Organization of rat vibrissa motor cortex and adjacent areas according to cytoarchitectonics, microstimulation, and intracellular stimulation of identified cells

J Comp Neurol. 2004 Nov 22;479(4):360-73. doi: 10.1002/cne.20306.


The relationship between motor maps and cytoarchitectonic subdivisions in rat frontal cortex is not well understood. We use cytoarchitectonic analysis of microstimulation sites and intracellular stimulation of identified cells to develop a cell-based partitioning scheme of rat vibrissa motor cortex and adjacent areas. The results suggest that rat primary motor cortex (M1) is composed of three cytoarchitectonic areas, the agranular medial field (AGm), the agranular lateral field (AG1), and the cingulate area 1 (Cg1), each of which represents movements of different body parts. Vibrissa motor cortex corresponds entirely and for the most part exclusively to AGm. In area AG1 body/head movements can be evoked. In posterior area Cg1 periocular/eye movements and in anterior area Cg1 nose movements can be evoked. In all of these areas stimulation thresholds are very low, and together they form a complete representation of the rat's body surface. A strong myelinization and an expanded layer 5 characterize area AGm. We suggest that both the strong myelinization and the expanded layer 5 of area AGm may represent cytoarchitectonic specializations related to control of high-speed whisking behavior.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Behavior, Animal / physiology
  • Brain Mapping*
  • Cell Shape / physiology
  • Efferent Pathways / physiology*
  • Electric Stimulation
  • Eye Movements / physiology
  • Gyrus Cinguli / physiology
  • Lysine / analogs & derivatives*
  • Mechanoreceptors / physiology
  • Motor Cortex / anatomy & histology
  • Motor Cortex / physiology*
  • Movement / physiology*
  • Nerve Fibers, Myelinated
  • Pyramidal Cells / cytology
  • Pyramidal Cells / physiology
  • Rats
  • Touch / physiology
  • Vibrissae / innervation*
  • Vibrissae / physiology


  • biocytin
  • Lysine