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Direct visuomotor transformations for reaching

Direct visuomotor transformations for reaching. VNI Lab Sangil, Kim. 물체에 손 뻗기 ?. 무슨 좌표로 target 을 나타낼 것인가 ? Eye? Head? Body? 처음 eye- , 나중 limb-coordinate At once? Or in serial order? Visually guided reaching visual area -> posterior parietal cortex (PPC) to the frontal lobe

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Direct visuomotor transformations for reaching

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  1. Direct visuomotor transformations for reaching VNI Lab Sangil, Kim

  2. 물체에 손 뻗기? • 무슨 좌표로 target을 나타낼 것인가? • Eye? Head? Body? • 처음 eye- , 나중 limb-coordinate • At once? Or in serial order? • Visually guided reaching • visual area -> posterior parietal cortex (PPC) to the frontal lobe • LIP (lateral intraparietal area) – saccadic eye movement • PRR (parietal reach region) – reach • Anterior intraparietal area - grasping

  3. 이전 연구 • Bastista(1999)- PRR area study • PRR are specialized for reaching -> probably code target location in limb coordinate • Eye coordinate >> limb coordinate

  4. 배경 • Problem of movement – define M • Target position in hand coordinate, Movement Vector • M = T (sensed location of target) – H (sensed location of hand) • Target : eye-coordinate • vs. Hand : eye? Body? - coordinate

  5. Question? • Eye-centered? or transforming? VS

  6. 실험1 상황 Area 5 • Target position, hand position, gaze direction 을 변화시킴 • Single cell-recording • 2 monkeys, 89 neurons • Cond 1&2 : same gaze, different initial had position • Cond 3&4 : same initial had position, different gaze

  7. 결과1 • Spike density histogram • cond 1 ≈ cond 4 • cond 2 ≈ cond 3 • eye & hand-coordinate 가 중요? 140 spikes/s 1s

  8. 다른 분석1 • Area 5 activity was best correlated when target locations were identical in both eye and hand coordinates.

  9. 다른 분석2 • Target location were same in eye coordinate, initial hand location were varied. • => partially shift. Consistent with simultaneous coding of target location in both eye and hand coordinates. Idealized neuron의 활동 Area 5 neuron의 활동

  10. 실험2 상황 • To test the hypothesis that neurons in area 5 code target location in both eye and hand coordinates. • Starting point 5개, reach point 5개, fixation 고정 • Area5 의 뉴런들의 반응이 fig. 4의 다른 coding model 에 의해 예상되는 반응과 바로 비교될 수 있어서 사용

  11. 결과 • b - One area 5 neuron • Contour - largely oblique • 비교를 위해서 각 response field의 gradient 를 구해서 resultant를 비교 • c - 각 gradient의 resultant • Blue – real data from one neuron • Red – idealized neuron • Black – population resultant(15 neurons) • similar

  12. discussion • Current result : remembered target locations are coded in both eye and hand coordinates in area 5. • 비슷한 결과가 target이 주어진 바로 직후의 활동에서도 관찰되었다. • reaching to remembered target locations • Entailing a direct transformation from eye-centred to hand-centred coordinates, although more indirect schemes may still operate in other contexts.

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