( D) Activity ± SEM for each interstimulus interval before training. Colored horizontal bars indicate the interstimulus intervals. Traces with lighter shading represent cells for which naive data are lacking. ( A– C) Smoothed and averaged simple spike activity after training with 150-ms (blue, n = 10) ( A), 200-ms (red, n = 7) ( B), and 300-ms (green, n = 6) ( C) interstimulus intervals. Time courses of conditioned responses after training with different interstimulus intervals and using conditional stimuli of different durations. For instance, they are extinguished by unpaired presentations of conditional and unconditional stimuli and show savings on retraining after extinction ( 7), they are adaptively timed ( 8), their latencies respond to changes in stimulus parameters in the same way ( 9, 10), and they are not acquired with interstimulus intervals below about 100 ms ( 11).įig. The conditioned Purkinje cell responses share a number of features with the overt conditioned blink responses. These pauses, conditioned Purkinje cell responses, cause disinhibition of the cerebellar nuclei and thereby generate the overt conditioned response ( 6, 7). During conditioning, tonically active Purkinje cells in a blink-controlling area of the cerebellar cortex acquire learned pauses in firing. The conditional stimulus is transmitted to the cerebellar cortex by the mossy and parallel fiber system, and the unconditional blink-eliciting stimulus is transmitted by the climbing fibers ( 5). The cerebellar cortex is necessary for the generation of such timed conditioned responses ( 3, 4). If the interstimulus interval is increased or decreased, the timing of the conditioned response will change accordingly after additional training ( 2). If a neutral conditional stimulus is followed repeatedly at a fixed temporal interval (an interstimulus interval) by an unconditional blink-eliciting stimulus, the conditional stimulus acquires the ability to elicit a blink that will be timed to occur just before the unconditional stimulus. Fine motor timing involves the cerebellum ( 1), as illustrated by eyeblink conditioning. Timing is an integral aspect of all movements, from tilting a coffee cup to pressing a piano key.
0 kommentar(er)
