Plasticity Of Characteristic Frequency In The Rat Auditory Cortical Neurons

Using conventional electrophysiological technique, we investigated the plasticity of characteristic frequency (CF) of neurons in rat auditory cortex (AC) by determining CF and frequency tuning curve (FTC) shifts of neurons.1. In the AC, when the frequency difference between conditioned stimulus frequency (CSF) and the CF of neuron was in 1.0 kHz with conditioned stimulation for 30 min, 61 of 120 neurons (50.8%) completely shifted their CF to the CSF. According to the CF shift direction, complete CF shifts were classified into three patterns: CF shifts toward lower frequency side (LFS) of neuron's FTC. CF shifts to higher frequency side (HFS) and CF shifts to both LFS and HFS. Among them, some neurons with higher CF, bigger Q10-dB value and symmetry index >0, the probability of CF shift toward HFS of FTC is higher than other neurons. The results suggest that the experience can alter CF in rat auditory cortical neurons.2. Parameters of conditioned stimulus and CS paired with noise differ the plasticity of neuron in primary cortex of rat(1) Intensity/Sound level of conditioned stimulus differs the type of CF plasticity. When the intensity/sound level was +5dB above minimum threshold and the CF of neuron was in 1.0 kHz with conditioned stimulation for 30 min, only 9. 09% neurons shift non-completely and the rest have no shift. When the intensity/sound level is +20dB above the...