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Amygdala Responses (amygdala + response)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

The volatility of the amygdala response to masked fearful eyes

HUMAN BRAIN MAPPING, Issue 10 2010
Thomas Straube
Abstract Recently, it has been suggested that backwardly masked, and thus subliminally presented, fearful eyes are processed by the amygdala. Here, we investigated in four functional magnetic resonance imaging experiments whether the amygdala responds to subliminally presented fearful eyes per se or whether an interaction of masked eyes with the masks or with parts of the masks used for backward masking might be responsible for the amygdala activation. In these experiments, we varied the mask as well as the position of the target eyes. The results show that the amygdala does not respond to masked fearful eyes per se but to an interaction between masked fearful eyes and the eyes of neutral faces used for masking. This finding questions the hypothesis that the amygdala processes context-free parts of the human face without awareness. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. [source]

Reduced amygdala activity during aversive conditioning in human narcolepsy

ANNALS OF NEUROLOGY, Issue 3 2010
Aurélie Ponz PhD
Narcolepsy with cataplexy is a sleep-wake disorder caused by a loss of hypothalamic hypocretins. Here we assessed the time course of amygdala activation during aversive conditioning in unmedicated patients with narcolepsy. Unlike healthy matched control subjects, narcolepsy patients had no enhancement of amygdala response to conditioned stimuli and no increase in functional coupling between the amygdala and medial prefrontal cortex. These findings suggest that human narcolepsy is accompanied by abnormal emotional learning, and that, in line with animal data, the hypocretin system and the amygdala are involved in this process. ANN NEUROL 2010;67:394,398 [source]

Differential amygdala responses to winning and losing: a functional magnetic resonance imaging study in humans

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2000
Tiziana Zalla
Abstract The amygdala has been shown to respond to many distinct types of affective stimuli, including reward and punishment feedback in animals. In humans, winning and losing situations can be considered as reward and punishment experiences, respectively. In this study, we used functional magnetic resonance imaging (fMRI) to measure regional brain activity when human subjects were given feedback on their performance during a simple response time task in a fictitious competitive tournament. Lexical stimuli were used to convey positive ,win' or negative ,lose' feedback. The frequency of positive and negative trials was parametrically varied by the experimenters independently from the subjects' actual performance and unbeknownst to them. The results showed that the parametric increase of winning was associated with left amygdala activation whereas the parametric increase of losing was associated with right amygdala activation. These findings provide functional evidence that the human amygdala differentially responds to changes in magnitude of positive or negative reinforcement conveyed by lexical stimuli. [source]

Serotonergic genes modulate amygdala activity in major depression

GENES, BRAIN AND BEHAVIOR, Issue 7 2007
U. Dannlowski
Serotonergic genes have been implicated in the pathogenesis of depression probably via their influence on neural activity during emotion processing. This study used an imaging genomics approach to investigate amygdala activity in major depression as a function of common functional polymorphisms in the serotonin transporter gene (5-HTTLPR) and the serotonin receptor 1A gene (5-HT1A -1019C/G). In 27 medicated patients with major depression, amygdala responses to happy, sad and angry faces were assessed using functional magnetic resonance imaging at 3 Tesla. Patients were genotyped for the 5-HT1A -1019C/G and the 5-HTTLPR polymorphism, including the newly described 5-HTT-rs25531 single nucleotide polymorphism. Risk allele carriers for either gene showed significantly increased bilateral amygdala activation in response to emotional stimuli, implicating an additive effect of both genotypes. Our data suggest that the genetic susceptibility for major depression might be transported via dysfunctional neural activity in brain regions critical for emotion processing. [source]

Amygdala,prefrontal dissociation of subliminal and supraliminal fear

HUMAN BRAIN MAPPING, Issue 8 2006
Leanne M. Williams
Abstract Facial expressions of fear are universally recognized signals of potential threat. Humans may have evolved specialized neural systems for responding to fear in the absence of conscious stimulus detection. We used functional neuroimaging to establish whether the amygdala and the medial prefrontal regions to which it projects are engaged by subliminal fearful faces and whether responses to subliminal fear are distinguished from those to supraliminal fear. We also examined the time course of amygdala-medial prefrontal responses to supraliminal and subliminal fear. Stimuli were fearful and neutral baseline faces, presented under subliminal (16.7 ms and masked) or supraliminal (500 ms) conditions. Skin conductance responses (SCRs) were recorded simultaneously as an objective index of fear perception. SPM2 was used to undertake search region-of-interest (ROI) analyses for the amygdala and medial prefrontal (including anterior cingulate) cortex, and complementary whole-brain analyses. Time series data were extracted from ROIs to examine activity across early versus late phases of the experiment. SCRs and amygdala activity were enhanced in response to both subliminal and supraliminal fear perception. Time series analysis showed a trend toward greater right amygdala responses to subliminal fear, but left-sided responses to supraliminal fear. Cortically, subliminal fear was distinguished by right ventral anterior cingulate activity and supraliminal fear by dorsal anterior cingulate and medial prefrontal activity. Although subcortical amygdala activity was relatively persistent for subliminal fear, supraliminal fear showed more sustained cortical activity. The findings suggest that preverbal processing of fear may occur via a direct rostral,ventral amygdala pathway without the need for conscious surveillance, whereas elaboration of consciously attended signals of fear may rely on higher-order processing within a dorsal cortico,amygdala pathway. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source]