Download T2 - Center for Neural Basis of Cognition

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
Why does the world stay still
when we move our eyes?
Hermann von Helmholtz
Treatise on
Physiological Optics,
1866
“Effort of will”
1) Remapping in monkey area LIP and extrastriate visual
cortex
1) Remapping in monkey area LIP and extrastriate visual
cortex
2) Remapping in split-brain monkeys
Behavior
Physiology
1) 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.
1) 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
FP
FP
T1
T1 appears
T2
FP
T1
T2 flashes briefly
T1
Saccade to T1
T2
Saccade to T2
Attain fixation
FP
FP
T1
T1 appears
T2
FP
T1
T2 flashes
Transfer of visual signals
WITHIN
T2
T1
T2
WITHIN
T2
T1
T2 T2’
WITHIN
VISUAL-ACROSS
T2
T2
T1
T2 T2’
T1
T2
WITHIN
VISUAL-ACROSS
T2
T2
T1
T2 T2’
T1
T2
T2’
Is performance impaired on visual-across sequences in
split-brain monkeys?
WITHIN
VISUAL-ACROSS
T2
T2
T1
T2 T2’
T1
T2
T2’
Central
Within
Central
Across
Across
Within
Day 1: Initial impairment for visual-across
Monkey
C
Monkey
E
Within Central Across
Across Central
Within
correct
incorrect
TRIALS
1-10
60-70
120-130
Within Central Across
Across Central Within
First day saccade endpoints
Vertical eye position (degrees)
Monkey C
Monkey E
Horizontal eye position (degrees)
Last day saccade endpoints
Vertical eye position (degrees)
Monkey C
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.
1) 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.
1) 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
1) 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?
Central
Within
Central
Across
Across
Within
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