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Mathematical operations in the visual brain

Mathematical operations in the visual brain. Guy A. Orban Laboratorium voor Neuro-en Psychofysiologie K.U. Leuven Medical School. Do neurons perform mathematical operations? What is being measured? Gradient selective neurons: a new family Do we have the same neurons in our brain.

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Mathematical operations in the visual brain

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  1. Mathematical operations in the visual brain Guy A. Orban Laboratorium voor Neuro-en Psychofysiologie K.U. Leuven Medical School

  2. Do neurons perform mathematical operations? What is being measured? Gradient selective neurons: a new family Do we have the same neurons in our brain

  3. Dorsal pathway AIP V1 MT/V5 MSTd FST Ventral pathway TEs

  4. Tanaka and Saito, ´89

  5. L. Lagae et al. ´94

  6. Orban et al PNAS 1992

  7. Do neurons perform mathematical operations? What is being measured? Gradient selective neurons: a new family Do we have the same neurons in our brain

  8. ORDRES DE DISPARITE: DERIVEES SPATIALES DE LA DISPARITE ordre zero premier ordre second ordre approximations G. Orban et al, Trends in Neurosci, ´06

  9. EXTRACTION DE LA FORME 3D DU MOUVEMENT: NEURONES Gradient haut-bas Gradient droite-gauche Neurone MT/V5 sélectif pour le gradient de vitesse et, indirectement, pour la direction du tilt (inclinaison en profondeur) B A D.K. Xiao et al, Eur. J. of Neurosci., ´97

  10. STIMULI  

  11. TEs: SELECTIVITE POUR LA DISPARITE D´ORDRE SUPERIEUR G. Orban et al, Trends in Neurosci, ´06

  12. TEs: CONVERGENCE OF 3D SHAPE CUES: STEREO AND TEXTURE A 100 spikes/sec B Y. Liu et al, J Neurosci, ´04

  13. EXTRACTION DE LA FORME 3D DU MOUVEMENT: fMRI SINGE EVEILLE Aires sensibles au mouvement et extraction de la forme 3D du mouvement K. Nelissen et al, The JoNS, ´06

  14. EXTRACTION DE LA FORME 3D DU MOUVEMENT: NEURONES Tests pour les neurones FST Premier Ordre: surface inclinée (8 orientations) Second ordre: surface cylindrique (4 orientations) Second ordre: bosse Second ordre: selle (2 orientations)

  15. The family of gradient selective neurons • Gradients of speed: linear: MT/V5, MSTd, FST higher order: FST • Gradients of disparity: linear: TEs, CIP, AIP, higher order: TEs, AIP, Premotv • Gradients of texture: linear: CIP, TEs

  16. Do neurons perform mathematical operations? What is being measured? Gradient selective neurons: a new family Do we have the same neurons in our brain?

  17. Monkey Single cells Monkey fMRI Human fMRINeural basis fMRI HomologiesScouting Monkey needs to be awake fMRI is also an efficient tool to test drug effects

  18. fMRI: SENSITIVITY TO CURVATURE in DEPTH Binocular disparity Stereo Monocular Two eyes: same images Two eyes: different images Curved (same profiles as used in single cell) Surfaces Flat

  19. Interaction: (Curved stereo-curved monocular) - (Flat stereo-flat monocular) Srivastava et al., 2007 Joly et al 2007 Poster 462.4 Monday pm Janssen et al., 2000 23

  20. Selection of subjects (n=22) 3D shape adjustment task

  21. Interaction: (Curved stereo-curved monocular)- (Flat stereo-flat monocular) L & R Post ITG (6-7) L & R DIPSA (15-16)

  22. Conclusions • 1 Even if they seem to perform mathematical operations, neurons match input to a template • 2 New family of gradient selective neurons: match input to first and higher order gradients • 3 Through the combination of single cell recording with fMRI in the awake monkey and humans we can show that similar neurons exist in the human brain

  23. Integrated Project NeuroProbes FP6: IST-027017.

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