scholarly journals Reorganization of Visual Cortical Maps after Focal Ischemic Lesions

2003 ◽  
Vol 23 (7) ◽  
pp. 811-820 ◽  
Author(s):  
Angelica Zepeda ◽  
Luis Vaca ◽  
Clorinda Arias ◽  
Frank Sengpiel
Keyword(s):  
Visual Cortex ◽  
Visual Space ◽  
Ischemic Lesion ◽  
Orientation Preference ◽  
Intrinsic Signals ◽  
Time Points ◽  
Imaging Results ◽  
Visual Cortical ◽  
Cortical Representations ◽  
Over Time

Plasticity after central lesions may result in the reorganization of cortical representations of the sensory input. Visual cortex reorganization has been extensively studied after peripheral (retinal) lesions, but focal cortical lesions have received less attention. In this study, we investigated the organization of retinotopic and orientation preference maps at different time points after a focal ischemic lesion in the primary visual cortex (V1). We induced a focal photochemical lesion in V1 of kittens and assessed, through optical imaging of intrinsic signals, the functional cortical layout immediately afterwards and at 4, 13, 33, and 40 days after lesion. We analyzed histologic sections and evaluated temporal changes of functional maps. Histological analysis showed a clear lesion at all time points, which shrank over time. Imaging results showed that the retinotopic and orientation preference maps reorganize to some extent after the lesion. Near the lesion, the cortical retinotopic representation of one degree of visual space expands over time, while at the same time the area of some orientation domains also increases. These results show that different cortical representations can reorganize after a lesion process and suggest a mechanism through which filling-in of a cortical scotoma can occur in cortically damaged patients.

Consistent mapping of orientation preference across irregular functional domains in ferret visual cortex

2001 ◽  
Vol 18 (1) ◽  
pp. 65-76 ◽  
Author(s):  
LEONARD E. WHITE ◽  
WILLIAM H. BOSKING ◽  
DAVID FITZPATRICK
Keyword(s):  
Visual Cortex ◽  
Activity Patterns ◽  
Ocular Dominance ◽  
Visual Space ◽  
Visual Environment ◽  
Cortical Circuits ◽  
Orientation Preference ◽  
Intrinsic Signals ◽  
Layer 4 ◽  
Consistent Mapping

The mammalian visual cortex harbors a number of functional maps that represent distinct attributes of stimuli in the visual environment. How different functional maps are accommodated within the same cortical space, especially in species that show marked irregularities in one or more functional maps, remains poorly understood. We used optical imaging of intrinsic signals and electrophysiological techniques to investigate the organization of the maps of orientation preference, ocular dominance, and visual space in ferret. This species shows striking nonuniformity in the arrangement of ocular dominance domains and disruption of the mapping of visual space along the V1/V2 border. We asked whether these irregularities would be reflected in the organization of the map of orientation preference. The results show that orientation preference is mapped consistently within both V1 and V2, and across the interareal boundary, with no reflection of the irregularities in the other maps. These observations demonstrate the accommodation of multiple functional maps within the same cortical space without systematic geometrical relationships that necessarily constrain the organization of each representation. Furthermore, they imply that the structure of the map of orientation preference reflects the architecture and activity patterns of cortical circuits that are independent of other columnar systems established in layer 4.

scholarly journals Inhibition of Cdk5 in PV Neurons Reactivates Experience-Dependent Plasticity in Adult Visual Cortex

2021 ◽  
Vol 23 (1) ◽  
pp. 186
Author(s):  
Xinxin Zhang ◽  
Huiping Tang ◽  
Sitong Li ◽  
Yueqin Liu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Plasticity ◽  
Ocular Dominance ◽  
Critical Role ◽  
Threshold Current ◽  
Inhibitory Neurons ◽  
Resting Membrane Potential ◽  
Intrinsic Signals ◽  
Single Action ◽  
Visual Cortical

Cyclin-dependent kinase 5 (Cdk5) has been shown to play a critical role in brain development, learning, memory and neural processing in general. Cdk5 is widely distributed in many neuron types in the central nervous system, while its cell-specific role is largely unknown. Our previous study showed that Cdk5 inhibition restored ocular dominance (OD) plasticity in adulthood. In this study, we specifically knocked down Cdk5 in different types of neurons in the visual cortex and examined OD plasticity by optical imaging of intrinsic signals. Downregulation of Cdk5 in parvalbumin-expressing (PV) inhibitory neurons, but not other neurons, reactivated adult mouse visual cortical plasticity. Cdk5 knockdown in PV neurons reduced the evoked firing rate, which was accompanied by an increment in the threshold current for the generation of a single action potential (AP) and hyperpolarization of the resting membrane potential. Moreover, chemogenetic activation of PV neurons in the visual cortex can attenuate the restoration of OD plasticity by Cdk5 inhibition. Taken together, our results suggest that Cdk5 in PV interneurons may play a role in modulating the excitation and inhibition balance to control the plasticity of the visual cortex.

scholarly journals Diversity of Feature Selectivity in Macaque Visual Cortex Arising from a Limited Number of Broadly Tuned Input Channels

2019 ◽  
Vol 29 (12) ◽  
pp. 5255-5268
Author(s):  
Yamni S Mohan ◽  
Jaikishan Jayakumar ◽  
Errol K J Lloyd ◽  
Ekaterina Levichkina ◽  
Trichur R Vidyasagar
Keyword(s):  
Visual Cortex ◽  
Full Range ◽  
Cortical Cells ◽  
Intrinsic Signals ◽  
Thalamic Input ◽  
Feature Selectivity ◽  
The One ◽  
Visual Cortical ◽  
Orientation Domain ◽  
Preferred Stimulus

AbstractSpike (action potential) responses of most primary visual cortical cells in the macaque are sharply tuned for the orientation of a line or an edge, and neurons preferring similar orientations are clustered together in cortical columns. The preferred stimulus orientation of these columns span the full range of orientations, as observed in recordings of spikes and in classical optical imaging of intrinsic signals. However, when we imaged the putative thalamic input to striate cortical cells that can be seen in imaging of intrinsic signals when they are analyzed on a larger spatial scale, we found that the orientation domain map of the primary visual cortex did not show the same diversity of orientations. This map was dominated by just the one orientation that is most commonly preferred by neurons in the retina and the lateral geniculate nucleus. This supports cortical feature selectivity and columnar architecture being built upon feed-forward signals transmitted from the thalamus in a very limited number of broadly tuned input channels.

A Continuous Smooth Map of Space in the Primary Visual Cortex of the Common Marmoset

Perception ◽  
10.1068/p5198 ◽  
2005 ◽  
Vol 34 (8) ◽  
pp. 967-974 ◽  
Author(s):  
Niall McLoughlin ◽  
Philippa Cotton ◽  
Ingo Schiessl
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Space ◽  
Common Marmoset ◽  
Fine Scale ◽  
Marmoset Monkey ◽  
The Common ◽  
Smooth Map ◽  
Cortical Representations ◽  
Fine Scale Mapping

We examined the fine-scale mapping of the visual world within the primary visual cortex of the marmoset monkey ( Callithrix jacchus) using differential optical imaging. We stimulated two sets of complementary stripe-like locations in turn, subtracting them to generate the cortical representations of continuous bands of visual space. Rotating this stimulus configuration makes it possible to map different spatial axes within the primary visual cortex. In a similar manner, shifting the stimulated locations between trials makes it possible to map retinotopy at an even finer scale. Using these methods we found no evidence of any local anisotropies or distortions in the cortical representation of visual space. This is despite the fact that orientation preference is mapped in a discontinuous manner across the surface of marmoset V1. Overall, our results indicate that space is mapped in a continuous and smooth manner in the primary visual cortex of the common marmoset.

scholarly journals No on-off Maps in Supragranular Layers of Ferret Visual Cortex

2002 ◽  
Vol 88 (4) ◽  
pp. 2163-2166 ◽  
Author(s):  
Barbara Chapman ◽  
Imke Gödecke
Keyword(s):  
Visual Cortex ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Visual Space ◽  
Cortical Layer ◽  
Cortical Function ◽  
Cortical Cells ◽  
Cortical Inputs ◽  
Cortical Receptive Fields ◽  
Visual Cortical

Primary visual cortex contains functional maps of a number of stimulus properties including ocular dominance, orientation, direction, color, and spatial frequency. These maps must be organized with respect to each other and to a single continuous retinotopic map of visual space such that each stimulus parameter is represented at each point in space. In the ferret, geniculo-cortical inputs to cortical layer IV are segregated into on- andoff-center patches, suggesting the possibility that there might be an additional cortical map in this species. We have used optical imaging of intrinsic signals to search for on-offmaps in ferret visual cortical cells and have found none. This suggests that the high degree of on-off segregation seen subcortically in the ferret may play a role in the development of visual cortical receptive fields rather than in adult cortical function.

scholarly journals Relation Between Retinotopical and Orientation Maps in Visual Cortex

1999 ◽  
Vol 11 (2) ◽  
pp. 375-379 ◽  
Author(s):  
Udo Ernst ◽  
Klaus Pawelzik ◽  
Misha Tsodyks ◽  
Terrence J. Sejnowski
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Visual Space ◽  
Collective Effects ◽  
Cortical Model ◽  
Orientation Preference ◽  
Cat Visual Cortex ◽  
Abrupt Changes ◽  
Orientation Maps ◽  
Local Distortions

A recent study of cat visual cortex reported abrupt changes in the positions of the receptive fields of adjacent neurons whose preferred orientations strongly differed (Das & Gilbert, 1997). Using a simple cortical model, we show that this covariation of discontinuities in maps of orientation preference and local distortions in maps of visual space reflects collective effects of the lateral cortical feedback.

Measuring Agency Change Across the Domain of Hypnosis

2019 ◽  
Author(s):  
Vince Polito ◽  
Amanda Barnier ◽  
Erik Woody
Keyword(s):  
Rating Scale ◽  
Sense Of Agency ◽  
Pass Rates ◽  
Current Experiment ◽  
Multidimensional Construct ◽  
Time Points ◽  
Hypnotic Induction ◽  
Different Types ◽  
Over Time ◽  
Postexperimental Inquiry

Building on Hilgard’s (1965) classic work, the domain of hypnosis has been conceptualised by Barnier, Dienes, and Mitchell (2008) as comprising three levels: (1) classic hypnotic items, (2) responding between and within items, and (3) state and trait. The current experiment investigates sense of agency across each of these three levels. Forty-six high hypnotisable participants completed an ideomotor (arm levitation), a challenge (arm rigidity) and a cognitive (anosmia) item either following a hypnotic induction (hypnosis condition) or without a hypnotic induction (wake condition). In a postexperimental inquiry, participants rated their feelings of control at three time points for each item: during the suggestion, test and cancellation phases. They also completed the Sense of Agency Rating Scale (Polito, Barnier, & Woody, 2013) for each item. Pass rates, control ratings, and agency scores fluctuated across the different types of items and for the three phases of each item; also, control ratings and agency scores often differed across participants who passed versus failed each item. Interestingly, whereas a hypnotic induction influenced the likelihood of passing items, it had no direct effect on agentive experiences. These results suggest that altered sense of agency is not a unidimensional or static quality “switched on” by hypnotic induction, but a dynamic multidimensional construct that varies across items, over time and according to whether individuals pass or fail suggestions.

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 Two Auxinic Herbicides Affect Brassica napus Plant Hormone Levels and Induce Molecular Changes in Transcription

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1153
Author(s):  
Jutta Ludwig-Müller ◽  
Roman Rattunde ◽  
Sabine Rößler ◽  
Katja Liedel ◽  
Freia Benade ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Expression Patterns ◽  
Growth Conditions ◽  
Growth Stages ◽  
Auxin Response ◽  
Time Points ◽  
Genes Encoding ◽  
Different Temperatures ◽  
Indigenous Plant ◽  
Over Time

With the introduction of the new auxinic herbicide halauxifen-methyl into the oilseed rape (Brassica napus) market, there is a need to understand how this new molecule interacts with indigenous plant hormones (e.g., IAA) in terms of crop response. The aim of this study was to investigate the molecular background by using different growth conditions under which three different auxinic herbicides were administered. These were halauxifen-methyl (Hal), alone and together with aminopyralid (AP) as well as picloram (Pic). Three different hormone classes were determined, free and conjugated indole-3-acetic acid (IAA), aminocyclopropane carboxylic acid (ACC) as a precursor for ethylene, and abscisic acid (ABA) at two different temperatures and growth stages as well as over time (2–168 h after treatment). At 15 °C growth temperature, the effect was more pronounced than at 9 °C, and generally, the younger leaves independent of the developmental stage showed a larger effect on the alterations of hormones. IAA and ACC showed reproducible alterations after auxinic herbicide treatments over time, while ABA did not. Finally, a transcriptome analysis after treatment with two auxinic herbicides, Hal and Pic, showed different expression patterns. Hal treatment leads to the upregulation of auxin and hormone responses at 48 h and 96 h. Pic treatment induced the hormone/auxin response already after 2 h, and this continued for the other time points. The more detailed analysis of the auxin response in the datasets indicate a role for GH3 genes and genes encoding auxin efflux proteins. The upregulation of the GH3 genes correlates with the increase in conjugated IAA at the same time points and treatments. Also, genes for were found that confirm the upregulation of the ethylene pathway.

scholarly journals Levels of physical activity in four domains and affective wellbeing before and during the Covid-19 pandemic

2021 ◽  
Vol 79 (1) ◽  
Author(s):  
Eliane S. Engels ◽  
Michael Mutz ◽  
Yolanda Demetriou ◽  
Anne K. Reimers
Keyword(s):  
Mental Health ◽  
Physical Activity ◽  
Protective Factor ◽  
Total Sample ◽  
Poor Mental Health ◽  
German Population ◽  
Time Points ◽  
Sport And Exercise ◽  
Over Time ◽  
Time Point

Abstract Background Latest studies indicated that the general mental health level is low during the pandemic. Probably, this deterioration of the mental health situation is partly due to declines in physical activity. The aim of this study was to investigate differences in and the association between affective wellbeing and levels of different domains of physical activity at three time points before and during the pandemic. Method We used a nationwide online panel with a trend data design encompassing a total sample of N = 3517, representing the German population (> 14 years). Four different activity domains (sport and exercise, light outdoor activity, housework/gardening, active travel) and affective wellbeing (positive and negative affect) were assessed at three time points before and during the Covid-19 pandemic (October 2019, March 2020, October 2020). Results Multivariate analyses of variance (MANOVA) indicate differences regarding affective wellbeing over the three time points with the lowest values at the second time point. Levels of activity in the four domains differed significantly over time with the strongest decrease for sport and exercise from the first to the second time point. Partial correlations indicated that the relationships between sport and exercise and positive affect were most consistent over time. Conclusions Overall, our findings suggest that physical activity plays a particularly important role in the pandemic period as a protective factor against poor mental health. Especially sports and exercise seem to be supportive and should be encouraged, e.g. by providing additional support in finding adequate outdoor, home-based or digital substitutes.

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