The Funcitonal Plasticity Of Pyramidal Neurons And Gabaergic Neurons In Barrel Cortex Induced By A Loss Of Vibirssa Sensory Input

Objective: By establishing animal models that the vibrissa sensory informationdecreased, we aim to analyze the changes of the spike encoding and intrinsic propertiesof pyramidal neurons and GABAergic neurons and to investigate the mechanismunderlying the plasticity of neuronal networks in barrel cortex.Methods:1. The vibrissae of mouse pups on the right side of snout were clipped lessthan1mm in length once24hours, which starting from PND7to PND17, to establishof animal models that the vibrissa sensory information decreased.2. Ten days afterprocedure, mouse’s olfactory function was tested in T maze and the successful rate ofmoving toward food direction was used to identify olfactory function.3. The corticalslices including barrel cortex (400m) were quickly sectioned from mice a week aftertheir wickers input decreased. The slices were then held in the oxygenated artificialcerebrospinal fluid (ACSF) at25C for1-2hours. A slice was transferred to asubmersion chamber and perfused with oxygenated ACSF at31C. Sequential spikepatterns (inter-spike intervals) and intrinsic properties (threshold potentials) ofGFP-labeled GABAergic neurons and pyramidal neurons in barrel cortex were recordedunder DIC/fluorescent microscopy (Nikon E600-FN) by an Axoclamp-200B amplifier.The spontaneous inhibitory postsynaptic currents (sIPSCs) including interval of events(IE) and amplitude of GABA neurons were collected by the voltage clamp whole-cellrecording method and inputted into pClampex10.1for data acquisition.Results:1. The food selection success rate in model group was significantly higher thanthat of normal mice;2. Compared with the normal groups, the capacity of spikeencoding in pyramidal neurons increased significantly, the action potential intervalshortened (P<0.05), and the threshold potential (Vts) reduced (P<0.05); the firing ofaction potentials of GABAergic neurons in barrel cortex reduced significantly, action potential of ISI interval prolonged (P<0.05), the threshold potential (Vts) increased(P<0.05) in model group.3. The experimental results of voltage clamp mode showedthat the sIPSC frequency and amplitudes were downregulated after a loss of whiskertactile input(P<0.05).Conclusion:1. Whisker input deprivation upregulates olfactory function in mice.2. Inmouse modal of whisker tactile deprivation, barrel cortical pyramidal neurons arefunctionally upregulated, whereas GABAergic neurons are downregulated.3. In a lossof whisker tactile sensation input,the upregulation of excitatory neurons anddownregulation of inhibitory neurons lead to the function of barrel cortex to be shiftedtoward strengthening, which enhances the sensitivity of neuronal networks in barrelcortex to whisker tactile input, a homeostatic process of neuronal encoding.