Post on 01-Apr-2015
Brian WhiteCentre for Neuroscience StudiesQueen’s, Kingston, Ontario, Canada
The Representation of Visual Salience in the Superior Colliculus
June 9th, 2012
Oculomotor Circuit
SCs = Superior Colliculus Superficial Layers
SCi = Superior Colliculus Intermediate Layers
THALAMUS
SCs
SCi
BRAINSTEM
FRONTALPARIETAL
OCCIPITAL
RETINA
AimDirectly test whether the SC shows evidence of a
sensory-driven saliency mapi.e., higher-order visual process associated with
computation of visual salience
which takes into account feature-specific spatial interactions between stimuli across the entire visual field
Experiment 1
We compared visually evoked SC activation across three task irrelevant stimulus conditions single item, popout, conjunction
Monkey’s task was to saccade to goal-related stimulus that ran orthogonal to the RF, where the salient item appeared
Task
(i) Single item cond(ii) Popout cond(iii) Conjunction cond
(i) Single item cond(ii) Popout cond(iii) Conjunction cond
(i) Single item cond(ii) Popout cond(iii) Conjunction cond
Abrupt onset Saccade
Abrupt onset Saccade
+
singleitemin RF
+
Abrupt onset Saccade
singleitemin RF
+
Abrupt onset Saccade
singleitem at
anti-location
Abrupt onset Saccade
+popout
stimulusin RF
Abrupt onset Saccade
+
popoutstimulusat anti-location
Abrupt onset Saccade
+conjunction
condition
0-1mm (SCs)N=14
SC Depth
1-3mm(SCi) N=9
Popout in RFPopout anti-location ConjunctionSingle item in RFSingle item anti-location
* *
SCs SCi
Single item in RFSingle item anti-locPopout item in RFPopout item anti-locConjunction
Local field potentials (LFP)
Experiment 2Same as Exp 1 except the RF was dragged over
salient item via a pursuit eye movement.
Same three conditions single item, popout, conjunction
Pursuit
N=19SCs
neurons
Single itemin RF
N=19SCs
neurons
Single itemin RF
N=19SCs
neurons
Single item at anti location
N=19SCs
neurons
Popout stimulusin RF
N=19SCs
neurons
Popout stimulusat anti location
N=19SCs
neurons
Conjunction condition
N=14SCi
neurons
SummarySC neurons (and LFPs) showed greater visual activation for
popout relative to conjunction and anti-popout conditions, even though the stimuli were task irrelevant.
This difference emerged after the initial visual transient. A similar pattern was observed previously in V4 (Burrows & Moore, 2009),
and LIP (Arcizet, Mirpour & Bisley 2011).
This difference was greatest for neurons within the dorsal most 1mm of the SC surface (i.e., the superficial visual layers) where the predominant inputs arise from visual cortex, not
parietal/frontal cortices.
Oculomotor Circuit
SCs = Superior Colliculus Superficial Layers
SCi = Superior Colliculus Intermediate Layers
FRONTALPARIETAL
BRAINSTEM
OCCIPITAL
THALAMUS
SCs
SCi
Oculomotor Circuit
SCs = Superior Colliculus Superficial Layers
SCi = Superior Colliculus Intermediate Layers
FRONTALPARIETAL
BRAINSTEM
OCCIPITAL
THALAMUS
saliency
SCs
SCi
Oculomotor Circuit
SCs = Superior Colliculus Superficial Layers
SCi = Superior Colliculus Intermediate Layers
FRONTALPARIETAL
BRAINSTEM
OCCIPITAL
THALAMUS
saliency
SCs
SCi
Munoz Lab Doug MunozTakuro Ikeda
Collaborators: Laurent IttiDavid Berg
Technical: Ann Lablans, Lindsey Duck, Donald Brien, Sean Hickman, Mike Lewis.
Funding: CIHR, DARPA