Effects Of Microelectric Stimulation Of Auditory Cortex Dordocaudal Field On The Response Properties Of The Anterior Field In Guinea Pig

Backgroundauditory plasticity mechanisims is the research focus of neuroscience.the plasticity plays very important role in controling brain variability and adaptability.many important functions of human brain,such as perception, learning, memory, language, consciousness, emotions and movement control,are all so closely related to auditory perception.Auditory plasticity refers to the ability of the auditorysystem structure and function change with environmental conditions.In the study of auditory plasticity, it is appropriate to use the wakefulness animals, which is more close to the normal. But it is difficult to take a long time recording of neuron action potential. The using of anesthetics, makes a long record of neuron action potential possible.stabilized after a certain time, whether there is a same law or not in Guinea pigs anesthesia? We use the spike counts and first spike latency of characteristic frequency as indicators to observe the effect of a single intraperitoneal injection of urethane or sodium pentobarbital anesthesia to the spike counts and first spike latency of guinea pig primary auditory cortex neurons. Experimental methods:1)13guinea pig,Weighted220～350g, either sex,were randomly divided into two groups, one group have5guinea pig, One group anesthetized with sodium pentobarbital another group anesthetized with urethane8(FSL5,FTC3).2) anesthesia methods:a single intraperitoneal injection of1%sodium pentobarbital, or20%urethane anesthetic. Recording areas:the primary auditory cortex. Recording Method:extracellular recording, selecting different intensities, from OdB to80dB with10dB a step, repeated40times in each intensity of the characteristic frequency (CF), recorded every three minutes. Data processing: analysis the spike counts and first spike latency of each period in CF and the MT to+30dB SPL, Compare the tendency of spike counts and first spike latency during anesthesia. After a single intraperitoneal injection of urethane,we observe is there any change in guinea pig primary auditory cortex neurons with the anesthesia metabolic processes using FTC as an indicator.Experimental results showed that:Result:With the Pentobarbital sodium anesthesia, the spike counts gradually reduced at the beginning of a period of time after anesthesia, and then gradually reduced with the time extended. The first spike latency in characteristic frequency (CF) gradually increased in the first3hours and decreased in the following3hours.With the Urethane anesthesia:the spike counts gradually increased after anesthesia, and then reduced gradually with the time extended. The first spike latency in characteristic frequency (CF) gradually increased,and then stabled at a certain level.Neurons characteristic frequency and the FTC by the anesthesia less affected.Conclusion:urethane anesthesia was maintained for a long time, the role of stable neuron characteristic frequency characteristics meet the requirements of long animal experiments. Such as micro-current to stimulate the auditory cortex dordocaudal neurons, and the anteriod field of the cortex, the anterior neural response characteristics which features change?We can take this speculation to the auditory cortex of the anterior and posterior region of neurons projecting relationship.Methods:1) experimental animals:21guinea pigs, weight220to350g, male or female.2) recording method:given the noise stimulus to find the neurons with acoustic response, and then different frequencies and different intensities of short pure-tone sweep will be performed to identify auditory cortex receptive fields.3) the intensity of electrical stimulation is800nA, the schedule for200us, the frequency of6Hz of micro-current to stimulate the auditory cortex after zone neurons30min record time I hear the acoustic response of the cortex of the. Record the anterior neurons receptive field after30min stimulate (current of800nA,200us,6Hz) of the posterior region of the auditory cortex.Data treatment:to extract the acoustic threshold,frequency tuning curve and the characteristic frequency of the neuron in Brainwave.Result:42neurons have been42neurons in the experimentx including21neurons in primary auditory cortex. Electrical stimulate the auditory cortex neurons in primary auditory changes in the acoustic response characteristics of cortical neurons, namely:1) the frequency tuning curve:nine neurons’curve of the overall enhancement, six neurons’curve perform a whole by inhibition while7neurons’curve unchanged.2) the acoustic response threshold:11neurons sound reaction threshold decreases(average of8dB).Four neurons increases in the acoustic response threshold (average of4dB).7neurons responding to the threshold unchanged.3) neurons characteristic frequency drift:four neurons’characteristic frequency drift from the original characteristic frequency.Conclusion:the stimulation of auditory cortex dorsocaudal field plays an excitatory role in the change of the characteristic response of the primary auditory cortex neurons.There are several possible reasons:first, the interactions of complex neural network in cortex;second, the involving of the limbic system;third,make regulations by brain stem or MGB.