Development of spatiotemporal frequency turning in rat lateral geniculate neuron / 中华实验眼科杂志

ABSTRACT

BackgroundRecent researches suggested that properties of neurons in the lateral geniculate neuron (LGN) may represent an important neural limitation on the development of basic spatial and temporal vision,and even binocular rivalry.However,previous studies on the properties of spatiotemporal frequency tuning of LGN were rather concentrated on a monkey or cat,whereas little is known about rat.ObjectiveThis study was to examine the development of spatiotemporal frequency tuning in rats LGN.MethodsTwenty Wistar rats were collected and divided into 14-16 day,20-22 day,27-30 day and 60 day groups according to the different ages after their eyes opened and 5 rats were assigned for each group.Extracellular single neuron recording was carried out in the rats to study the spatio-temporal receptive field properties of neurons in LGN by sinusoidal gratings visual stimuli.Dynamic changes of the spatio-temporal receptive field properties of neurons in LGN with the development of Wistar rats were evaluated.ResultsThe differences between band-pass and low-pass distribution of temporal frequency or spatial frequency of rat LGN were not statistically significant (x2 =0.68,0.47,P＞0.05 ).The optimal temporal frequency of receptive field in rat LGN went up to the maximum value until 60 day in Wistar rats.The mean optimal temporal frequencies of neurons in the four different age groups were ( 2.5 ± 1.3 ),( 2.6± 1.2),(2.6± 1.1 ) and ( 3.6± 1.1 ) Hz with significant differences among the 4 groups (F=4.53,P＜0.05 ),and those in the 14-16 day group,20-22 day group,27- 30 day group were significantly lower than in the 60 days group ( q =4.43,4.10,4.03,P ＜ 0.05 ).No significant differences were seen among the 14-16 day group,20-22 day group and 27-30 day group ( P＞0.05 ).The optimal spatial frequency values in the four groups were ( 0.04 ± 0.04 ),( 0.04 ± 0.03 ),( 0.05 ± 0.03 ),( 0.05 ± 0.04 ) cpd,respectively without statistical difference among them ( F =0.58,P ＞ 0.05 ).The temporal and spatial bandwidth values in the various age groups were not statistically significant among the four groups ( F =0.37,1.22,P＞0.05). Conclusions The development of temporal and spatial frequency characteristics of the rat LGN receptive field may be related to its functional visual pathway.