FIGURE 1.

Schematic depiction of a neural ensemble (hypothetical). (A) Coronal section of a rat brain. One hypothetical neural ensemble is comprised of neurons synchronously experiencing suprathreshold depolarizations. These neurons are distributed unevenly across several brain regions, including cortical layers 2–6, neostriatum, hippocampus, and amygdala. Each black dot denotes 50 neurons. (B) Intracellular recordings show a plateau depolarization (UP state) crowned by action potentials (APs). Note that neurons do not fire APs in the DOWN state. Also, the onsets and offsets of UP states are not perfectly synchronized. However, in one brief period of time (marked by the gray column – “ensemble period”) all relevant neurons are in the UP state; they all joined the dynamic neural ensemble.