Chen Xin, Liang Zhiyin, Shen Wei, Shou Tiande
Vision Research Laboratory, Center for Brain Science Research, Department of Ophthalmology and Vision Science and State Key Laboratory of Medical Neurobiology, School of Life Sciences, Fudan University, Shanghai, China.
Invest Ophthalmol Vis Sci. 2005 Jul;46(7):2611-9. doi: 10.1167/iovs.04-0874.
To study and compare responses of different types of cortical neurons in the primary visual cortex in cats to grating stimuli before and during brief elevation of intraocular pressure (IOP).
Single-unit electrophysiological recordings were performed in anesthetized and paralyzed cats. The IOP was elevated by injecting saline into the anterior chamber of the cat's eyes through a syringe needle. The IOP was elevated to a level at which the retinal perfusion pressure (arterial pressure minus IOP) was maintained at approximately 30 mmHg for a period of 4 minutes. The responses of simple and complex cells in the primary visual cortex to visually drifting sinusoidal gratings were measured before and during the elevation of IOP.
The response amplitude of all the cortical cells in the primary visual cortex declined during a brief elevation of IOP. The decrease in the response of simple cells was always more significant than that of complex cells. The differential decrease between the two major types of cells was independent of the cell's receptive field location and cortical depth. There was a mild tendency for cells with higher preferred spatial frequencies to be more sensitive than those with lower frequencies. The preferred orientation and direction of most cortical cells remained roughly unchanged though their orientation and direction biases decreased. An increase in the animal's blood pressure, which returned the retinal perfusion pressure to a normal level, compensated for the decreased response induced by the elevation of IOP.
The differential effects of a brief elevation of IOP on the response of simple and complex cells in the visual cortex are general and may originate from the retina through the lateral geniculate nucleus (LGN), where different effects of elevation of IOP are exerted on X- and Y-type retinal ganglion cells. The results may suggest differential behavior of neurons tin the parvo and magno pathways of the primate.
研究并比较猫初级视觉皮层中不同类型的皮质神经元在眼内压（IOP）短暂升高之前及期间对光栅刺激的反应。
在麻醉并麻痹的猫身上进行单单位电生理记录。通过注射器针头向猫眼的前房注射生理盐水来升高眼内压。将眼内压升高到视网膜灌注压（动脉压减去眼内压）维持在约30 mmHg的水平，并持续4分钟。在眼内压升高之前及期间，测量初级视觉皮层中简单细胞和复杂细胞对视觉上漂移的正弦光栅的反应。
在眼内压短暂升高期间，初级视觉皮层中所有皮质细胞的反应幅度均下降。简单细胞反应的下降总是比复杂细胞更显著。这两种主要类型细胞之间的差异下降与细胞的感受野位置和皮质深度无关。具有较高偏好空间频率的细胞比具有较低频率的细胞有更轻微的更敏感趋势。大多数皮质细胞的偏好方向和方向大致保持不变，尽管它们的方向和方向偏差有所减小。动物血压升高使视网膜灌注压恢复到正常水平，补偿了眼内压升高引起的反应下降。
眼内压短暂升高对视觉皮层中简单细胞和复杂细胞反应的不同影响是普遍存在的，可能通过外侧膝状体核（LGN）从视网膜起源，在那里眼内压升高对X型和Y型视网膜神经节细胞有不同影响。结果可能提示灵长类动物小细胞和大细胞通路中神经元的不同行为。
