Rhythmically firing neostriatal neurons in monkey: activity patterns during reaction-time hand movements.

Published

Journal Article

While previous studies have identified rhythmically firing neurons (RFNs) in monkey neostriatum and these rhythmic firing patterns have been shown to evolve in neostriatal tonically active neurons (TANs) after dopamine input depletion, the activity patterns of RFNs during motor behavior are still far from completely understood. We examined the single-unit activity patterns of neostriatal neurons, recorded in awake behaving monkeys during a wrist movement task, for evidence of rhythmic activity. Monkeys made ballistic wrist flexion and extension movements in response to vibrotactile cues. Animals held a steady wrist position for 0.5 to 2.0 s while awaiting the onset of the go-cues (hold period). Although the majority of neostriatal neurons (274/306) did not fire rhythmically, approximately 10% of the neurons (32/306) fired rhythmically at 10-50 Hz during the hold period. Most RFNs (28/32) showed significant activity changes during the time between go-cue presentation and movement onset (premovement activity). One-half of RFNs exhibited premovement activity that differed as a function of movement direction. Only one RFN may have responded to the delivery of a fruit juice reward. Neuronal firing was analyzed using interspike interval distributions, autocorrelations, and serial correlation techniques. These analyses showed that the activity patterns of most RFNs were consistent with an integrate-and-fire model of neuronal rhythm generation. Changes in RFN activity patterns during the premovement interval and intertrial variations in firing frequency could be explained by changes in the general level of excitatory input. These observations are consistent with the firing properties reported for neostriatal cholinergic interneurons. It has been suggested that tonically active neurons may be cholinergic interneurons and that these neurons show changes in activity related to specific aspects of behavioral paradigms, such as rewards. RFNs may constitute a special class of TANs. The results presented here suggest that RFNs may have a role in movement initiation. We speculate that RFNs may modulate the propagation of cortical oscillations via basal ganglia-thalamic-cortical loops.

Full Text

Cited Authors

  • Lebedev, MA; Nelson, RJ

Published Date

  • October 1999

Published In

Volume / Issue

  • 82 / 4

Start / End Page

  • 1832 - 1842

PubMed ID

  • 10515972

Pubmed Central ID

  • 10515972

Electronic International Standard Serial Number (EISSN)

  • 1522-1598

International Standard Serial Number (ISSN)

  • 0022-3077

Digital Object Identifier (DOI)

  • 10.1152/jn.1999.82.4.1832

Language

  • eng