CHANGES IN INTRINSIC OPTICAL SIGNAL OF RAT NEOCORTICAL SLICES FOLLOWING AFFERENT STIMULATION

Changes in intrinsic optical signal of rat neocortical slices followin g afferent stimulation were recorded using darkfield infrared-videomic roscopy. Response amplitude was linearly related to stimulation intens ity. The intensity of the optical signal reached its maximum 3 s after onset of stimulation and redecayed with a mean time constant of 23 +/ - 7.1 s. The optical signal had a columnar shape. The size of the colu mn was independent from stimulation intensity with stimuli of medium a mplitudes. The extent of the optical signal corresponded to the extent of the electrical activation. Changes in intrinsic optical properties may be a useful tool for the study of spread of excitation in neurona l tissue in vitro.