Network synchrony in the nucleus accumbens in vivo.

Nucleus accumbens neurons show membrane potential fluctuations between a very negative resting membrane potential and periodical plateau depolarizations. Because action potential firing occurs only during the depolarized state, the control of transitions between states is important for information processing within this region, with an impact on accumbens-related behaviors. It has been proposed that ensembles of active neurons in the nucleus accumbens could be based on a population of cells depolarizing simultaneously into the UP state. In this study, in vivo intracellular recordings from accumbens neurons were performed simultaneously with local field potential recordings to examine whether the nucleus accumbens can exhibit synchronization of membrane potential states in a population of neurons. These simultaneous recordings indicated that local field potential shifts occurred synchronously with transitions to the UP state. Furthermore, manipulations that evoked prolonged plateau depolarizations also evoked field potentials of similar duration. Such signals likely occurred because of simultaneous membrane potential changes in a population of neurons. Together with our previous studies, these results suggest that membrane potential states in the nucleus accumbens can be synchronized by synaptic inputs from the hippocampus.