Amygdala circuitry mediating reversible and bidirectional control of anxiety.

Anxiety-a sustained state of heightened apprehension in the absence of immediate threat-becomes severely debilitating in disease states. Anxiety disorders represent the most common of psychiatric diseases (28% lifetime prevalence). Although it has been proposed that the amygdala, a brain region important for emotional processing, has a role in anxiety, the neural mechanisms that control anxiety remain unclear. Tye and coauthors explore the neural circuits underlying anxiety-related behaviours by using optogenetics with two-photon microscopy, anxiety assays in freely moving mice, and electrophysiology. With the capability of optogenetics to control not only cell types but also specific connections between cells, they observed that temporally precise optogenetic stimulation of basolateral amygdala terminals in the central nucleus of the amygdala exerted an acute, reversible anxiolytic effect. Conversely, selective optogenetic inhibition of the same projection with a third-generation halorhodopsin increased anxiety-related behaviours. Together, these results implicate these specific projections as critical circuit elements for acute anxiety control and demonstrate the importance of optogenetically targeting defined projections, beyond simply targeting cell types, in the study of circuit function relevant to neuropsychiatric disease.

Tye KM et al., Nature (2011): doi: 10.1038/nature09820

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09820.html