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Abstract:
Abstract: Stimuli that signal threat are readily processed by
the fear neural circuit, of which the amygdala is an essential
component, eliciting a variety of defensive responses. It has been
suggested that in addition to triggering these automatic responses,
this circuit should also have the capacity to redirect the current
focus of attention towards the source of danger. We investigated
the neural mechanisms underlying the influence of aversive stimuli
on spatial attention, using event-related fMRI. To do so, we
combined a classical discriminative fear conditioning paradigm and
a variation of the covert spatial orientation attention task.
Subjects were required to detect a dot probe appearing on either
side of the visual field, which was immediately preceded by t he
CS+ and CS-, presented side by side for 50ms. Subjects responded
faster to the probe when its location coincided with that of the
CS+ ("congruent" trials) than in the opposite condition
("incongruent" trials). These behavioural results showing the capa
city of aversive stimuli to grab attention were confirmed by the
imaging findings, which showed activation of the neural network
previously identified as being involved in spatial attention, when
contrasted with trials where there was no attentional shift. These
results are interpreted in the context of current theories of
emotion-attention interactions, and their potential relevance to
the understanding of fear-related disorders is discussed.
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