Comparison of escape learning and memory function between marginal division of striatum and hippocampus in rats

Gang JIANG; Siyun SHU; Xinmin BAO; Xuan CHANG

ABSTRACT

BACKGROUND:

Hippocampal structure in brain is the division related to learning and memory, generally it is closely relevant to spatial cognitive activity. Marginal division of striatum is a latest discovered subdivision related to learning and memory function of brain, whether is its learning and memory function different from that in hippocampus?

OBJECTIVE:

To compare the difference, function and importance in learning and memory function between marginal division of striatum and hippocampus in brain and observe the difference in escape learning and memory between marginal division of striatum and hippocampus.

DESIGN:

Completely randomized controlled experiment.

SETTING:

Institute of Neuroscience in Zhujiang Hospital Affiliated to First Military Medical University of Chinese PLA.MATERIALS The experiment was performed in Institute of Neuroscience in Zhujiang Hospital Affiliated to First Military Medical University of Chinese PLA from March 2002 to July 2003. Totally 109 normal male adult SD rats were employed and 75 rats of them were screened as the qualified animals by twice Y-maze test. Randomly, 25 rats were divided into damaged marginal division of striatum group (DMD group), 10 rats were into bilateral fimbria-fornix transection group (FFT group), 30 rats were into the control of marginal division of striatum (MD control) and 10 rats were into the control of bilateral fimbria-fornix group (FF control). After 24 hours training in Y-maze,In DMD group, 10 g/L kainic acid 0.1 to 0.2 μL was used to damage bilateral marginal division of striatum of rats. In MD control, physiological saline of minim dose was injected in bilateral marginal division of striatum of rats. In FFT group, bilateral fimbria-fornix was transectioned. In FF control, the cortical tissue of the superficial layer of bilateral fimbria-fornix was transectioned. The operation was done on the second day after the 2nd screening. The behavior of rats in learning and memory was observed in Y-maze on the 5th day after operation (during 30 times of maze test, if success frequency ≥ 15,normal capacity of learning and memory was identified.).MAIN OUTCOME

MEASURES:

Success frequency of rats in different groups in Y-maze learning before and after operation.

RESULTS:

Of 109 normal male adult SD rats, 75 rats were screened to be qualified after twice Y-maze test. During the experiment, 3 rats were died and other 32 rats fell into disuse for the drug or physiological saline was not injected accurately to the marginal division of striatum. Terminally, 40 rats entered the analysis in total, of which, 11 rats were in DMD group, 9 rats in MD quency in Y-maze learning of rats in DMD group after operation was lower than MD control, FFT group and FF control [(9.27±4.29) times, (22.56±4.25)frequency in Y-maze learning of rats in DMD group after operation was also significantly lower than that before operation [(9.27±4.29) time, (18.27±3.07)FFT group was basically same as FF control and MD control (P=0.660 and P=0.489) and it was basically same to the success frequency in Y-maze learning before operation (P=0.700).

CONCLUSION:

The learning of Y-maze in rats with damaged marginal division of striatum was remarkably reduced and there was no obvious change in learning and memory between the rats with fimbria-fornix transaction and without transaction. It is verified that marginal division of striatum can reflex complex learning and memory behavior in electric Y-maze test, which cannot be achieved in hippocampus. It is further explained the difference of the two divisions in controlling learning and memory in cerebrum, the marginal division of striatum is able to control hippocampus in learning and memory function.