Binocular form deprivation influences the visual cortex

Abstract

α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eye-opening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.

Keywords: binocular form deprivation; excitatory postsynaptic currents; neural development; neural regeneration; regeneration; visual cortex; visual development; whole-cell recording; α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors.

Figure 1

Isolation of AMPA-EPSCs in the rat visual cortex. Postsynaptic currents (PSCs) were evoked with a stimulus of 0.5 mA and 100 μs duration, and the voltages were clamped at –30 mV. The vertical line of each trace represents the stimulus event. In the same cell, trace A represents a PSC recorded without using any receptor blockers (AMPA or N-methyl-D-aspartate or gamma-aminobutyric acid receptor blocker bicuculline methiodide, or D,L-2-amino5-phosphonovalerate, or 6-cyano-7-nitroquinoxaline-2, 3-dione). Trace B is an AMPA-EPSC recorded by adding bicuculline methiodide (20 μM) and D,L-2-amino-5phosphonovalerate (50 μM) to the artificial cerebrospinal fluid (at least 5 minutes). Trace C indicates that all the components of the PSC were blocked by adding bicuculline methiodide (20 μM), 6-cyano-7-nitroquinoxaline-2,3-dione (20 μM) and D,L-2-amino-5-phosphonovalerate (50 μM) to the artificial cerebrospinal fluid. Trace D represents a PSC recorded after washing out all the blockers showing almost complete recovery of the PSC and that the isolation of AMPA-EPSCs is stable. AMPA-EPSCs: Excitatory postsynaptic currents (EPSCs) mediated by α-amino-3-hydroxy-5-methyl-4isoxazolepropionic acid (AMPA) receptors.