Figure 5.

Corticothalamic connections are essential for cortically evoked postinhibitory rebound excitation in cortical neurons. Intracellular recordings from two cortical neurons, one in an intact-brain animal, the other from an isolated cortical slab in vivo, are shown. Recordings shown were made from cats under ketamine/xylazine anesthesia. (Top Left) Inhibitory-rebound sequence in the neuron and field potential from the depth of area 4 evoked by area-4 stimulation. (Top Right) Responses in the neuron and depth field potential to stimulus applied in the isolated slab from cortical area 7. Note the absence of spontaneous activity in the area-7 slab. (Bottom) Responses are expanded to show an absence of inhibitory-rebound sequence in the isolated slab. Arrows indicate membrane potential in the intact cortex (−62 mV) and the isolated slab (−75 mV).