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