Abstract
Abstract: :
Purpose: To characterize the spatio-temporal properties of retinal ganglion cell receptive fields in the mouse. Methods: Extracellular single-unit ganglion cell responses were recorded from the optic nerve in mice. The size, shape and type of the receptive field centers were studied using small spots of light. Drifting and contrast reversal sine-wave gratings of various spatial, temporal frequencies and contrast were generated by a Vision Research Graphics system. Spots of varying diameters also were computer generated and used to determine the degree of surround inhibition and the sustained or transient nature of the response. Results: Single-unit recordings were obtained from the axons of 44 ganglion cells in 29 mice. Most cells had circular receptive fields whose center sizes varied from 2.0 to 24 degrees (deg.) and were either ON (n=29) or OFF (n=15). For both drifting and contrast reversal sine-wave gratings, spatial frequency response functions had peaks between 0.01-0.08 cycles/degree (c/deg.), high frequency cutoffs between 0.08 and 0.5 c/deg. Area response functions had optimal diameters that ranged from 2 to 24 deg. For most cells, the response to spots of increasing diameter revealed the presence of an antagonistic surround. High temporal frequency cutoffs ranged between 4.0 and 20.0 Hz with optimal temporal frequencies between 0.5 to 8.0 Hz.The majority of the cells with small receptive fields had a low temporal frequency resolution (4.0-6.0 Hz cutoff, optimum <2.0 Hz).Cells with larger receptive field centers were more responsive at higher temporal frequencies, with an average cutoff at 20.0 Hz and peak response at ≷4.0 Hz. X-like and Y-like cells with characteristic spatial summation properties were observed. Contrast response functions were measured for both X-like (n=3) and Y-like (n=3) ganglion cells. Both types showed a linear increase in the response modulation with increasing contrast. Conclusion: The spatio-temporal properties of ganglion cell receptive fields in the mouse retina are significantly poorer compared to those published for the cat and primates.The results of this work are similar to previously published in vitro recordings of mouse retinal ganglion cells. These data will serve as a baseline for characterizing receptive field properties of retinal ganglion cells in a variety of transgenic and knockout mice.
Keywords: 415 ganglion cells • 540 receptive fields • 554 retina