Awareness of one’s own personality and identity, with associated thoughts and feelings, allows us to self-reflect, develop as individuals in a social context, and generate complex behaviors. However, the neural correlates of self-awareness remain poorly understood.
In contrast, we have a relatively good understanding of the neurocognitive basis of perceptual awareness (the awareness of events and objects in the external world), which is associated with the activity of the lateral frontoparietal association cortices. Apart from being dissociated from the brain correlates of perceptual awareness, the neural basis of self-awareness should also be differentiated from the processing of self-related information without awareness, for example, when we turn our head automatically when someone calls our name.
To pinpoint neural responses that are specific to self-awareness, we used the blood-oxygen-level-dependent (BOLD) adaptation approach, which goes beyond spatial limitations of conventional functional-MRI, and the visual masking procedure, which enables a dissociation between aware and unaware processing of the same sensory stimulus.
We found that self-awareness was uniquely associated with the medial frontopolar-retrosplenial areas, whereas perceptual awareness and unaware self-processing with the lateral frontoparietal areas and the inferior temporal cortex, respectively. Thus, the brain basis of conceptual self-awareness is neuroanatomically distinct from the network mediating perceptual awareness or unaware processing of self-related information.
Full text:
Tacikowski, P., Berger, C. C., Ehrsson, H. H. (2017). Dissociating the neural basis of conceptual self-awareness from perceptual awareness and unaware self-processing. Cerebral Cortex, 27: 3768-3781. PDF
(A) Self- and other-related stimuli (names, surnames, dates of birth, nationality codes) were presented visually and the participant's task was to decide (by pressing one of the two buttons) whether stimuli occurring at the end of each trial (targets; indicated here by orange triangles) were related to themselves or another person. In half of the trials, stimuli appearing before the targets (primes; white triangles) were immediately preceded and followed by visual masks, which made aware processing of these primes highly demanding. In the other half of the trials, there were no masks, which made aware processing easy. Stimuli durations and intervals are indicated in milliseconds, next to the time axis. (B) As intended, the masking procedure made discrimination of primes more difficult (zero indicates chance level; medians ± interquartile ranges). (C) The priming effect (reaction times: incongruent > congruent trials) was significantly stronger in the self conditions than in the other conditions, and stronger in the aware than unaware conditions (means ± standard errors).
Brain regions related to (A) conceptual self-awareness, (B) perceptual awareness, (C) unaware processing of self-related information, and (D) unaware processing of all types of stimuli. Areas showing significant BOLD-adaptation are highlighted in red. Bar plots show the BOLD-adaptation effect (incongruent > congruent trials). Error bars denote standard errors. Abbreviations: FG - fusiform gyrus; HI - hippocampus; IPS - intraparietal sulcus; IT - inferior temporal cortex; MFP - medial frontal pole; PCS - precentral sulcus; PH - parahippocampal gyrus; RSC -retrosplenial cortex; SMA - supplementary motor area; TP - temporal pole.
Neural responses selective to self-awareness (SA; green) are based on the BOLD-adaptation analysis. A map of default mode network functional connectivity (red) is based on resting-state data collected from the same group of participants. The overlap is present especially in the medial prefrontal and posterior cingulate regions (yellow).