Receptor Mechanism Of Surround Suppression In Cat Primary Visual Cortex Based On Single-unit Recording And Neuron Tracing

In the primary visual cortex of cats and monkeys,there is a larger area in the extraclassical receptive field.Stimulation alone does not cause cell discharge,but surround stimulation can modulate the response of neurons in the receptive field.This area is called integration field,which plays an important role in visual information processing.Based on the presence or absence of surround suppression,we subdivided the neurons into two categories:surround-suppressive(SS)cells and surround-non-suppressive(SN)cells.It is unknown whether these two types of surround suppression properties are related to receptor distribution on these cells.Using in vivo single-unit recording and juxtacellular injection of tracer,combined with immunocytochemistry,we studied the distribution of receptors on the cell membranes of the strong SS(surround suppression index SI?0.4)and SN(SI=0)neurons.The main work of this paper consists of constructing the electrophysiological system used in the experiment,using the single-unit recording technique and the area summation method to study the surround suppression properties of the cat primary visual cortex neurons,juxtacellular injection of biocytin,neurons with two surround suppression properties were labeled(strong surround suppression and no surround suppression),and excitatory and inhibitory receptors on the cells were labeled by immunohistochemistry.A three-axis scan of the tissue sections was performed using a laser scanning confocal microscope(LSM510)to obtain immunofluorescence images of a series of tissue sections.This paper iniovatively developed a tissue sections immunofluorescence image preprocessing software based on threshold segmentation algorithm.By preprocessing the original immunofluorescence slice image,the image background was removed,and the labeled cells and their receptors on the membrane were extracted.The processed series of images can be reconstructed using commercial software to achieve three-dimensional reconstruction,and the reconstructed projection map can be used to further analyze the receptors on the labeled cell bodies and proximal dendrites.In this paper,ImageJ software was used to quantitatively analyze the receptor density of labeled cells.By comparing the traditional single immunofluorescence section analysis method and the projection map analysis method developed in this paper,it is found that the results obtained by the two methods are basically the same,and the method of this paper is more convenient and intuitive,and more cellular structure information is obtained.The new method for studying the visual cognitive function neuroreceptor mechanism constructed in this paper may provide new ideas and methodological support for solving the neural mechanism of visual information processing,and this research method is expected to get innovative and important findings.The study found that the excitatory and inhibitory receptor densities of SS and SN neurons are significantly different.Compared with SN neurons,SS neurons have smaller cell bodies and lower excitatory receptor(glutamate receptor)density,while the inhibitory receptor(gamma-aminobutyric acid receptor)is higher.In addition,based on previous studies found clusters of SS and SN neurons,this paper studied the receptor distribution characteristics of neurons within 100 micrometers around labeled neurons(SS and SN),and found SS clustered neurons compared to SN clustered neurons have also achieved above results.These studies suggest that the difference in surround suppression properties of the two types of neurons may be related to the distribution of receptors,and the receptor may also have a cluster distribution pattern.