Lesions of the medial prefrontal cortex of guinea pig inhibit acoustic startle reflex / 中华行为医学与脑科学杂志

ABSTRACT

Objective To observe and analyze the role of different subfields of medial prefrontal cortex (mPFC) in the expression course of startle reflex.Methods 24 healthy male British kind of albino guinea pigs were randomly divided into 4 groupsanterior cingulated cortex lesion ( n =6) and sham-lesion ( n =6) ( Experiment 1 ) ; prelimbic cortex lesion/joint lesion of prelimbic cortex and anterior cingulated cortex(n=6) and sham-lesion ( n =6) ( Experiment 2 ).The animals were injected lidocaine ( lesion ) or physiological saline ( sham-lesion ).Each group received paired training of conditioned stimulus( CS,a tone) and unconditioned stimulus (US,a air puff),to observe the acoustic startle reflex(ASR) change of these groups.Results As the results of experiment 1 suggested,SR rate did not change significantly after anterior cingulated cortex lesion ( time effectF =15.421,P =0.098 ; group effectF =14.753,P =0.084).As the results of experiment 2 suggested,SR rate did not change significantly after prelimbic cortex lesion ( time effectF =14.975,P =0.178 ; group effectF =18.643,P =0.089).When prelimbic cortex and anterior cingulated cortex were lesioned at the same time,SR rate declined significantly and didn ' t recover with the following training ( group effectF =67.743,P =0.009 ).ConclusionLesions of the prelimbic cortex and anterior cingulated cortex in mPFC cause the significantly decline of acoustic startle reflex( ASR),which don' t recover with the following training.This study indicates that mPFC involves in the regulation of ASR,but the regulation mechanism needs to be discussed.