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Akinetopsia is a rare neurological syndrome characterized by an impaired perception of movement, often resulting from brain damage due to ischemia, epilepsy, or medication. It is also known as visual motion blindness, and patients with this condition are unable to perceive motion normally even with perfect visual acuity. This report aims to present a case of a patient in their late 40 s who developed akinetopsia and also an impairment in movement perception of objects without emitting sounds, after experiencing a late relapse of breast cancer with the occurrence of multiple brain metastases. The patient also experienced visual hallucinations, night terrors, and difficulty forming anterograde memory. Neuroimaging with MRI revealed severe brain damage, especially in the middle temporal area of the visual cortex. Akinetopsia is a rare phenomenon, and this is the first known case of its association with brain metastases.

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The visual system can regulate its sensitivity depending on the prevailing contrast conditions. This is known as contrast adaptation and reflects contrast gain changes at different stages along the visual pathway. Recently, it has been shown that depriving an eye of visual stimulation for a short period of time can lead to neuroplastic changes in ocular dominance as the result of homeostatic changes in contrast gain. Here we examine, on the basis of previously published results, whether the neuroplastic ocular dominance changes are just manifestation of the mechanism responsible for contrast adaptation. The evidence suggests that these two visual processes are separate and do not have a common neural substrate.

Braille reading and other tactile discrimination tasks recruit the visual cortex of both blind and normally sighted individuals undergoing short-term visual deprivation. Prior functional magnetic resonance imaging (fMRI) work in patient \'S\', a visually impaired adult with the rare ability to read both highly magnified print visually and Braille by touch, found that foveal representations of S\'s visual cortex were recruited during tactile perception, whereas peripheral regions were recruited during visual perception. Here, we test the causal nature of tactile responses in the visual cortex of S by combining tactile and visual psychophysics with repetitive transcranial magnetic stimulation. First, we replicate the previous fMRI findings in S. Second, we demonstrate that transient disruption of S\'s foveal visual cortex has no measurable impact on S\'s tactile processing performance compared to that of healthy controls - a pattern not predicted by the fMRI results. Third, stimulation of foveal visual cortex maximally disrupted visual processing performance in both S and controls, suggesting the possibility of preserved visual processing within S\'s foveal representation. Finally, stimulation of somatosensory cortex induced the expected disruption to tactile processing performance in both S and controls. These data suggest that tactile responses in S\'s foveal representation reflect unmasking of latent connections between visual and somatosensory cortices and not behaviourally relevant cross-modal plasticity. Unlike studies in congenitally blind individuals, it is possible that the absence of complete visual loss in S has limited the degree of causally impactful cross-modal reorganisation.

BACKGROUND: Intermittent exotropia (IXT) is the most common type of divergent squint. IXT is primarily a cortical neurologic dysfunction disorder, occurring as a result of the insufficient maintenance of sensory and motor fusion. Recent reports have demonstrated the relationship between IXT and visual cortical impairment. We planned to assess blood oxygen level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) in patients with IXT during the preoperative and postoperative follow-ups to evaluate the functional changes in the visual cortex.
METHODS: A total of 90 Chinese subjects will be recruited, and their ages will be between 18 and 40 years old. The subjects will include the surgical treatment (ST) group (45 subjects with IXT who will undergo surgery) and the HC group (45 age-matched, sex-matched and education-matched healthy volunteers). The assessments will include the following aspects: fMRI and general ophthalmic examinations, optometry measurements and strabismus-related tests, such as the ocular deviation, binocular vision test and Newcastle Control Score (NCS). Each subject will complete the resting-state BOLD-fMRI, and the sequences will include echo planar imaging (EPI) pulse and 3-dimensional brain volume (3D-BRAVO) to acquire high-resolution images. The follow-up schedule will be 6 and 12 months after the surgery. The primary outcome will be determined by cortex changes in BOLD-fMRI in the ST group before and after surgery. We will also compare the HC group with the preoperative subjects in the ST group. The secondary outcomes will be changes in strabismus-related examinations, such as binocular visual function and NCS.
BACKGROUND: Ethical approval was obtained from the Medical Ethics Committee of Beijing Tongren Hospital. We plan to publish the results of this study in a peer-reviewed journal article.
BACKGROUND: ChiCTR2100048852.

Impairment of the geniculostriate pathway results in scotomas in the corresponding part of the visual field. Here, we present a case of patient IB with left eye microphthalmia and with lesions in most of the left geniculostriate pathway, including the Lateral Geniculate Nucleus (LGN). Despite the severe lesions, the patient has a very narrow scotoma in the peripheral part of the lower-right-hemifield only (beyond 15° of eccentricity) and complete visual field representation in the primary visual cortex. Population receptive field mapping (pRF) of the patient\'s visual field reveals orderly eccentricity maps together with contralateral activation in both hemispheres. With diffusion tractography, we revealed connections between superior colliculus (SC) and cortical structures in the hemisphere affected by the lesions, which could mediate the retinotopic reorganization at the cortical level. Our results indicate an astonishing case for the flexibility of the developing retinotopic maps where the contralateral thalamus receives fibers from both the nasal and temporal retinae.

BACKGROUND: Pediatric gunshot wounds (GSWs) to the head are not well studied in the literature, especially in civilians. With a dearth of case-based and clinically relevant information, pediatric neurosurgeons may be challenged when considering the risks and benefits of removing retained bullet fragments in different intracranial locations. We explore the literature and highlight the key factors in the surgical decision-making case of a 16-year-old girl with GSW to the visual cortex.
METHODS: A 16-year-old girl was shot in the head in a parieto-occipital trajectory with the bullet crossing midline, lodging in the occipital lobe into the straight sinus. Her initial Glasgow Coma Scale was 7, and she was urgently stabilized with intracranial pressure monitoring and external ventricular drainage. She underwent craniectomy, debridement, and irrigation and then a reoperation for further debridement and culture 2 weeks later for persistent fevers; cultures remained negative. The retained bullet was not removed. At 18 months post-injury, she had normal speech and motor function, moderate memory dysfunction, and 3-quadrant field loss with retained macular vision.
CONCLUSIONS: Pediatric penetrating GSWs to the head may be challenging to manage since literature is sparse. In this case, the primary focus of management was to maintain normal intracranial pressure, reduce risk of infection, and preserve potentially viable visual cortex. In the civilian context of available antibiotics and serial imaging, it may be possible to manage retained bullets conservatively without delayed complications.

The sparse coding algorithm has served as a model for early processing in mammalian vision. It has been assumed that the brain uses sparse coding to exploit statistical properties of the sensory stream. We hypothesize that sparse coding discovers patterns from the data set, which can be used to estimate a set of stimulus parameters by simple readout. In this study, we chose a model of stereo vision to test our hypothesis. We used the Locally Competitive Algorithm (LCA), followed by a naïve Bayes classifier, to infer stereo disparity. From the results we report three observations. First, disparity inference was successful with this naturalistic processing pipeline. Second, an expanded, highly redundant representation is required to robustly identify the input patterns. Third, the inference error can be predicted from the number of active coefficients in the LCA representation. We conclude that sparse coding can generate a suitable general representation for subsequent inference tasks.

The authors report intraoperative mapping with cortical visual evoked potentials during occipital tumor resection. This approach was valuable to reduce the risk of visual cortex and visual pathways damage and, accordingly, the likelihood of postoperative visual impairment. The peculiarity of this case is registration of clear cortical visual evoked potentials in various positions before and after tumor resection. Intraoperative monitoring was valuable to avoid damage to visual cortex and visual pathways during tumor resection. There was no postoperative visual deterioration. Moreover, we observed partial recovery of visual fields after resection of occipital malignant tumor.
В работе приводится клинический случай, показывающий возможность использования корковых зрительных вызванных потенциалов (ЗВП) при удалении опухоли затылочной доли для уменьшения риска повреждения зрительной коры и зрительных проводящих путей и, соответственно, для снижения вероятности ухудшения зрения после операции. Особенность клинического случая заключается в том, что нам удалось зарегистрировать четкие компоненты ЗВП в различных позициях до и после удаления опухоли. Благодаря проведенному мониторингу при удалении опухоли удалось обойти зрительную кору и проводящие зрительные пути. После нейрохирургического вмешательства с интраоперационной регистрацией корковых ЗВП нарастания зрительного дефицита не было, более того, отмечено частичное восстановление полей зрения после радикального удаления злокачественной опухоли затылочной доли.