title: Macaque retinal ganglion cell responses to visual patterns: harmonic composition, noise, and psychophysical detectability.
abstract: The goal of these experiments was to test how well cell responses to visual patterns can be predicted from the sinewave tuning curve. Magnocellular (MC) and parvocellular (PC) ganglion cell responses to different spatial waveforms (sinewave, squarewave, and ramp waveforms) were measured across a range of spatial frequencies. Sinewave spatial tuning curves were fit with standard Gaussian models. From these fits, waveforms and spatial tuning of a cell's responses to the other waveforms were predicted for different harmonics by scaling in amplitude for the power in the waveform's Fourier expansion series over spatial frequency. Since higher spatial harmonics move at a higher temporal frequency, an additional scaling for each harmonic by the MC (bandpass) or PC (lowpass) temporal response was included, together with response phase. Finally, the model included a rectifying nonlinearity. This provided a largely satisfactory estimation of MC and PC cell responses to complex waveforms. As a consequence of their transient responses, MC responses to complex waveforms were found to have significantly more energy in higher spatial harmonic components than PC responses. Response variance (noise) was also quantified as a function of harmonic component. Noise increased to some degree for the higher harmonics. The data are relevant for psychophysical detection or discrimination of visual patterns, and we discuss the results in this context.
authors.affiliation: College of Optometry, State University of New York, New York, New York;
authors.forename: Bonnie
authors.initials: B
authors.lastname: Cooper
authors.affiliation: College of Optometry, State University of New York, New York, New York; Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; and blee@sunyopt.edu.
authors.forename: Barry B
authors.initials: BB
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Dingcai
authors.initials: D
authors.lastname: Cao
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D005583:Fourier Analysis; D008253:Macaca mulatta; D008297:Male; D008954:Models, Biological; D016011:Normal Distribution; D010775:Photic Stimulation; D011601:Psychophysics; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: ganglion cell; grating; magnocellular; parvocellular