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Cortical visual impairment

Antti J Luikku, Anette Hall, Ossi Nerg, Anne M Koivisto, Mikko Hiltunen, Seppo Helisalmi, Sanna-Kaisa Herukka, Anna Sutela, Maria Kojoukhova, Jussi Mattila, Jyrki Lötjönen, Jaana Rummukainen, Irina Alafuzoff, Juha E Jääskeläinen, Anne M Remes, Hilkka Soininen, Ville Leinonen
OBJECTIVES: Optimal selection of idiopathic normal pressure hydrocephalus (iNPH) patients for shunt surgery is challenging. Disease State Index (DSI) is a statistical method that merges multimodal data to assist clinical decision-making. It has previously been shown to be useful in predicting progression in mild cognitive impairment and differentiating Alzheimer's disease (AD) and frontotemporal dementia. In this study, we use the DSI method to predict shunt surgery response for patients with iNPH...
October 14, 2016: Acta Neurochirurgica
Bao-Hua Liu, Andrew D Huberman, Massimo Scanziani
The mammalian visual cortex massively innervates the brainstem, a phylogenetically older structure, via cortico-fugal axonal projections. Many cortico-fugal projections target brainstem nuclei that mediate innate motor behaviours, but the function of these projections remains poorly understood. A prime example of such behaviours is the optokinetic reflex (OKR), an innate eye movement mediated by the brainstem accessory optic system, that stabilizes images on the retina as the animal moves through the environment and is thus crucial for vision...
October 12, 2016: Nature
T A Polyakova, O S Levin
AIM: To study a role of cerebral microbleeds (CMB) in the diagnosis of main cerebrovascular and neurodegenerative diseases with cognitive impairment. MATERIAL AND METHODS: CMB were studied in 120 patients with Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and vascular dementia using 1.5T MRI in T2 * gradient echo. An impact of CMB on cognitive functions and the relationship with signs of vascular and neurodegenerative lesions of the brain were studied as well...
2016: Zhurnal Nevrologii i Psikhiatrii Imeni S.S. Korsakova
Maximilian Bruchmann, Catharina Korsukewitz, Julia Krämer, Heinz Wiendl, Sven G Meuth
Optic neuritis (ON) has detrimental effects on the transmission of neuronal signals generated at the earliest stages of visual information processing. The amount, as well as the speed of transmitted visual signals is impaired. Measurements of visual evoked potentials (VEP) are often implemented in clinical routine. However, the specificity of VEPs is limited because multiple cortical areas are involved in the generation of P1 potentials, including feedback signals from higher cortical areas. Here, we show that dichoptic metacontrast masking can be used to estimate the temporal delay caused by ON...
2016: PloS One
Shahin Nasr, Herminia D Rosas
: The caudate nucleus is a part of the visual corticostriatal loop (VCSL), receiving input from different visual areas and projecting back to the same cortical areas via globus pallidus, substantia nigra, and thalamus. Despite perceptual and navigation impairments in patients with VCSL disruption due to caudate atrophy (e.g., Huntington's disease, HD), the relevance of the caudate nucleus and VCSL on cortical visual processing is not fully understood. In a series of fMRI experiments, we found that the caudate showed a stronger functional connection to parahippocampal place area (PPA) compared with adjacent regions (e...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Julia Neitzel, Marion Ortner, Marleen Haupt, Petra Redel, Timo Grimmer, Igor Yakushev, Alexander Drzezga, Peter Bublak, Christoph Preul, Christian Sorg, Kathrin Finke
Posterior cortical atrophy is dominated by progressive degradation of parieto-occipital grey and white matter, and represents in most cases a variant of Alzheimer's disease. Patients with posterior cortical atrophy are characterized by increasing higher visual and visuo-spatial impairments. In particular, a key symptom of posterior cortical atrophy is simultanagnosia i.e. the inability to perceive multiple visual objects at the same time. Two neuro-cognitive mechanisms have been suggested to underlie simultanagnosia, either reduced visual short-term memory capacity or decreased visual processing speed possibly resulting from white matter impairments over and above damage to cortical brain areas...
October 3, 2016: Brain: a Journal of Neurology
Long Xie, John B Pluta, Sandhitsu R Das, Laura E M Wisse, Hongzhi Wang, Lauren Mancuso, Dasha Kliot, Brian B Avants, Song-Lin Ding, José V Manjón, David A Wolk, Paul A Yushkevich
RATIONALE: The human perirhinal cortex (PRC) plays critical roles in episodic and semantic memory and visual perception. The PRC consists of Brodmann areas 35 and 36 (BA35, BA36). In Alzheimer's disease (AD), BA35 is the first cortical site affected by neurofibrillary tangle pathology, which is closely linked to neural injury in AD. Large anatomical variability, manifested in the form of different cortical folding and branching patterns, makes it difficult to segment the PRC in MRI scans...
October 1, 2016: NeuroImage
Kali Woodruff Carr, Ahren B Fitzroy, Adam Tierney, Travis White-Schwoch, Nina Kraus
Speech communication involves integration and coordination of sensory perception and motor production, requiring precise temporal coupling. Beat synchronization, the coordination of movement with a pacing sound, can be used as an index of this sensorimotor timing. We assessed adolescents' synchronization and capacity to correct asynchronies when given online visual feedback. Variability of synchronization while receiving feedback predicted phonological memory and reading sub-skills, as well as maturation of cortical auditory processing; less variable synchronization during the presence of feedback tracked with maturation of cortical processing of sound onsets and resting gamma activity...
October 1, 2016: Brain and Language
Olaia Lucas-Jiménez, Natalia Ojeda, Javier Peña, María Díez-Cirarda, Alberto Cabrera-Zubizarreta, Juan Carlos Gómez-Esteban, María Ángeles Gómez-Beldarrain, Naroa Ibarretxe-Bilbao
OBJECTIVE: To assess whether functional neural connectivity is disrupted between the regions of the default mode network (DMN) in Parkinson's disease (PD) and how this connectivity is related to cognition, brain gray matter structure and white matter integrity and diffusivity. METHODS: Thirty-seven PD patients and 16 healthy controls were evaluated, using resting-state functional magnetic resonance imaging (MRI), T1-weighted MRI, diffusion-weighted imaging and a battery of cognitive tests...
September 10, 2016: Parkinsonism & related Disorders
Hyung-Jun Im, Jarang Hahm, Hyejin Kang, Hongyoon Choi, Hyekyoung Lee, Do Won Hwang, E Edmund Kim, June-Key Chung, Dong Soo Lee
Movement impairments in Parkinson's disease (PD) are caused by the degeneration of dopaminergic neurons and the consequent disruption of connectivity in the cortico-striatal-thalamic loop. This study evaluated brain metabolic connectivity in a 6-Hydroxydopamine (6-OHDA)-induced mouse model of PD using (18)F-fluorodeoxy glucose positron emission tomography (FDG PET). Fourteen PD-model mice and ten control mice were used for the analysis. Voxel-wise t-tests on FDG PET results yielded no significant regional metabolic differences between the PD and control groups...
2016: Scientific Reports
Chengji Piao, Xiaofei Deng, Xingyue Wang, Yiran Yuan, Zhengkui Liu, Jing Liang
The medial prefrontal cortex (mPFC) and its output area, the nucleus accumbens (NAc), are implicated in mediating attentional set-shifting. Patients with posttraumatic stress disorder (PTSD) exhibit difficulties in the disengagement of attention from traumatic cues, which is associated with impairments in set-shifting ability. However, unknown is whether alterations in corticostriatal function underlie deficits in this behavioral flexibility in individuals with PTSD. An animal model of single prolonged stress (SPS) has been partially validated as a model for PTSD, in which SPS rats recapitulate the pathophysiological abnormalities and behavioral characteristics of PTSD...
September 8, 2016: Behavioural Brain Research
Hannah Glick, Anu Sharma
This review explores cross-modal cortical plasticity as a result of auditory deprivation in populations with hearing loss across the age spectrum, from development to adulthood. Cross-modal plasticity refers to the phenomenon when deprivation in one sensory modality (e.g. the auditory modality as in deafness or hearing loss) results in the recruitment of cortical resources of the deprived modality by intact sensory modalities (e.g. visual or somatosensory systems). We discuss recruitment of auditory cortical resources for visual and somatosensory processing in deafness and in lesser degrees of hearing loss...
September 6, 2016: Hearing Research
Nada Yousif, Richard Z Fu, Bilal Abou-El-Ela Bourquin, Vamsee Bhrugubanda, Simon R Schultz, Barry M Seemungal
UNLABELLED: When processing sensory signals, the brain must account for noise, both noise in the stimulus and that arising from within its own neuronal circuitry. Dopamine receptor activation is known to enhance both visual cortical signal-to-noise-ratio (SNR) and visual perceptual performance; however, it is unknown whether these two dopamine-mediated phenomena are linked. To assess this, we used single-pulse transcranial magnetic stimulation (TMS) applied to visual cortical area V5/MT to reduce the SNR focally and thus disrupt visual motion discrimination performance to visual targets located in the same retinotopic space...
September 7, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Madhu Nagappa, Parayil Sankaran Bindu, Shwetha Chiplunkar, Periasamy Govindaraj, Gayathri Narayanappa, Ayyappan Krishnan, M M Srinivas Bharath, Aarthi Swaminathan, Jitender Saini, Hanumanthapura R Arvinda, Sanjib Sinha, Pavagada S Mathuranath, Arun B Taly
Deficiency of gamma-amino-butyrate aminotransferase (ABAT) is a rare inherited disorder. A six-month-old girl presented with hyper-somnolence, hyperkinetic movements of distal extremities during wakefulness, hypotonia, bi-pyramidal signs, and impaired response to sound and visual stimuli. Brain MRI at five months showed restricted diffusion along the internal capsule and genu of corpus callosum. A follow up MRI at 18months, showed hyperintensities in brainstem, external and internal capsule, 'trilaminated' appearance of posterior limb of internal capsule and dysmyelination of sub-cortical white matter...
September 2, 2016: Brain & Development
Antonello Baldassarre, Paolo Capotosto, Giorgia Committeri, Maurizio Corbetta
The ability to learn and process visual stimuli more efficiently is important for survival. Previous neuroimaging studies have shown that perceptual learning on a shape identification task differently modulates activity in both frontal-parietal cortical regions and visual cortex (Sigman et al., 2005;Lewis et al., 2009). Specifically, fronto-parietal regions (i.e. intra parietal sulcus, pIPS) became less activated for trained as compared to untrained stimuli, while visual regions (i.e. V2d/V3 and LO) exhibited higher activation for familiar shape...
August 31, 2016: NeuroImage
Kenji Ogawa, Fumihito Imai
Previous neuropsychological studies of ideomotor apraxia (IMA) indicated impairments in pantomime actions for tool use for both right and left hands following lesions of parieto-premotor cortices in the left hemisphere. Using functional magnetic resonance imaging (fMRI) with multi-voxel pattern analysis (MVPA), we tested the hypothesis that the left parieto-premotor cortices are involved in the storage or retrieval of hand-independent representation of tool-use actions. In the fMRI scanner, one of three kinds of tools was displayed in pictures or letters, and the participants made pantomimes of the use of these tools using the right hand for the picture stimuli or with the left hand for the letters...
September 3, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Angela C Nolin, Ryan M Mulhern, Maria V Panchenko, Ana Pisarek-Horowitz, Zhiyong Wang, Orian S Shirihai, Steven C Borkan, Andrea Havasi
Proteinuria is a major risk factor for chronic kidney disease progression. Furthermore, exposure of proximal tubular epithelial cells to excess albumin promotes tubular atrophy and fibrosis, key predictors of progressive organ dysfunction. However, the link between proteinuria and tubular damage is unclear. We propose that pathologic albumin exposure impairs proximal tubular autophagy, an essential process for recycling damaged organelles and toxic intracellular macromolecules. In both mouse primary proximal tubule and immortalized human kidney cells, albumin exposure decreased the number of autophagosomes, visualized by the autophagosome-specific fluorescent markers monodansylcadaverine and GFP-LC3, respectively...
August 31, 2016: American Journal of Physiology. Renal Physiology
Gaia Bonassi, Elisa Pelosin, Carla Ogliastro, Cecilia Cerulli, Giovanni Abbruzzese, Laura Avanzino
Mirror visual feedback (MVF) therapy has been applied to improve upper limb function in stroke. When combined with motor training, MVF improves the performance of the trained and untrained hand by enhancing the excitability of both primary motor cortices (M1s). Bradykinesia is a typical feature of Parkinson's disease (PD), characterized by slowness in the execution of movement. This condition is often asymmetrical and possibly supported by a volitional hypoactivation of M1. MVF therapy could tentatively treat bradykinesia since the untrained hand, which benefits from the exercise, is generally more severely impaired in undertaking sequential movements...
2016: Neural Plasticity
Maciej Perdziak, Dagmara K Witkowska, Wojciech Gryncewicz, Jan K Ober
Amblyopia is a developmental disorder of vision usually associated with the presence of strabismus and/or anisometropia during early childhood. Subject literature has shown that both the amblyopic and fellow eyes (especially in strabismic subjects) may manifest a variety of perceptual and oculomotor deficits. Previous studies using simple saccadic responses (pro-saccades) showed an increased saccadic latency only for the amblyopic eye viewing conditions. So far, there have appeared no saccadic latency studies in strabismic amblyopia for more complex volitional saccades...
August 1, 2016: Journal of Vision
Richard A Armstrong
Corticobasal degeneration is a rare, progressive neurodegenerative disease and a member of the 'parkinsonian' group of disorders, which also includes Parkinson's disease, progressive supranuclear palsy, dementia with Lewy bodies and multiple system atrophy. The most common initial symptom is limb clumsiness, usually affecting one side of the body, with or without accompanying rigidity or tremor. Subsequently, the disease affects gait and there is a slow progression to influence ipsilateral arms and legs. Apraxia and dementia are the most common cortical signs...
August 23, 2016: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
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