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

Abstract

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.

What insects can tell us about the origins of consciousness

“…Conversely, there is evidence of preserved consciousness even in patients who lack a cortex (9). Further, although cortical damage can have profound effects on the contents of consciousness, damage to any portion of the cortex alone can spare the basic capacity for subjective experience (17)(18)(19)(20)(21)(22). Cortical damage alone can have profound effects on the contents of consciousness, but even massive cortical damage seems to spare subjective experience itself (8,17,18).…”

“…Further, although cortical damage can have profound effects on the contents of consciousness, damage to any portion of the cortex alone can spare the basic capacity for subjective experience (17)(18)(19)(20)(21)(22). Cortical damage alone can have profound effects on the contents of consciousness, but even massive cortical damage seems to spare subjective experience itself (8,17,18). Indeed, there is evidence of residual conscious awareness in patients with severe cortical damage who are otherwise unresponsive to the world, suggesting that preserved subcortical structures may continue to support subjective experience (23,24).…”

Animal Consciousness

“…Other structures of the midbrain (thalamus, periaqueductal gray, reticular formation) and the basal ganglia (ventral striatum, substantia nigra) combine these sources of information into an integrated model. If present, higher cortical areas and the hippocampus do have a strong input in this system, but the functioning of the system does not depend on this input (Barron and Klein, 2016;Philippi et al, 2012).…”

“…Other observations (Philippi et al, 2012) suggest that certain aspects of higher order conscious processing are possible if only small parts of the cortex are still functional. A patient with extensive bilateral damage to the insula, the anterior cingulate cortex, the medial prefrontal cortex and the medial temporal lobes had not only "core consciousness", but also higher-order levels of consciousness.…”

Leveraging Neuroscience and Education to Prevent Youth Aggression and Violence

“…This is not an easy answer from a neurological perspective. Parts of the brain implicated in awareness of self as self, emotions, body, environment, and others includes a dynamic interweaving of activity between the brain stem, limbic system, and wide spread areas of the cerebral cortex (Schapira, 2007;Benarroch, Daube, Flemming, & Westmoreland, 2008;Jacobson & Marcus, 2008;Shewmon, Holmes, & Byrne, 1999;Merker, 2007;Philippi et al, 2012). Given that research is still emerging and some of that research is contradictory, it may be helpful to inquire into what brain regions are activated during self-referential reflection, particularly if that is the kind of reflection that can be taught and is also needed to select a positive goal-directed choice when stress response physiology has been activated.…”