented the development of stress-induced deficits in social exploration, social memory and CA1-dependent cognition. Our findings highlight a fundamental role for ​MMP-9 in the effects of chronic stress on brain function and behaviour.

Nectins are emerging as both targets^{24, 43} and mediators²⁵ of stress actions in hippocampal-dependent memory and structural plasticity. We found molecular-, regional-, cellular compartment- and stress duration-dependent changes, with reduced ​nectin-3 expression after 21 days, but not 1 day, of restraint stress in the CA1 synaptoneurosomal, but not the total fraction. This was paralleled by deficits in several social behaviours and in a CA1-dependent cognitive task. Our results from cell culture experiments suggested that NMDA receptor activation during stress exposure might be implicated in the cleavage of ​nectin-3 in CA1 and its associated behavioural alterations. Previous work has implicated NMDA receptor activation in chronic stress-induced structural alterations in the hippocampus^{12, 44, 45}. Our in vivo study involving the pharmacological administration of the NMDA receptor antagonist ​MK-801, either systemically or directly into the CA1 region, confirmed that this treatment prevented the stress-induced reduction of ​nectin-3 expression in the CA1 synaptoneurosomal fraction as well as the behavioural impairments induced by stress in the sociability and temporal order task.

Using AAV-induced OE of ​nectin-3 either in the whole hippocampus or specifically in the CA1 area, we obtained evidence for a causal role of ​nectin-3 reduction in chronic stress-induced behavioural alterations, with the exception of the aggressive phenotype. We confirmed that the effects of ​nectin-3 OE were not due to altered physiological responses to the stress procedure (for example, body weight changes or ​corticosterone responses) or to changes in anxiety or locomotion. We found increased ​nectin-1 expression associated with AAV-​nectin-3 OE throughout the hippocampus, consistent with evidence in knockout mice indicating that downregulation of either ​nectin-1 or ​nectin-3 induces a parallel decrease in the levels of the other nectins in the hippocampus⁴⁶. ​Synaptophysin levels were not changed by ​nectin-3 OE and/or chronic stress, which is line with findings described for ​nectin-3 knockout mice⁴⁶. In addition, using the same chronic restraint stress protocol as described here, changes in the size of postsynaptic densities were observed but not in synaptic density in the CA1 (ref. 5). Interestingly, consistent with evidence that nectins recruit cadherins to cooperatively promote cell adhesion⁴⁷, we found a reduction in the CA1 perisynaptic ​N-cadherin levels. The specificity of these molecular changes in CA1 was supported by a lack of significant changes in the stressed animals’ synaptoneurosomal compartment of ​SynCAM-1 in the same brain region. To verify that the molecular changes specifically observed in CA1 were associated with well-established CA1-dependent behaviours, we tested animals in the temporal order task that is sensitive to CA1, but not to CA3, lesions⁴⁰. With regard to region-specificity, our findings for CA1 are in contrast with recent evidence in mice showing reduced ​nectin-3 expression in CA3 (refs 24, 25). This disparity may be attributed to differences in the animal species or stress procedures.

MMPs are a family of proteolytic enzymes that degrade components of the extracellular matrix and cleave specific cell-surface proteins⁴⁸, making them particularly suitable to sustain neural remodelling processes¹⁵. The degradation of cell adhesion molecules is one of the main mechanisms whereby MMPs affect neural plasticity^{9, 22} and the synapse-associated ​nectin-3 decrease suggested the potential involvement of proteolytic processing. ​Nectin-1 has been shown to undergo ectodomain shedding by alpha-secretase³²; however, the molecular players involved in ​nectin-3 shedding remained unknown.

We found that decreased ​nectin-3 expression in the hippocampal CA1, but not in the CA3, synaptoneurosomes of the stressed animals is accompanied by increased gelatinase activity. This suggested an increase in ​MMP-2 and/or ​MMP-9 activity, as these two MMPs are the most prominent gelatinases expressed in the brain. Our cell culture experiments also indicated that NMDA receptor stimulation leads to increased ​nectin-3 proteolytic cleavage that is ​MMP-9 dependent. The involvement of ​MMP-9 and not ​MMP-2 is consistent with a previous study showing that ​MMP-2 does not interact with ​nectin-3 (ref. 49). Furthermore, we provide direct evidence that ​MMP-9 cleaves recombinant ​nectin-3. Interestingly, ​MMP-9 cleaves several postsynaptic proteins involved in trans-synaptic adhesion via their interaction with presynaptic proteins. The list of such ​MMP-9 targets includes ​β-dystroglycan that binds to neurexins⁴² as well as ​neuroligin-1 also binding neurexins⁵⁰. Our findings are in line with previous reports implicating hippocampal ​MMP-9 in changes in dendritic spine morphology⁵¹ as well as in the cellular processes that contribute to a stressful learning task²⁰. Importantly, we show that intra-CA1 treatment with a specific ​MMP-9 inhibitor prevented the emergence of chronic stress-induced effects in social exploration and CA1-dependent cognition. Therefore, our results are consistent other findings that indicate a crucial role for extracellular proteolysis in the stress-induced behavioural alterations, with former studies highlighting the role of serine proteases, including the ​tissue-plasminogen activator¹² and ​neuropsin¹⁰.

Although deregulated social behaviour is a hallmark of many psychiatric disorders⁵², studies focusing on the link between chronic stress and psychopathology has mainly concentrated on studies in mood and cognition^{2, 7}, whereas the effects of stress on social behaviours are much less known. In agreement with our previous study⁸, we confirm here that chronic restraint stress for 21 days leads to clear alterations in the social domain, including reduced sociability, impaired social memory and increased aggressive behaviours. The hippocampus has been implicated in social behaviours both in rodents⁵³ and in humans⁵⁴. Consistent with our findings, social recognition in rats was disrupted by CA1 damage⁵⁵. However, although the effects of stress on sociability and social memory were rescued with ​nectin-3 OE, increased aggressive behaviours were not modified by this treatment. We have recently found that targeting the cell adhesion molecule ​neuroligin-2 expression or function in the hippocampus alters aggressive behaviour^{8, 56}, suggesting the involvement of the hippocampus in the regulation of aggression. However, it should be noted that those treatments were not confined to the CA1 area, which, on its own, might not modulate aggressive behaviours.

In summary, our findings identify a key role for ​MMP-9 proteolytic processing of ​nectin-3 in the hippocampal CA1, through a mechanism that engages NMDA receptors, among the processes leading to chronic stress-induced changes in social and cognitive behaviours. In addition to ​nectin-3, recently identified as potential mediators in stress-related disorders²⁵, our study highlights ​MMP-9 activity as a novel target for the treatment of stress-related neuropsychiatric disorders, in particular depression, which is typically characterized by deficits in the social and cognitive domains.

Frederick Travis, PhD - We Create Our Reality

Frederick Travis, PhD, is the director of the Center for Brain, Consciousness, and Cognition at the Maharishi University of Management, an institution dedicated to promoting transcendental meditation (TM [image a copyright symbol here]) in all possible venues.

This talk was given at Stanford University.

We Create Our Reality

Published on Aug 1, 2014


Frederick Travis, PhD, director of the Center for Brain, Consciousness, and Cognition, explains that the concept "We create our reality" is more than a philosophical statement. It is a physical reality driven by neural plasticity—every experience changes the brain. Therefore, choose transcendental experiences and higher states of consciousness naturally unfold.

About the Center for Brain, Consciousness, and Cognition

The Center for Brain, Consciousness, and Cognition was created in 1972 when Maharishi University of Management was founded.  The purpose of the Brain Center was to delineate brain and physiological functioning during higher stages of human development. We have focused our research on practice of the Transcendental Meditation (TM) technique, because this meditation practice readily leads to the state of Transcendental Consciousness, pure self-awareness or inner wakefulness.  With regular TM practice, meditation experiences become integrated with waking, sleeping and dreaming.  The co-existence of these states is described in the Vedic tradition as the first stabilized state of enlightenment, called Cosmic Consciousness. 

Our research has delineated:

1. sub-stages during Transcendental Meditation practice (Travis 2001);

2. brain patterns and subjective experiences of Transcendental Consciousness, defined as “pure self-awareness” free from the processes and contents of knowing, a proposed fourth state of consciousness (Farrow and Hebert, 1982; Travis and Wallace 1997; Travis and Pearson 2000);

3. distinction between TM and eyes closed rest (Travis and Wallace 1999);

4. brain patterns and subjective experiences of  the first stabilized state of enlightenment called Cosmic Consciousness during sleep (Mason, Alexander et al. 1997) and during activity (Travis, Tecce et al. 2002; Travis, Arenander et al. 2004).

This research has culminated in a Brain Integration Scale that quantifies the progressive integration of experiences during Transcendental Meditation practice with waking—becoming more in touch with ones inner resources.  Scores on the Brain Integration Scale systematically increase with TM practice in college students (Travis and Arenander 2006; Travis, Haaga et al. 2009).  Brain Integration Scale scores are also higher in professional athletes who won medals in the Olympics, World Games or National Games for three consecutive years compared to professional athletes who did not consistently place (Harung, Travis et al. in press).   Thus, higher scores on the Brain Integration Scale may reflect greater connection with ones inner resources and so be more successful in life.   

References:
Farrow, J. T. and J. R. Hebert (1982). "Breath suspension during the Transcendental Meditation technique." Psychosom Med 44(2): 133-53.
Harung, H., F. Travis, et al. (in press). "High Levels of Brain Integration in World-class Norwegian Athletes: Towards a Brain Measure of Mental Fitness." Scandanavian Journal of Exercise and Sport.
Mason, L. I., C. N. Alexander, et al. (1997). "Electrophysiological correlates of higher states of consciousness during sleep in long-term practitioners of the Transcendental Meditation program." Sleep. 20(2): 102-10.
Travis, F. (2001). "Autonomic and EEG patterns distinguish transcending from other experiences during Transcendental Meditation practice." International Journal of Psychophysiology 42(1): 1-9.
Travis, F. and A. Arenander (2006). "Cross-sectional and longitudinal study of effects of Transcendental Meditation practice on interhemispheric frontal asymmetry and frontal coherence." International Journal of Neuroscience 116(12): 1519-38.
Travis, F., A. Arenander, et al. (2004). "Psychological and physiological characteristics of a proposed object-referral/self-referral continuum of self-awareness." Consciousness and Cognition 13(2): 401-20.
Travis, F., D. A. Haaga, et al. (2009). "Effects of Transcendental Meditation practice on brain functioning and stress reactivity in college students." International Journal of Psychophysiology 71(2): 170-6.
Travis, F. and C. Pearson (2000). "Pure consciousness: distinct phenomenological and physiological correlates of "consciousness itself"." The International Journal of Neuroscience. 100: 77-89.
Travis, F. and R. K. Wallace (1997). "Autonomic patterns during respiratory suspensions: possible markers of Transcendental Consciousness." Psychophysiology. 34(1): 39-46.
Travis, F. and R. K. Wallace (1999). "Autonomic and EEG patterns during eyes-closed rest and transcendental meditation (TM) practice: the basis for a neural model of TM practice." Consciousness and Cognition 8(3): 302-18.
Travis, F. T., J. Tecce, et al. (2002). "Patterns of EEG Coherence, Power, and Contingent Negative Variation Characterize the Integration of Transcendental and Waking States." Biological Psychology. 61: 293-319.

Stanislas Dehaene - Advances in Understanding the Signatures of Consciousness

The Edmond and Lily Safra Center for Brain Sciences hosts every Thursday Neuroscientists from around the globe to present their recent study. Earlier this year, Stanislas Dehaene gave a talk on the work of his lab in understanding the signatures of consciousness, the distinct markers of brain activity that correlate with subjective reports of conscious experience.

Stanislas Dehaene is a professor at the Collège de France, author, and (since 1989) director of INSERM Unit 562, Cognitive Neuroimaging. He has worked on a number of topics, including numerical cognition, the neural basis of reading and the neural correlates of consciousness. 

Advances in Understanding the Signatures of Consciousness

Published on May 1, 2014
Talk given on February 27, 2014

• A lecture given by: Stanislas Dehaene, Experimental Cognitive Psychology - Collège de France
• On the topic of: "Advances in understanding the signatures of consciousness"

Inability to Ignore Irrelevant Stimuli Impairs Working Memory and Cognition in Schizophrenia

This new research article helps explain one of the symptoms I have notice in clients suffering from the symptoms identified as schizophrenia - an apparent inability to filter external (and internal) stimuli. One of the intrusive elements seems to be memory, and because so many people with schizophrenia have histories of severe neglect and/or trauma, random details from those memories seem to frequently invade consciousness.

One of the ways I have seen this manifest is in what appears to be random verbal associative thinking. One name, place, or idea will lead to an internal association that seems random from the outside but for the client it flows naturally, from one thing to the next.

Anyway, this is important new material for those of us who serve clients with these symptoms.

'Noisy' memory in schizophrenia (7/25/2014)

Philadelphia, PA, July 14, 2014 - The inability to ignore irrelevant stimuli underlies the impaired working memory and cognition often experienced by individuals diagnosed with schizophrenia, reports a new study in the current issue of Biological Psychiatry.

Our brains are usually good at focusing on the information that we are trying to learn and filtering out the "noise" or thoughts that aren't relevant. However, memory impairment in schizophrenia may be related in part to a problem with this filtering process, which Dr. Teal Eich at Columbia University and her colleagues studied.

"Our assumption was that understanding the impairments in the component processes of working memory - the ability to hold and manipulate information in the mind - among patients with schizophrenia could be fundamental to understanding not only cognitive function in the disorder, which is widespread and has debilitating consequences, but also the disorder itself," Eich explained.

The researchers recruited patients with schizophrenia and a control group of healthy volunteers to complete an item recognition task in the laboratory while undergoing a functional magnetic resonance imaging scan. In particular, they focused on analyzing potential activation differences in the ventro-lateral prefrontal cortex (VLPFC), a region of the brain implicated in working memory.

The design of the task allowed for the assessment of the various components of working memory: 1) maintaining the memory itself, 2) inhibiting or ignoring irrelevant information, and 3) during memory retrieval, controlling the interference of irrelevant information.

While simply maintaining the memory, both groups showed a similar degree of activation in the VLPFC. During the inhibition phase, VLPFC activity is expected to decrease, which was indeed observed in the healthy group, but not in the patients. Finally, during interference control, patients performed worse and showed increased VLPFC activation compared to the healthy volunteers. Overall, the patients showed altered VLPFC functioning and significant impairments in their ability to control working memory.

"Our findings show that these patients have a specific deficit in inhibiting information in working memory, leading to impaired distinctions between relevant and irrelevant thoughts," said Eich. "This result may provide valuable insights into the potential brain mechanisms underlying the reasons why these affected individuals are unable to control or put out of mind certain thoughts or ideas."

This study adds to a growing literature suggesting that cognitive functions require both the activation of one set of regions and the inhibition of others. The failure to suppress activation may be just as disruptive to cortical functions as deficits in cortical activation.

Many years ago, the pioneering scientist Patricia Goldman-Rakic and her colleagues showed that the inhibition of regional prefrontal cortical activity was dependent upon the integrity of the GABA (gamma-aminobutyric acid) system in the brain, a chemical system with abnormalities associated with schizophrenia.

"We need to determine whether the cortical inhibitory deficits described in this study can be attributed to particular brain chemical signaling abnormalities," said Dr. John Krystal, Editor of Biological Psychiatry. "If so, this type of study could be used to guide therapeutic strategies to enhance working memory function."

Note: This story has been adapted from a news release issued by the Elsevier

* * * * *

Here is the abstract from the original article at Biological Psychiatry.

Full Citation:
Eich, TS, Nee, DE, Insel, C, Malapani, C, Smith, EE. (2014, Jul 15). Neural Correlates of Impaired Cognitive Control over Working Memory in Schizophrenia. Biological Psychiatry; 76(2): 146–153. DOI: http://dx.doi.org/10.1016/j.biopsych.2013.09.032 [Epub ahead of print, Nov. 18, 2013]

Neural Correlates of Impaired Cognitive Control over Working Memory in Schizophrenia

Teal S. Eich, Derek Evan Nee, Catherine Insel, Chara Malapani, Edward E. Smith [†]

†Deceased (EES).

ABSTRACT

Background

One of the most common deficits in patients with schizophrenia (SZ) is in working memory (WM), which has wide-reaching impacts across cognition. However, previous approaches to studying WM in SZ have used tasks that require multiple cognitive-control processes, making it difficult to determine which specific cognitive and neural processes underlie the WM impairment.

Methods

We used functional magnetic resonance imaging to investigate component processes of WM in SZ. Eighteen healthy controls (HCs) and 18 patients with SZ performed an item-recognition task that permitted separate neural assessments of 1) WM maintenance, 2) inhibition, and 3) interference control in response to recognition probes.

Results

Before inhibitory demands, posterior ventrolateral prefrontal cortex (VLPFC), an area involved in WM maintenance, was activated to a similar degree in both HCs and patients, indicating preserved maintenance operations in SZ. When cued to inhibit items from WM, HCs showed reduced activation in posterior VLPFC, commensurate with appropriately inhibiting items from WM. However, these inhibition-related reductions were absent in patients. When later probed with items that should have been inhibited, patients showed reduced behavioral performance and increased activation in mid-VLPFC, an area implicated in interference control. A mediation analysis indicated that impaired inhibition led to increased reliance on interference control and reduced behavioral performance.

Conclusions

In SZ, impaired control over memory, manifested through proactive inhibitory deficits, leads to increased reliance on reactive interference-control processes. The strain on interference-control processes results in reduced behavioral performance. Thus, inhibitory deficits in SZ may underlie widespread impairments in WM and cognition.

Bruce Hood on the Domesticated Brain (The RSA)

Bruce Hood is the author of The Self Illusion: How the Social Brain Creates Identity (2012). His new book is The Domesticated Brain: A Pelican Introduction, and he was at The RSA in England recently to talk about the new book.

Bruce Hood on the Domesticated Brain

7th May 2014

Listen to the audio  (full recording including audience Q&A)

RSA Replay is now a featured playlist on our Youtube channel, it is the full recording of the event including audience Q&A.

To celebrate the return of Pelican books, Penguin’s groundbreaking and iconic series of intelligent guides to essential topics, we are delighted to announce a new events series bringing together expert minds and curious observers in order to bring vital subjects to life.

Why do we care what others think? What keeps us bound together? How does the brain shape our behaviour?

How did the brain evolve from an organ whose primary function was to help us survive in a threatening world, to an organ which influences our thoughts and behaviour and navigates us through an equally unpredictable social landscape? In the third of these special RSA events, Bruce Hood, award-winning psychologist and director of the Cognitive Development Centre at the University of Bristol will give us a clear and comprehensible insight into the complex mysteries of the brain.

Speaker: Bruce Hood, award-winning psychologist and Director of the Cognitive Development Centre at the University of Bristol.

Chair: Timandra Harkness, writer and performer.



Pelican first appeared in 1937 with the publication of George Bernard Shaw’s ‘The Intelligent Women’s Guide to Socialism, Capitalism, Sovietism and Fascism’ and continued with thousands of books across a massive range of subjects. Aimed at the everyday reader, Pelicans combined intellectual rigour with simple, clear and accessible prose.

Selling over 250 million copies, Pelican in its heyday was seen as influencing the intellectual culture in Britain by lowering the traditional barriers to knowledge. At the time, this confidence in the tastes of the ordinary reader was unusual, and gave Pelican a democratic, populist bent. The first Pelican books cost the same amount as a packet of cigarettes, a radical price at the time, and became especially popular among a self-educating post-war generation.

Speakers

• Timandra Harkness
• Professor Bruce Hood

Books

The Domesticated Brain: A Pelican Introduction by Bruce Hood (Pelican, 2014)

This is an old article (from 2011), but it offers an excellent overview of the progress that has been made in applying dynamic systems theory to cognitive development. The following is from a book chapter on Dynamic Systems Theories by Esther Thelen and Linda B. Smith:

Dynamic systems is a recent theoretical approach to the study of development. In its contemporary formulation, the theory grows directly from advances in understanding complex and nonlinear systems in physics and mathematics, but it also follows a long and rich tradition of systems thinking in biology and psychology. The term dynamic systems, in its most generic form, means systems of elements that change over time.

The authors then offer two themes that recur frequently in the history of developmental theory and in dynamic systems theory:

1. Development can only be understood as the multiple, mutual, and continuous interaction of all the levels of the developing system, from the molecular to the cultural.

2. Development can only be understood as nested processes that unfold over many timescales from milliseconds to years.

Thelen, E. & Smith, L.B. (2006). Dynamic Systems Theories. In Handbook of Child Psychology, Volume 1, Theoretical Models of Human Development, 6th Edition, William Damon (Editor), Richard M. Lerner (Volume editor), pp 258-312. 

For more general background, see the following articles:

• Complex Dynamical Systems Theory, by Professor Alicia Juarrero, author of Dynamics in action: Intentional behavior as a complex system. www.cognitive-edge.com
• Cognition as a dynamic system: Principles from embodiment, by Linda B. Smith; Developmental Review 25 (2005) 278–298.
• Development as a dynamic system, by Linda B. Smith and Esther Thelen; Trends in Cognitive Sciences, Vol.7 No.8, August 2003.

With that background, then, here is the feature article:

Full Citation:
Spencer, JP, Perone, S, and Buss, AT. (2011, Dec). Twenty years and going strong: A dynamic systems revolution in motor and cognitive development. Child Dev Perspect. 5(4): 260–266. doi:  10.1111/j.1750-8606.2011.00194.x

Twenty years and going strong: A dynamic systems revolution in motor and cognitive development

John P. Spencer, Sammy Perone, and Aaron T. Buss

Abstract

This article reviews the major contributions of dynamic systems theory in advancing thinking about development, the empirical insights the theory has generated, and the key challenges for the theory on the horizon. The first section discusses the emergence of dynamic systems theory in developmental science, the core concepts of the theory, and the resonance it has with other approaches that adopt a systems metatheory. The second section reviews the work of Esther Thelen and colleagues, who revolutionized how researchers think about the field of motor development. It also reviews recent extensions of this work to the domain of cognitive development. Here, the focus is on dynamic field theory, a formal, neurally grounded approach that has yielded novel insights into the embodied nature of cognition. The final section proposes that the key challenge on the horizon is to formally specify how interactions among multiple levels of analysis interact across multiple time scales to create developmental change.

_____

Twenty years is a long time for an individual scientist, but a relatively brief period for a scientific theory. This tension of time scales underlies our evaluation of dynamic systems theory (DST) and development below. In particular, we take the long view in our evaluation—to evaluate a new theoretical perspective in its infancy. From this vantage point, the differential success of individual variants of DST is normal; most critical is the evaluation en masse. In our view, DST has been extremely successful on the whole—in some cases, “revolutionary.” In the sections that follow, we explain our optimism, grounding our evaluation both in past accomplishments and in future prospects. Time will tell whether the word “revolution” reflects more than just our optimism.

What are the greatest contributions of the DST approach to development over the past 20 years?

Recent decades have seen a shift in thinking about development. Instead of characterizing what changes over development, there is a new emphasis on the how of developmental change (see Elman et al., 1997; Plumert & Spencer, 2007; Thelen & Smith, 1994). These explorations have revealed that simple notions of cause and effect are inadequate to explain development. Rather, change occurs within complex systems with many components that interact over multiple time scales, from the second-to-second unfolding of behavior to the longer time scales of learning, development, and evolution (see Christiansen & Kirby, 2003).

The introduction of DST into psychology has spurred this new way of thinking about change. Critically, DST did not emerge in isolation. Rather, it is one contributor to a broad shift in developmental science toward a systems metatheory (see Lerner, 2006) that encompasses a wide range of work from developmental systems theory (e.g., Gottlieb, 1991; Kuo, 1921; Lehrman, 1950), sociocultural and situated approaches (e.g., Baltes, 1987; Bronfrenbrenner & Ceci, 1994; Elder, 1998), ecological psychology (e.g., Adolph, 1997; Gibson & Pick, 2000; Turvey, 1990), and connectionism (e.g., Bates & Elman, 1993; Elman, 1990; Rumelhart & McClelland, 1986).

Within this family of work, confusion can arise in the distinction between two DSTs: dynamic systems theory and developmental systems theory (see Fox-Keller, 2005). These perspectives share many core principles; we can distinguish them by their histories and foci. Developmental systems theory was based on early work at the intersection of behavioral development, biology, and evolution by pioneers such as Lehrman and Kuo (see Ford & Lerner, 1992; Gottlieb, 1991; Griffiths & Gray, 1994; Kuo, 1921). This approach has focused on how development unfolds through an epigenetic process with cascading interactions across multiple levels of causation, from genes to environments (Johnston & Edwards, 2002). Dynamic systems theory, by contrast, developed from the mathematical analysis of complex physical systems (Gleick, 1998; Smith & Thelen, 2003). Consequently, this approach provides a way of mathematically specifying the concepts of systems metatheory while supporting the abstraction of these concepts into more cognitive domains (see, Spencer & Schöner, 2003). Thus, the aim of many dynamic systems approaches is to formally implement developmental processes to shed light on how behavior changes over time (Spencer et al., 2009; van Geert, 1991, 1998; van der Maas & Molenaar, 1992; van der Maas & Dolan, 2006; Warren, 2006). In this sense, dynamic systems theory and developmental systems theory share an emphasis on the step-by-step processes and multilevel interactions that shape development.

A key characteristic of systems metatheory that both approaches share is the rejection of classical dichotomies that have pervaded psychology for centuries: nature versus nurture, stability versus change, and so on (for discussion, see Spencer et al., 2009). In their place, systems metatheory takes the “organism in context” as its central unit of study, an inseparable unit in which it is impossible to isolate the behavioral and developmental state of the organism from external influences. Furthermore, behavior and development are emergent properties of system-wide interactions that can create something new from the many interacting components in the system (see Munakata & McClelland, 2003; Spencer & Perone, 2008; Thelen, 1992).

It is often helpful to consider historical change through the lens of contrast. According to Lerner (2006), systems metatheory has supplanted other influential metatheories, but which ones? To answer this, we conducted a survey of the fourth through sixth editions of the Handbook of Child Psychology: Theoretical Models of Human Development. These editions span more than 20 years in developmental psychology (from 1983 to 2006). Although this book is just one indication of how the field is changing, our survey revealed that four theoretical viewpoints have disappeared from the Handbook over time: nativism, cognitive and information processing, symbolic approaches, and Piaget’s theory. Of course, scholars still actively pursue all of these perspectives. It is notable, however, that they have something in common—an attempt to carve up behavior and development into parts (broad parts like nature versus nurture; specific parts like cognitive modules; or temporal partitions such as stages of processing or stages of development). Systems metatheory rejects this inherent partitioning.

Within the broad class of theories that make up systems metatheory, a central challenge is to examine what each perspective contributes. DST has had a particularly strong influence, bringing several critical concepts into mainstream developmental science. The first concept is that systems are self-organizing. Complex physical systems (such as the human child) comprise many interacting elements that span multiple levels from the molecular (for example, genes) to the neural to the behavioral to the social. Within the DS perspective, organization and structure come “for free” from the nonlinear and time-dependent interactions that emerge from this multilevel and high-dimensional mix (e.g., Prigogine & Nicolis, 1971). Thus, there is no need to build pattern into the system ahead of time because the system has an intrinsic tendency to create pattern. This gives physical systems a creative spark that we contend is central to the very notion of development—development is fundamentally about the emergence of something qualitatively new that was not there before.

Of course, the notion of qualitative change over development is not unique to DST (see, e.g., Gottlieb, 1991; Munakata & McClelland, 2003; Piaget, 1954; von Bertalannfy, 1950). But we contend that DST clarifies the distinction between quantitative and qualitative change (see Spencer & Perone, 2008; van Geert, 1998). According to DST, qualitative change occurs when there is a change in the layout of attractors, or special “habitual” states around which behavior coheres: when a new attractor appears, there is a qualitative change in the system. Although qualitative change can be special—it can reflect the emergence of something new that was not there before—it is not in opposition to quantitative change. Rather, quantitative changes in one aspect of the system can give rise to qualitatively new behaviors. This is one example where a classic dichotomy withers away in the face of a formal, systems viewpoint.

One of the historical challenges in defining qualitative and quantitative change is that changes occur over multiple time scales. For instance, a skilled infant can go from a crawling posture to a walking posture within a matter of seconds, but how is this “on-the-fly” transition related to the more gradual shift in the likelihood of crawling versus walking that unfolds across months in development (see Adolph, 1997)? In particular, it can be difficult to specify when the infant “has” walking, why walking comes and goes in different situations, and what drives this change over time. Again, DST has a unique perspective on these challenges. There is no competence/performance distinction in DST (see Thelen & Smith, 1994); rather, the emphasis is on how people assemble behavior in the moment in context. But because DST integrates processes over multiple time scales, it can explain why behavioral attractors—which form in real time—can emerge and become more likely over the longer times of learning and development (for discussion, see Spencer & Perone, 2008).

Another issue that researchers have directly examined using DST is the concept of “soft assembly.” According to this concept, behavior is always assembled from multiple interacting components that can be freely combined from moment to moment on the basis of the context, task, and developmental history of the organism. Esther Thelen talked about this as a form of improvisation in which components freely interact and assemble themselves in new, inventive ways (like musicians playing jazz). This gives behavior an intrinsic sense of exploration and flexibility, issues that Goldfield and colleagues (Goldfield, Kay, & Warren, 1993) have examined formally.

This characterization of behavior and development has led to an additional insight about the embodied nature of cognition. In particular, if behavior is softly assembled from many components in the moment, then the brain is not the “controller” of behavior. Rather, it is necessary to understand how the brain capitalizes on the dynamics of the body and how the body informs the brain in the construction of behavior. This has led to an emphasis on embodied cognitive dynamics (see Schöner, 2009; Spencer, Perone, & Johnson, 2009), that is, to a view of cognition in which brain and body are in continual dialogue from second to second.

A final strength of the DS approach is that it has generated a host of productive tools, including rich empirical programs (Samuelson & Horst, 2008; Smith, Thelen, Titzer, & McLin, 1999; Thelen & Ulrich, 1991; van der Maas & Dolan, 2006), formal modeling tools that can capture and quantify the emergence and construction of behavior over development (such as growth models, oscillator models, dynamic neural field models), and statistical tools that can describe the patterns of behavior observed over development (Lewis, Lamey, & Douglas, 1999; Molenaar, Boomsma, & Dolan, 1993; van der Maas & Dolan, 2006). These tools have enabled researchers to move beyond the characterization of what changes over development toward a deeper understanding of how these changes occur.

What is your critical evaluation of the progress of DS-inspired empirical research?

DST has led to a revolutionary change in how people think about motor development, and this type of revolutionary thinking is starting to take hold in cognitive development as well. We review the basis for this optimistic assessment below. Note that we focus on motor and cognitive development because these are our “home” domains. We will leave it to the other authors in this issue to evaluate other fields.

The dominant view of motor development for much of the 20th century was that the development of action occurred in a series of relatively fixed motor milestones. The emphasis was on normative development, the concept of motor programs that controlled action, and a sequence of milestones that was largely under genetic or biological control (for review, see Adolph & Berger, 2006). The landscape has shifted dramatically in the last 20 years, thanks in large part to the work of Esther Thelen (as well as other systems thinkers, most notably, Gibson, 1988; see Adolph & Berger, 2006). Today the field views motor development as emergent and exploratory with a new emphasis on individual development in context. Although this revolution in thinking was spurred by dynamic systems concepts, it was also driven forward by a wealth of empirical research.

For instance, Esther Thelen conducted a now-classic set of studies investigating the early disappearance of the stepping reflex. Thelen’s early work on stepping revealed that the coordination patterns that underlie stepping and kicking were strikingly similar. The puzzle was that newborn stepping disappeared within the first three months, whereas kicking continued and increased in frequency. To explain the disappearance of stepping, several researchers had proposed that maturing cortical centers inhibit the primitive stepping reflex or that stepping was phylogenetically programmed to disappear (e.g., Andre-Thomas & Autgaerden, 1966).

To probe the mystery of the disappearing steps, Thelen conducted a longitudinal study that focused on the detailed development of individual infants. Thelen, Fisher, and Ridley-Johnson (1984) found a clue in the fact that chubby babies and those who gained weight fastest were the first to stop stepping. This led to the hypothesis that it requires more strength for young infants to lift their legs when upright (in a stepping position) than when lying down (in a kicking position). To test this idea, Thelen and colleagues conducted two ingenious studies. In one, they placed small leg weights on two-month-old babies, similar in amount to the weight they would gain in the ensuing month. This significantly reduced stepping. In the other, they submerged older infants whose stepping had begun to wane in water up to chest levels. Robust stepping now reappeared. These data demonstrated that traditional explanations of neural maturation and innate capacities were insufficient to explain the emergence of new patterns and the flexibility of motor behavior.

Since this seminal work, Thelen and her colleagues have intensively examined the development of alternating leg movements (Thelen & Ulrich, 1991), the emergence of crawling (Adolph, Vereijken, & Denny, 1988), the emergence of walking (e.g., Adolph, 1997; Thelen & Ulrich, 1991), and the development of reaching (Corbetta, Thelen, & Johnson, 2000; Thelen, Corbetta & Spencer, 1996; Thelen et al., 1993). In all cases, these researchers have shown that new action patterns emerge in the moment from the self-organization of multiple components. The stepping studies elegantly illustrated this, showing how multiple factors cohere in a moment in time to create or hinder leg movements. And, further, these studies illustrate how changes in the components of the motor system over the longer time scale of development interact with real-time behavior.

In summary, DS concepts have led to a radical change in the conceptualization of motor development. But what about cognition? There have been a variety of DS approaches to cognitive development. For instance, researchers have used the concepts of DST to study early word learning (e.g., Samuelson, Schutte & Horst, 2008), language development (e.g., van Geert, 1991), the development of intelligence (e.g., Fischer & Bidell, 1998), and conceptual development and conservation behavior (e.g., van der Maas & Molenaar, 1992). A survey of these different approaches is beyond the scope of this article (see Spencer, Thomas & McClelland, 2009). We focus, instead, on one particular flavor of cognitive dynamics—dynamic field theory (DFT)—that emerged out of the motor approach that Thelen and colleagues pioneered (for discussion, see Spencer & Schöner, 2003).

The starting point for the DF approach was to consider several facts about neural systems. Neural systems are noisy, densely interconnected, and time-dependent; they pass continuous, graded, and metric information to one another; and they are continuously coupled via both short-range and long-range connections (Braitenberg & Schüz, 1991; Constantinidis & Steinmetz, 1996; Edelman, 1987; Rao, Rainer, & Miller, 1997). These neural facts raise deep theoretical challenges. How can a collection of neurons “represent” information amidst near-constant bombardment by other neural signals (Skarda & Freeman, 1987), and how do neurons, in concert with the body, generate stable, reliable behavior? To address these challenges, the DF framework emphasizes stable patterns of neural interaction at the level of population dynamics (see also Spivey, 2007). That is, rather than building networks that start from a set of spiking neurons, we have chosen to focus on the emergent product of the dynamics at the neural level—attractors at the level of the neural population.

The first steps toward a neurally grounded theory of cognitive development came from Thelen and Smith’s studies of the Piagetian A-not-B error (see Smith et al., 1999; Thelen, Schöner, Scheier, & Smith, 2001). This early work formalized a DFT of infant perseverative reaching, arguably the most comprehensive theory of infants’ performance in the Piagetian A-not-B task (Clearfield, Dineva, Smith, Diedrich, & Thelen, 2009; Smith et al., 1999; Spencer, Dineva, & Smith, 2009; Thelen et al., 2001). DFT has generated a host of novel behavioral predictions, and it explains how perseverative reaching arises as a function of (1) the infants’ history of prior reaches to A (Smith et al., 1999), (2) a bodily feel and visual perspective of reaching to A (Smith et al., 1999), (3) the distinctiveness of the targets and perceptual cues in the task space (Clearfield et al, 2009), (4) the delay between the cueing and reaching events (Diamond, 1985), (5) the number of targets in the task space, (6) the characteristics of the hidden object (and whether there is any hidden object whatsoever; see Smith et al., 1999), and (7) changes in infants’ reaching skill and working memory abilities over development (Clearfield, Diedrich, Smith, & Thelen, 2006; for related studies with older children, see Schutte, Spencer, & Schöner, 2003; Spencer, Smith, & Thelen, 2001).

More recently, we have extended the DF approach to a host of other topics in cognitive development. These topics include the processes that underlie habituation in infancy (Perone & Spencer, 2009; Schöner & Thelen, 2006), the control of autonomous robots and the development of exploratory motor behavior (Dineva, Faubel, Sandamirskaya, Spencer, & Schöner, 2008; Steinhage & Schöner, 1998), the development of visuospatial cognition (Simmering, Spencer, & Schutte, 2008), the processes that underlie visual working memory and the development of change detection abilities (Simmering, 2008), the processes that underlie early word learning behaviors (Samuelson et al., 2008), and the development of executive function (Buss & Spencer, 2008). This broad coverage of multiple aspects of development with the same theoretical framework underlies our optimism that the concepts of DST can have a revolutionary impact on cognitive development just as they had in motor development. Time will tell.

What are the challenges and necessary directions for the next 20 years?

A major accomplishment of DS approaches has been to move beyond the conceptual level to establish a tight link between formal theory and empirical research, leading to a greater understanding of the processes that underlie developmental change. Although there have been many successful applications of DS concepts, significant challenges remain. For instance, soft assembly makes it difficult to define the components of the “system” or subsystem under study. Similarly, the multiply determined nature of dynamic systems makes it difficult to identify “cause” because different factors can lead to different outcomes depending on the context and history of the individual.

In addition to these conceptual challenges, researchers in the next 20 years will have to build theories that formally connect processes across multiple levels of analysis. Figure 1 shows the nested, interacting systems that contribute to the organization of behavioral development from genetic to social levels. Each of these levels and the interactions among them are highly complex; thus, understanding how development happens as these levels interact over time will require formal theories that specify the nature of those interactions (for related ideas, see Gottlieb, 1991; Johnston & Edwards, 2002; Johnston & Lickliter, 2009). To date, multiple approaches have attempted to understand behavioral development at the different levels shown in Figure 1, but these efforts have not been tightly integrated across levels.

Figure 1
A central challenge on the horizon for dynamic systems theory is to formally integrate across reciprocally interacting levels from genetic to social and to integrate these levels across multiple time scales from in-the-moment interactions to learning ...

In addition to the challenge of formally connecting processes at multiple levels, it will be important to tackle a second challenge: integrating time scales. Within DST, nested, interacting systems come together to create developmental change as those systems interact through time. In particular, the multiple systems in Figure 1 produce a coherent behavioral system in the moment, and those in-the-moment behaviors have consequences that carry forward across the longer time scales of learning and development (see Smith & Thelen, 2003 for a discussion). Our research using DFT has effectively integrated real-time behavior with changes over learning (see, e.g., Lipinski, Spencer, & Samuelson, 2010; Schöner & Thelen, 2006; Thelen et al., 2001). Other approaches have examined these time scales as well (e.g., French, Mareschal, Mermillod, & Quinn, 2004; McMurray, Horst, Toscano, & Samuelson, 2009), but the longer time scales of development have been more elusive (but see Simmering et al., 2008; Schutte et al., 2003; Schutte & Spencer, 2009, for efforts in this direction).

One difficulty in this regard is that it is often hard to get a clear sense of developmental change empirically. Adolph, Robinson, Young, and Gill-Alvarez (2008), for example, showed how different views of developmental change are created simply by sampling rate of change. But developmental scientists face theoretical challenges in terms of integrating behavior over very long time scales. Spencer and Perone (2008) have taken one step toward addressing this issue by probing change in neural dynamics over relatively long time scales. In particular, they showed that the gradual accumulation of neural excitation in a simple, dynamic neural system created qualitative changes in the state in which the system operated. That is, as the system gradually accumulated a history, the system was biased to settle into new neural attractor states. We believe that it is possible to generalize from these concepts, and we are currently working to scale this demonstration up guided by a rich, longitudinal empirical data set (see Perone & Spencer, 2009).

Integrating dynamics across multiple systems and time scales is a daunting task. Even more challenging is to achieve this integration at the level of the individual child in context. But this is a critically important goal because it opens the door for examining atypical development. If we understand the complex dynamics through which systems interact over time at the level of individual children, we will be well positioned to create individual interventions that help steer the child toward positive developmental outcomes. That would indeed be revolutionary. Perhaps in the next 20 years we will realize this vision.

Acknowledgments

Preparation of this manuscript was supported by NIH RO1MH62480 awarded to John P. Spencer.

References available at the NHI/NCBI site.

Recap of Cognitive Neuroscience Society’s Annual Meeting (Scientific American Mind)

Here is a summary of some of the research presented at the 2014 Cognitive Neuroscience Society Annual Meeting. Daisy Yuhas at Scientific American Observations blog does the summarizing.

Brains in Boston: Weekend Recap of Cognitive Neuroscience Society’s Annual Meeting

By Daisy Yuhas | April 8, 2014



Greetings from Boston where the 21st annual meeting of the Cognitive Neuroscience Society is underway. Saturday and Sunday were packed with symposia, lectures and more than 400 posters. Here are just a few of the highlights.

The bilingual brain has been a hot topic at the meeting this year, particularly as researchers grapple with the benefits and challenges of language learning. In news that will make many college language majors happy, a group of researchers led by Harriet Wood Bowden of the University of Tennessee-Knoxville have demonstrated that years of language study alter a person’s brain processing to be more like a native speaker’s brain. They found that native English speaking students with about seven semesters of study in Spanish show very similar brain activation to native speakers when processing spoken Spanish grammar. The study used electroencephalography, or EEG, in which electrodes are placed along the scalp to pick up and measure the electrical activity of neurons in the brain below. By contrast, students who have more recently begun studying Spanish show markedly different processing of these elements of the language. The study focused on the recognition of noun-adjective agreement, particularly in gender and number.

Accents, however, can remain harder to master. Columbia University researchers worked with native Spanish speakers to study the difficulties encountered in hearing and reproducing English vowel sounds that are not used in Spanish. The research focused on the distinction between the extended o sound in “dock” and the soft u sound in “duck,” which is not part of spoken Spanish. The scientists used electroencephalograms to measure the brain responses to these vowel sounds in native-English and native-Spanish speakers. The Spanish speakers responded just like English speakers to the “dock” vowel sound, but not to the “duck,” sound, which was harder for the former group to identify. The finding is part of a larger body of research hinting at the possibility that vowel sounds like the o in dock that are produced on the periphery of the vocal tract are easier to perceive than the soft u sound produced in the middle of the vocal tract. By identifying these kinds of preferences, the researchers hope to better train language-learners to attune to sounds beyond their native tongue’s typical repertoire.

Birth control does not appear to effect cognition, according to Lena Ficco and colleagues of the University of Massachusetts Amherst. In one of the few neuroendocrinological studies presented, Ficco investigated whether contraception containing ethinyl estradiol changed the mental map-making or verbal abilities of women who had been taking this form of birth control for several years. Both verbal and navigation tasks are supported by estrogen. But because ethinyl estradiol suppresses estrogen, Ficco wondered whether there might be cognitive costs in taking contraception. Instead she observed no differences between women on these pills and a control group of non-pill-using women during the low-estrogen phase of their menstrual cycle. In future, Ficco hopes to assess whether length of pill use in an older population relates to any cognitive changes.

Researchers at Notre Dame University have some preliminary evidence that alcohol can set your body’s internal alarm clock. It can, in fact, make a relaxing Sunday morning seem like a manic Monday. The group wanted to investigate how alcohol, a physiological stressor, would alter the body’s cortisol awakening response, in which a flood of the stress hormone cortisol peaks as a person wakes up. Earlier work has demonstrated that this response is tied to psychological stress, prompting earlier rising on weekdays or during other anxious time periods. The Notre Dame group found that college students who consumed about four drinks on a weekend evening would awaken the next morning with significantly higher cortisol levels than non-drinkers. In fact, the researchers suggest that the stress-inducing effect is similar to that produced by cortisol levels on a weekday.

Finally, researchers have worked out a new nuance of the sound-induced flash illusion. In this illusion, an individual will either see a flash of light and hear two beeps or see two flashes and hear one beep. The curious thing is that people will report seeing two flashes if they hear two beeps, and just one flash if they heard one beep. Scientists at the University of Milan-Bicocca in Italy decided to replicate this illusion with a slight twist. Instead of actually flashing lights, they asked their subjects to keep their eyes closed and then used magnetic fields to change the electric currents surrounding neurons and stimulate the occipital lobe (a technique called transcranial magnetic stimulation). This stimulation triggered phosphenes, or the sensation of a flash of light—albeit without any actual light flashing. Because of how these phantom flashes are induced directly in the visual system, this approach enabled the researchers to time the stimuli and response to decipher whether this illusion depended on visual processing shortly after encountering a flash or beep. Indeed, they found that their subjects would report seeing two phosphenes after the researchers had induced just one flash with two auditory beeps, provided the stimuli were presented within relatively short succession. This suggests that the experiences in the brain’s early visual cortex can be modulated by sound. Lead author Silvia Convento explains that this kind of sensory overlap likely reflects brain organization that was beneficial to our ancestors. Even if it introduces some errors, the linkage would allow our brains gather and organize information from the environment more rapidly.

The lectures and symposia thus far have brought together a nice mix of history and hypotheses. Jon Kaas, who studies the organization of the mammalian brain at Vanderbilt University, for example, presented some of his ongoing work mapping the possible “sub-regions” of the motor cortex. The idea was inspired in part by research done in 2009 by neuroscientist Michael Graziano at Princeton University, who demonstrated that by stimulating a specific location on the motor cortex of an anaesthetized monkey, the animal would carry out a behavior such as bringing its hand to its mouth. Kaas has since investigated this and similar behaviors —including grasping, reaching, and climbing behaviors— in several primate species, including galagos, squirrel monkeys and owl monkeys. His findings have led him to the conclusion that the motor cortex may be divided into functional sub-regions with a specific active purpose, that direct movement across the body, and that the organization of these sub-regions could be consistent across primates.

In a totally different vein, a symposium on developmental cognitive neuroscience reflected on how lessons in this field could potentially guide policy on education and the justice system. For example, Margaret Sheridan of Harvard University reviewed the most recent published findings from the Romanian Orphanage Study, which reveal how extreme deprivation brutally inhibits mental development. This research complements ongoing study of the cognitive struggles of children growing up in poverty. On a more positive note, there are interventions that could help these children close the gap. Neuropsychologist Helen Neville of the University of Oregon discussed how her group has succeeded in training young children to improve their attention skills, often through simple and fun activities that ask children to concentrate and ignore distractions.

One of the most moving moments of the conference was in the opening keynote address by MIT neuroscientist Suzanne Corkin. Corkin spoke about the legacy of H.M., a patient who underwent a procedure to prevent epileptic seizures that left him unable to form new memories. Corkin, who spent decades studying H.M., discussed how he helped illuminate the distinctions between different memory forms and where they are located in the brain (to learn more about H.M., check out the May/June issue of Scientific American Mind). But Corkin also discussed the man behind the initials, describing his gentle and remarkably upbeat disposition, given that he was repeatedly confronting a confusing, context-free present. Her talk included a poignant and powerful audio recording of Corkin and H.M. chatting in 1992. In the excerpt, H.M. professes to “not mind” all of the tests and studies, saying simply, “I figure what’s wrong about me helps you help others.”


About the Author: Daisy Yuhas is an associate editor at Scientific American Mind. You can follow her on Twitter, @daisyyuhas

~ The views expressed are those of the author and are not necessarily those of Scientific American.