Differential prefrontal cortex and amygdala habituation to repeatedly presented emotional stimuli

Abstract

Repeated presentations of emotional facial expressions were used to assess habituation in the human brain using fMRI. Significant fMRI signal decrement was present in the left dorsolateral prefrontal and premotor cortex, and right amygdala. Within the left prefrontal cortex greater habituation to happy vs fearful stimuli was evident, suggesting devotion of sustained neural resources for processing of threat vs safety signals. In the amygdala, significantly greater habituation was observed on the right compared to the left. In contrast, the left amygdala was significantly more activated than the right to the contrast of fear vs happy. We speculate that the right amygdala is part of a dynamic emotional stimulus detection system, while the left is specialized for sustained stimulus evaluations.

Neural mechanisms underlying food motivation in children and adolescents

“…Although our results suggest that the patterns of response within the amygdala (pre-meal increase, postmeal normalization) parallel those seen in OFC/MFC, closer analysis indicates that increased activity is confined to the first run of the pre-meal condition. This finding is consistent with habituation effects to repeatedly presented stimuli previously reported in the amygdala (Wright et al, 2001) and likely reflects an initial response, with drop-off in activation after the salience of the stimuli has been assessed (Whalen, 1998). Thus, following an initial assessment of food stimuli salience, the amygdala may no longer be crucial to the overall process of monitoring the body's motivational status.…”

“…Due to the likelihood of habituation within the amygdala over time (Wright et al, 2001), mean percent signal change values within this region were examined further. Within the amygdala, significant habituation (as defined by greater activation in run 1 vs. run 2) was exhibited during the pre-meal state [t(1,15) = 2.65, P < 0.05], but not during the post-meal session [t(1,16) = 0.52, n.s.]…”

fMRI Evidence of a Hot-Cold Empathy Gap in Hypothetical and Real Aversive Choices

“…This is a surprising result and contrary to Kang et al (2011), which reported more overall activity in real trials. However, since real bidding in the current study was deliberately confounded with experience (the real bids come later in the trial sequence) this deactivation could be due to either the real vs. hypothetical treatment, or to the general effect of stimulus experience and neural habituation reducing brain activity; this is a well-established effect (Thompson and Spencer, 1966;Wright et al, 2001;Fischer et al, 2003;Phan et al, 2003;Yamaguchi et al, 2004). The more diagnostic and interesting analysis therefore focuses on regions in which activity scales with bid amounts differentially in hypothetical and real conditions.…”

Hippocampal networks habituate as novelty accumulates

“…Throughout the ventral visual stream, neural responses to repeated presentations of visually identical stimuli progressively decrease (Henson et al 2003). Similarly, the amygdala and other structures implicated in fear processing habituate to cumulative exposure to trialunique stimuli that depict fear (Breiter et al 1996;Wright et al 2001;Fischer et al 2003) or signal threat (Buchel et al 1998;LaBar et al 1998). Habituation has been proposed to be biologically adaptive: As a stimulus or feature is repeated, it provides less information about the environment, and demands fewer processing resources (Sokolov 1963;Rankin et al 2009).…”