Transcript EXTRACTION DE LA FORME 3D DU

Mathematical operations in the
visual brain
Guy A. Orban
Laboratorium voor Neuro-en Psychofysiologie
K.U. Leuven Medical School
1) Do neurons perform
mathematical operations?
What is being measured?
2) Gradient selective neurons: a
new family
3) Do we have the same neurons
in our brain
Dorsal pathway
AIP
V1
MT/V5 MSTd
FST
Ventral pathway
TEs
Tanaka and Saito, ´89
L. Lagae et al. ´94
Orban et al PNAS 1992
1) Do neurons perform
mathematical operations?
What is being measured?
2) Gradient selective neurons: a
new family
3) Do we have the same neurons
in our brain
ORDRES DE DISPARITE: DERIVEES SPATIALES DE LA DISPARITE
ordre zero
approximations
premier ordre
second ordre
G. Orban et al, Trends in Neurosci, ´06
EXTRACTION DE LA FORME 3D DU MOUVEMENT: NEURONES
Neurone MT/V5 sélectif pour le gradient de vitesse et, indirectement,
pour la direction du tilt (inclinaison en profondeur)
A
Gradient haut-bas
B
Gradient droite-gauche
D.K. Xiao et al, Eur. J. of Neurosci., ´97
STIMULI


TEs: SELECTIVITE POUR LA DISPARITE D´ORDRE SUPERIEUR
G. Orban et al, Trends in Neurosci, ´06
TEs: CONVERGENCE OF 3D SHAPE CUES: STEREO AND TEXTURE
A
B
100 spikes/sec
Y. Liu et al, J Neurosci, ´04
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
EXTRACTION DE LA FORME 3D DU MOUVEMENT: NEURONES
Tests pour les neurones FST
Premier Ordre: surface inclinée
(8 orientations)
Second ordre: bosse
Second ordre: surface cylindrique
(4 orientations)
Second ordre: selle
(2 orientations)
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
1) Do neurons perform
mathematical operations?
What is being measured?
2) Gradient selective neurons: a
new family
3) Do we have the same neurons
in our brain?
Monkey Single cells
Monkey fMRI
Neural basis fMRI
Scouting
Human fMRI
Homologies
Monkey needs to be awake
fMRI is also an efficient tool to test drug effects
fMRI: SENSITIVITY TO CURVATURE in DEPTH
Binocular disparity
Stereo
Two eyes:
different images
Curved
(same profiles
as used in
single cell)
Surfaces
Flat
Monocular
Two eyes:
same images
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
Selection of subjects (n=22)
3D shape adjustment task
Interaction: (Curved stereo-curved monocular)(Flat stereo-flat monocular)
L & R Post ITG (6-7)
L & R DIPSA (15-16)
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
Integrated Project NeuroProbes
FP6: IST-027017.