Neural activity associated with self-reflection

Abstract

Background: Self-referential cognitions are important for self-monitoring and self-regulation. Previous studies have addressed the neural correlates of self-referential processes in response to or related to external stimuli. We here investigated brain activity associated with a short, exclusively mental process of self-reflection in the absence of external stimuli or behavioural requirements. Healthy subjects reflected either on themselves, a personally known or an unknown person during functional magnetic resonance imaging (fMRI). The reflection period was initialized by a cue and followed by photographs of the respective persons (perception of pictures of oneself or the other person).

Results: Self-reflection, compared with reflecting on the other persons and to a major part also compared with perceiving photographs of one-self, was associated with more prominent dorsomedial and lateral prefrontal, insular, anterior and posterior cingulate activations. Whereas some of these areas showed activity in the "other"-conditions as well, self-selective characteristics were revealed in right dorsolateral prefrontal and posterior cingulate cortex for self-reflection; in anterior cingulate cortex for self-perception and in the left inferior parietal lobe for self-reflection and -perception.

Conclusions: Altogether, cingulate, medial and lateral prefrontal, insular and inferior parietal regions show relevance for self-related cognitions, with in part self-specificity in terms of comparison with the known-, unknown- and perception-conditions. Notably, the results are obtained here without behavioural response supporting the reliability of this methodological approach of applying a solely mental intervention. We suggest considering the reported structures when investigating psychopathologically affected self-related processing.

Figure 1

Brain activity during reflection on oneself. Analysis of selected regions (yellow circles) with activation during reflecting on oneself, resulting from the conjoined contrast (refl-self > refl-known) & (refl-self > refl-unknown) & (refl-self > perc-self) – (2). The colour-coded maps indicate those areas of the brain with greater t activity during self-reflection than under all other conditions (p < 0.005, Monte Carlo simulation with cluster wise correction p < 0.01). The time courses indicate the mean and standard errors of blood oxygen-level-dependent signal changes under primary conditions. (A) DMPFC. (B) Ventrolateral prefrontal cortex and insula (VLPFC/Ins. L). (C) DLPFC R. (D) Posterior cingulate cortex (PCC). All regions have greater activity during the reflection periods than during perception of the photograph. All other significant clusters were also activated under the ‘other’-reflection-conditions.

Figure 2

Beta-weights (beta, y-axis) of the single contrasts. Given are the beta-weights within selected regions of interest, derived from the contrast analyses in (A + B) reflection-self (r-self) > reflection-known (r-known) and -unknown (r-uk) and perc-self (p-self), and (C + D) perception-self > perception-known (p-known) and -unknown (p-uk). (A) DMPFC, (B) left ventrolateral prefrontal cortex/insula (Ins L), (C) ACC, (D) right IPL/SSC.

Figure 3

Brain activity during perception of pictures of oneself. Analysis of selected regions according to the contrast self-perception with greater activity than under known and unknown perception (p < 0.005, Monte Carlo Simulation with cluster wise correction for multiple comparisons p < 0.01). (A) ACC and (B) IPL/SSC R, which were also active during self-reflection. (C) The occipital visual cortex region was less active during self-perception than under the other conditions.

Figure 4

Schematic summary of the paradigm. The paradigm comprises a cued reflection period followed by perception of a photograph to the cued person for the indicated periods of time. For each condition, the same standardized set of photographs was shown in a random order. The subjects were instructed to reflect on the cued person in the ‘reflection’ period and to view the photograph during the ‘perception’ period (photos reprinted here with explicit consent of the shown subjects).