Post on 04-Mar-2021
transcript
Traveling Waves of Activity in Visual
Cortex During Binocular Rivalry
Collaborators:
Sang-Hun Lee, Seoul National University
Randolph Blake, Vanderbilt University
Perceptleft eye right eye
t
dominancein percept
Spatiotemporal dynamics during
binocular rivalry
Right eye
Left eye Ocular dominancecolumns
L
Binocularneurons
V1
R
R
L
V1 suppression hypothesis
• Early versus late.
• Eye versus pattern.
• Transitions vs sustained periods of
dominance.
• Role of attention.
• Local processing vs feedback from higher
visual areas.
Unresolved issues
Pattern rivalry
Left eye Right eye
Kovacs et al, PNAS (1996)
Binocular rivalry in monkey IT
Sheinberg & Logothetis, PNAS (1997)
Binocular rivalry in human IT
Tong et al, Neuron (1998)
Display
left eye right eye
Percept
Wilson, Blake & Lee (2001)
Latency
L / R / N
Perceptual traveling waves
Percept
Brain
Predicted and measured responses
Meas
ured f
MR
I r
esp
onse
(% c
han
ge im
age int
ens
ity)
Time (sec)0 3 6 9
1
2
0
Lee, Blake, & Heeger, Nature Neurosci (2005)
Predic
ted
neur
al a
ctiv
ity
Time
PerceptPeak fMRI response
Perceptual and neural traveling waves
Lee, Blake, & Heeger, Nature Neurosci (2005)
Latency (s)
# o
f tr
ials
1 3
Behavior
fMR
I r
esp
onse
lat
enc
y
(sec)
0 1 2 34.5
5.0
5.5
6.0
Distance (cm)
Behavioral latency
1-1.5 sec
1.5-2 sec
2-3 sec
6.5
Infer ~115 ms timing
difference over ~3.5 mm
distance.
Activity correlates with perceived latency
Lee, Blake, & Heeger, Nature Neurosci (2005)
t
FMRIresponse
time to peakpeak amplitude
Localcontrast
Neuralactivity
Estimating neural activity
Model of cortical activity
& hemodynamic impulse
Localcontrast
Rt
Rh
Rl
Neuralactivity
e-t/τ1 sin(2πf1t) - a e-t/τ
2 sin(2πf2t)Hemodynamic
impulse
PredictedfMRI response
9s
t
0
1
2
time (sec)
fMR
I r
esp
onse
(%
)
0 2 4 6 80
.5
1
time (sec)
0
.5
1
time (sec)
DN PN
SL
fixed parameters:
τ2=7.4, f
2=.12
a
f1
τ1
Rh/Rl
Rt
.1
.053
7.0
5.5
.5
SL
.1
.065
6.5
6.5
.75
PN
.08
.035
7.0
8
.5
DN
0 2 4 6 8
0 2 4 6 8
Model fits
Lee, Blake, & Heeger, Nature Neurosci (2005)
Estimated neural latencyN
eur
al lat
enc
y
Time
Lee, Blake, & Heeger, Nature Neurosci (2005)
0
0.5
1.0
1.5
2.0
2.5
0 1 2 3
Est
imat
ed n
eur
al lat
enc
y (s
ec)
Distance (cm)
DN
PN
SL
Observer
Ave speed = 2 cm/sec
Attention signals in V1
Gandhi, Heeger, & Boynton, PNAS (1999)
left eye right eye
Diverted attention
displayC
C2DA3B42D...Detect repetition
C
Time
0
.4
.8
-.4
-.8
0 3 6 9
0
.4
.8
-.4
-.8
fMR
I r
esp
onse
(% c
han
ge int
ens
ity)
0 3 6 9
Time (sec) Time (sec)
Rivalry (perceived) Diverted attention
Waves in V1 without
attention/perception
Diverting attention eliminates
waves in V2 & V3
0
10
20
30
-10
-20Dif
fere
nce in
tim
e t
o pe
ak (
%) V1 V2 V3
Rivalry tracked
Replay tracked
Rivalry diverted-attention
Replay diverted-attention
0 2 4 6 8
Time (sec)
fMR
I re
sponse (
%)
0 2 4 6 8
Time (sec)
fMR
I re
sponse (
%)
0 2 4 6 8
Time (sec)
fMR
I re
sponse (
%)
10
-20
-10
20
0
Diffe
rence in tim
e to p
eak (
%)
Rivalry-tracked inverted
No wave carrier
V1 V2 V3
.2
0
.4
.6
-.2
-.4
-.6
.2
0
.4
.6
-.2
-.4
-.6
.2
0
.4
.6
-.2
-.4
-.6
Rivalry-tracked inverted Trigger only
No wave carrier
Control experiments
Summary
- V1 activity correlated with spatio-temporal dynamics of
perceptual waves during binocular rivalry.
- The velocity of neural waves in V1 matched the latency
of perceptual waves.
- Neural waves in V1 were still present when attention
was diverted, but weaker in amplitude and faster in
velocity.
- V2 and V3 exhibited cortical waves of activity during
rivalry but the waves were eliminated when attention was
diverted.
Implications
- Neural wave propagation is intrinsic to V1.
- Attention is required for neural waves to be
consciously perceived, through interactions between V1
and later visual areas.
- Constrains models of binocular rivalry (rivalry
hierarchy: both early and late).
- Constrains models of processing and circuitry in V1
(waves are slow relative to action potential propagation
and synaptic transmission).