老年猫初级视皮层细胞对视觉刺激空间频率调谐反应的选择性下降(英文)

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

目的探讨猫的初级视皮层(V1)细胞对视觉刺激空间频率的选择性是否受年龄影响。方法采用在体细胞外单细胞记录技术分别记录青、老年猫V1神经元对不同空间频率光栅刺激的调谐反应。结果数据统计分析结果显示,诱导老年猫V1神经元出现最大诱发反应幅度的平均最优刺激空间频率(optimal spatial frequency, OSF)相较于青年猫的OSF显著降低。此外,老年猫V1神经元达到半幅反应的平均高频截止空间频率(cut-off spatial frequency,CSF)也显著小于青年猫的CSF。结论该结果与在老年猴初级视皮层的研究报道一致,表明年龄相关的视皮层细胞对刺激空间频率的选择性下降可能是哺乳动物中普遍存在的现象,也可能是导致老年性视敏度下降的重要原因。

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.