Who gates whose activity and what is the contribution of this gating mechanism in the adaptive processes of the ventral striatum?

Leaders: Anthony Grace and Celeste Napier.


ABSTRACT:

Modern electrophysiological evaluations of the ventral striatum have provided important new insights into the mechanisms underlying striatal neuronal responses to stimuli and the way they adapt to long-term alterations in these stimuli. For example, recent investigations have shown that convergent excitatory inputs do more than merely provide additive influences; instead, the hippocampal and amygdalar input to the accumbens can gate the way that these neurons respond to other afferent inputs. Synaptic inputs also can modulate the integration of information via interaction with gap junctions which provides another means by which accumbal neurons are modulated by the network in which they are embedded.

One factor that is pervasive within limbic systems is the capacity of the system for adaptive changes. It is now well established that these processes can occur at essentially every "level" of electrophysiologically determined function, including alterations in channel conduction and afferent inputs, that culminate in changes in firing rate and/or pattern of ventral striatal ouput neurons. Reconfiguration of this system can occur in response to environmental circumstance, damage (e.g., DA-depleting lesions), or pharmacological insult (e.g., repeated cocaine, amphetamine, or morphine administration). The type of alterations that the system is capable of performing, however, is strongly dependent on the developmental stage at which the insult occurs. Thus, lesions made during gestation or in neonatal rats produce far different consequences than those that occur in the adult animal. Particularly important advancements also have been made toward understanding the contribution of interactions among systems in the adaptive process. These interactions occur at the synaptic level (e.g., long-term potentiation, cortical regulation of subcortical DA systems) and involve the history of the insult (e.g., repeated drug drug administration or withdrawal time). Consequently, electrophysiological evaluations of the adaptive processes within the ventral striatum must be made with an understanding of the conditions that drive adaptation and include assessments of interactions among systems and how these interactions dictate the reconfiguration process. It is this aspect of the neurophysiology of ventral striatal adaptations that we focused our attention.

Members: Frank White, Charles Yang, Kathy Cunningham, and Wolfram Schultz.