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Sensorimotor multivariate projects
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Sensorimotor multivariate projects Frank Leone, Ivan Toni, Pieter Medendorp
description
Frank Leone, Ivan Toni, Pieter Medendorp. Sensorimotor multivariate projects. Sensorimotor multivariate projects. Distributed meeting, 24 November 2011. Two projects. Saccade generation 18 locations Effector specificity Three effectors Repetition suppression General approach: - PowerPoint PPT Presentation
Transcript of Sensorimotor multivariate projects
Sensorimotor multivariate projectsFrank Leone, Ivan Toni, Pieter Medendorp
Saccade generation• 18 locations
Effector specificity• Three effectors• Repetition suppression
General approach:• Have multiple blocks• Fit GLM per block• Have multiple values per voxel (e.g.,
dir, amp, loc)• Classify t-values (SVM, searchlight)
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Two projects
The domain: saccade generation
Both the Frontal Eye Fields (FEF)and Posterior Parietal Cortex (PPC)feature tuning for saccade
• Direction• Amplitude?
It is unclear why no amplitude selectivity has been found in humans
Taking advantage of the increased sensitivity of multivariate analysis, we are busy filling this gap
Primates Humans
Direction
FEF Bruce & Goldberg, 1985Schall et al, 1995
Kastner et al, 2007Hagler Jr. & Sereno,
2007
PPC Gnadt & Andersen, 1988Thier & Andersen, 1998
Sereno et al, 2001Hagler Jr. & Sereno,
2007
Amplitude
FEF Bruce & Goldberg, 1985 ?
PPC Gnadt & Andersen, 1988Thier & Andersen, 1998 ?
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Background
Standard delayed saccade setup
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Distributed meeting, 24 November 2011
Sensorimotor multivariate projects
Sereno kinda way
• Presentation– Consistent delays– Around the clock– Phase-based
analysis
• Result: nice maps
Phase-based mapping a la Sereno
& PhaseFreq
Am
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Sereno et al, 2001
Distributed meeting, 24 November 2011
Sensorimotor multivariate projects
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500 ms.
3000 ms.
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750 ms.
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750 ms.
The domain: saccade generation
Both the Frontal Eye Fields (FEF)and Posterior Parietal Cortex (PPC)feature tuning for saccade
• Direction• Amplitude?
It is unclear why no amplitude selectivity has been found in humans
Taking advantage of the increased sensitivity of multivariate analysis, we are busy filling this gap
Primates Humans
Direction
FEF Bruce & Goldberg, 1985Schall et al, 1995
Kastner et al, 2007Hagler Jr. & Sereno,
2007
PPC Gnadt & Andersen, 1988Thier & Andersen, 1998
Sereno et al, 2001Hagler Jr. & Sereno,
2007
Amplitude
FEF Bruce & Goldberg, 1985 ?
PPC Gnadt & Andersen, 1988Thier & Andersen, 1998 ?
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Background
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Methods: paradigm
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500 ms.
6*500 ms.
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750 ms.
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750 ms.
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Methods: Analysis
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
- Stimulus spike
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Fitted per location
The classifier actually got:
Direction
Amplitude
Location
And was trained to classify location
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Surface based
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Methods: SummaryDelayed saccade task
18 targets:- 6 directions- 3 amplitudes
GLM for all 18 locations to get beta’s/t statistics
Move searchlight over the brain, try to distinguish locations
Calculate back to direction and amplitude
Noting performance, significance, and tuning
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500 ms.6*500 ms.
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750 ms.
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750 ms.
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Results: Performance
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Results: Max voxel tuning
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Results: Regional tuning
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
So…Found direction, amplitude, and location information
in the expected regions
Can look at this tuning in greater detail than possible before.
- Model focused on stimulus
- It is actually a regression problem
- Participants not perfect
But…
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Effector specificity projectSfN 2011 poster
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
So:Specificity as expected, gradients confirmed
Interesting similarities and differences between importance and confusion
Include sides
Include repetition suppression
Analyze using RSA (* 2)
To do:
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
Sensorimotor multivariate projects
Distributed meeting, 24 November 2011
General conclusionMulti-valued searchlight
Using t-values per block
Makes for great performance
Confusion matrices
For behavior/EMG
Is the next step to make
