Oscillations in the premotor cortex: single-unit activity from awake, behaving monkeys.


Journal Article

We examined single-unit activity in the dorsal premotor cortex for evidence of fast neuronal oscillations. Four rhesus monkeys performed a task in which visuospatial instruction stimuli indicated the direction of forelimb movement to be executed on each trial. After an instructed delay period of 1.5-3 s, movements to either the right or left of a central origin were triggered by a second visuospatial stimulus. From a database of 579 single units, 78 units (13%) contained periodic peaks in their autocorrelation histograms (ACHs), with oscillation frequencies typically 20-30 Hz (mean 27 Hz). An additional 26 units (5%) had oscillatory features that were identified in joint interspike-interval (ISI) plots. Three observations, taken together, suggest entrainment by rhythmic drive extrinsic to these neurons: shuffling ISIs attenuated ACH peaks, indicating a dependency on serial-order effects; oscillation frequency did not change during either increases or decreases in firing rate; and joint ISI plots contained features consistent with a rhythmicity interrupted by intervening discharges. In some cells, oscillations occurred for only one of the two directions of movement. During the delay period, such directional selectivity was observed in 37 units (60% of delay-period oscillators). For at least 17 of these units, we could exclude the possibility that oscillatory directional selectivity resulted from the difficulty in detecting oscillations due to low discharge rates (for one of the two movement directions). Directional selectivity in fast oscillations shows that they can reflect specific aspects of an intended action.

Full Text

Cited Authors

  • Lebedev, MA; Wise, SP

Published Date

  • January 2000

Published In

Volume / Issue

  • 130 / 2

Start / End Page

  • 195 - 215

PubMed ID

  • 10672473

Pubmed Central ID

  • 10672473

Electronic International Standard Serial Number (EISSN)

  • 1432-1106

International Standard Serial Number (ISSN)

  • 0014-4819

Digital Object Identifier (DOI)

  • 10.1007/s002210050022


  • eng