OS - the outer segment of photoreceptors
IS - the inner segment of photoreceptors
ONL - outer core layer
OPL - outer plexus
INL - inner core layer
IPL - inner plexus
GC - ganglion layer
BM - Bruch membrane
P - pigment epithelial cells
R - sticks
C - cones
Arrow and dashed line - outer boundary membrane
H - horizontal cells
B - bipolar cells
M - Mueller Cells
A - amacrine cells
G - ganglion cells
AX - axons
Horizontal cells are a layer of associative neurons of the retina .
Horizontal cells are located in the retina immediately after the photoreceptors and give them a large number of dendrites , which, intertwined, form a continuous dense lace. Their axons can stretch for considerable distances and have highly branched terminal formations. Horizontal cells are interconnected by electrical synapses and form functional syncytium . The excitation of one horizontal cell extends to others. In the central fossa ( lat. Fovea ) of the retina of primates, one horizontal cell connects to about 6 cones , and on the periphery, from 30-40. The dendritic field of a horizontal cell at the periphery of the retina reaches a diameter of 250 microns. At the same time, the size of the receptive fields of horizontal cells can vary within 300 μm ÷ 5 mm [1] , which significantly exceeds the length of the dendritic branches. Due to this, horizontal cells can form the periphery of receptive fields of bipolar neurons [2] [3] [4] [5] [6] [7] [8] . When photoreceptors are illuminated, horizontal cells respondhyperpolarization .
Photoreceptors together with horizontal cells and bipolar form the so-called triad [4] . The triad consists of of the presynaptic photoreceptor membrane , into which the dendrite of the bipolar enters, and on the sides of it, processes of horizontal cells enter. The meaning and principles of the triad are still unknown. Due to such connections between photoreceptors, horizontal cells and bipolar, the center of the receptive field of the bipolar is formed directly by transmitting a signal from photoreceptors, the periphery is formed due to an indirect path through horizontal cells due to excitatory or inhibitory synapses.
Notes
- ↑ Izmailov I.A., Sokolov E.N., Chernoryzov A.M. Psychophysiology of color vision. - M .: Publishing house of Moscow University, 1989. - 206 p.
- ↑ Schoolboy-Yarros E.G., Kalinina A.V. Retinal neurons. - M .: Nauka, 1986 .-- 208 p.
- ↑ Masland R. Functional organization of the retina // In the world of science. - 1987, No. 4 - p. 58-68.
- ↑ 1 2 Byzov A. L. Polishchuk N. A. On the feedback mechanism from horizontal cells to photoreceptors: a chemical or electrical hypothesis? // Sensory systems. - 1987. T1, No. 4. - p. 344-352.
- ↑ Byzov A. L., Golubtsov K.V. Model of a neuron-regulator of synaptic transmission efficiency // Biophysics. - 1978. - Vol. 23 No. 1. - p. 119-125.
- ↑ Schmidt R. Teus G. Human physiology. t.1. -M.: Mir, 1996 .-- 328 p.
- ↑ Dacey D. Lee B. Stafford D. Horizontal cells of the primate retina: cone specifity without spectral opponency // Science. - 1996. Vol. 271, No. 5429. p. 656-659.
- ↑ Glaser V. D. Vision and thinking. - L .: Nauka, 1985, - 248 p.