The Function Plasticity Of Different Types Of Neurons In The Associative Learning And Memory At Olfactory Cortex In Mice

Objective: By establishing animal model of associative learning memory and adopting Tmaze experiment to test whether information extraction is mutual, using the method ofelectrophysiology experiment, we aim to analyze the changes of synaptic transmissioneffect and intrinsic properties of Glutamatergic neurons and GABAergic neurons toinvestigate cellular mechanism in olfactory cortex.Methods:1. The establishment of the animal model of associative learning memory:Establishing whisker tactile and olfactory sensation about behavioral in mice(PND10).We chose butyl acetate as the odor source of olfactory stimuli for the conditionedstimulus, However,the unconditioned stimulus is5Hz whisker tactile stimuli.2.The mice were divided into four groups: normal group, olfactory stimulation group,whisker stimulation group and whisker-olfactory stimulation group. Application T mazemouse olfactory function changes, the experiment mice were given5Hz tentacles tactilestimulation, the mice avoided the probability of butyl acetate as the identification ofindicators raised its olfactory function3. Patch clamp experiments: the cortical slices including olfactory (400μm) were quicklysectioned from mice10days after successes of conditioned reflex,The slices were thenheld in oxygenated artificial cerebrospinal fluid (ASCF) at25℃for1-2hours. A Slicewas transferred to a submersion chamber and perfused with oxygenated ASCF at31℃. Sequential spike patters(inter-spike intervals) and intrinsic properties(ARP；Vts；Vr；Input-Output) of Glutamatergic neurons and GABAergic neurons in olfactory cortexwere recorded under DIC/fluorescent microscopy(Ninkon E600-FN) by anAxoclamp-200B amplifier. recorded the sIPSCs and sEPSCs Interval of including thecurrent interval events(IE) and current amplitude (Amplitude) data with voltage clampwhole-cell recording method, processed the input signal data with Clampex10.1.Results:1.Behavioral results:（1）The successful rates of avoiding the butyl acetate inmice only accepted olfactory stimulation showed higher than those in controlmice(P<0.05).（2）Compared with control group,the successful rates of avoiding the butylacetate of the whisker stimulation group in mice has no obvious change(P>0.05).（3）The mice which accepted whisker-olfactory stimulation for10days can establish conditionedreflex when given5Hz whisker tactile stimulation as the conditioned stimulus, whichmanifest higher in the successful rates of avoiding the butyl acetate than the controlgroup(P<0.01). They also showed significant difference compared with the tactiletraining group(P<0.05).2. The experiment results of Patch clamp:(1) The experimental results of voltage clampmode showed that the sEPSCs frequency and amplitude at Glutamatergic neurons wereupregulated after whisker-olfactory stimulation（P<0.05). the frequency and amplitudewere downregulated after whisker-olfactory stimulation of the sIPSCs at Glutamatergicneurons and sEPSCs at GABAergic neurons（P<0.05).(2) compared with control groups,the intrinsic properties of Glutamatergic neurons inolfactory cortex from mice with whisker-olfactory stimulation show the significantincreased in spike encoding, the action potential interval shortened(P<0.01) as well as theabsolute refractory periods（P<0.05) and the number Issue of per unit time in actionpotential increased（P<0.05). The intrinsic properties of GABAergic neurons show thesignificant decreased in spike encoding, the action potential interval increasesd(P<0.01)as well as the absolute refractory periods prolonged（P<0.05) and the number Issue of perunit time in action potential decreased （P<0.05).Conclusion:1.The olfactory in mice increased sensitivity after the repeated stimulation.so the olfactory may changes plasticity of facilitation.2. The mice which acceptedwhisker-olfactory stimulation formed associative learning memory, when gived theconditioned stimulus, the probability of mouse avoidance of butyl acetate were high,indicating that the information extraction in associative learning memory is mutual.3.Theoffunction of Glutamatergic neurons upregulated and downregulated of GABAergicneurons in olfactory cortex lead to the olfactory function enhancement.