Galanin Improves the Performance of Rats During the Auditory Discrimination Tasks

In another study, we have found that the neurons in the auditory cortex of anesthetized rat increased their responses to the auditory stimulus each time after direct local infusion of galanin. In the present study we investigated whether galanin application can amplify the neuronal signals in the auditory cortex produced by electrical stimulation in the cortex. We adopted a behavioral apparatus having three holes. The rat approached the center hole before approaching the leftmost and the right most holes after a cue was delivered. The rat with bilateral implantations of electrode arrays in both hemispheres of the auditory cortex was trained to approach the left or right hole of a behavioral apparatus to retrieve a reward depending on whether the right or left auditory cortex was electrically stimulated. A drug infusion cannula was implanted in each hemisphere of the auditory cortex. After training, the rat was able to perform the task with the correct rate of 100%. We will then adjust the current of electrical stimulus to adjust performance to a correct rate of about 70% and examine whether infusion of galanin into one hemisphere would increase the correct rate of reward retrieval in the opposite hole. At a different session at which we set the baseline performance at 80% correct rate, infusion of galanin antagonist (M40) worsened the performance in the correct rate. Moreover, Artificial Cerebral Spinal Fluid (ACSF) was used as the vehicle control to make sure the increase or the decrease of the correct rate is correlated to galanin or M40. Our results of the present study would provide strong evidence that galanin is an attention related chemical from behavioral experiment.