RESUMO
Synaptic responses of single neurons in the locomotor strip" were recorded extracellularly. Neurons of the rostral part of the strip produced short-latency responses to stimulation of the mesencephalic "locomotor region". Neurons of the caudal part of the strip responded to microstimulation of other sites of the strip, rostral ones included. When the distance between the site of stimulation and a neuron along the strip was less than 2--3 mm, short-latency (1.2--1.6 ms) responses were recorded. Thresholds and latencies grew with the distance. Polysynaptic responses with a 3--4 ms latency could be potentiated when repetitive (30--40 pulses per s) stimulation was used instead of a single stimulus. The results suggest that axons in the "locomotor strip" are oriented in a rostrocaudal direction and give off collaterals to neighbour neurons. The "locomotor strip" can be an integrative centre "intercalated" between the rostral centers of the brain and the spinal cord.
Assuntos
Tronco Encefálico/fisiologia , Animais , Mapeamento Encefálico , Tronco Encefálico/anatomia & histologia , Gatos , Potenciais Evocados , Locomoção , Tempo de Reação , Sinapses/fisiologia , Transmissão SinápticaRESUMO
The mathematical model of the spike activity of a neuron with synaptic input from many other neurons [1], describes adequately the firing of 5 from 7 neurons in the tegmentum of mesencephalic cat and changes of their activity evoked by glutamate iontophoresis. For these 5 neurons the estimates of the PSPs' average frequency of the threshold depolarization and of the constant decay of the EPSP were received. For different neurons the values of these parameters are 4--100 KHz, 100--800 average unitary EPSPs and 4--30 msec correspondingly. The stationary value of the average membrane potential (SVAMP) in all 5 neurons was removed significantly from the resting potential toward the threshold potential. SWAMP could be changed by the glutamate iontophoresis in such a degree to overlap the threshold potential.
