Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
1 R. Rao, 599E: Lecture 3
CSE 599E
Lecture 3:
Recording/Stimulation Techniques
2 R. Rao, 599E: Lecture 3
What’s on the menu?
F Recording and Stimulation Techniques Invasive
Semi-Invasive
Non-Invasive
3 R. Rao, 599E: Lecture 3
Components of Brain-Computer Interfacing
4 R. Rao, 599E: Lecture 3
Invasive Recording
Intracellular Recording
at the Soma
Extracellular Recording
near the Soma soma (cell body)
5 R. Rao, 599E: Lecture 3
Intracellular Recording using Patch Clamp
6 R. Rao, 599E: Lecture 3
Array of silicon electrodes with platinum-plated tips
Extracellular recording of neural spikes
Array is implanted in an area of the cerebral cortex
(Work of Andersen & colleagues, Caltech)
Extracellular Recording using Multielectrode Arrays
7 R. Rao, 599E: Lecture 3
From Spikes to Firing Rate
Extracellular spike train
Rectangular Window (100 ms)
Sliding Window (100 ms)
Gaussian Window ( = 100 ms)
Causal Window (1/ = 100 ms)
8 R. Rao, 599E: Lecture 3
From Firing Rates to Tuning Curves: Tuning Curve of a Neuron in Primary Motor Cortex (M1)
Spike trains as a function of hand reaching direction
Cosine Tuning Curve
Preferred direction
9 R. Rao, 599E: Lecture 3
Movement Direction can be Predicted from a
Population of M1 Neurons’ Firing Rates
Population vector = sum of
preferred directions weighted
by their firing rates
Population vectors
(decoded movement
direction)
Actual arm movement
direction
Actual arm movement
direction
10 R. Rao, 599E: Lecture 3
Somatotopic
Organization of
M1 (a.k.a. the
“homunculus”)
11 R. Rao, 599E: Lecture 3
Semi-Invasive Recording
12 R. Rao, 599E: Lecture 3
Electrocorticography
(photo courtesy Seattle Times)
13 R. Rao, 599E: Lecture 3
Optical Imaging
Transgenic mouse
expressing green
fluorescent protein
(GFP) in a
subpopulation of
neurons
Oregon Green
calcium
sensitive dye
stained
neurons
14 R. Rao, 599E: Lecture 3
Non-Invasive Recording
15 R. Rao, 599E: Lecture 3
Electroencephalography (EEG)
10-20 System for Electrode Locations
Measures electrical fluctuations caused by post-synaptic
potentials from thousands of neurons oriented radially to scalp Tens of microvolts range
Poor spatial resolution (cm2)
Good temporal resolution (ms)
16 R. Rao, 599E: Lecture 3
Example of EEG Oscillatory Potentials
17 R. Rao, 599E: Lecture 3
Magnetoencephalography (MEG)
Measures magnetic fields produced by activity of thousands of
cortical neurons oriented perpendicular to the cortical surface Magnetic fields not distorted by skull and scalp
Better spatial resolution than EEG
Expensive and bulky
18 R. Rao, 599E: Lecture 3
Functional Magnetic Resonance Imaging (fMRI)
F Measures changes in blood
flow due to increased
activation of neurons in an
area
F Relies on paramagnetic
properties of oxygenated
and deoxygenated
hemoglobin in the blood
F Produces images showing
blood-oxygenation-level-
dependent signal changes
(BOLD)
19 R. Rao, 599E: Lecture 3
Example fMRI Images (word reading task)
http://www.med.nyu.edu/thesenlab/group/fmri.html
20 R. Rao, 599E: Lecture 3
Functional Near-Infrared Spectroscopy (fNIR)
21 R. Rao, 599E: Lecture 3
Stimulation
22 R. Rao, 599E: Lecture 3
Extracellular Microelectrodes
F Examples: Cochear implant, DBS
23 R. Rao, 599E: Lecture 3
Microstimulation can alter decision making
(Hanks et al., 2006)
24 R. Rao, 599E: Lecture 3
Transcranial Magnetic Stimulation (TMS)
25 R. Rao, 599E: Lecture 3
Next Class:
Signal Processing and
Machine Learning for BCI