Fig. 8. Thalamocortical synchronization at the early, middle and late portion of spindles in motor cortex and thalamus.

A. Simultaneous intracellular recordings during spindles from area 4 of the motor cortex (blue) and the VL nucleus of the thalamus (red). Upper trace: local field potential from motor cortical area 4. Middle trace: intracellular recording from the same cortical area. Lower trace: intracellular recording from the corresponding thalamic VL nucleus. Note that at spindle onset, the thalamocortical neuron exhibits rhythmic IPSPs without rebound action potentials, and the cortical neuron does not show rhythmic EPSPs.

B. Expanded from (A) as indicated by the horizontal line. During waxing but not waning phases, the cortical neuron has rhythmic depolarizing potentials in synchrony with oscillations in the thalamocortical neuron.

C1. Superposition of segments of local field potentials, intracellular activities of cortical and thalamocortical neurons during an early phase of spindles. Zero time is set at the maximal hyperpolarization achieved by thalamocortical neurons during a particular cycle of spindle (vertical line).

C2. The same arrangement as (C1), but for the waxing phase of the spindle, showing desynchronization between thalamic and cortical firing.