Neural Encoding of Motor Tasks in the Premotor and Motor Cortices
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Presented in April 2019 at the Neural Engineering Poster day at the University of Florida. Based on data from the Hatopoulos laboratory. Using spike trains, peri-event time histographs, and tuning curves to examine how the brain encodes the planning and execution of motor tasks in the dorsal premotor and primary motor cortices. Winner of Best Poster Overall
![Neural Encoding of Motor Tasks in the Premotor and Primary Motor Cortices
Ray Ward1, Aysegul Gunduz, Ph.D1
J. Crayton Pruitt Family Department of Biomedical Engineering
Neural coding: Representing the world as neural activity
Different parts of the brain encode movement
METHODS: DATA ACQUISITION & ANALYSIS
INTRO RESULTS: ANALYZING THE DATA
Data Acquisition
Fig. 1. A macaque operating a manipulandum : An arm-like
apparatus that can be slid along a 2D plane, positioned in
the center of 8 LEDs.
Data collected and spike sorted as premotor or primary
motor cortex neurons by the Hatsopoulos laboratory
One LED flashes to
indicate a direction
during “instruction” cue
“Go” cue is given and
macaque moves
manipulandum to
indicated LED
Wait 1s
Data Analysis
Spike Trains
Peri-Event Time Histographs
Tuning Curves
RESULTS: TUNING CURVE-FITTING
STIMULI NEURAL
ACTIVITY
ENCODING
DECODING
Internal &
External
EXECUTEPLAN
PREMOTOR PRIMARY
MOTOR CORTEXCORTEX
Raster Plots of Spike Trains
▸ Shows the spike trains from all trials
▸ Each tick represents a spike in neural activity
Trial-trial
variability
Activity around
specific event
Peri-Event Time Histographs (PETHs)
▸ Center a 2s window on a specific event
▸ Divide that window into smaller bins
▸ Count the spikes across all trials
SELECT
Effect of variable
on activity
Orientation Tuning Curves
▸ Take same 2s window from PETHs
▸ Find mean firing rate for each orientation
Neuron
Curve Fitting
Model
Number
of Terms
Adjusted
R2
RMSE
Premotor Cortex
Fourier 1 0.88 1.24
Gaussian 1 0.63 2.21
Sum of Sines
2 0.71 1.94
2 0.86 1.34
Primary Motor
Cortex
Fourier 1 0.43 3.67
Gaussian 1 0.31 4.02
Sum of sines
2 -0.29 5.50
2 0.29 4.10
Dorsal Premotor Cortex (PMd)
DISCUSSION
Increased activity around cue of interest
▸ R2 : Describes the proportion of variance model captures
▸ Adjusted R2 : Penalizes unnecessary additional terms
▸ RMSE: Root mean square of the error
Tuning curves show preferential orientation
▸ Increased activity at 148° for PMd & 156° for M1
Fourier series model best fit for tuning curve
▸ Makes sense: orientation is periodic so curve is periodic
▸ Possibly affected by bimodal raw data for M1
▸ Fourier series fits best: highest adjusted R2 lowest RMSE
▸ PMd: Movement selection/planning after instruction cue
▸ M1 : Movement execution after go cue
Goodness of Fit
REFERENCES
Primary Motor Cortex (M1)
Centered on “instruction” cue Centered on “go” cue
Time [s]Time [s]
Time [s]Time [s]
TrialNumber
TrialNumber
Spikes
SpikesFiringRate[Hz]
FiringRate[Hz]
Orientation [°]Orientation [°]
1J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
[1]
[3]
[1 ] L. Paninski,J. Pillow, andJ. Lewi,“Statisticalmodelsfor neural encoding, decoding,andoptimal
stimulus design,”Prog.BrainRes., vol. 165, pp. 493–507,2007.
[2]D. Purves et al., Eds., Neuroscience,Sixth Edit.Sinauer Associates,2018.
[3] P. DayanandL. F. Abbott, TheoreticalNeuroscience:ComputationalandMathematicalModeling of
NeuralSystems, FirstMIT. MIT Press Books,2005.
[4] D. C. Montgomery andG. C. Runger,AppliedStatisticsandProbabilityforEngineers,Third Edit.John
Wiley & Sons, Inc.
[4]](https://image.slidesharecdn.com/neuralposter2-190610194732/85/Neural-Encoding-of-Motor-Tasks-in-the-Premotor-and-Motor-Cortices-1-320.jpg)
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Neural Encoding of Motor Tasks in the Premotor and Motor Cortices
- 1. Neural Encoding of Motor Tasks in the Premotor and Primary Motor Cortices Ray Ward1, Aysegul Gunduz, Ph.D1 J. Crayton Pruitt Family Department of Biomedical Engineering Neural coding: Representing the world as neural activity Different parts of the brain encode movement METHODS: DATA ACQUISITION & ANALYSIS INTRO RESULTS: ANALYZING THE DATA Data Acquisition Fig. 1. A macaque operating a manipulandum : An arm-like apparatus that can be slid along a 2D plane, positioned in the center of 8 LEDs. Data collected and spike sorted as premotor or primary motor cortex neurons by the Hatsopoulos laboratory One LED flashes to indicate a direction during “instruction” cue “Go” cue is given and macaque moves manipulandum to indicated LED Wait 1s Data Analysis Spike Trains Peri-Event Time Histographs Tuning Curves RESULTS: TUNING CURVE-FITTING STIMULI NEURAL ACTIVITY ENCODING DECODING Internal & External EXECUTEPLAN PREMOTOR PRIMARY MOTOR CORTEXCORTEX Raster Plots of Spike Trains ▸ Shows the spike trains from all trials ▸ Each tick represents a spike in neural activity Trial-trial variability Activity around specific event Peri-Event Time Histographs (PETHs) ▸ Center a 2s window on a specific event ▸ Divide that window into smaller bins ▸ Count the spikes across all trials SELECT Effect of variable on activity Orientation Tuning Curves ▸ Take same 2s window from PETHs ▸ Find mean firing rate for each orientation Neuron Curve Fitting Model Number of Terms Adjusted R2 RMSE Premotor Cortex Fourier 1 0.88 1.24 Gaussian 1 0.63 2.21 Sum of Sines 2 0.71 1.94 2 0.86 1.34 Primary Motor Cortex Fourier 1 0.43 3.67 Gaussian 1 0.31 4.02 Sum of sines 2 -0.29 5.50 2 0.29 4.10 Dorsal Premotor Cortex (PMd) DISCUSSION Increased activity around cue of interest ▸ R2 : Describes the proportion of variance model captures ▸ Adjusted R2 : Penalizes unnecessary additional terms ▸ RMSE: Root mean square of the error Tuning curves show preferential orientation ▸ Increased activity at 148° for PMd & 156° for M1 Fourier series model best fit for tuning curve ▸ Makes sense: orientation is periodic so curve is periodic ▸ Possibly affected by bimodal raw data for M1 ▸ Fourier series fits best: highest adjusted R2 lowest RMSE ▸ PMd: Movement selection/planning after instruction cue ▸ M1 : Movement execution after go cue Goodness of Fit REFERENCES Primary Motor Cortex (M1) Centered on “instruction” cue Centered on “go” cue Time [s]Time [s] Time [s]Time [s] TrialNumber TrialNumber Spikes SpikesFiringRate[Hz] FiringRate[Hz] Orientation [°]Orientation [°] 1J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA [1] [3] [1 ] L. Paninski,J. Pillow, andJ. Lewi,“Statisticalmodelsfor neural encoding, decoding,andoptimal stimulus design,”Prog.BrainRes., vol. 165, pp. 493–507,2007. [2]D. Purves et al., Eds., Neuroscience,Sixth Edit.Sinauer Associates,2018. [3] P. DayanandL. F. Abbott, TheoreticalNeuroscience:ComputationalandMathematicalModeling of NeuralSystems, FirstMIT. MIT Press Books,2005. [4] D. C. Montgomery andG. C. Runger,AppliedStatisticsandProbabilityforEngineers,Third Edit.John Wiley & Sons, Inc. [4]