Long-term effects of monocular deprivation revealed with binocular rivalry gratings modulated in luminance and in color

Abstract

During development, within a specific temporal window called the critical period, the mammalian visual cortex is highly plastic and literally shaped by visual experience; to what extent this extraordinary plasticity is retained in the adult brain is still a debated issue. We tested the residual plastic potential of the adult visual cortex for both achromatic and chromatic vision by measuring binocular rivalry in adult humans following 150 minutes of monocular patching. Paradoxically, monocular deprivation resulted in lengthening of the mean phase duration of both luminance-modulated and equiluminant stimuli for the deprived eye and complementary shortening of nondeprived phase durations, suggesting an initial homeostatic compensation for the lack of information following monocular deprivation. When equiluminant gratings were tested, the effect was measurable for at least 180 minutes after reexposure to binocular vision, compared with 90 minutes for achromatic gratings. Our results suggest that chromatic vision shows a high degree of plasticity, retaining the effect for a duration (180 minutes) longer than that of the deprivation period (150 minutes) and twice as long as that found with achromatic gratings. The results are in line with evidence showing a higher vulnerability of the P pathway to the effects of visual deprivation during development and a slower development of chromatic vision in humans.

Short-term plasticity of the human adult visual cortex measured with 7T BOLD

“…the deprived eye. However, this fits well with the concept of homeostatic plasticity that was introduced only very recently in animal work during the developmental period (34,35), and from our previous studies (26)(27)(28)(29). Homeostatic plasticity acts upon the excitation-inhibition ratio, probably regulated by intra-cortical circuitry (33,37), boosting of the response-gain for the circuitry with lower firing rates during deprivation.…”

“…Prior psychophysical studies have shown that deprivation of form vision shifts eye dominance in favor of the deprived eye for small centrally presented targets, but the effect is short-lived, attenuated by more than 50% within the first 10 minutes (28,29). It is a challenge to be able to detect such short-lived effect with BOLD.…”

“…For example, selective deprivation of one cardinal orientation over few hours leads to paradoxically enhanced sensitivity to the deprived orientation (25). Similarly, short-term monocular deprivation leads to a transient boost of the deprived eye responses (26)(27)(28)(29)(30)(31)(32).…”

Short-Term Monocular Deprivation Enhances Physiological Pupillary Oscillations

“…Immediately after eye-patch removal, we measured binocular rivalry for 18 minutes in four separate 180 sec blocks separated by a two-minute break to allow the subject to rest: this is the standard protocol used in the previous studies on MD from our laboratory [2, 3, 49]. Two minutes after the last binocular rivalry block (20 minutes after eye-patch removal), we measured the pupillary diameter in one 120 sec block.…”

“…Specifically, after a few hours of monocular deprivation, ocular dominance unexpectedly shifts in favor of the deprived eye [1–7]. For example, monocular deprivation has dramatic perceptual consequences on the dynamics of binocular rivalry (a particular form of bistable perception that engages strong competition between the monocular signals [8]): following deprivation, the deprived eye dominates rivalrous perception for twice as long as the nondeprived eye, indicating a strong shift of ocular dominance in favor of the deprived eye [2, 3]. This apparently counterintuitive effect reflects a compensatory reaction of the visual system to the transient impoverishment of monocular visual input that is likely mediated by an upregulation of contrast-gain control mechanisms of the deprived eye (this hypothesis is supported by evidence that short-term monocular deprivation increases apparent contrast of the deprived eye [2]).…”