Wednesday, April 10, 2013
Diverging neural pathways assemble a behavioural state from separable features in anxiety
"Animals encounter environmental conditions that require rapid switching among different behavioural states to increase the likelihood of survival and reproduction. Such states consist of a constellation of changes coordinated by distinct modalities of nervous system output1,2, and understanding this behavioural-state assembly from diverse features is of fundamental interest. A well-studied example is fear, in which the amygdala is thought to modulate various aspects of fear expression by multiple downstream targets1–4. Here we tested whether specific diverging projections causally recruit separable features to coordinate a behavioural state, focusing on anxiety as a state not only important in normal and pathological behaviour5 , but also exhibiting many disparate features that are quantifiable in mice."
"Many complexities are involved in anxiety, including brain regions, hormonal changes, and physiological manifestations beyond those investigated here. For example, none of our manipulations altered heart rate (Supplementary Fig. 24), consistent with a previous report suggesting the BNST does not modulate this feature of anxiety17 and pointing to the need for further exploration of sympathetic pathways. Moreover, the anxious state may be parsed still further to delineate additional features, such as changes in exploratory drive or in novelty seeking, which could involve networks not explored here. It is likely that complex circuit structure and dynamics are required to assemble behavioural states in animals with highly diverse repertoires of internal states and adaptations to the environment."