1 / 13

Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex

Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex. Jason N. D. Kerr, Christiaan P. J. de Kock, David S. Greenberg, Randy M. Bruno, Bert Sakmann, and Fritjof Helmchen. Take Home Points:. 1. Sparse spiking, no precise patterns.

helene
Download Presentation

Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spatial Organization of Neuronal Population Responses in Layer 2/3 of Rat Barrel Cortex Jason N. D. Kerr,Christiaan P. J. de Kock, David S. Greenberg, Randy M. Bruno,Bert Sakmann,and Fritjof Helmchen Take Home Points: 1. Sparse spiking, no precise patterns. 2. Spatially organized probalistic spiking patterns. 3. Position Not related direction sensitivity (unlike afferents) 4. Population coding: Each feature  many neurons. Each neuron  several features. • May facilitate integration of multiple whiskers.

  2. Mutual Information : How much information two things share. . . . . ? A measure of how knowledge about one thing reduces your uncertainty about another thing. ~ a more sophisticated correlation.

  3. Rationale: Large single cell variability. Sparse and short-lived patterns BUT could have an unambiguous pattern, but requires many neurons. (Think sample size) Methodologically: Development of spatial maps of neural activity. – normally impossible with extracellular recording.

  4. Rat Barrel Cortex • Rodent somatosensory cortex. • Single whisker  discrete structures (whisker barrels) separated by regions called septa. • Same geometric order as whiskers. • Model system for cortical columns. • Organized into layers. Layer IV (L4): individual neurons -- consistent trial-to-trial, strong directional tuning. • However, L2/L3 layer does not. 1: Woolsey and Van der Loos, 1970

  5. Methods Calcium Indictors Location of all cells Single-cell and single-spike resolution. Two-Photon Microscopy Skull exposed, optical imaging while stimulating whisker. Patch-clamp recordings – visually targeted. Random whisker deflected for 500ms. Interstim ~3-6 sec Cortex sectioned and area of WB determined. ….. Then a significant variety of analysis.

  6. Layout & Identification Deflection  transients similar to spontaneous ones. Electrical and microscopy produced similar results.

  7. Question: Spatial organization? Stimulated whisker Septa near whisker. Conclusion: (1) Depends on distance from BCC (2) Highly variable Nearby whiskers (3) For both onset & offset (4) Highly significant topology. (5) Offset ~ onset, but smaller. (6) Spontaneous: all similar.

  8. Tuning amount varied by individual. Little individual direction tuning. Tuning corrected for Spiking rate. No spatial organization for directional tuning.

  9. Question: Sparse/Dense responses? Conclusions: (1) Varies trial-to-trial (2) Varies greatly between cells. (3) Onset-Offset active cells may vary.

  10. Fraction active by location: Stimulus – different. Spontaneous – similar. Assuming independence does not match the data.  Correlated Activity Subsets activated not consistent trial-to-trial.

  11. Correlations present in spontaneous, but increased with stimulus. Distance between neurons  means little. Distance from BCC  significant meaning. For both spontaneous and stimulus. “During sensory stimulation, neighboring neurons may be bound together by common inputs.” Question: Is effect of distance to BCC on correlation a result of pairs in the BCC being packed closely? Conclusion: No. < 40µm pair distance

  12. Stimulus detection always > false positive. Classification accuracy improves with population size considered. % small errors increased with size. % large errors decreased with size.

  13. Summary Spatially organized – but probalistically Correlated spiking, but variant No discrete subpopulations observed.

More Related