Self-reflection and the inner voice: activation of the left inferior frontal gyrus during perceptual and conceptual self-referential thinking.

Alain Morin,Breanne Hamper

doi:10.2174/1874440001206010078

Abstract

Inner speech involvement in self-reflection was examined by reviewing 130 studies assessing brain activation during self-referential processing in key self-domains: agency, self-recognition, emotions, personality traits, autobiographical memory, and miscellaneous (e.g., prospection, judgments). The left inferior frontal gyrus (LIFG) has been shown to be reliably recruited during inner speech production. The percentage of studies reporting LIFG activity for each self-dimension was calculated. Fifty five percent of all studies reviewed indicated LIFG (and presumably inner speech) activity during self-reflection tasks; on average LIFG activation is observed 16% of the time during completion of non-self tasks (e.g., attention, perception). The highest LIFG activation rate was observed during retrieval of autobiographical information. The LIFG was significantly more recruited during conceptual tasks (e.g., prospection, traits) than during perceptual tasks (agency and self-recognition). This constitutes additional evidence supporting the idea of a participation of inner speech in self-related thinking.

Highlights

Self-referential activity is currently the target of numerous brain-imaging studies aimed at determining what brain areas get reliably activated during self-reflection tasks
We submit that 55% represents a significant percentage, especially when compared to left inferior frontal gyrus (LIFG) activation percentages that have been observed during various non-self tasks
Consistent with the idea of a greater inner speech involvement in conceptual self-domains, we found that 63.7% of all conceptual studies (n = 102; autobiography, miscellaneous, emotions, and traits) reported activation of the LIFG, as opposed to 25% of all perceptual studies (n = 28) of agency and face/voice self-recognition

Summary

Introduction

Self-referential activity is currently the target of numerous brain-imaging studies aimed at determining what brain areas get reliably activated during self-reflection tasks. Most self-reflection tasks employed in brain-imaging studies require one form or another of memory and evaluation involving a certain degree of uncertainty (e.g., does this personality trait apply to me?). Consistent with this hypothesis, most aforementioned brain areas recruited during self-reflection are activated during memory recall and inferential reasoning. Another elementary process potentially recruited during self-reflection is the inner voice [8,9,10,11,12]. Deterioration of inner speech following a left lateralized stroke is associated with self-awareness deficits [10]

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Conclusion