Long-Evans rats have a larger cortical topographic representation of movement than Fischer-344 rats: A microstimulation study of motor cortex in naïve and skilled reaching-trained rats

Penny M. VandenBerg, Theresa M. Hogg, Jeffrey A. Kleim, Ian Q. Whishaw

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Intracortical microstimulation of the frontal cortex evokes movements in the contralateral limbs, paws, and digits of placental mammals including the laboratory rat. The topographic representation of movement in the rat consists of a rostral forelimb area (RFA), a caudal forelimb area (CFA), and a hind limb area (HLA). The size of these representations can vary between individual animals and the proportional representation of the body parts within regions can also change as a function of experience. To date, there have been no investigations of strain differences in the cortical map of rats, and this was the objective of the present investigation. The effect of cortical stimulation was compared in young male Long-Evans rats and Fischer-344 rats. The overall size of the motor cortex representation was greater in Long-Evans rats compared to Fischer-344 rats and the threshold required to elicit a movement was higher in the Fischer-344 rats. An additional set of animals were trained in a skilled reaching task to rule out the possibility that experiential differences in the groups could account for the result and to examine the relationship between the differences in topography of cortical movement representations and motor performance. The Long-Evans rats were quantitatively and qualitatively better in skilled reaching than the Fischer-344 rats. Also, Long-Evans rats exhibited a relatively larger area of the topographic representation and lower thresholds for eliciting movement in the contralateral forelimb. This is the first study to describe pronounced strain-related differences in the microstimulation-topographic map of the motor cortex. The results are discussed in relation to using strain differences as a way of examining the behavioral, the physiological, and the anatomical organization of the motor system.

Original languageEnglish (US)
Pages (from-to)197-203
Number of pages7
JournalBrain Research Bulletin
Volume59
Issue number3
DOIs
StatePublished - Nov 30 2002
Externally publishedYes

Keywords

  • Corticospinal stimulation and movement
  • Fischer-344 motor cortex
  • Long-Evans rat motor cortex
  • Microstimulation of motor cortex
  • Motor cortex
  • Rat motor cortex
  • Skilled reaching
  • Stain differences in skilled reaching
  • Strain differences in motor cortex

ASJC Scopus subject areas

  • Neuroscience(all)

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