Active Vision Carol Colby Rebecca Berman Cathy Dunn Chris Genovese Laura Heiser Eli Merriam Kae Nakamura Department of Neuroscience Center for the Neural Basis of Cognition University of Pittsburgh Department of Statistics Carnegie Mellon University This is based on Seville07 which was 30 minutes at high speed. Physio + imaging. This set of slides was also used for Istanbul and Columbia and presumably for Barcelona07. For San Diego, I removed the human split brain material.

Why does the world stay still when we move our eyes? Hermann von Helmholtz Treatise on Physiological Optics, 1866 “Effort of will”

Remapping in monkey area LIP and extrastriate visual cortex

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology 3) Remapping in human cortex Parietal cortex Striate and extrastriate visual cortex

LIP memory guided saccade Stimulus On Saccade

Stimulus appears outside of RF Saccade moves RF to stimulus location

Single step task

Spatial updating or remapping The brain combines visual and corollary discharge signals to create a representation of space that takes our eye movements into account

LIP Summary Area LIP neurons encode attended spatial locations.

LIP Summary Area LIP neurons encode attended spatial locations. The spatial representation of an attended location is remapped when the eyes move.

LIP Summary Area LIP neurons encode attended spatial locations. The spatial representation of an attended location is remapped when the eyes move. Remapping is initiated by a corollary discharge of the eye movement command.

LIP Summary Area LIP neurons encode attended spatial locations. The spatial representation of an attended location is remapped when the eyes move. Remapping is initiated by a corollary discharge of the eye movement command. Remapping produces a representation that is oculocentric: a location is represented in the coordinates of the movement needed to acquire the location.

LIP Summary Area LIP neurons encode attended spatial locations. The spatial representation of an attended location is remapped when the eyes move. Remapping is initiated by a corollary discharge of the eye movement command. Remapping produces a representation that is oculocentric: a location is represented in the coordinates of the movement needed to acquire the location. Remapping allows humans and monkeys to perform a spatial memory task accurately.

LIP V3A FEF V3 V2 V1 SC LGN Oculomotor System Retina

Stimulus appears outside of RF Saccade moves RF to stimulus location

Stimulus alone control Saccade alone control

Single step task

Extrastriate Summary Remapping occurs at early stages of the visual hierarchy.

Extrastriate Summary Remapping occurs at early stages of the visual hierarchy. Corollary discharge has an impact far back into the system.

Extrastriate Summary Remapping occurs at early stages of the visual hierarchy. Corollary discharge has an impact far back into the system. Remapping implies widespread connectivity in which many neurons have rapid access to information well beyond the classical receptive field.

Extrastriate Summary Remapping occurs at early stages of the visual hierarchy. Corollary discharge has an impact far back into the system. Remapping implies widespread connectivity in which many neurons have rapid access to information well beyond the classical receptive field. Vision is an active process of building representations.

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology 3) Remapping in human cortex Parietal cortex Striate and extrastriate visual cortex

Stimulus appears outside of RF Saccade moves RF to stimulus location

What is the brain circuit that produces remapping?

The obvious pathway for visual signals: forebrain commissures

Are the forebrain commissures necessary for updating visual signals across the vertical meridian? Behavior in double step task Physiology in single step and double step task

Attain fixation T1 appears T2 flashes briefly Saccade to T1 FP T1 appears FP T1 T2 flashes briefly T1 T2 FP Saccade to T1 T1 Saccade to T2 T2

Attain fixation FP T1 appears FP T1 T2 flashes T1 T2 FP

Transfer of visual signals WITHIN T2 T1 T2

WITHIN T2 T1 T2 T2’

WITHIN VISUAL-ACROSS T2 T1 T2 T1 T2 T2’ T2

WITHIN VISUAL-ACROSS T2 T1 T2 T1 T2 T2’ T2 T2’

Is performance impaired on visual-across sequences in split-brain monkeys? WITHIN VISUAL-ACROSS T2 T2 T1 T1 T2 T2’ T2 T2’

Central Central Within Across Across Within

Day 1: Initial impairment for visual-across Monkey C Monkey E Within Across Central correct incorrect

TRIALS 1-10 60-70 120-130 Within Central Across Within Central Across

First day saccade endpoints Monkey C Vertical eye position (degrees) Monkey E Horizontal eye position (degrees)

Last day saccade endpoints Monkey C Vertical eye position (degrees) Monkey E Monkey E Horizontal eye position (degrees)

Are the forebrain commissures necessary for updating spatial information across the vertical meridian?

Are the forebrain commissures necessary for updating spatial information across the vertical meridian? No. The FC are the primary route but not the only route.

Are the forebrain commissures necessary for updating spatial information across the vertical meridian? No. The FC are the primary route but not the only route. What are LIP neurons doing?

Stimulus appears outside of RF Saccade moves RF to stimulus location

SINGLE STEP STIMULUS ALONE SACCADE ALONE

Population activity in area LIP

SINGLE STEP DOUBLE STEP

Split Brain Monkey Summary The forebrain commissures normally transmit remapped visual signals across the vertical meridian but they are not required.

Split Brain Monkey Summary The forebrain commissures normally transmit remapped visual signals across the vertical meridian but they are not required. Single neurons in area LIP continue to encode remapped stimulus traces in split-brain animals.

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology 3) Remapping in human cortex Parietal cortex Striate and extrastriate visual cortex

Functional Imaging Predictions 1) Robust activation in cortex ipsilateral to the stimulus.

Functional Imaging Predictions 1) Robust activation in cortex ipsilateral to the stimulus. 2) Ipsilateral activation should be smaller than the contralateral visual response.

Functional Imaging Predictions 1) Robust activation in cortex ipsilateral to the stimulus. 2) Ipsilateral activation should be smaller than the contralateral visual response. 3) It should not be attributable to the stimulus alone or to the saccade alone.

Functional Imaging Predictions 1) Robust activation in cortex ipsilateral to the stimulus. 2) Ipsilateral activation should be smaller than the contralateral visual response. 3) It should not be attributable to the stimulus alone or to the saccade alone. 4) Ipsilateral activation should occur around the time of the saccade.

Contralateral Visual Response

Ipsilateral Remapped Response

Ipsilateral Remapped Response

Visual and Remapped Responses

Human Parietal Imaging Summary Remapping in humans produces activity in parietal cortex ipsilateral to the visual stimulus.

Human Parietal Imaging Summary Remapping in humans produces activity in parietal cortex ipsilateral to the visual stimulus. Remapped activity is lower amplitude than visual activity.

Human Parietal Imaging Summary Remapping in humans produces activity in parietal cortex ipsilateral to the visual stimulus. Remapped activity is lower amplitude than visual activity. It cannot be attributed to the stimulus or the saccade alone.

Human Parietal Imaging Summary Remapping in humans produces activity in parietal cortex ipsilateral to the visual stimulus. Remapped activity is lower amplitude than visual activity. It cannot be attributed to the stimulus or the saccade alone. It occurs in conjunction with the eye movement.

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology 3) Remapping in human cortex Parietal cortex Striate and extrastriate visual cortex

Contralateral Visual Response

Ipsilateral Remapped Response

Remapping in Multiple Visual Areas

Remapping in monkey area LIP and extrastriate visual cortex 2) Remapping in split-brain monkeys Behavior Physiology 3) Remapping in human cortex Parietal cortex Striate and extrastriate visual cortex

Human Imaging Summary Remapping in humans produces activity in the hemisphere ipsilateral to the stimulus.

Human Imaging Summary Remapping in humans produces activity in the hemisphere ipsilateral to the stimulus. Remapped activity is present in human parietal, extrastriate and striate cortex.

Human Imaging Summary Remapping in humans produces activity in the hemisphere ipsilateral to the stimulus. Remapped activity is present in human parietal, extrastriate and striate cortex. Remapped visual signals are more prevalent at higher levels of the visual system hierarchy.

Human Imaging Summary Remapping in humans produces activity in the hemisphere ipsilateral to the stimulus. Remapped activity is present in human parietal, extrastriate and striate cortex. Remapped visual signals are more prevalent at higher levels of the visual system hierarchy. Remapping occurs in parietal and visual cortex.

Conclusions Remapping of visual signals is widespread in monkey cortex.

Conclusions Remapping of visual signals is widespread in monkey cortex. Split-brain monkeys are able to remap visual signals across the vertical meridian.

Conclusions Remapping of visual signals is widespread in monkey cortex. Split-brain monkeys are able to remap visual signals across the vertical meridian. Remapped visual signals are present in area LIP in split-brain monkeys.

Conclusions Remapping of visual signals is widespread in monkey cortex. Split-brain monkeys are able to remap visual signals across the vertical meridian. Remapped visual signals are present in area LIP in split-brain monkeys. Remapped visual signals are robust in human parietal and visual cortex.

Conclusions Remapping of visual signals is widespread in monkey cortex. Split-brain monkeys are able to remap visual signals across the vertical meridian. Remapped visual signals are present in area LIP in split-brain monkeys. Remapped visual signals are robust in human parietal and visual cortex. Vision is an active process of building representations from sensory, cognitive and motor signals.

Learning? Or a monkey trick? Within Across Central

no monkey tricks..

Both monkeys really update the visual representation Monkey EM Monkey CH

Magnitude of Remapped Response

Intact Subjects Split Brain Subject

Strength of Parietal Responses in Split Brain and Intact Subjects