Functional state of corticostriatal synapses determines their expression of short- and long-term plasticity.
Relationships between presynaptic function and short- and long-term plasticity were investigated at adult corticostriatal synapses. Wide variability was observed in the expression of short- and long-term synaptic plasticity. Intracellular records from 47 cells produced 17 examples of LTD (<90% of control), 10 examples of no long-term change (between 90-110% of control), and 20 examples of LTP (>110% of control). Similar variation existed in paired-pulse and posttetanic plasticities. The variability expressed in all three forms of plasticity appears to be related, based on correlations found between the paired-pulse ratio (PPR) and tetanus-induced short- (3 min posttetanus) and long-term plasticities (16-20 min posttetanus). These data suggest that tetanus-induced changes in synaptic strength are related to the intrinsic, preconditioned behavior of synapses. Every cell showing paired-pulse depression also expressed LTD in response to high-frequency activation of its afferents. Those synapses showing paired-pulse potentiation tended to express LTP, although exceptions did exist. Similar relationships were found in a parallel analysis of population spikes. PPR also changed in association with the expression of posttetanic and long-term depression. Greater paired-pulse potentiation was observed in medial intracellular recordings, but no medial to lateral differences were seen in posttetanic plasticities. Field recordings also showed a medial bias toward paired-pulse and posttetanic potentiation, but not in long-term plasticity. Block of postsynaptic L-type Ca(2+) channels with nifedipine eliminated LTD expression, but overall no differences were found between nifedipine and control cells.
Akopian
G
G
Ethel Percy Andrus Gerontology Center, USC Program in Neuroscience, University of Southern California, Los Angeles, California 90089-0191, USA.
Musleh
W
W
Smith
R
R
Walsh
J P
JP
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D051381:Rats; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D002121:Calcium Channel Blockers; D009543:Nifedipine