The volatility of the amygdala response to masked fearful eyes

Abstract

Some people search for intense sensations such as being scared by frightening movies while others do not. The brain mechanisms underlying such inter-individual differences are not clear. Testing theoretical models, we investigated neural correlates of anxiety and the personality trait sensation seeking in 40 subjects who watched threatening and neutral scenes from scary movies during functional magnetic resonance imaging. Threat versus neutral scenes induced increased activation in anterior cingulate cortex, insula, thalamus, and visual areas. Movie-induced anxiety correlated positively with activation in dorsomedial prefrontal cortex, indicating a role for this area in the subjective experience of being scared. Sensation seeking-scores correlated positively with brain activation to threat versus neutral scenes in visual areas and in thalamus and anterior insula, i.e. regions involved in the induction and representation of arousal states. For the insula and thalamus, these outcomes were partly due to an inverse relation between sensation seeking scores and brain activation during neutral film clips. These results support models predicting cerebral hypoactivation in high sensation seekers during neutral stimulation, which may be compensated by more intense sensations such as watching scary movies.

Oxytocin Modulates Amygdala Reactivity to Masked Fearful Eyes

“…Furthermore, we investigated whether a single dose of intranasal oxytocin would alter neural reactivity to masked fearful eye whites within the amygdala and associated areas. Under placebo conditions, we noted enhanced amygdala reactivity to fearful as compared with happy eye whites masked with a neutral face, thereby replicating previous studies' results (Straube et al, 2010;Whalen et al, 2004). In addition, we observed the same effect within the pulvinar that is known to be extensively interconnected with the amygdala both anatomically (Tamietto et al, 2012) and functionally (Morris et al, 1999;Troiani et al, 2014).…”

“…However, amygdala responses to masked fearful expressions have been shown to rely on an interaction between emotional and masking stimuli (Kim et al, 2010). Correspondingly, the enhanced amygdala response to fearful eye whites in backward masking paradigms was found to disappear when either the position of the eye stimuli was changed or when the neutral face mask was replaced by another masking stimulus (Straube et al, 2010), suggesting that the amygdala mainly responds to salient events within the eye region of the masking stimulus that are potentially associated with fear. Whether this response is indeed associated with fear detection or whether the amygdala reacts more generally to any salient increase in eye white area has not been investigated yet.…”

Visual Attention Modulates Brain Activation to Angry Voices

“…Amygdalar responses were found even when subjects' attention was distracted from facial expressions (Vuilleumier et al, 2001) or when the presentation of the stimuli was below the threshold of conscious perception (Whalen et al, 2004), supporting the hypothesis of a crucial role of the amygdala in the automatic detection of threat (LeDoux, 1996). However, the assumption of completely automatic amygdalar responses to visual threat was questioned by findings showing the absence of activation in the amygdala and visual areas to threat-related visual stimuli during exhaustion of attentional resources (Pessoa et al, 2002;Bishop et al, 2007;Straube et al, 2007) or when controlling for perceptual (Straube et al, 2010) or experimental artifacts (Pessoa et al, 2005).…”

“…The analysis was conducted in regions of interest (ROI; superior temporal region, including the superior temporal gyrus, superior temporal sulcus, and amygdale), which showed automatic responses to angry prosody in previous studies, and exploratory for the whole brain. ROIs were defined with help of Talairach daemon software (Lancaster et al, 2000) and according to our previous studies (Straube et al, 2004(Straube et al, , 2005(Straube et al, , 2010Quadflieg et al, 2008). Statistical parametric maps resulting from the voxelwise analysis were considered significant for statistical values that survived a cluster-based correction for multiple comparisons as implemented in Brain Voyager (Goebel et al, 2006), which is based on a 3D extension of the randomization procedure described by Forman and colleagues (1995).…”

Unconscious discrimination of social cues from eye whites in infants

“…The EEG recording was prepared while the infant was sitting on his/her caregiver's lap. For the recording, an elastic cap was used, in which 27 AgAgCl electrodes were mounted according to the [10][11][12][13][14][15][16][17][18][19][20] system. The Cz electrode was used as a reference during recording.…”