Decline of selectivity of V1 neurons to visual stimulus spatial frequencies in old cats

Objective To examine whether the selectivity of visual cortical neurons to stimulus spatial frequencies would be affected by aging in cats. Methods In vivo extracellular single-unit recording techniques were employed to record the tuning responses of V1 neurons to different stimulus spatial frequencies in old and young adult cats. Results Statistical analysis showed that the mean optimal spatial frequency of grating stimuli that evoked the maximal response of V1 neurons in old cats was significantly lower than that in young adult cats. Furthermore, the mean high cut-off spatial frequency of grating stimuli that evoked the half amplitude of the maximal response of V1 neurons in old cats was also significantly lower than that in young adult cats. Conclusion These results are consistent with those reported in the V1 of old monkeys, suggesting that the age-related decline in the selectivity of visual cortical cells to spatial frequency could be generalized to all mammalian species and might contribute to visual acuity reduction in senescent individuals.