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1.
Neuroimage ; 299: 120844, 2024 Oct 01.
Article in English | MEDLINE | ID: mdl-39260781

ABSTRACT

Congenital blindness offers a unique opportunity to investigate human brain plasticity. The influence of congenital visual loss on the asymmetry of the structural network remains poorly understood. To address this question, we recruited 21 participants with congenital blindness (CB) and 21 age-matched sighted controls (SCs). Employing diffusion and structural magnetic resonance imaging, we constructed hemispheric white matter (WM) networks using deterministic fiber tractography and applied graph theory methodologies to assess topological efficiency (i.e., network global efficiency, network local efficiency, and nodal local efficiency) within these networks. Statistical analyses revealed a consistent leftward asymmetry in global efficiency across both groups. However, a different pattern emerged in network local efficiency, with the CB group exhibiting a symmetric state, while the SC group showed a leftward asymmetry. Specifically, compared to the SC group, the CB group exhibited a decrease in local efficiency in the left hemisphere, which was caused by a reduction in the nodal properties of some key regions mainly distributed in the left occipital lobe. Furthermore, interhemispheric tracts connecting these key regions exhibited significant structural changes primarily in the splenium of the corpus callosum. This result confirms the initial observation that the reorganization in asymmetry of the WM network following congenital visual loss is associated with structural changes in the corpus callosum. These findings provide novel insights into the neuroplasticity and adaptability of the brain, particularly at the network level.


Subject(s)
Blindness , Diffusion Tensor Imaging , Neuronal Plasticity , White Matter , Humans , White Matter/diagnostic imaging , White Matter/pathology , Male , Female , Neuronal Plasticity/physiology , Adult , Blindness/congenital , Blindness/physiopathology , Blindness/diagnostic imaging , Blindness/pathology , Young Adult , Diffusion Tensor Imaging/methods , Nerve Net/diagnostic imaging , Nerve Net/physiopathology , Nerve Net/pathology , Magnetic Resonance Imaging , Adolescent , Sensory Deprivation/physiology
2.
PLoS One ; 19(9): e0310033, 2024.
Article in English | MEDLINE | ID: mdl-39321152

ABSTRACT

This study explores spatial perception of depth by employing a novel proof of concept sensory substitution algorithm. The algorithm taps into existing cognitive scaffolds such as language and cross modal correspondences by naming objects in the scene while representing their elevation and depth by manipulation of the auditory properties for each axis. While the representation of verticality utilized a previously tested correspondence with pitch, the representation of depth employed an ecologically inspired manipulation, based on the loss of gain and filtration of higher frequency sounds over distance. The study, involving 40 participants, seven of which were blind (5) or visually impaired (2), investigates the intrinsicness of an ecologically inspired mapping of auditory cues for depth by comparing it to an interchanged condition where the mappings of the two axes are swapped. All participants successfully learned to use the algorithm following a very brief period of training, with the blind and visually impaired participants showing similar levels of success for learning to use the algorithm as did their sighted counterparts. A significant difference was found at baseline between the two conditions, indicating the intuitiveness of the original ecologically inspired mapping. Despite this, participants were able to achieve similar success rates following the training in both conditions. The findings indicate that both intrinsic and learned cues come into play with respect to depth perception. Moreover, they suggest that by employing perceptual learning, novel sensory mappings can be trained in adulthood. Regarding the blind and visually impaired, the results also support the convergence view, which claims that with training, their spatial abilities can converge with those of the sighted. Finally, we discuss how the algorithm can open new avenues for accessibility technologies, virtual reality, and other practical applications.


Subject(s)
Algorithms , Blindness , Cues , Depth Perception , Visually Impaired Persons , Humans , Male , Female , Adult , Depth Perception/physiology , Blindness/physiopathology , Middle Aged , Learning/physiology , Young Adult
3.
J Vis ; 24(9): 3, 2024 Sep 03.
Article in English | MEDLINE | ID: mdl-39226067

ABSTRACT

The present study investigated the role of early visual experience in the development of postural control (balance) and locomotion (gait). In a cross-sectional design, balance and gait were assessed in 59 participants (ages 7-43 years) with a history of (a) transient congenital blindness, (b) transient late-onset blindness, (c) permanent congenitally blindness, or (d) permanent late-onset blindness, as well as in normally sighted controls. Cataract-reversal participants who experienced a transient phase of blindness and gained sight through cataract removal surgery showed worse balance performance compared with sighted controls even when tested with eyes closed. Individuals with reversed congenital cataracts performed worse than individuals with reversed developmental (late emerging) cataracts. Balance performance in congenitally cataract-reversal participants when tested with eyes closed was not significantly different from that in permanently blind participants. In contrast, their gait parameters did not differ significantly from those of sighted controls. The present findings highlight both the need for visual calibration of proprioceptive and vestibular systems and the crossmodal adaptability of locomotor functions.


Subject(s)
Blindness , Postural Balance , Humans , Postural Balance/physiology , Adolescent , Adult , Child , Female , Male , Blindness/physiopathology , Cross-Sectional Studies , Young Adult , Gait/physiology , Cataract/physiopathology , Proprioception/physiology , Cataract Extraction/methods
4.
BMJ Open Ophthalmol ; 9(1)2024 Aug 05.
Article in English | MEDLINE | ID: mdl-39103235

ABSTRACT

OBJECTIVE: To quantitatively evaluate visual evoked potentials (VEPs) in prosthetic vision and simulated visual reduction. METHODS AND ANALYSIS: Four blind patients implanted with the Argus II retinal prosthesis and seven sighted controls participated. VEPs were recorded with pattern-reversal stimuli (2 cycles of a horizontal square wave grating, 0.1 cycle/degree) at 1.07 reversals per second (rps) for Argus II subjects and 3.37 rps for controls. Argus II patients had both eyes patched, viewing the pattern solely through their implant. Controls viewed the pattern monocularly, either with their best-corrected vision or with simulated visual reduction (field restriction, added blur or reduced display contrast). RESULTS: VEPs recorded in Argus II patients displayed a similar shape to normal VEPs when controls viewed the pattern without simulated visual reduction. In sighted controls, adding blur significantly delayed the P100 peak time by 8.7 ms, 95% CI (0.9, 16.6). Reducing stimulus contrast to 32% and 6% of full display contrast significantly decreased P100 amplitude to 55% (37%, 82%) and 20% (13%, 31%), respectively. Restriction on the field of view had no impact on either the amplitude or the peak latency of P100. CONCLUSION: The early visual cortex in retinal prosthesis users remains responsive to retinal input, showing a similar response profile to that of sighted controls. Pattern-reversal VEP offers valuable insights for objectively evaluating artificial vision therapy systems (AVTSs) when selecting, fitting and training implant users, but the uncertainties in the exact timing and location of electrode stimulation must be considered when interpreting the results.


Subject(s)
Blindness , Evoked Potentials, Visual , Visual Prosthesis , Humans , Evoked Potentials, Visual/physiology , Male , Female , Blindness/physiopathology , Middle Aged , Aged , Visual Acuity/physiology , Adult
5.
Cereb Cortex ; 34(8)2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39152673

ABSTRACT

Blindness is associated with heightened sensory abilities, such as improved hearing and tactile acuity. Moreover, recent evidence suggests that blind individuals are better than sighted individuals at perceiving their own heartbeat, suggesting enhanced interoceptive accuracy. Structural changes in the occipital cortex have been hypothesized as the basis of these behavioral enhancements. Indeed, several studies have shown that congenitally blind individuals have increased cortical thickness within occipital areas compared to sighted individuals, but how these structural differences relate to behavioral enhancements is unclear. This study investigated the relationship between cardiac interoceptive accuracy and cortical thickness in 23 congenitally blind individuals and 23 matched sighted controls. Our results show a significant positive correlation between performance in a heartbeat counting task and cortical thickness only in the blind group, indicating a connection between structural changes in occipital areas and blind individuals' enhanced ability to perceive heartbeats.


Subject(s)
Blindness , Heart Rate , Occipital Lobe , Humans , Male , Female , Occipital Lobe/diagnostic imaging , Occipital Lobe/physiology , Adult , Heart Rate/physiology , Blindness/physiopathology , Middle Aged , Magnetic Resonance Imaging , Young Adult , Interoception/physiology
6.
Adv Gerontol ; 37(3): 238-242, 2024.
Article in Russian | MEDLINE | ID: mdl-39139115

ABSTRACT

Visual impairment due to ophthalmological diseases significantly affects functional activity in everyday life, since good eyesight is crucial in daily activities. Data from 837 respondents were studied, allowing for analysis of such medical and demographic indicators as age, gender, level of education, visual acuity arterial hypertension and diabetes mellitus. To measure functional status, the main activities in daily life (ADL) and instrumental activities in daily life (IADL) were evaluated using a modified version of the Katz scale and the IADL OARS scale. Statistical methods of Mantel-Hansel Chi-squared analysis were used to assess differences in the prevalence of functional blindness and visual deficit. The study showed that medical and demographic factors have a relatively smaller impact on vision deficiency compared to functional blindness, with age being a significant factor in both cases. Among the medical and demographic factors, the age of patients, as well as diabetes mellitus, significantly increase the development of visual deficiency and functional blindness. Functional blindness, in comparison with visual deficiency, causes more significant restrictions on activities in everyday life and instrumental activities in everyday life, and also causes dependence on help from others.


Subject(s)
Activities of Daily Living , Vision Disorders , Humans , Female , Male , Aged , Vision Disorders/epidemiology , Vision Disorders/physiopathology , Vision Disorders/etiology , Visual Acuity , Blindness/epidemiology , Blindness/etiology , Blindness/physiopathology , Middle Aged , Russia/epidemiology , Aged, 80 and over , Age Factors
7.
Curr Biol ; 34(17): 4047-4055.e3, 2024 Sep 09.
Article in English | MEDLINE | ID: mdl-39116886

ABSTRACT

In his 1872 monograph, Charles Darwin posited that "… the habit of expressing our feelings by certain movements, though now rendered innate, had been in some manner gradually acquired."1 Nearly 150 years later, researchers are still teasing apart innate versus experience-dependent contributions to expression recognition. Indeed, studies have shown that face detection is surprisingly resilient to early visual deprivation,2,3,4,5 pointing to plasticity that extends beyond dogmatic critical periods.6,7,8 However, it remains unclear whether such resilience extends to downstream processing, such as the ability to recognize facial expressions. The extent to which innate versus experience-dependent mechanisms contribute to this ability has yet to be fully explored.9,10,11,12,13 To investigate the impact of early visual experience on facial-expression recognition, we studied children with congenital cataracts who have undergone sight-correcting treatment14,15 and tracked their longitudinal skill acquisition as they gain sight late in life. We introduce and explore two potential facilitators of late-life plasticity: the availability of newborn-like coarse visual acuity prior to treatment16 and the privileged role of motion following treatment.4,17,18 We find that early visual deprivation does not preclude partial acquisition of facial-expression recognition. While rudimentary pretreatment vision is sufficient to allow a low level of expression recognition, it does not facilitate post-treatment improvements. Additionally, only children commencing vision with high visual acuity privilege the use of dynamic cues. We conclude that skipping typical visual experience early in development and introducing high-resolution imagery late in development restricts, but does not preclude, facial-expression skill acquisition and that the representational mechanisms driving this learning differ from those that emerge during typical visual development.


Subject(s)
Blindness , Facial Expression , Humans , Blindness/physiopathology , Child , Male , Female , Adolescent , Facial Recognition/physiology , Child, Preschool , Visual Acuity/physiology
8.
PLoS One ; 19(7): e0306478, 2024.
Article in English | MEDLINE | ID: mdl-38980866

ABSTRACT

Neuroplastic changes appear in people with visual impairment (VI) and they show greater tactile abilities. Improvements in performance could be associated with the development of enhanced early attentional processes based on neuroplasticity. Currently, the various early attentional and cortical remapping strategies that are utilized by people with early (EB) and late-onset blindness (LB) remain unclear. Thus, more research is required to develop effective rehabilitation programs and substitution devices. Our objective was to explore the differences in spatial tactile brain processing in adults with EB, LB and a sighted control group (CG). In this cross-sectional study 27 participants with VI were categorized into EB (n = 14) and LB (n = 13) groups. They were then compared with a CG (n = 15). A vibrotactile device and event-related potentials (ERPs) were utilized while participants performed a spatial tactile line recognition task. The P100 latency and cortical areas of maximal activity were analyzed during the task. The three groups had no statistical differences in P100 latency (p>0.05). All subjects showed significant activation in the right superior frontal areas. Only individuals with VI activated the left superior frontal regions. In EB subjects, a higher activation was found in the mid-frontal and occipital areas. A higher activation of the mid-frontal, anterior cingulate cortex and orbitofrontal zones was observed in LB participants. Compared to the CG, LB individuals showed greater activity in the left orbitofrontal zone, while EB exhibited greater activity in the right superior parietal cortex. The EB had greater activity in the left orbitofrontal region compared to the LB. People with VI may not have faster early attentional processing. EB subjects activate the occipital lobe and right superior parietal cortex during tactile stimulation because of an early lack of visual stimuli and a multimodal information processing. In individuals with LB and EB the orbitofrontal area is activated, suggesting greater emotional processing.


Subject(s)
Attention , Humans , Male , Cross-Sectional Studies , Female , Adult , Attention/physiology , Middle Aged , Evoked Potentials/physiology , Touch/physiology , Touch Perception/physiology , Neuronal Plasticity/physiology , Blindness/physiopathology , Cerebral Cortex/physiopathology , Cerebral Cortex/physiology , Physical Stimulation , Young Adult , Electroencephalography , Brain Mapping/methods
9.
Eur J Neurosci ; 60(4): 4624-4638, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39034499

ABSTRACT

Recent studies have shown that during the typical resting-state, echo planar imaging (EPI) time series obtained from the eye orbit area correlate with brain regions associated with oculomotor control and lower-level visual cortex. Here, we asked whether congenitally blind (CB) shows similar patterns, suggesting a hard-wired constraint on connectivity. We find that orbital EPI signals in CB do correlate with activity in the motor cortex, but less so with activity in the visual cortex. However, the temporal patterns of this eye movement-related signal differed strongly between CB and sighted controls. Furthermore, in CB, a few participants showed uncoordinated orbital EPI signals between the two eyes, each correlated with activity in different brain networks. Our findings suggest a retained circuitry between motor cortex and eye movements in blind, but also a moderate reorganization due to the absence of visual input, and the inability of CB to control their eye movements or sense their positions.


Subject(s)
Blindness , Eye Movements , Humans , Blindness/physiopathology , Blindness/congenital , Eye Movements/physiology , Adult , Female , Male , Middle Aged , Motor Cortex/physiopathology , Motor Cortex/diagnostic imaging , Visual Cortex/physiopathology , Visual Cortex/diagnostic imaging , Nerve Net/physiopathology , Nerve Net/diagnostic imaging , Echo-Planar Imaging/methods , Young Adult , Brain Mapping/methods
10.
Proc Natl Acad Sci U S A ; 121(32): e2320251121, 2024 Aug 06.
Article in English | MEDLINE | ID: mdl-39078671

ABSTRACT

The primary visual cortex (V1) in blindness is engaged in a wide spectrum of tasks and sensory modalities, including audition, touch, language, and memory. This widespread involvement raises questions regarding the constancy of its role and whether it might exhibit flexibility in its function over time, connecting to diverse network functions specific to task demands. This would suggest that reorganized V1 assumes a role like multiple-demand system regions. Alternatively, varying patterns of plasticity in blind V1 may be attributed to individual factors, with different blind individuals recruiting V1 preferentially for different functions. In support of this, we recently showed that V1 functional connectivity (FC) varies greatly across blind individuals. But do these represent stable individual patterns of plasticity, or are they driven more by instantaneous changes, like a multiple-demand system now inhabiting V1? Here, we tested whether individual FC patterns from the V1 of blind individuals are stable over time. We show that over two years, FC from the V1 is unique and highly stable in a small sample of repeatedly sampled congenitally blind individuals. Further, using multivoxel pattern analysis, we demonstrate that the unique reorganization patterns of these individuals allow decoding of participant identity. Together with recent evidence for substantial individual differences in V1 connectivity, this indicates that there may be a consistent role for V1 in blindness, which may differ for each individual. Further, it suggests that the variability in visual reorganization in blindness across individuals could be used to seek stable neuromarkers for sight rehabilitation and assistive approaches.


Subject(s)
Blindness , Neuronal Plasticity , Humans , Blindness/physiopathology , Neuronal Plasticity/physiology , Male , Female , Adult , Middle Aged , Magnetic Resonance Imaging , Primary Visual Cortex/physiology , Longitudinal Studies , Visual Cortex/physiopathology , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Brain Mapping/methods
11.
Cereb Cortex ; 34(6)2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38897817

ABSTRACT

Recent work suggests that the adult human brain is very adaptable when it comes to sensory processing. In this context, it has also been suggested that structural "blueprints" may fundamentally constrain neuroplastic change, e.g. in response to sensory deprivation. Here, we trained 12 blind participants and 14 sighted participants in echolocation over a 10-week period, and used MRI in a pre-post design to measure functional and structural brain changes. We found that blind participants and sighted participants together showed a training-induced increase in activation in left and right V1 in response to echoes, a finding difficult to reconcile with the view that sensory cortex is strictly organized by modality. Further, blind participants and sighted participants showed a training induced increase in activation in right A1 in response to sounds per se (i.e. not echo-specific), and this was accompanied by an increase in gray matter density in right A1 in blind participants and in adjacent acoustic areas in sighted participants. The similarity in functional results between sighted participants and blind participants is consistent with the idea that reorganization may be governed by similar principles in the two groups, yet our structural analyses also showed differences between the groups suggesting that a more nuanced view may be required.


Subject(s)
Auditory Cortex , Blindness , Magnetic Resonance Imaging , Visual Cortex , Humans , Blindness/physiopathology , Blindness/diagnostic imaging , Male , Adult , Female , Auditory Cortex/diagnostic imaging , Auditory Cortex/physiology , Auditory Cortex/physiopathology , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Young Adult , Neuronal Plasticity/physiology , Acoustic Stimulation , Brain Mapping , Middle Aged , Auditory Perception/physiology , Echolocation/physiology
12.
Acta Psychol (Amst) ; 247: 104330, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38852319

ABSTRACT

In the context of blindness, studies on the recognition of facial expressions of emotions by touch are essential to define the compensatory touch abilities and to create adapted tools on emotions. This study is the first to examine the effect of visual experience in the recognition of tactile drawings of facial expressions of emotions by children with different visual experiences. To this end, we compared the recognition rates of tactile drawings of emotions between blind children, children with low vision and sighted children aged 6-12 years. Results revealed no effect of visual experience on recognition rates. However, an effect of emotions and an interaction effect between emotions and visual experience were found. Indeed, while all children had a low average recognition rate, the drawings of fear, anger and disgust were particularly poorly recognized. Moreover, sighted children were significantly better at recognizing the drawings of surprise and sadness than the blind children who only showed high recognition rates for joy. The results of this study support the importance of developing emotion tools that can be understood by children with different visual experiences.


Subject(s)
Blindness , Emotions , Facial Expression , Humans , Child , Male , Female , Blindness/physiopathology , Blindness/psychology , Emotions/physiology , Vision, Low/physiopathology , Recognition, Psychology/physiology , Touch Perception/physiology , Facial Recognition/physiology
13.
Optom Vis Sci ; 101(6): 388-392, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38861713

ABSTRACT

SIGNIFICANCE: There is little literature linking mobility aids for people with sight loss to the functions, activities, and participation domains of the International Classification of Functioning, Disability and Health (ICF). Future studies on this relationship should be funded and pursued to better understand ways to maximize the benefit of mobility aids. PURPOSE: The ICF domains of functions, activities, and participation are potentially health-supporting aspects of daily living that may be impeded for people with sight loss. Although mobility aids facilitate safely navigating obstacles to optimize independence, it is not clear if they have any effect on functions, activities, or participation. This review explores the current literature to establish the associations between mobility aids and ICF domains. METHODS: An established scoping review methodological framework was used to systematically search, select, and synthesize the existing literature. RESULTS: Of 116 unique retrieved articles, three observational studies were eligible for inclusion with a total of 124 participants. A small experimental study found that blind adults had slower Timed Up and Go times than sighted and better performance with a long cane than without. One observational study found that physical activity was strongly related to level of visual acuity but with no independent impact of mobility aids. A single mixed-methods study explored travel frequency for blind people with assistance dogs and considered constraints to participation. CONCLUSIONS: Despite the included studies involving some aspect of mobility aid use by people with sight loss, to date, no study has focused exclusively on mobility aid intervention for people with sight loss within the physical function, physical activity, and participation domains of the ICF. There is no reliable evidence on the associations between mobility aids and physical function, physical activity, and participation. This is an important knowledge gap for determining the most suitable aids, as well as their use, to best facilitate health-supporting activities.


Subject(s)
Activities of Daily Living , Blindness , Humans , Blindness/rehabilitation , Blindness/physiopathology , Mobility Limitation , International Classification of Functioning, Disability and Health , Disability Evaluation , Self-Help Devices , Visually Impaired Persons/rehabilitation
14.
Nat Commun ; 15(1): 4481, 2024 May 27.
Article in English | MEDLINE | ID: mdl-38802397

ABSTRACT

Retinal degeneration, a leading cause of irreversible low vision and blindness globally, can be partially addressed by retina prostheses which stimulate remaining neurons in the retina. However, existing electrode-based treatments are invasive, posing substantial risks to patients and healthcare providers. Here, we introduce a completely noninvasive ultrasonic retina prosthesis, featuring a customized ultrasound two-dimensional array which allows for simultaneous imaging and stimulation. With synchronous three-dimensional imaging guidance and auto-alignment technology, ultrasonic retina prosthesis can generate programmed ultrasound waves to dynamically and precisely form arbitrary wave patterns on the retina. Neuron responses in the brain's visual center mirrored these patterns, evidencing successful artificial vision creation, which was further corroborated in behavior experiments. Quantitative analysis of the spatial-temporal resolution and field of view demonstrated advanced performance of ultrasonic retina prosthesis and elucidated the biophysical mechanism of retinal stimulation. As a noninvasive blindness prosthesis, ultrasonic retina prosthesis could lead to a more effective, widely acceptable treatment for blind patients. Its real-time imaging-guided stimulation strategy with a single ultrasound array, could also benefit ultrasound neurostimulation in other diseases.


Subject(s)
Blindness , Retina , Visual Prosthesis , Retina/diagnostic imaging , Retina/physiology , Animals , Blindness/therapy , Blindness/physiopathology , Retinal Degeneration/therapy , Retinal Degeneration/diagnostic imaging , Ultrasonic Waves , Humans , Neurons/physiology , Ultrasonography/methods , Vision, Ocular/physiology
15.
Sensors (Basel) ; 24(9)2024 May 06.
Article in English | MEDLINE | ID: mdl-38733054

ABSTRACT

The problem of supporting visually impaired and blind people in meaningful interactions with objects is often neglected. To address this issue, we adapted a tactile belt for enhanced spatial navigation into a bracelet worn on the wrist that allows visually impaired people to grasp target objects. Participants' performance in locating and grasping target items when guided using the bracelet, which provides direction commands via vibrotactile signals, was compared to their performance when receiving auditory instructions. While participants were faster with the auditory commands, they also performed well with the bracelet, encouraging future development of this system and similar systems.


Subject(s)
Hand Strength , Touch , Visually Impaired Persons , Humans , Male , Touch/physiology , Female , Hand Strength/physiology , Adult , Blindness/physiopathology , Blindness/rehabilitation , Movement/physiology , Middle Aged
16.
PLoS One ; 19(5): e0304008, 2024.
Article in English | MEDLINE | ID: mdl-38814897

ABSTRACT

The current study investigated spatial scaling of tactile maps among blind adults and blindfolded sighted controls. We were specifically interested in identifying spatial scaling strategies as well as effects of different scaling directions (up versus down) on participants' performance. To this aim, we asked late blind participants (with visual memory, Experiment 1) and early blind participants (without visual memory, Experiment 2) as well as sighted blindfolded controls to encode a map including a target and to place a response disc at the same spot on an empty, constant-sized referent space. Maps had five different sizes resulting in five scaling factors (1:3, 1:2, 1:1, 2:1, 3:1), allowing to investigate different scaling directions (up and down) in a single, comprehensive design. Accuracy and speed of learning about the target location as well as responding served as dependent variables. We hypothesized that participants who can use visual mental representations (i.e., late blind and blindfolded sighted participants) may adopt mental transformation scaling strategies. However, our results did not support this hypothesis. At the same time, we predicted the usage of relative distance scaling strategies in early blind participants, which was supported by our findings. Moreover, our results suggested that tactile maps can be scaled as accurately and even faster by blind participants than by sighted participants. Furthermore, irrespective of the visual status, participants of each visual status group gravitated their responses towards the center of the space. Overall, it seems that a lack of visual imagery does not impair early blind adults' spatial scaling ability but causes them to use a different strategy than sighted and late blind individuals.


Subject(s)
Blindness , Humans , Blindness/physiopathology , Male , Female , Adult , Middle Aged , Space Perception/physiology , Touch Perception/physiology , Young Adult , Touch/physiology
17.
eNeuro ; 11(5)2024 May.
Article in English | MEDLINE | ID: mdl-38811162

ABSTRACT

This study compared the impact of spectral and temporal degradation on vocoded speech recognition between early-blind and sighted subjects. The participants included 25 early-blind subjects (30.32 ± 4.88 years; male:female, 14:11) and 25 age- and sex-matched sighted subjects. Tests included monosyllable recognition in noise at various signal-to-noise ratios (-18 to -4 dB), matrix sentence-in-noise recognition, and vocoded speech recognition with different numbers of channels (4, 8, 16, and 32) and temporal envelope cutoff frequencies (50 vs 500 Hz). Cortical-evoked potentials (N2 and P3b) were measured in response to spectrally and temporally degraded stimuli. The early-blind subjects displayed superior monosyllable and sentence recognition than sighted subjects (all p < 0.01). In the vocoded speech recognition test, a three-way repeated-measure analysis of variance (two groups × four channels × two cutoff frequencies) revealed significant main effects of group, channel, and cutoff frequency (all p < 0.001). Early-blind subjects showed increased sensitivity to spectral degradation for speech recognition, evident in the significant interaction between group and channel (p = 0.007). N2 responses in early-blind subjects exhibited shorter latency and greater amplitude in the 8-channel (p = 0.022 and 0.034, respectively) and shorter latency in the 16-channel (p = 0.049) compared with sighted subjects. In conclusion, early-blind subjects demonstrated speech recognition advantages over sighted subjects, even in the presence of spectral and temporal degradation. Spectral degradation had a greater impact on speech recognition in early-blind subjects, while the effect of temporal degradation was similar in both groups.


Subject(s)
Blindness , Speech Perception , Humans , Male , Female , Speech Perception/physiology , Adult , Blindness/physiopathology , Young Adult , Electroencephalography/methods , Acoustic Stimulation , Recognition, Psychology/physiology , Evoked Potentials, Auditory/physiology
18.
PLoS One ; 19(5): e0300793, 2024.
Article in English | MEDLINE | ID: mdl-38748713

ABSTRACT

In nature, animals must navigate to forage according to their sensory inputs. Different species use different sensory modalities to locate food efficiently. For teleosts, food emits visual, mechanical, chemical, and/or possibly weak-electrical signals, which can be detected by optic, auditory/lateral line, and olfactory/taste buds sensory systems. However, how fish respond to and use different sensory inputs when locating food, as well as the evolution of these sensory modalities, remain unclear. We examined the Mexican tetra, Astyanax mexicanus, which is composed of two different morphs: a sighted riverine (surface fish) and a blind cave morph (cavefish). Compared with surface fish, cavefish have enhanced non-visual sensory systems, including the mechanosensory lateral line system, chemical sensors comprising the olfactory system and taste buds, and the auditory system to help navigate toward food sources. We tested how visual, chemical, and mechanical stimuli evoke food-seeking behavior. In contrast to our expectations, both surface fish and cavefish did not follow a gradient of chemical stimulus (food extract) but used it as a cue for the ambient existence of food. Surface fish followed visual cues (red plastic beads and food pellets), but, in the dark, were likely to rely on mechanosensors-the lateral line and/or tactile sensor-as cavefish did. Our results indicate cavefish used a similar sensory modality to surface fish in the dark, while affinity levels to stimuli were higher in cavefish. In addition, cavefish evolved an extended circling strategy to forage, which may yield a higher chance to capture food by swimming-by the food multiple times instead of once through zigzag motion. In summary, we propose that ancestors of cavefish, similar to the modern surface fish, evolved extended food-seeking behaviors, including circling motion, to adapt to the dark.


Subject(s)
Characidae , Feeding Behavior , Animals , Feeding Behavior/physiology , Characidae/physiology , Biological Evolution , Caves , Cues , Blindness/physiopathology
19.
Ophthalmic Genet ; 45(4): 343-350, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38629455

ABSTRACT

BACKGROUND: Homocystinuria (HCU) is a rare metabolic disease that affects many organs, including the eyes. Aims: to assess visual functions, ocular characteristics, visual quality of life and time from the onset of ocular manifestations to HCU-diagnosis in patients with HCU. MATERIAL AND METHODS: Eighteen patients underwent ophthalmological examinations and visual quality of life questionnaires. RESULTS: Best corrected decimal visual acuity was median 1.0 (range amaurosis - 1.3) right eye and 1.0 (range amaurosis -1.3) left eye. Five patients presented with severe myopia as first HCU manifestation, duration to HCU diagnosis was mean 13.6 years (range 2-25). Two patients had suffered ectopia lentis as first HCU manifestation, HCU diagnosis was established mean 8.0 years (range 7-9) later. One patient had suffered both from thrombosis and ectopia lentis prior to diagnosis. Another four patients suffered thromboembolic events before diagnosis. Median VFQ-25 composite score was 93 (68-98). CONCLUSIONS: The prevalence of myopia, ectopia lentis and monocular blindness was high in HCU-patients, which was reflected in their visual quality of life. Diagnosis was often delayed after the first ocular manifestation, increasing the risk of other severe non-ocular complications.


Subject(s)
Ectopia Lentis , Homocystinuria , Myopia , Quality of Life , Visual Acuity , Humans , Homocystinuria/complications , Homocystinuria/diagnosis , Female , Male , Visual Acuity/physiology , Adult , Child , Adolescent , Myopia/physiopathology , Young Adult , Surveys and Questionnaires , Middle Aged , Child, Preschool , Blindness/physiopathology , Blindness/psychology
20.
Ophthalmology ; 131(10): 1175-1184, 2024 Oct.
Article in English | MEDLINE | ID: mdl-38583493

ABSTRACT

PURPOSE: To describe the clinical outcome and late-stage findings of extensive macular atrophy with pseudodrusen-like appearance (EMAP). DESIGN: Retrospective cohort study. PARTICIPANTS: Seventy-eight patients (156 eyes) affected by EMAP. METHODS: We collected data on best-corrected visual acuity, kinetic perimetry, OCT, short-wavelength autofluorescence, and near-infrared autofluorescence findings. Genetic testing for the TIMP3 and C1QTNF5 genes was performed via Sanger sequencing for 58 patients, with no pathogenic variants identified. MAIN OUTCOME MEASURES: The primary outcomes were best-corrected visual acuity at the last examination, visual field at the last examination, and incidence rates and time-to-event curves for blindness with the United States Social Security Administration and World Health Organization (WHO) criteria, foveal involvement, and atrophy enlargement beyond the 30° and 55° field of view. Imaging findings at the last examination were secondary outcomes. RESULTS: At the most recent visit, mean age was 70.9 ± 5.2 years. Using United States criteria, 58.1% of the patients were blind, and 25.8% were blind according to WHO criteria. All eyes showed large central scotomas, which were associated with visual field constriction in 22.2% of eyes. We detected focal openings or large dehiscences of Bruch's membrane (BM) in 25.4% of eyes. Near-infrared autofluorescence showed increased visibility of the choroidal vessels beyond the atrophy in 87.2% of eyes. The incidence rates for blindness were 3.95 per 100 patient-years with United States criteria and 1.54 per 100 patient-years according to WHO criteria. The incidence rates were 22.8 per 100 eye-years for foveal involvement, 12.0 per 100 eye-years for atrophy enlargement beyond 30°, and 6.6 per 100 eye-years for atrophy enlargement beyond 55°. The estimates were not influenced by the age at onset. CONCLUSIONS: We identified characteristic imaging findings, including BM ruptures, in elder patients with EMAP and calculated incidence rates for different functional and anatomic outcomes. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.


Subject(s)
Disease Progression , Fluorescein Angiography , Retinal Drusen , Tomography, Optical Coherence , Visual Acuity , Visual Fields , Humans , Male , Female , Aged , Visual Acuity/physiology , Retrospective Studies , Tomography, Optical Coherence/methods , Retinal Drusen/diagnosis , Retinal Drusen/genetics , Visual Fields/physiology , Fluorescein Angiography/methods , Middle Aged , Visual Field Tests , Macular Degeneration/diagnosis , Macular Degeneration/genetics , Macular Degeneration/physiopathology , Macula Lutea/pathology , Atrophy , Tissue Inhibitor of Metalloproteinase-3/genetics , Tissue Inhibitor of Metalloproteinase-3/metabolism , Blindness/diagnosis , Blindness/etiology , Blindness/physiopathology , Aged, 80 and over , Scotoma/diagnosis , Scotoma/physiopathology
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