Thursday, August 23, 2012

Preserved Self-Awareness following Extensive Bilateral Brain Damage to the Insula, Anterior Cingulate, and Medial Prefrontal Cortices

Whenever we think we have it figured out - in this case the "it" is self-awareness - we find something that totally disrupts what we think we know. This research article tells the story of Patient R, who had lost considerable brain tissue following a viral infection, including the chunks of the brain's three 'self-awareness' regions - the insular cortex, anterior cingulated cortex, and medial prefrontal cortex.

The patient, despite these brain tissue losses, still maintains a fairly solid self-awareness, although he experiences amnesia that impacts his narrative sense of self.

New Scientist offered a nice summary:

Location of the mind remains a mystery

Where does the mind reside? It's a question that's occupied the best brains for thousands of years. Now, a patient who is self-aware – despite lacking three regions of the brain thought to be essential for self-awareness – demonstrates that the mind remains as elusive as ever.

The finding suggests that mental functions might not be tied to fixed brain regions. Instead, the mind might be more like a virtual machine running on distributed computers, with brain resources allocated in a flexible manner, says David Rudrauf at the University of Iowa in Iowa City, who led the study of the patient.

Recent advances in functional neuroimaging – a technique that measures brain activity in the hope of finding correlations between mental functions and specific regions of the brain – have led to a wealth of studies that map particular functions onto regions.

Previous neuroimaging studies had suggested that three regions – the insular cortex, anterior cingulated cortex and medial prefrontal cortex – are critical for self-awareness. But for Rudrauf the question wasn't settled.

So when his team heard about patient R, who had lost brain tissue including the chunks of the three 'self-awareness' regions following a viral infection, they immediately thought he could help set the record straight.

Not a zombie

According to the models based on neuroimaging, says Rudrauf, "patients with no insula should be like zombies".

But patient R displays a strong concept of selfhood. Rudrauf's team confirmed this by checking whether he could recognise himself in photographs and by performing the tickle test – based on the observation that you can't tickle yourself. They concluded that many aspects of R's self-awareness remained unaffected. "Having interacted with him it was clear from the get go that there was no way that [the theories based on neuroimaging] could be true," says Rudrauf.

However, R does have severe amnesia, which prevents him from learning new information, and he struggles with social interaction.

Self-awareness and other high-level cognitive functions probably do not relate to the brain in a simple way, says Rudrauf. "They involve layers of abstraction and mechanisms that cannot be explained by standard functional-neuroanatomy." He suggests that there are fundamental mechanisms yet to be discovered. "We would all like simple answers to complicated questions, and we tend to oversimplify our conceptions about the brain and the mind," he says.

Linda Clare, a psychologist at Bangor University, UK, is also not surprised by the finding. "Awareness has many manifestations," she says. "It's not just a matter of a few brain cells."
Journal Reference: 
Philippi CL, Feinstein JS, Khalsa SS, Damasio A, Tranel D, et al. (2012). Preserved Self-Awareness following Extensive Bilateral Brain Damage to the Insula, Anterior Cingulate, and Medial Prefrontal Cortices. PLoS ONE, 7(8): e38413. doi:10.1371/journal.pone.0038413

PLOS ONE is open access, so the article is freely available online. Here is the abstract:

Preserved Self-Awareness following Extensive Bilateral Brain Damage to the Insula, Anterior Cingulate, and Medial Prefrontal Cortices

Carissa L. Philippi1#, Justin S. Feinstein1#*, Sahib S. Khalsa2, Antonio Damasio3, Daniel Tranel1, Gregory Landini4, Kenneth Williford5, David Rudrauf1#*

1 Division of Behavioral Neurology and Cognitive Neuroscience, Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America, 2 Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California, United States of America, 3 Brain and Creativity Institute and Dornsife Cognitive Neuroscience Imaging Center, University of Southern California, Los Angeles, California, United States of America, 4 Department of Philosophy, University of Iowa, Iowa City, Iowa, United States of America, 5 Department of Philosophy, University of Texas Arlington, Arlington, Texas, United States of America


It has been proposed that self-awareness (SA), a multifaceted phenomenon central to human consciousness, depends critically on specific brain regions, namely the insular cortex, the anterior cingulate cortex (ACC), and the medial prefrontal cortex (mPFC). Such a proposal predicts that damage to these regions should disrupt or even abolish SA. We tested this prediction in a rare neurological patient with extensive bilateral brain damage encompassing the insula, ACC, mPFC, and the medial temporal lobes. In spite of severe amnesia, which partially affected his “autobiographical self”, the patient's SA remained fundamentally intact. His Core SA, including basic self-recognition and sense of self-agency, was preserved. His Extended SA and Introspective SA were also largely intact, as he has a stable self-concept and intact higher-order metacognitive abilities. The results suggest that the insular cortex, ACC and mPFC are not required for most aspects of SA. Our findings are compatible with the hypothesis that SA is likely to emerge from more distributed interactions among brain networks including those in the brainstem, thalamus, and posteromedial cortices.


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