Download Yang Dan

Temporal Specificity in the
Cortical Plasticity of Visual
Space Representation
Interdisciplinary Program in Brain Science
Eye Movement & Vision Research LAB
Hwang, Jae Won
http://www.pgd.hawaii.edu/~cecily/courses/gg313/DA_book/node94.html
Cross Correlation
• Autocorrelation is the correlation between two copies of
the same time-series.
• Autocorrelations can be high for large lags if the data “repeats”.
http://www.pgd.hawaii.edu/~cecily/courses/gg313/DA_book/node95.html
Cross Correlation(cont’d)
• Cross Correlation is to compare two different time series at
various lags rather than two identical series.
• From cross correlation we would expect to learn
two things:
1) The strength of the relationship between the two series
2) The lag that maximizes the coherence
Spike Timing-dependent Plasticity
• A→B stimulation may
strengthen a→b connections
weaken b→a connections
• Synaptic modifications induced by
A→B stimuli may cause the receptive
fields of both groups to shift toward A.
• The shift toward A of receptive fields
should cause a rightward shift in
perception.
Spike Timing of Cortical Neurons
Cross Correlation of Model Neurons
Changes induced by Conditioning
• Intragroup Correlation
Changes induced by Conditioning(cont’d)
• Intergroup Correlation
Shifts in Receptive Fields
Human Perception Localization
• Conditioning-induced shifts in
human perceptual localization.
• Three-bar bisection test
Conclusion
• Asynchronous visual stimuli in different retinal regions induced rapid
changes in cortical representation of visual space, which was likely
mediated by spike timing-dependent modification of intracortical
connections.
• Spike timing-dependent modification of intracortical connections
provides the most natural explanation, although mechanisms related to
contrast adaptation may have caused the conditioning-induced reduction
in receptive field size.