scholarly journals Monitoring Visual Cortical Activities During Progressive Retinal Degeneration Using Functional Bioluminescence Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Darryl Narcisse ◽  
Sourajit M. Mustafi ◽  
Michael Carlson ◽  
Sanghoon Kim ◽  
Subrata Batabyal ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Retinal Degeneration ◽  
Activation Parameter ◽  
Bioluminescence Imaging ◽  
Imaging Modality ◽  
Therapeutic Interventions ◽  
Neural Activation ◽  
Retinal Degenerative Diseases ◽  
Longitudinal Imaging ◽  
Visual Cortical

Mouse models of inherited retinal degenerative diseases such as retinitis pigmentosa are characterized by degeneration of photoreceptors, which hinders the generation of signal to be transmitted to the visual cortex. By monitoring Ca2+-bioluminescence neural activity, we quantified changes in visual cortical activities in response to visual stimuli in RD10 mice during progression of retinal degeneration, which correlated with progressive deteriorations of electro-retinography signal from the eyes. The number of active neurons in the visual cortex, the intensity of Ca2+-bioluminescence response, and neural activation parameter showed progressive deterioration during aging. Further, we correlated the thinning of retina as measured by Optical Coherence Tomography with the decrease in visual cortical activities as retinal degeneration progressed. The present study establishes Ca2+-bioluminescence monitoring as a longitudinal imaging modality to characterize activities in visual cortex of retinal degenerative disease models and therapeutic interventions.

Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject

2020 ◽  
Vol 132 (6) ◽  
pp. 2000-2007 ◽  
Author(s):  
Soroush Niketeghad ◽  
Abirami Muralidharan ◽  
Uday Patel ◽  
Jessy D. Dorn ◽  
Laura Bonelli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Adverse Events ◽  
Clinical Intervention ◽  
Occipital Cortex ◽  
Neuronal Population ◽  
Serious Adverse Events ◽  
Stimulation Parameters ◽  
The Right ◽  
Visual Cortical ◽  
Stimulation Of

Stimulation of primary visual cortices has the potential to restore some degree of vision to blind individuals. Developing safe and reliable visual cortical prostheses requires assessment of the long-term stability, feasibility, and safety of generating stimulation-evoked perceptions.A NeuroPace responsive neurostimulation system was implanted in a blind individual with an 8-year history of bare light perception, and stimulation-evoked phosphenes were evaluated over 19 months (41 test sessions). Electrical stimulation was delivered via two four-contact subdural electrode strips implanted over the right medial occipital cortex. Current and charge thresholds for eliciting visual perception (phosphenes) were measured, as were the shape, size, location, and intensity of the phosphenes. Adverse events were also assessed.Stimulation of all contacts resulted in phosphene perception. Phosphenes appeared completely or partially in the left hemifield. Stimulation of the electrodes below the calcarine sulcus elicited phosphenes in the superior hemifield and vice versa. Changing the stimulation parameters of frequency, pulse width, and burst duration affected current thresholds for eliciting phosphenes, and increasing the amplitude or frequency of stimulation resulted in brighter perceptions. While stimulation thresholds decreased between an average of 5% and 12% after 19 months, spatial mapping of phosphenes remained consistent over time. Although no serious adverse events were observed, the subject experienced mild headaches and dizziness in three instances, symptoms that did not persist for more than a few hours and for which no clinical intervention was required.Using an off-the-shelf neurostimulator, the authors were able to reliably generate phosphenes in different areas of the visual field over 19 months with no serious adverse events, providing preliminary proof of feasibility and safety to proceed with visual epicortical prosthetic clinical trials. Moreover, they systematically explored the relationship between stimulation parameters and phosphene thresholds and discovered the direct relation of perception thresholds based on primary visual cortex (V1) neuronal population excitation thresholds.

scholarly journals In Vivo Imaging of Biodegradable Implants and Related Tissue Biomarkers

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2348
Author(s):  
Leon Riehakainen ◽  
Chiara Cavallini ◽  
Paolo Armanetti ◽  
Daniele Panetta ◽  
Davide Caramella ◽  
...  
Keyword(s):  
Imaging Modality ◽  
Imaging Techniques ◽  
Special Focus ◽  
Tissue Remodelling ◽  
Biodegradable Implant ◽  
Advantages And Disadvantages ◽  
Non Invasive ◽  
Positron Emission ◽  
Longitudinal Imaging

Non-invasive longitudinal imaging of osseointegration of bone implants is essential to ensure a comprehensive, physical and biochemical understanding of the processes related to a successful implant integration and its long-term clinical outcome. This study critically reviews the present imaging techniques that may play a role to assess the initial stability, bone quality and quantity, associated tissue remodelling dependent on implanted material, implantation site (surrounding tissues and placement depth), and biomarkers that may be targeted. An updated list of biodegradable implant materials that have been reported in the literature, from metal, polymer and ceramic categories, is provided with reference to the use of specific imaging modalities (computed tomography, positron emission tomography, ultrasound, photoacoustic and magnetic resonance imaging) suitable for longitudinal and non-invasive imaging in humans. The advantages and disadvantages of the single imaging modality are discussed with a special focus on preclinical imaging for biodegradable implant research. Indeed, the investigation of a new implant commonly requires histological examination, which is invasive and does not allow longitudinal studies, thus requiring a large number of animals for preclinical testing. For this reason, an update of the multimodal and multi-parametric imaging capabilities will be here presented with a specific focus on modern biomaterial research.

Critical periods for functional and anatomical compensation in lateral suprasylvian visual area following removal of visual cortex in cats

1984 ◽  
Vol 52 (5) ◽  
pp. 941-960 ◽  
Author(s):  
L. Tong ◽  
R. E. Kalil ◽  
P. D. Spear
Keyword(s):  
Visual Cortex ◽  
Critical Period ◽  
Ocular Dominance ◽  
Direction Selectivity ◽  
Visual Area ◽  
Critical Periods ◽  
Cortex Lesion ◽  
Thalamic Projections ◽  
Adult Cats ◽  
Visual Cortical

Previous experiments have found that neurons in the cat's lateral suprasylvian (LS) visual area of cortex show functional compensation following removal of visual cortical areas 17, 18, and 19 on the day of birth. Correspondingly, an enhanced retino-thalamic pathway to LS cortex develops in these cats. The present experiments investigated the critical periods for these changes. Unilateral lesions of areas 17, 18, and 19 were made in cats ranging in age from 1 day postnatal to 26 wk. When the cats were adult, single-cell recordings were made from LS cortex ipsilateral to the lesion. In addition, transneuronal autoradiographic methods were used to trace the retino-thalamic projections to LS cortex in many of the same animals. Following lesions in 18- and 26-wk-old cats, there is a marked reduction in direction-selective LS cortex cells and an increase in cells that respond best to stationary flashing stimuli. These results are similar to those following visual cortex lesions in adult cats. In contrast, the percentages of cells with these properties are normal following lesions made from 1 day to 12 wk of age. Thus the critical period for development of direction selectivity and greater responses to moving than to stationary flashing stimuli in LS cortex following a visual cortex lesion ends between 12 and 18 wk of age. Following lesions in 26-wk-old cats, there is a decrease in the percentage of cells that respond to the ipsilateral eye, which is similar to results following visual cortex lesions in adult cats. However, ocular dominance is normal following lesions made from 1 day to 18 wk of age. Thus the critical period for development of responses to the ipsilateral eye following a lesion ends between 18 and 26 wk of age. Following visual cortex lesions in 2-, 4-, or 8-wk-old cats, about 30% of the LS cortex cells display orientation selectivity to elongated slits of light. In contrast, few or no cells display this property in normal adult cats, cats with lesions made on the day of birth, or cats with lesions made at 12 wk of age or later. Thus an anomalous property develops for many LS cells, and the critical period for this property begins later (between 1 day and 2 wk) and ends earlier (between 8 and 12 wk) than those for other properties.(ABSTRACT TRUNCATED AT 400 WORDS)

Altered glial gene expression, density, and architecture in the visual cortex upon retinal degeneration

2011 ◽  
Vol 1422 ◽  
pp. 46-56 ◽  
Author(s):  
Ashley Cornett ◽  
Joseph F. Sucic ◽  
Dylan Hillsburg ◽  
Lindsay Cyr ◽  
Catherine Johnson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Visual Cortex ◽  
Retinal Degeneration

scholarly journals The Development of Active Binocular Vision under Normal and Alternate Rearing Conditions

2020 ◽  
Author(s):  
Lukas Klimmasch ◽  
Johann Schneider ◽  
Alexander Lelais ◽  
Bertram E. Shi ◽  
Jochen Triesch
Keyword(s):  
Visual Cortex ◽  
Binocular Vision ◽  
Cortical Neurons ◽  
Orientation Tuning ◽  
Active Perception ◽  
Efficient Coding ◽  
Rearing Conditions ◽  
Active Binocular Vision ◽  
Experimental Findings ◽  
Visual Cortical

AbstractThe development of binocular vision is an active learning process comprising the development of disparity tuned neurons in visual cortex and the establishment of precise vergence control of the eyes. We present a computational model for the learning and self-calibration of active binocular vision based on the Active Efficient Coding framework, an extension of classic efficient coding ideas to active perception. Under normal rearing conditions, the model develops disparity tuned neurons and precise vergence control, allowing it to correctly interpret random dot stereogramms. Under altered rearing conditions modeled after neurophysiological experiments, the model qualitatively reproduces key experimental findings on changes in binocularity and disparity tuning. Furthermore, the model makes testable predictions regarding how altered rearing conditions impede the learning of precise vergence control. Finally, the model predicts a surprising new effect that impaired vergence control affects the statistics of orientation tuning in visual cortical neurons.

scholarly journals Decoding brain responses to pixelized images in the primary visual cortex: implications for visual cortical prostheses

2015 ◽  
Vol 10 (10) ◽  
pp. 1622 ◽  
Author(s):  
Wen-sheng Hou ◽  
Bing-bing Guo ◽  
Xiao-lin Zheng ◽  
Zhen-gang Lu ◽  
Xing Wang ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Brain Responses ◽  
Visual Cortical

Bioluminescence imaging of Arc expression enables detection of activity-dependent and plastic changes in the visual cortex of adult mice

2010 ◽  
Vol 216 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Hironori Izumi ◽  
Tetsuya Ishimoto ◽  
Hiroshi Yamamoto ◽  
Hisao Nishijo ◽  
Hisashi Mori
Keyword(s):  
Visual Cortex ◽  
Bioluminescence Imaging ◽  
Adult Mice ◽  
Plastic Changes ◽  
Activity Dependent

scholarly journals Critical periods in amblyopia

2018 ◽  
Vol 35 ◽  
Author(s):  
TAKAO K. HENSCH ◽  
ELIZABETH M. QUINLAN
Keyword(s):  
Visual Cortex ◽  
Critical Period ◽  
Molecular Mechanisms ◽  
Ocular Dominance ◽  
Molecular Genetic ◽  
Monocular Deprivation ◽  
Critical Periods ◽  
Developmental Constraints ◽  
Early Postnatal Development ◽  
Visual Cortical

AbstractThe shift in ocular dominance (OD) of binocular neurons induced by monocular deprivation is the canonical model of synaptic plasticity confined to a postnatal critical period. Developmental constraints on this plasticity not only lend stability to the mature visual cortical circuitry but also impede the ability to recover from amblyopia beyond an early window. Advances with mouse models utilizing the power of molecular, genetic, and imaging tools are beginning to unravel the circuit, cellular, and molecular mechanisms controlling the onset and closure of the critical periods of plasticity in the primary visual cortex (V1). Emerging evidence suggests that mechanisms enabling plasticity in juveniles are not simply lost with age but rather that plasticity is actively constrained by the developmental up-regulation of molecular ‘brakes’. Lifting these brakes enhances plasticity in the adult visual cortex, and can be harnessed to promote recovery from amblyopia. The reactivation of plasticity by experimental manipulations has revised the idea that robust OD plasticity is limited to early postnatal development. Here, we discuss recent insights into the neurobiology of the initiation and termination of critical periods and how our increasingly mechanistic understanding of these processes can be leveraged toward improved clinical treatment of adult amblyopia.

Predictability-dependent encoding of statistical regularities in the early visual cortex

2022 ◽  
Author(s):  
Andrea Kóbor ◽  
Karolina Janacsek ◽  
Petra Hermann ◽  
Zsofia Zavecz ◽  
Vera Varga ◽  
...  
Keyword(s):  
Visual Cortex ◽  
The Other ◽  
Block Type ◽  
Statistical Knowledge ◽  
Early Visual Cortex ◽  
Statistical Regularities ◽  
Visual Cortical ◽  
Increased Activity ◽  
The Brain ◽  
Subsequent Task

Previous research recognized that humans could extract statistical regularities of the environment to automatically predict upcoming events. However, it has remained unexplored how the brain encodes the distribution of statistical regularities if it continuously changes. To investigate this question, we devised an fMRI paradigm where participants (N = 32) completed a visual four-choice reaction time (RT) task consisting of statistical regularities. Two types of blocks involving the same perceptual elements alternated with one another throughout the task: While the distribution of statistical regularities was predictable in one block type, it was unpredictable in the other. Participants were unaware of the presence of statistical regularities and of their changing distribution across the subsequent task blocks. Based on the RT results, although statistical regularities were processed similarly in both the predictable and unpredictable blocks, participants acquired less statistical knowledge in the unpredictable as compared with the predictable blocks. Whole-brain random-effects analyses showed increased activity in the early visual cortex and decreased activity in the precuneus for the predictable as compared with the unpredictable blocks. Therefore, the actual predictability of statistical regularities is likely to be represented already at the early stages of visual cortical processing. However, decreased precuneus activity suggests that these representations are imperfectly updated to track the multiple shifts in predictability throughout the task. The results also highlight that the processing of statistical regularities in a changing environment could be habitual.

Cerebral Blood Flow of the Neonatal Brain after Hypoxic-Ischemic Injury

2021 ◽  
Author(s):  
Luis Octavio Tierradentro-García ◽  
Sandra Saade-Lemus ◽  
Colbey Freeman ◽  
Matthew Kirschen ◽  
Hao Huang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Near Infrared ◽  
Imaging Modality ◽  
Brain Perfusion ◽  
Correlation Spectroscopy ◽  
Therapeutic Interventions ◽  
Routine Practice ◽  
Diffuse Correlation Spectroscopy ◽  
Positron Emission

Objective Hypoxic-ischemic encephalopathy (HIE) in infants can have long-term adverse neurodevelopmental effects and markedly reduce quality of life. Both the initial hypoperfusion and the subsequent rapid reperfusion can cause deleterious effects in brain tissue. Cerebral blood flow (CBF) assessment in newborns with HIE can help detect abnormalities in brain perfusion to guide therapy and prognosticate patient outcomes. Study Design The review will provide an overview of the pathophysiological implications of CBF derangements in neonatal HIE, current and emerging techniques for CBF quantification, and the potential to utilize CBF as a physiologic target in managing neonates with acute HIE. Conclusion The alterations of CBF in infants during hypoxia-ischemia have been studied by using different neuroimaging techniques, including nitrous oxide and xenon clearance, transcranial Doppler ultrasonography, contrast-enhanced ultrasound, arterial spin labeling MRI, 18F-FDG positron emission tomography, near-infrared spectroscopy (NIRS), functional NIRS, and diffuse correlation spectroscopy. Consensus is lacking regarding the clinical significance of CBF estimations detected by these different modalities. Heterogeneity in the imaging modality used, regional versus global estimations of CBF, time for the scan, and variables impacting brain perfusion and cohort clinical characteristics should be considered when translating the findings described in the literature to routine practice and implementation of therapeutic interventions. Key Points

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