Involvement of the pallidal-thalamocortical circuit in adaptive behavior

Interconnections among the ventral mesencephalon, nucleus accumbens, and ventral pallidum are critical in the initiation of adaptive behavioral responses to environmental stimuli. Within this circuit are two highly topographically organized subcircuits that are differentially interconnected with limbic and motor circuitry in the brain. However, there is not a great deal of anatomical interconnection between the limbic and motor subcircuits. A polysynaptic connection between the two subcircuits involves projections from the limbic ventral pallidum to the mediodorsal thalamus to the prefrontal cortex back to the motor regions of the nucleus accumbens. In the present report we show that this connection is critical in the expression of motor behavior elicited by opioids and the capacity of a rat to perform in a task requiring spatial working memory.