Study On The Mechanism Of Dendritic Signal Attenuation

Exploring how neurons process the input they receive to generate action potentials that can activate their postsynaptic neurons is critical to understanding how the brain works.This thesis mainly studies the mechanism that affects the attenuation of dendritic signals.The results of the research enable us to understand the role of synaptic input position,dendritic spikes,dendritic diameter and other factors in neuron dendritic signal processing.These results can also provide help in exploring the ways in which dendrites integrate synaptic input,and in turn promote research on the connection between neural activity and behavior.Specifically,by establishing a multi-compartment dynamic model consistent with the morphological structure of real fast spiking basket neurons and corresponding biophysical data,the mechanism affecting the attenuation of dendritic signals was explored,and the following results were obtained:1.The synaptic potential encounters substantial attenuation during the transmission from the distal dendrites to the soma,and the attenuation mainly occurs at the distal dendritic site,that is,the farther away from the soma,the stronger the filtering effect of the dendrites.2.The size of the local excitatory postsynaptic potential(EPSP)generated at the synapse is not only related to the diameter of the dendrites,but also related to whether the voltage-dependent ion channels on the dendrites can be activated,thereby triggering local dendritic spikes.By comparing the EPSPs produced on the soma with and without local spikes initiated on the distal dendrites,we found that although the dendritic spikes could not propagate reliably in the dendrites,they could transfer additional charges to the soma and offset some serious filtering caused by the characteristics of dendritic cable.3.The size of the dendritic diameter is inversely proportional to its filtering effect on synaptic input.The smaller the dendritic diameter,the greater the attenuation of synaptic input on it.The simulation results at three different types of dendritic bifurcations show that no significant voltage attenuation can be observed at any type of bifurcation.It is guessed that the possible reason is that the strong attenuation of the dendritic signal caused by the bifurcation of the dendritic tree is reflected in the high frequency of the dendritic branches.The large number of branches in the neuron dendritic tree leads to the accumulation of the amount of attenuation.The dendritic bifurcation is not obvious.