Electrically evoked saccades from the dorsomedial frontal cortex and frontal eye fields: a parametric evaluation reveals differences between areas.

Published

Journal Article

Using electrical stimulation to evoke saccades from the dorsomedial frontal cortex (DMFC) and frontal eye fields (FEF) of rhesus monkeys, parametric tests were conducted to compare the excitability properties of these regions. Pulse frequency and pulse current, pulse frequency and train duration, and pulse current and pulse duration were varied to determine threshold functions for a 50% probability of evoking a saccade. Also a wide range of frequencies were tested to evoke saccades, while holding all other parameters constant. For frequencies beyond 150 Hz, the probability of evoking saccades decreased for the DMFC, whereas for the FEF this probability remained at 100%. To evoke saccades readily from the DMFC, train durations of greater than 200 ms were needed; for the FEF, durations of less than 100 ms were sufficient. Even though the chronaxies of neurons residing in the DMFC and FEF were similar (ranging from 0.1 to 0.24 ms) significantly higher currents were required to evoke saccades from the DMFC than FEF. Thus the stimulation parameters that are optimal for evoking saccades from the DMFC differ from those that are optimal for evoking saccades from the FEF. Although the excitability of neurons in the DMFC and FEF are similar (due to similar chronaxies), we suggest that the density of saccade-relevant neurons is higher in the FEF than in the DMFC.

Full Text

Duke Authors

Cited Authors

  • Tehovnik, EJ; Sommer, MA

Published Date

  • December 1997

Published In

Volume / Issue

  • 117 / 3

Start / End Page

  • 369 - 378

PubMed ID

  • 9438704

Pubmed Central ID

  • 9438704

Electronic International Standard Serial Number (EISSN)

  • 1432-1106

International Standard Serial Number (ISSN)

  • 0014-4819

Digital Object Identifier (DOI)

  • 10.1007/s002210050231

Language

  • eng