Bilateral Topography of Cortical Projections to MI Cortex

Open Access
Colechio, Elizabeth M
Graduate Program:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 08, 2009
Committee Members:
  • Kevin Douglas Alloway, Thesis Advisor
  • sensorimotor integration
  • retrograde tracing
  • whiskers
  • motor cortex
  • somatosensory cortex
To determine the cortical regions that project to primary motor (MI) cortex, we injected retrograde tracers into physiologically-identified sites in rat MI. Microscopic examination of tangential sections revealed dense populations of labeled neuronal soma in multiple areas of the ipsilateral cortex and in the contralateral MI. Neurons labeled by different tracers were usually segregated from each other when the two tracers were injected separately into whisker and forelimb regions. The contralateral MI region contained more labeled neurons than any other cortical region when the tracer was injected into the MI whisker region. By contrast, when the tracer was injected into the MI forepaw representation, similar percentages of labeled neurons were present in the contralateral MI and ipsilateral SI cortical areas. The higher proportion of neurons in the contralateral MI whisker region suggests that callosal connections between the MI whisker regions may contribute to bilateral coordination of whisking behavior.