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(Processing Subject Data)
(Processing Subject Data)
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   text = "RPIT1"
   text = "RPIT1"
==Things to do==
==Things to do==

Revision as of 18:59, 11 November 2008

Brain picture
Beauchamp Lab Notebook

Old Protocols


September 2008 E-Phys Protocol

9/22/2008 Setup and Surgery
1. Identify potential electrodes with combined fMRI/CT
2. Create log file on log computer
3. Record resting activity and assess recording setup (Test signal-to-noise, etc.)

Microelectrode array experiments
Some things to look at:

1. Stimulus selectivity
How does the stimulus-selectivity of microelectrodes differ from large electrodes?
How does stimulus-selectivity vary within a single microelectrode array (MEA)?
2. Response latency/duration
Within an object-selective visual area, do different patches of cortex depolarize at different latencies or for different durations?
3. Receptive Field Size
Do small electrodes have different RFs than big electrodes?
How does RF size vary within and between object-selective visual areas?
4. Gamma oscillation
5. Adaptation
Do microelectrodes demonstrate different adaptation behavior than large electrodes?
6. Choice probability
Does the pattern of activity in object-selective cortical areas (as measured by MEAs) correlate in any way with the subject's behavior?


1. Perception thresholds
Perception thresholds may be lower with microelectrodes because of high current density.
2. Percepts in higher visual areas
If the microelectrodes have smaller RFs or are more feature-selective than the large electrodes, it could mean that sending current through them would activate a more functionally-segregated group of neurons than has previously been possible. If so, microstimulation with microelectrodes may be more likely to evoke percepts in higher-level visual areas than with the large electrodes.

Ryan's Adaptation Experiments
1) Target-detection Selectivity – 20 minutes

• 80 stimuli (+5 target stimuli), 20 blocks
• Stop-sign task (patient reports stop-signs)

2) Repeat-detection Selectivity – 20 minutes

• 80 stimuli, 20 blocks
• One-back task (patient reports repetitions of images)

3) Multiple-repetitions adaptation - 5 minutes

• trial structure: 8 nonselective stimuli, 8 of the same selective stimulus, 8 nonselective stimuli, 8 different selective stimuli. Stopsign appear at random or at the end of each run.
• A rudimentary way to approximate this would be to have several copies of the same image in the image folder, and selecting all of them in the selectivity plugin.


• Now that we can record from all the electrodes simultaneously, it will be less important to identify selective categories. By showing equal amount of all the categories, we can get good sample sizes for several differently-selective electrodes.
•It would be nice to have a modified version of the current Selectivity plugin to satisfy these conditions:
2. Selective stimuli are directly repeated every 8-12 images
3. The stimulus preceding the repeat is always a nonselective stimulus

Electrophysiology Protocols

Presurgical Scanning



In the EMU

Setup Apparatus

Receptive Field Mapping

Electrical Stimulation


Perceptual Biasing


Making Grayscale From Color Images


Todo list

Get rid of bad looking stimuli; make detailed protocol


Processing Subject Data



 3drefit -zdel 1.000 DE_CTSDE+orig


 3dinfo DE_CTSDE+orig




 3dcopy DE_CTSDE+orig DE_CTSDEshift

Then, recenter the z-axis

 3drefit -zorigin 80 DE_CTSDEshift+orig

3dinfo returns





Next, the electrodes positions are manually located and saved as Tags. Then, these positions can be used to create an Electrodes file for display as spheres in SUMA. To label the electrodes, a separate file can be created with the label for each electrode. Sample file electrodes.1D

 -20.43       81.53       4.254  0.0 0.0 0.0 1.0  1.1   
 -28.43       76.84       4.254  0.0 0.0 0.0 1.0  1.1           
 -36.43       70.28       4.254  0.0 0.0 0.0 1.0  1.1             
 -42.43       61.84       4.254  0.0 0.0 0.0 1.0  1.1           
 -48.43       54.34       4.254  0.0 0.0 0.0 1.0  1.1            
 -52.43       44.03       4.254  0.0 0.0 0.0 1.0  1.1            

Sample file

 coord_type = "mobile"
 default_SO_label = "CURRENT"
 bond = "surface"
   default_color = '1.0 1.0 1.0'
 default_font = 'he14'
 coord = "-20.43       81.53       4.254"
 col = "0.1 0.9 0.1"
 text = "RPIT1"

Things to do


Enable online scrambling LOOKING INTO IT
Enable online color to black and white conversion LOOKING INTO IT


Analyze data from LR to see where the RFs are




can we extend stimulation into the response window?

Personal tools