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C534

C534. Lecture 3: Premotor cortex. PMC. sensorimotor mapping Ablation effects (Passingham) Delay period activity (Wise, Boussaoud) Vocabulary of actions (Rizzolatti) Vocabulary of spatially organised postures (Graziano). Passingham Ablation of PMC

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C534

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  1. C534 Lecture 3: Premotor cortex

  2. PMC • sensorimotor mapping • Ablation effects (Passingham) • Delay period activity (Wise, Boussaoud) • Vocabulary of actions (Rizzolatti) • Vocabulary of spatially organised postures (Graziano)

  3. Passingham • Ablation of PMC • Monkey cannot acquire arbitrary sensory-motor mappings • Control of internally-generated sequences unaffected

  4. Premotor cortex active between instruction and movement (Wise et al)

  5. Attention/intention • Is delay period activity: • Attention to the sensory information that specifies which movement to make? • Or • Preparatory Intention to make the movement that the sensory information specified?

  6. Premotor cortex Attention and intention(Boussaoud) SAM: attend here MIC: colour means moveL or R when colour goes OFF (instructed delay) PMC is not predicting the Sensory input, but mapping it To drive the motor output

  7. Premotor cortex

  8. Premotor- Parietal circuits

  9. Rizzolatti vocabulary • Some PMC cells (canonicals) respond either when grasping object w. specific grip, or viewing the object without action

  10. Graziano 2002 (MI and PMC) Microstimulation of PMC drives armto a specific location in body spaceirrespective of starting location Stimulation >500 ms… Defensive postures? Vocabulary of motor/spatial positions? PMC area outlined in red

  11. Premotor cortex stimulation Evokes primarily movements To postures in upper contralateral space Figure 6. Topography of Hand and Arm Postures in the Precentral Gyrus Based on 201 Stimulation Sites in Monkey 1A similar map (not shown) was found in monkey 2. Most points represent two to three sites tested at different depths. Sites plotted to the left of the line labeled Central Sulcus were located in the anterior bank of the sulcus.(A) Distribution of hand positions along the vertical axis, in upper, middle, and lower space. Each site was categorized based on the center of the range of evoked final positions. Height categories were defined as follows: LOWER = 0 to 12 cm from bottom of monkey, MIDDLE = 12 to 24 cm, UPPER = 24 to 36 cm. Dashes show electrode penetrations where no arm postures were found; usually the postures from these locations involved the mouth or face.(B) Distribution of hand positions along the horizontal axis, in contralateral, central, or ipsilateral space. Horizontal categories were defined as follows: CONTRALATERAL = 6 to 18 cm contralateral to midline, CENTRAL = within 6 cm of midline (central 12 cm of space), IPSILATERAL = 6 to 18 cm ipsilateral to midline.

  12. Figure 7. Specialized Subregions within the Map of Stimulation-Evoked Postures Based on Data from Monkey 1Circles show hand-to-mouth sites; these always involved a grip posture of the hand in addition to a movement of the arm that brought the hand to the mouth. Triangles show other sites where stimulation evoked both a hand and an arm posture; these sites often involved the hand moving into central space and the fingers shaping into a specific configuration. Squares show sites where bimodal, visual-tactile responses were found and stimulation evoked defensive movements.

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