Study of spindle-spike interactions: features of basal ganglia control.

Changes in cortical spindle distribution following penicillin (PCN) injections were studied in feline generalized PCN epilepsy. PCN activation caused no substantial changes in spindle duration, frequency and intraburst frequency, while significant reductions in the amplitude of the negative waves were noted. At the same time combinations of spindle waves and epileptic complexes were recorded with one or more spikes randomly occurring at the beginning, in the middle, or at the end of a spindle envelope. Low frequency stimulation of the caudate nucleus induced a certain degree of enhancement in cortical precruciate spike frequency while high frequency activation of the entopeduncular nucleus caused significant inhibition of cortical spike frequency. The results are discussed in the light of the reciprocal interrelationship between spindles and spikes. Furthermore, the role played by the caudate and the entopeduncular nucleus in the control of the cortico-thalamo-cortical circuit is also emphasized.