110429 journal club
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Transcript of 110429 journal club
Experimental Setup
• 21 Adult Rats (308 cells)• General Anesthesia for surgery
– Pentobarbital + atropine, recover 4-5hr
• IM d-tubocurarine to paralyze muscles• Glass microelectrodes 7-12Mohm with fast green,
3M KCl• Oscillatory and ramp hold stimuli from a
polygraph motor– 1-2mm displacement, 15-100mm/s^2.
• Generally, histograms are 15 repetitions
Unit WaveformsRegular Fast Spiking
Layer 4 15-50 /s spont firingTimecourse 2x faster than RSSmaller amplitude that shrinks during burstsBroad directional selectivity
Layer 2-6 1-15/s spont firingMore reliable evoked firing up to 40Hz750-3000uVL4 - Sharp spatial tuning (<90 degrees)
Evoked Spike EntrainmentRegular Fast Spiking
Typically first pulse only, max 1AP/cycleSome frequency tuning
Typically every pulse, burst/cycle
15 stims8Hz 20Hz 40Hz 8Hz 20Hz 40Hz
Deflection Response Examples
FSU w/ inhibition
20Hz?
A-E = Different RSUs
Direction Selective Transient Direction Selective Maintained Transient & Maintained
Directional Tuning
Spontaneous Rate
Away from Rest
Towards Rest
12 UnitsGenerally 2mm displacement
Transient
Steady-State
FSUs
SimilarAcross whiskers
SimilarAcross Stim style
Layer specific distribution of single/multiwhisker units
Location via lesion, dyes, currentsSingle Whisker UnitsII/III = 61%IV = 85%V/VI = 36%
Rows
Same
Diff
Whiskers
2
>3
Experimental Setup
• 16 Adult Rats (124 cells)
• General Anesthesia for surgery– Pentobarbital + atropine, recover 4-5hr
• IP gallamine triethiodide + pancuronium bromide to paralyze muscles
• Glass microelectrodes 7-12Mohm with fast green, 3M NaCl
• Orthogonal piezos on tube, 2-5 tubes on whiskers– 1mm displacement, 200ms, 100-135mm/s^2.
Asymmetry of surround inhibition
• PW = C2.
• SWs = C1, C3
• Suppression greater C3-> C2 lesser C1->C2
How do the response characteristics of S1 thalamcortical projection neurons
differ from their targets?
Experimental Setup
• 26 Adult Rats – 242 RSU, 135 TCU
• General Anesthesia for surgery
– Ether + Pentobarbital
• Fentanyl anesthesia
• Glass microelectrodes 7-12Mohm with fast green
• Guide hole triangulation of barrel
• Double Barrel 3M NaCL / HRP
Thalamocortical vs. Regular spiking
TCU : Minimal surround inhibitionBroader multiwhisker sensitivity
Response dynamics
TCU : Similar spikes per deflection onsetMore spikes per offsetHigher rates in the 33% slowly adapting units
Strong Directional selectivity in TCUs
Directionally consistentReponds to ON one way,OFF opposite way
Directional tuning of TCU inhibitionSW excitatory response required SW excitatory response not required
Inhibitory receptive field comparison
RSU – Single WhiskerRSU – Multi WhiskerTCU – Single WhiskerTCU – Multi Whisker
Cell class comparisonSpontaneous & Transient spike rate
Proportion / Rate ofsustained activity
Proportion of cells Proportion of cells
What is the timing and propagation of signals from whisker through cortical
layers and across cortical columns
Experimental Protocol
• Adult Rats
• Urethane anesthesia
• Localization by dye staining and CO
• Carbon fiber microelectrodes (382 cells)
• Modal latency was measured from the major peak in the latency histogram, providing this peak was 3+ counts.
• 3+ cells / penetration (min 1 in IV)