Effects Of Visual Deprivation Research Articles

Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals

BackgroundDynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability.MethodsThe current study was conducted on 20 congenital blind and 10 sighted people (15–38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path.ResultsIn the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis.ConclusionVisual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Brief Visual Deprivation Effects on Brain Oscillations During Kinesthetic and Visual-motor Imagery.

It is widely recognized that opening and closing the eyes can direct attention to external or internal stimuli processing. This has been confirmed by studies showing the effects of changes in visual stimulation changes on cerebral activity during different tasks, e.g., motor imagery and execution. However, an essential aspect of creating a mental representation of motion, such as imagery perspective, has not yet been investigated in the present context. Our study aimed to verify the effect of brief visual deprivation (under eyes open [EO] and eyes closed [EC] conditions) on brain wave oscillations and behavioral performance during kinesthetic imagery (KMI) and visual-motor imagery (VMI) tasks. We focused on the alpha and beta rhythms from visual- and motor-related EEG activity sources. Additionally, we used machine learning algorithms to establish whether the registered differences in brain oscillations might affect motor imagery brain-computer interface (MI-BCI) performance. The results showed that the occipital areas in the EC condition presented significantly stronger desynchronization during VMI tasks, which is typical for enhanced visual stimuli processing. Furthermore, the stronger desynchronization of alpha rhythms from motor areas in the EO, than EC condition confirmed previous effects obtained during real movements. It was also found that simulating movement under EC/EO conditions affected signal classification accuracy, which has practical implications for MI-BCI effectiveness. These findings suggest that shifting processing toward external or internal stimuli modulates brain rhythm oscillations associated with different perspectives on the mental representation of movement.

The effect of visual deprivation on basic taste modalities

AbstractIn this pilot study, the effects of temporary visual deprivation on sensitivity to the basic tastes in normal sighted subjects were assessed. The sip‐and‐spit method to assess taste recognition thresholds was applied. The recognition thresholds of five basic tastes were assessed in two conditions: when the participants were blindfolded and when their blindfolds were removed and their eyes were open. In the blindfolded condition, the recognition threshold for sweet taste (saccharose) was lower than in the eyes open condition (means: 2.49 g/L vs. 3.80 g/L, p = .046). For bitter taste, a similar tendency was observed, but the difference did not reach statistical significance (means: 0.11 g/L vs. 0.13 g/L, p = .078). No difference in taste recognition thresholds between these two conditions were noted for salty, sour, and umami. Thus, the impact of temporary visual deprivation on taste experience seems stronger for sweet than for other taste modalities.Practical ApplicationsOur pilot study suggests potential applications, for example, re‐evaluating sugar content in foods served in dim/dark environments, like cinemas or blind cafés where food is consumed in total darkness. The sweet taste recognition threshold for saccharose being lower by 1.3 g/L in dark surroundings than in lit environments may become an incentive for beverages/snacks/desserts producers to lower sugar content. Coco‐Cola Original Taste has 10.6 g of sugar/100 mL, and a 1‐L Coca‐Cola serving (one of the cinema‐sized beverages) contains 106 g of sugar (22 teaspoons). An appropriate reduction of sugar in such beverages should not change their taste/palatability, and may benefit consumers and producers (Valicente et al., 2023, Journal of Sensory Studies, 38(1), e12803). For instance, Coca‐Cola/Coke is produced by mixing a relevant syrup with water and adding CO2 (Coca‐Cola Original Taste/Zero Sugar/Cherry, etc.); producing an additional syrup with lower than original sugar content seems feasible for a company regularly introducing new products to the market.

Effects of visual deprivation on the injury of lower extremities among functional ankle instability patients during drop landing: A kinetics perspective.

Background: The ankle is prone to injury during drop landing with usual residual symptoms, and functional ankle instability (FAI) is the most common. Vision guarantees the postural stability of patients with FAI, and visual deprivation (VD) increases their risk of injury when completing various movements. This study explored injury risk during drop landing in patients with FAI under VD through the kinetics of lower extremities. Methods: A total of 12 males with FAI participated in the study (age, 23.0 ± 0.8years; height, 1.68 ± 0.06m; weight, and 62.2 ± 10.4kg) completed single-leg drop landings under visual presence (VP) and VD conditions. Ground reaction force (GRF), time to peak GRF, joint torque, and vertical length variation (ΔL) were measured. Results: Significant effects were detected in the group for time to peak lateral GRF (p = 0.004), hip extensor torque (p = 0.022), ankle plantarflexion torque (p < 0.001), ankle varus torque (p = 0.021), lower extremity stiffness (p = 0.035), and ankle stiffness (p < 0.001). Significant effects of conditions were detected for vertical GRF, time to peak vertical and lateral GRF, loading rate, hip extensor torque, knee extensor torque, hip varus torque, knee varus torque, lower extremity stiffness, and ankle stiffness (p < 0.05). ΔL was affected by VD with a significant difference (p < 0.001). Conclusion: In patients with FAI, an unstable extremity has a higher injury risk than a stable extremity, and VD increases such risk. However, because the influence of the central nervous system on hip strategy is also affected, the effect on the unstable extremity is more significant and more likely to result in injury. Deepening the squat range may be an effective preventive measure for reducing injury risk of unstable extremities during drop landing.

Effects of Visual Deprivation on Remodeling of Nodes of Ranvier in Optic Nerve.

Oligodendrocytes, the myelinating cells of the CNS, promote rapid action potential conduction along axons. Changes in the geometry of gaps between myelin segments, known as nodes of Ranvier, affect the conduction speed of neuronal impulses and can ultimately alter neural synchronization and circuit function. In contrast to synaptic plasticity, much less is known about how neural activity may affect node of Ranvier structure. Recently, perinodal astrocytes have been shown to remodel nodes of Ranvier by regulating thrombin proteolysis, but it is not known whether neural activity influences this process. To test this hypothesis, we used transgenic mice with astrocytic expression of a dominant-negative vesicle-associated membrane protein 2 ([gfap]dnVAMP2) to reduce exocytosis of thrombin inhibitors, modulating astrocytic regulation of paranodal loop attachment to induce nodal remodeling, under normal conditions and in adult mice maintained in darkness from postnatal day 40 (P40) to P70. This mechanism of nodal lengthening proceeded normally following binocular visual deprivation (BVD). The effect of BVD on nodal plasticity in animals with unimpaired astrocyte function has not been previously investigated. We find that when exocytosis from astrocytes was unimpaired, nodal gap length was not altered by BVD in adult mice. We conclude that if perinodal astrocytes participate in activity-dependent myelin remodeling through exocytosis, then, as with synaptic plasticity in the visual system, the process must be driven by alterations in neuronal firing other than those produced by BVD.

Effects of Congenital Blindness on Ultrasonic Vocalizations and Social Behaviors in the ZRDBA Mouse.

Mice produce ultrasonic vocalizations (USVs) at different ages and social contexts, including maternal-pup separation, social play in juveniles, social interactions, and mating in adults. The USVs' recording can be used as an index of sensory detection, internal state, and social motivation. While sensory deprivation may alter USVs' emission and some social behaviors in deaf and anosmic rodents, little is known about the effects of visual deprivation in rodents. This longitudinal study aimed to assess acoustic communication and social behaviors using a mouse model of congenital blindness. Anophthalmic and sighted mice were assayed to a series of behavioral tests at three different ages, namely, the maternal isolation-induced pup USV test and the home odor discrimination and preference test on postnatal day (PND) 7, the juvenile social test on PND 30–35, and the female urine-induced USVs and scent-marking behavior at 2–3 months. Our results evidenced that (1) at PND 7, USVs' total number between both groups was similar, all mice vocalized less during the second isolation period than the first period, and both phenotypes showed similar discrimination and preference, favoring exploration of the home bedding odor; (2) at PND 30–35, anophthalmic mice engaged less in social behaviors in the juvenile play test than sighted ones, but the number of total USVs produced is not affected; and (3) at adulthood, when exposed to a female urine spot, anophthalmic male mice displayed faster responses in terms of USVs' emission and sniffing behavior, associated with a longer time spent exploring the female urinary odor. Interestingly, acoustic behavior in the pups and adults was correlated in sighted mice only. Together, our study reveals that congenital visual deprivation had no effect on the number of USVs emitted in the pups and juveniles, but affected the USVs' emission in the adult male and impacted the social behavior in juvenile and adult mice.

Development and experience-dependent modulation of the defensive behaviors of mice to visual threats

Rodents demonstrate defensive behaviors such as fleeing or freezing upon recognizing a looming shadow above them. Although individuals’ experiences in their habitat can modulate the defensive behavior phenotype, the effects of systematically manipulating the individual’s visual experience on vision-guided defensive behaviors have not been studied. We aimed to describe the developmental process of defensive behaviors in response to visual threats and the effects of visual deprivation. We found that the probability of escape response occurrence increased 3 weeks postnatally, and then stabilized. When visual experience was perturbed by dark rearing from postnatal day (P) 21 for a week, the developmental increase in escape probability was clearly suppressed, while the freezing probability increased. Intriguingly, exposure to the looming stimuli at P28 reversed the suppression of escape response development at P35. These results clearly indicate that the development of defensive behaviors in response to looming stimuli is affected by an individual’s sensory experience.

Invited Session III: Reawakening plasticity in visual cortex: Recovery from the effects of visual deprivation beyond peak plasticity

Visual experience during early postnatal life plays an important role in the development of neural circuits that support normal vision. Conditions that disrupt visual experience can alter the structure and function of neurons to produce a functional impairment, amblyopia, in the affected eye that can last a lifetime. Susceptibility to the neural modifications presumed to underlie amblyopia is confined to the early years of life during the so-called critical period. Up until recently, recovery from the effects of visual deprivation was likewise thought to be possible only early in life; however, research in rodents has demonstrated that under certain conditions recovery can occur at ages beyond the critical period. We have observed a remarkable recovery from the effects of visual deprivation in cats following temporary retinal inactivation with intraocular application of tetrodotoxin, a potent neural anesthetic. Notably, retinal inactivation produces rapid and significant structural and functional recovery at ages beyond what can be achieved with conventional therapy. This talk will present results from our studies on the use of retinal inactivation to resource plasticity capacity and promote recovery from the effects of early visual deprivation.

Auditory Behavior in Adult-Blinded Mice.

Cross-modal plasticity occurs when the function of remaining senses is enhanced following deprivation or loss of a sensory modality. Auditory neural responses are enhanced in the auditory cortex, including increased sensitivity and frequency selectivity, following short-term visual deprivation in adult mice (Petrus et al. Neuron 81:664-673, 2014). Whether or not these visual deprivation-induced neural changes translate into improved auditory perception and performance remains unclear. As an initial investigation of the effects of adult visual deprivation on auditory behaviors, CBA/CaJ mice underwent binocular enucleation at 3-4weeks old and were tested on a battery of learned behavioral tasks, acoustic startle response (ASR), and prepulse inhibition (PPI) tests beginning at least 2weeks after the enucleation procedure. Auditory brain stem responses (ABRs) were also measured to screen for potential effects of visual deprivation on non-behavioral hearing function. Control and enucleated mice showed similar tone detection sensitivity and frequency discrimination in a conditioned lick suppression test. Both groups showed normal reactivity to sound as measured by ASR in a quiet background. However, when startle-eliciting stimuli were presented in noise, enucleated mice showed decreased ASR amplitude relative to controls. Control and enucleated mice displayed no significant differences in ASR habituation, PPI tests, or ABR thresholds, or wave morphology. Our findings suggest that while adult-onset visual deprivation induces cross-modal plasticity at the synaptic and circuit levels, it does not substantially influence simple auditory behavioral performance.

Cellular effects of visual deprivation

Neurodevelopment Myelination speeds the progress of action potentials along neuronal axons. Yang et al. studied changes in myelination in the mouse visual cortex in response to visual experience (see the Perspective by Yalcin and Monje). With normal vision, myelination is continuously remodeled. As ocular dominance shifts in response to monocular deprivation, myelination patterns change on certain inhibitory interneurons but not on excitatory callosal projection neurons. Myelin sheaths are both added and subtracted, segments of myelin elongate and contract, and preexisting oligodendrocytes make new myelin sheaths. This adaptive myelination helps to diversify neuronal function and remodel neuronal circuits in response to sensory experience. Science , this issue p. [eabd2109][1]; see also p. [1414][2] [1]: /lookup/doi/10.1126/science.abd2109 [2]: /lookup/doi/10.1126/science.abf4646

Structural brain plasticity induced by early blindness.

It is well established that early blindness results in behavioural adaptations. While the functional effects of visual deprivation have been well researched, anatomical studies are scarce. The aim of this study was to investigate whole brain structural plasticity in a mouse model of congenital blindness. Volumetric analyses were conducted on high-resolution MRI images and histological sections from the same brains. These morphometric measurements were compared between anophthalmic and sighted ZRDBA mice obtained by breeding ZRDCT and DBA mice. Results from MRI analyses using the Multiple Automatically Generated Templates (MAGeT) method showed smaller volume for the primary visual cortex and superior colliculi in anophthalmic compared with sighted mice. Deformation-based morphometry revealed smaller volumes within the dorsal lateral geniculate nuclei and the lateral secondary visual cortex and larger volumes within olfactory areas, piriform cortex, orbital areas and the amygdala, in anophthalmic compared with sighted mice. Histological analyses revealed a larger volume for the amygdala and smaller volume for the superior colliculi, primary visual cortex and medial secondary visual cortex, in anophthalmic compared with sighted mice. The absence of superficial visual layers of the superior colliculus and the thinner cortical layer IV of the primary and secondary visual cortices may explain the smaller volume of these areas, although this was observed in a limited sample. The present study shows large-scale brain plasticity in a mouse model of congenital blindness. In addition, the congruence of MRI and histological findings support the use of MRI to investigate structural brain plasticity in the mouse.

Effect of Visual Experience on Spatial Learning of Rats

Background: Visual information acquired through observation plays a pivotal role in learning a movement pattern and motor control. Objectives: This study aimed to analyze the effect of visual deprivation on learning in rats. Methods: The study sample consisted of 12 male rats, divided into three groups. Group I consisted of four rats and was considered the control group. Transection of the two optic nerves was performed on rats of group II on the seventh day after birth and group III on the seventh week after birth to develop the early blind and late blind models, respectively. A T-shaped maze device was utilized to evaluate the learning behavior of rats. Rats of groups II and III were blinded by the optic nerve surgery. In total, 20 trials per day were conducted for nine consecutive days, in which the time and number of correct arm entries were recorded. The ANOVA and Kruskal-Wallis tests were employed to analyze the results in SPSS software (version 16.0). A p-value of less than 0.05 was considered statistically significant. Results: There was a significant difference between the three groups regarding the number of correct arm entries on days one, three, and seven (P&lt;0.05). There was also a significant difference between the three groups regarding how long it took them to enter the target box on days two and three (P&lt;0.05). Group III had a lower number of entries to the target box and it took them a significantly longer time to enter the target box, compared to the other groups. Conclusion: According to the results, visual deprivation may affect the learning of rats during the early days; however, their learning levels increased over the following days. Moreover, the early blinded rats had a higher level of learning than the lately blinded adult rats and the same level of learning as that of the sighted adult rats.

The Effect of Blindness on Spatial Asymmetries.

The human cerebral cortex is asymmetrically organized with hemispheric lateralization pervading nearly all neural systems of the brain. Whether the lack of normal visual development affects hemispheric specialization subserving the deployment of visuospatial attention asymmetries is controversial. In principle, indeed, the lack of early visual experience may affect the lateralization of spatial functions, and the blind may rely on a different sensory input compared to the sighted. In this review article, we thus present a current state-of-the-art synthesis of empirical evidence concerning the effects of visual deprivation on the lateralization of various spatial processes (i.e., including line bisection, mirror symmetry, and localization tasks). Overall, the evidence reviewed indicates that spatial processes are supported by a right hemispheric network in the blind, hence, analogously to the sighted. Such a right-hemisphere dominance, however, seems more accentuated in the blind as compared to the sighted as indexed by the greater leftward bias shown in different spatial tasks. This is possibly the result of the more pronounced involvement of the right parietal cortex during spatial tasks in blind individuals compared to the sighted, as well as of the additional recruitment of the right occipital cortex, which would reflect the cross-modal plastic phenomena that largely characterize the blind brain.

Experience-Dependent Development and Maintenance of Binocular Neurons in the Mouse Visual Cortex

SUMMARYThe development of neuronal circuits requires both hard-wired gene expression and experience-dependent plasticity. Sensory processing, such as binocular vision, is especially sensitive to perturbations of experience. We investigated the experience-dependent development of the binocular visual cortex at single-cell resolution by using two-photon calcium imaging in awake mice. At eye-opening, the majority of visually responsive neurons are monocular. Binocular neurons emerge later with visual experience and acquire distinct visual response properties. Surprisingly, rather than mirroring the effects of visual deprivation, mice that lack the plasticity gene Arc show increased numbers of binocular neurons and a shift in ocular dominance during development. Strikingly, acutely removing Arc in the adult binocular visual cortex also increases the number of binocular neurons, suggesting that the maintenance of binocular circuits requires ongoing plasticity. Thus, experience-dependent plasticity is critical for the development and maintenance of circuits required to process binocular vision.

Blindness, Psychosis, and the Visual Construction of the World.

The relationship between visual loss and psychosis is complex: congenital visual loss appears to be protective against the development of a psychotic disorder, particularly schizophrenia. In later life, however, visual deprivation or visual loss can give rise to hallucinosis, disorders of visual insight such as blindsight or Anton syndrome, or, in the context of neurodegenerative disorders, more complex psychotic presentations. We draw on a computational psychiatric approach to consider the foundational role of vision in the construction of representations of the world and the effects of visual loss at different developmental stages. Using a Bayesian prediction error minimization model, we describe how congenital visual loss may be protective against the development of the kind of computational deficits postulated to underlie schizophrenia, by increasing the precision (and consequent stability) of higher-level (including supramodal) priors, focusing on visual loss-induced changes in NMDA receptor structure and function as a possible mechanistic substrate. In simple terms, we argue that when people cannot see from birth, they rely more heavily on the context they extract from the other senses, and the resulting model of the world is more impervious to the false inferences, made in the face of inevitably noisy perceptual input, that characterize schizophrenia. We show how a Bayesian prediction error minimization framework can also explain the relationship between later visual loss and other psychotic symptoms, as well as the effects of visual deprivation and hallucinogenic drugs, and outline experimentally testable hypotheses generated by this approach.

Dynamics of postural control in individuals with ankle instability: Effect of visual input and orthotic use

The present study investigated the effect of visual deprivation and the use of an ankle orthosis on the dynamics of center of pressure (COP) trajectories during unilateral stance in individuals with ankle instability (AI). Sixteen individuals with AI and nine healthy individuals performed four trials of 30s unilateral stance on a force platform with 1) eyes open wearing no orthosis, 2) eyes closed wearing no orthosis, 3) eyes open wearing orthosis, and 4) eyes closed wearing orthosis. The anterior-posterior and mediolateral COP trajectory were extracted. Regularity was quantified by sample entropy, dimensionality was quantified by correlation dimension and level of time dependency was quantified by entropic half-life. The AI individuals had lower sample entropy and longer entropic half-life in their COP trajectories. The effect of visual deprivation did not differ between groups. Wearing an ankle orthosis increased the sample entropy in the anterior-posterior direction and decreased the correlation dimension in the mediolateral direction for the AI group only. Individuals with AI have higher COP trajectory regularity and higher level of time dependency compared to healthy individuals. Additionally, individuals with AI do not alter the dynamics of their postural control during unilateral stance with visual deprivation compared to healthy individuals. This suggests that alterations in visual or somatosensory information differently affect the executed postural movement pattern. Finally, wearing an orthosis significantly alters the COP dynamics of individuals with AI.

Congenital blindness limits allocentric to egocentric switching ability.

Many everyday spatial activities require the cooperation or switching between egocentric (subject-to-object) and allocentric (object-to-object) spatial representations. The literature on blind people has reported that the lack of vision (congenital blindness) may limit the capacity to represent allocentric spatial information. However, research has mainly focused on the selective involvement of egocentric or allocentric representations, not the switching between them. Here we investigated the effect of visual deprivation on the ability to switch between spatial frames of reference. To this aim, congenitally blind (long-term visual deprivation), blindfolded sighted (temporary visual deprivation) and sighted (full visual availability) participants were compared on the Ego-Allo switching task. This task assessed the capacity to verbally judge the relative distances between memorized stimuli in switching (from egocentric-to-allocentric: Ego-Allo; from allocentric-to-egocentric: Allo-Ego) and non-switching (only-egocentric: Ego-Ego; only-allocentric: Allo-Allo) conditions. Results showed a difficulty in congenitally blind participants when switching from allocentric to egocentric representations, not when the first anchor point was egocentric. In line with previous results, a deficit in processing allocentric representations in non-switching conditions also emerged. These findings suggest that the allocentric deficit in congenital blindness may determine a difficulty in simultaneously maintaining and combining different spatial representations. This deficit alters the capacity to switch between reference frames specifically when the first anchor point is external and not body-centered.

Monocular deprivation induces dendritic spine elimination in the developing mouse visual cortex

It is well established that visual deprivation has a profound impact on the responsiveness of neurons in the developing visual cortex. The effect of visual deprivation on synaptic connectivity remains unclear. Using transcranial two-photon microscopy, we examined the effect of visual deprivation and subsequent recovery on dendritic spine remodeling of layer 5 pyramidal neurons in the mouse primary visual cortex. We found that monocular deprivation (MD), but not binocular deprivation (BD), increased dendritic spine elimination over 3 days in the binocular region of 4-week-old adolescent mice. This MD-induced dendritic spine elimination persisted during subsequent 2–4 days of binocular recovery. Furthermore, we found that average dendritic spine sizes were decreased and increased following 3-day MD and BD, respectively. These spine size changes induced by MD or BD tended to be reversed during subsequent binocular recovery. Taken together, these findings reveal differential effects of MD and BD on synaptic connectivity of layer 5 pyramidal neurons and underscore the persistent impact of MD on synapse loss in the developing visual cortex.

Compensations to auditory feedback perturbations in congenitally blind and sighted speakers: Acoustic and articulatory data.

This study investigated the effects of visual deprivation on the relationship between speech perception and production by examining compensatory responses to real-time perturbations in auditory feedback. Specifically, acoustic and articulatory data were recorded while sighted and congenitally blind French speakers produced several repetitions of the vowel /ø/. At the acoustic level, blind speakers produced larger compensatory responses to altered vowels than their sighted peers. At the articulatory level, blind speakers also produced larger displacements of the upper lip, the tongue tip, and the tongue dorsum in compensatory responses. These findings suggest that blind speakers tolerate less discrepancy between actual and expected auditory feedback than sighted speakers. The study also suggests that sighted speakers have acquired more constrained somatosensory goals through the influence of visual cues perceived in face-to-face conversation, leading them to tolerate less discrepancy between expected and altered articulatory positions compared to blind speakers and thus resulting in smaller observed compensatory responses.

Effects of visual deprivation on primary motor cortex excitability: a study on healthy subjects based on repetitive transcranial magnetic stimulation.

We investigated whether rapid changes in visual input or dark adaptation modify primary motor cortex (M1) excitability in healthy subjects. Repetitive transcranial magnetic stimulation (rTMS), consisting of 10 stimuli delivered at 5Hz at 120% of the resting motor threshold, was delivered over the M1 in 14 healthy volunteers. They were instructed to relax under eyes-open (EO) and eyes-closed (EC) resting conditions. Two experimental sessions were performed. In the first session, subjects were tested under both EO and EC conditions in order to determine whether short visual deprivation affected M1 excitability as tested through changes in the motor-evoked potential (MEP) amplitude during rTMS. In the second session, rTMS was delivered both under EO conditions with room lights on and after 30min of blindfolding to evaluate the effects of prolonged visual deprivation on M1 excitability. Short-term visual deprivation lasting 2.5s left the MEP facilitation unchanged during the 5-Hz rTMS trains, while 30min of blindfolding significantly reduced MEP facilitation. Short-term visual deprivation did not significantly affect M1 excitability, whereas dark adaptation reduced rTMS-induced MEP facilitation, modulating motor cortical excitability.