TEMPORAL CODING IN THE GUINEA-PIG AUDITORY-CORTEX AS REVEALED BY OPTICAL IMAGING AND ITS PATTERN-TIME-SERIES ANALYSIS

The neural network structure of a guinea-pig's primary auditory cortex is estimated by applying pattern-time-series analysis to the auditory evoked responses. Spatiotemporal patterns in click-evoked responses, observed by optical recording with voltage-sensitive dye, are analyzed by time series analysis using a multivariable autoregressive (MAR) mo del. Oscillatory neural activities with a distribution of about 10 sim ilar to 40 Hz in the click-induced evoked responses are found in the c ortical response field. The cortical regions where the distributed neu ral oscillations are generated are identified by pattern-time-series a nalysis. In addition, two types of cortico-cortical connections, unila teral and bilateral connections between the cortical points, are specu lated to be the causes of oscillatory neural activity transfer. It can be said that the so-called synchronized neural oscillation, in the se nse of coherency or correlation between the two evoked responses at th e oscillatory frequency, does not necessarily represent real cortico-c ortical neural connections at the evoked response points.