Postsynaptic control of the induction of long-term changes in efficacy of transmission at neocortical synapses in slices of rat brain.

摘要: 1. Long-term potentiation (LTP) is an enduring, activity-induced increase in the efficacy of synaptic transmission, which has been considered as a possible neural substrate for learning. Recent experiments have shown that LTP can be induced hippocampal CA1 neurons when presynaptic volley paired repetitively with depolarization postsynaptic cell, brought about intracellularly applied depolarizing current pulses (20, 33). We repeated these neocortical neurons, transverse slices rat sensorimotor cortex vitro. 2. Stable intracellular recordings were obtained from 28 (mean resting potential -78 mV, mean spike amplitude 95 input resistance 41 M omega) mostly layers V and VI. Two different afferent pathways stimulated alternately at 0.2 Hz to evoke subthreshold composite excitatory potentials (EPSPs). One micromolar bicuculline methiodide was added bathing medium most experiments. 3. Repetitive pairing one coincident pulse (100-200 ms long) magnitude sufficient make neuron fire 6 13 action potentials/pulse, gave rise after 30-50 pairings 4 significant enduring EPSP. The persisted without decrement long recording continued (range 15-50 min ended) but unpaired EPSP unchanged. During LTP, membrane apparent also 4. In two cells prolonged depression while unaffected. Membrane not changed. remaining 22 neither nor altered. 5. Brief, tetanic stimulation pathway 11 had ineffective. A variety effects produced (LTP, depression, or posttetanic potentiation). All confined pathway. 6. conclude some by depolarization, experimental paradigm conforms Hebb9s (17) model associative conditioning. Depression other same design.(ABSTRACT TRUNCATED AT 400 WORDS)