IGERT poster.pptx
The Adaptive Field and Information Storage in the Retina! Stanford IGERT Program in Emergent Functions of Neural Systems!
David B. Kastner1 & Stephen A. Baccus2! 1Neuroscience Program 2Department of Neurobiology, Stanford University School of Medicine, Stanford, CA!
Direction selectivity!
The retina stores the location of a previously moving object!
A mechanistic model of sensitization! Intensity
The retina performs sophisticated computations to process the visual world.! Pattern adaptation!
0
10
Time (s)
Hosoya et al. 2005!
Differential motion sensitivity!
0 .2
Time (s)
v
Time (s)
0 .2
÷
Time (s)
w
v
One period of the stimulus (top) and average response for one type of ganglion cell (bottom)!
-
0 1 Time (s)
Synapse! y
Camouflage presents a challenge to the visual system, since the object mimics the spatial pattern of the background. But, motion distinguishes the spatio-temporal pattern of object and background. Storage of the location of the moving object would assist camouflage detection!
Methods! Salamander retinas were removed from the animal, and perfused with Ringerʼs solution to keep it alive. Ganglion cells were recorded extracellularly with a 60 electrode array. Stimuli were presented using Matlab Psychophysics Toolbox.!
Adapting On
0 5
Adapting Off
Time (s)
÷
1
Time (s)
w
y
z
÷
z
Sensitization may arise through a combination of inhibitory and excitatory adapting pathways. Letters show interim stages in the model.! -1
0
1 -1
0
1 -1
0
1
Sensitization requires inhibition!
Distance from center (mm) Normalized firing rate binned over the objectʼs position at the end of fast motion (Early) and averaged across trials.!
Adaptive index
However, the higher brain performs additional types of computation, a prominent one being information storage, a computation from which visual processing can benefit. !
Sensitizing 2
Sensitization underlies information storage! Learly
Llate
300 µm!
1
Picro
0
-1 0
1
2
Time (h)
Intensity
Olveczky et al. 2003!
These computations can be classified into two general categories: feature selectivity, the highlighting of a useful feature in the visual world, or efficient encoding, a reduction of redundancies in the visual world.!
Normalized rate
A local increase in sensitivity stores location information! Barlow & Hill 1963! Huberman et al. 2009!
Excitatory channel!
Inhibitory channel!
Stimulus!
Example response histograms (left) and average behavior (right) before during and after addition of picrotoxin, a drug that blocks one of the major inhibitory neurotransmitters of the retina—GABA.!
4s
Conclusions!
Three kinds of adaptive fields!
• The retina can perform information storage!
Video monitor!
• Ganglion cells control their sensitivity using three different adaptive fields! • Monophasic adapting!
P
P
B
B
G
P H
B A
A
G
P H
H
B A
G
P H B A
G
G
• Monophasic sensitizing!
Response histograms for three cells, each at two locations relative to the local high contrast.!
Sensitizing!
Adapting On!
Adapting Off!
array!
The distance between a cell and the stimulus was measured by taking the difference between the center of the stimulus and the center of the region in space to which the cell was most sensitive, its receptive field! The nature of the adaptation of a cell was captured by the adaptive index (A), a measure which we have previously shown to be a good stand-in for the sensitivity of a cell.!
A=
d
0.4 0.8mm
Learly − Llate Learly + Llate
0.4 0.8
0.4 0.8
Adaptive Indices (A) for all cells, as a function of distance (d) from the high contrast spot!
• Center adapting, surround sensitizing ! • Sensitization within the adaptive field enables information storage! • Sensitization may arise through a combination of known retinal processes! • Sensitization requires inhibition, a form of retinal processing whose role in adaptation has been largely absent ! SAB supported by grants from the NEI, Pew Charitable Trust, McKnight Foundation, and Sloan Foundation. DBK supported by the Stanford MSTP, and the Stanford IGERT program on emergent functions of neural systems, NSF Award # 0801700.
David B. Kastner1 & Stephen A. Baccus2! 1Neuroscience Program 2Department of Neurobiology, Stanford University School of Medicine, Stanford, CA!
Direction selectivity!
The retina stores the location of a previously moving object!
A mechanistic model of sensitization! Intensity
The retina performs sophisticated computations to process the visual world.! Pattern adaptation!
0
10
Time (s)
Hosoya et al. 2005!
Differential motion sensitivity!
0 .2
Time (s)
v
Time (s)
0 .2
÷
Time (s)
w
v
One period of the stimulus (top) and average response for one type of ganglion cell (bottom)!
-
0 1 Time (s)
Synapse! y
Camouflage presents a challenge to the visual system, since the object mimics the spatial pattern of the background. But, motion distinguishes the spatio-temporal pattern of object and background. Storage of the location of the moving object would assist camouflage detection!
Methods! Salamander retinas were removed from the animal, and perfused with Ringerʼs solution to keep it alive. Ganglion cells were recorded extracellularly with a 60 electrode array. Stimuli were presented using Matlab Psychophysics Toolbox.!
Adapting On
0 5
Adapting Off
Time (s)
÷
1
Time (s)
w
y
z
÷
z
Sensitization may arise through a combination of inhibitory and excitatory adapting pathways. Letters show interim stages in the model.! -1
0
1 -1
0
1 -1
0
1
Sensitization requires inhibition!
Distance from center (mm) Normalized firing rate binned over the objectʼs position at the end of fast motion (Early) and averaged across trials.!
Adaptive index
However, the higher brain performs additional types of computation, a prominent one being information storage, a computation from which visual processing can benefit. !
Sensitizing 2
Sensitization underlies information storage! Learly
Llate
300 µm!
1
Picro
0
-1 0
1
2
Time (h)
Intensity
Olveczky et al. 2003!
These computations can be classified into two general categories: feature selectivity, the highlighting of a useful feature in the visual world, or efficient encoding, a reduction of redundancies in the visual world.!
Normalized rate
A local increase in sensitivity stores location information! Barlow & Hill 1963! Huberman et al. 2009!
Excitatory channel!
Inhibitory channel!
Stimulus!
Example response histograms (left) and average behavior (right) before during and after addition of picrotoxin, a drug that blocks one of the major inhibitory neurotransmitters of the retina—GABA.!
4s
Conclusions!
Three kinds of adaptive fields!
• The retina can perform information storage!
Video monitor!
• Ganglion cells control their sensitivity using three different adaptive fields! • Monophasic adapting!
P
P
B
B
G
P H
B A
A
G
P H
H
B A
G
P H B A
G
G
• Monophasic sensitizing!
Response histograms for three cells, each at two locations relative to the local high contrast.!
Sensitizing!
Adapting On!
Adapting Off!
array!
The distance between a cell and the stimulus was measured by taking the difference between the center of the stimulus and the center of the region in space to which the cell was most sensitive, its receptive field! The nature of the adaptation of a cell was captured by the adaptive index (A), a measure which we have previously shown to be a good stand-in for the sensitivity of a cell.!
A=
d
0.4 0.8mm
Learly − Llate Learly + Llate
0.4 0.8
0.4 0.8
Adaptive Indices (A) for all cells, as a function of distance (d) from the high contrast spot!
• Center adapting, surround sensitizing ! • Sensitization within the adaptive field enables information storage! • Sensitization may arise through a combination of known retinal processes! • Sensitization requires inhibition, a form of retinal processing whose role in adaptation has been largely absent ! SAB supported by grants from the NEI, Pew Charitable Trust, McKnight Foundation, and Sloan Foundation. DBK supported by the Stanford MSTP, and the Stanford IGERT program on emergent functions of neural systems, NSF Award # 0801700.
