Effects of frontal cortex lesions on action sequence learning in the rat.

Academic Article

Abstract

  • To understand the role of frontal cortex in motor sequence learning we compared the effects of motor (M1), premotor (M2) and midline frontal (MFr) cortical lesions on rats making nose-pokes guided by luminance cues. Organizational demands were manipulated by varying the number (1 vs. 5) and predictability (random vs. repeated) of nose-pokes in a response. Learning was studied by comparing sessions with random or repeated cues. All cortical lesions increased reaction time (RT) during response initiation. These effects were larger for nose-pokes initiating sequential responses but spared RT for nose-pokes completing them. Repetition learning had significant effects on the speed and accuracy of single nose-poke responses that were unaffected by any of the cortical lesions. Repetition learning had more complex effects on sequential responding. RTs increased for nose-pokes initiating sequences over several sessions of continuous repetition and then decreased or leveled off. RTs decreased incrementally across all repetition sessions for subsequent nose-pokes in repeated sequences, following a time-course consistent with habit learning. Lesions involving M2 and MFr cortex exacerbated the increase in RT during initiation without affecting the incremental decrease in RT for nose-pokes completing repeated sequences. These results were confirmed by analyses of interference effects when training shifted from repeated (learned) to random (novel) sequences or to a new repeated sequence. These results implicate dorsomedial frontal cortex in organizational aspects of sensory-guided responding and motor sequence learning reflected in RT during response initiation.
  • Authors

  • Bailey, Kathleen R
  • Mair, Robert
  • Status

    Publication Date

  • May 2007
  • Published In

    Keywords

  • Animals
  • Cues
  • Denervation
  • Exploratory Behavior
  • Frontal Lobe
  • Gyrus Cinguli
  • Learning
  • Male
  • Motor Cortex
  • Movement
  • Nerve Net
  • Neural Pathways
  • Neuropsychological Tests
  • Prefrontal Cortex
  • Psychomotor Performance
  • Rats
  • Rats, Long-Evans
  • Reaction Time
  • Sensation
  • Touch
  • Visual Perception
  • Digital Object Identifier (doi)

    Pubmed Id

  • 17561850
  • Start Page

  • 2905
  • End Page

  • 2915
  • Volume

  • 25
  • Issue

  • 9