Efficiency of information coding in various L/M retinal cone ratios

Previous evidence has shown that the number of L and M cones in retina varies significantly between subjects. However, it is not clear how the variation of L/M ratio changes the behavioral performance of the subject. A model of transformation of data from retina to visual cortex for evaluation of various L/M cones ratios is presented. While L/M cone ratios close to 1 brings the best performance for one of postreceptoral [magnocellular] channels, we showed that the performance in the second channel [parvocells] will improve when the ratio furthers away from 1. effects of different ratios of S were also explored

glance at psychophysics software programs

Visual stimulation with precise control of stimulus has transformed the field of psychophysics since the introduction of personal computers. Luminance and chromatic features of stimulus, timing, and position of the stimulus are the main features that could be defined using programs written specifically for psychophysical experiments. In this manuscript, software used for the psychophysical experiments have been reviewed and evaluated for ease of use, license, popularity, and expandability

Functional assessment of magno, parvo and konio-cellular pathways; current state and future clinical applications

The information generated by cone photoreceptors in the retina is compressed and transferred to higher processing centers through three distinct types of ganglion cells known as magno, parvo and konio cells. These ganglion cells, which travel from the retina to the lateral geniculate nucleus [LGN] and then to the primary visual cortex, have different structural and functional characteristics, and are organized in distinct layers in the LGN and the primary visual cortex. Magno cells are large, have thick axons and usually collect input from many retinal cells. Parvo cells are smaller, with fine axons and less myelin than mango cells. Konio cells are diverse small cells with wide fields of input consisting of different cells types. The three cellular pathways also differ in function. Magno cells respond rapidly to changing stimuli, while parvo cells need time to respond. The distinct patterns of structure and function in these cells have provided an opportunity for clinical assessment of their function. Functional assessment of these cells is currently used in the field of ophthalmology where frequency-doubling technology perimetry selectively assesses the function of magno cells. Evidence has accrued that the three pathways show characteristic patterns of malfunctions in multiple sclerosis, schizophrenia, Parkinson's and Alzheimer's diseases, and several other disorders. The combination of behavioral assessment with other techniques, such as event related potentials and functional magnetic resonance imaging, seems to bear promising future clinical applications