ABSTRACT
In this study, the on- and off-responses elicited by luminance square wave and sawtooth stimuli at different temporal frequencies and contrasts are described quantitatively. Adding on- and off-responses reveals response asymmetries. Full-field stimuli were produced using a Ganzfeld bowl with arrays of light-emitting diodes (LEDs) as light sources. ERG responses were recorded from six normal subjects. The amplitudes and implicit times of components of the on- and off-responses and the additions were analyzed. The amplitudes of the on-, off- and addition components elicited by square wave stimuli did not depend on temporal frequency with the exception of the late negative components, which decreased with increasing temporal frequency up to 4 Hz. The amplitudes of all components elicited by sawtooth stimuli, except the P-on, decreased with increasing temporal frequency. The amplitude of all components elicited by square wave and sawtooth stimuli were positively correlated with stimulus contrast. The implicit times of the on-components to square wave stimuli and all response components to sawtooth stimuli decreased with increasing temporal frequency. Contrast had an effect on the implicit times of the N-on, P-on, P-off and P-add components elicited by square wave stimuli and the N-on, P-on, P-add and LN-on components elicited by sawtooth stimuli. The asymmetries between on- and off-responses can possibly be used to reveal inner retinal contributions and may therefore be interesting in detecting glaucomatous changes...
Subject(s)
Humans , Adult , Middle Aged , Electroretinography , Photic StimulationABSTRACT
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.
ABSTRACT
AIM: To investigate the sensibility of pattern visual evoked potential (P-VEP) on the diagnosis of glaucoma in different temporal frequency.METHODS: The P-VEP were recorded in 51 eyes of 30 primary glaucoma (PG) patients, 16 eyes of 13 ocular hypertension (OHT) patients and 46 eyes of 23 age-equivalent normal people using an array of different temporal frequency and then the patients were compared respectively with the normal group.RESULTS: The P100 wave amplitude in OHT group was significantly lowered at 8Hz, and was lowered at all temporal frequency in PG group, especially when the temporal frequency was higher.CONCLUSION: The P-VEP can be abnormal when the PG is still in its early stage, so it can be an index of early diagnosis and this is more obvious when the temporal frequency is higher, especially at 8Hz.