Spike Frequency Adaptation Affects the Synchronization Properties of Networks of Cortical Oscillator

Oscillations in many regions of the cortex have common temporal characteristics with dominant frequencies centered around the 40 Hz (gamma) frequency range and the 5-10 Hz (theta) frequency range. Experimental results also reveal spatially synchronous oscillations which are stimulus dependent (Gray and Singer, 1987; Gray et al., 1989; Engel et al., 1992). This rhythmic activity suggests that the coherence of neural populations is a crucial feature of corti-cal dynamics (Gray, 1994). Using both simulations and a theoretical coupled oscillator approach, we demonstrate that the spike frequency adaptation seen in many pyramidal cells plays a subtle but important role in the dynamics of cortical networks. Without adaptation, exci-tatory connections among model pyramidal cells are desynchronizing. However, the slow processes associated with adaptation encourage stable synchronous behavior.