Where does the mind reside? It鈥檚 a question that鈥檚 occupied the best brains for thousands of years. Now, a patient who is self-aware 鈥� despite lacking three regions of the brain thought to be essential for self-awareness 鈥� 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 鈥� a technique that measures brain activity in the hope of finding correlations between mental functions and specific regions of the brain 鈥� have led to a wealth of studies that map particular functions onto regions.
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Previous neuroimaging studies had suggested that three regions 鈥� the insular cortex, anterior cingulate cortex and medial prefrontal cortex 鈥� are critical for self-awareness. But for Rudrauf the question wasn鈥檛 settled.
So when his team heard about patient R, who had lost brain tissue including the chunks of the three 鈥榮elf-awareness鈥� 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, 鈥減atients with no insula should be like zombies鈥�.
But patient R displays a strong concept of selfhood. Rudrauf鈥檚 team confirmed this by checking whether he could recognise himself in photographs and by performing the tickle test 鈥� based on the observation that you can鈥檛 tickle yourself. They concluded that many aspects of R鈥檚 self-awareness remained unaffected. 鈥淗aving interacted with him it was clear from the get go that there was no way that [the theories based on neuroimaging] could be true,鈥� 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. 鈥淭hey involve layers of abstraction and mechanisms that cannot be explained by standard functional-neuroanatomy.鈥� He suggests that there are fundamental mechanisms yet to be discovered. 鈥淲e would all like simple answers to complicated questions, and we tend to oversimplify our conceptions about the brain and the mind,鈥� he says.
, a psychologist at Bangor University, UK, is also not surprised by the finding. 鈥淎wareness has many manifestations,鈥� she says. 鈥淚t鈥檚 not just a matter of a few brain cells.鈥�
Journal reference: , DOI:10.1371/journal.pone.0038413
