The Dual-Peak Response In Chicken Retinal Ganglion Cells

In the present study, we investigated the spatiotemporal characteristics of ganglion cells'response in chicken retina. This thesis consists three parts: 1. the dual-peak response and its internal temporal characters, and the possible mechanisms; 2. the relationship between dual-peak response and the characters of light stimulation; 3. related data analysis for chicken retinal ganglion cells based on multi-channel recording.In our experiment with repetitive light stimulation, it was found that the temporal characters of some ganglion cells'response would change obviously along with stimulation. These cells would respond like normal transient or sustained cells at the very beginning. However, their response would become"dual-peak"after several repeats of stimulus. For the"dual-peak"response, these neurons responded to light stimulus with two successive components: a transient increase of firing rate which lasted for less than 100 ms with a small latency (around 50 ms) to the stimulus, and another prolonged light response appeared in about 100 ms after the first transient response. Moreover, our data demonstrated a temporal adaptation process in the later phase of firing activities when repeated flashes were applied. Meanwhile, the earlier phase had a more stable latency in response to the stimulus. Application of picrotoxin could evoke the dual-peak responses in transient ganglion cells. These results suggest that the origination of the two response components might be distinct and the later one is likely related to GABAergic pathways.Besides of that, it is also found that different kind of color stimulation could lead ganglion cells'response to different temporal patterns although these cells could be classified as non-color-opponent ganglion cells in classical theory. For example, one cell might respond like sustained cells under red stimulation but"dual-peak"cells under green light. A statistical result showed that about 37.5% of the ganglion cells (464 in total) could show the dual-peak response under specific color stimulation. This result suggested that in chick retina, the color information might be encoded not only by the color-opponent ganglion cells, but also the spatial-temporal patterns of some ganglion cells that are traditionally classified as non-color-opponent subtype. Considering about the previous result about GABA receptors, this phenomenon also suggested specific color stimulation might influence the GABAergic pathway and hence affect the spatial-temporal characters of retinal ganglion cells'activity.Conventional single electrode recording could record the activities of limited number of neurons simultaneously (usually less than 5) and only requires simple methods for analyzing. However, data from dozens to several hundred neurons could be achieved with multi-channel recording at the same time. It has become an important manner to find proper methods to analyze the huge amount of data effectively. Based on the experimental data recorded from chicken retinal ganglion cells, we used several methods for analysis and comparison.