Figure 1.

Hippocampus gating of information flow from the prefrontal cortex via modulation of nucleus accumbens neuronal activity. (A) Recording of the membrane potential of a Nacc neuron showing oscillations between a quiescent “down” state (V_down membrane potential) and a firing “up” state (V_up membrane potential). (B) Projections from the hippocampus and the prefrontal cortex converge onto Nacc neurons, which in turn project on the ventral pallidum, which itself sends projections onto the thalamus. Hippocampus input appears to shift Nacc neurons from their down to their up state, thus efficiently gating prefrontal input to the Nacc (modified with permission from Grace, 2000). VP: ventral pallidum.