Neuromodulation of Early Multisensory Interactions in the Visual Cortex

Merging information derived from different sensory channels allows the brain to amplify minimal signals to reduce their ambiguity, thereby improving the ability of orienting to, detecting, and identifying environmental events. Although multisensory interactions have been mostly ascribed to the activity of higher-order heteromodal areas, multisensory convergence may arise even in primary sensory-specific areas located very early along the cortical processing stream. In three experiments, we investigated early multisensory interactions in lower-level visual areas, by using a novel approach, based on the coupling of behavioral stimulation with two noninvasive brain stimulation techniques, namely, TMS and transcranial direct current stimulation (tDCS). First, we showed that redundant multisensory stimuli can increase visual cortical excitability, as measured by means of phosphene induction by occipital TMS; such physiological enhancement is followed by a behavioral facilitation through the amplification of signal intensity in sensory-specific visual areas. The more sensory inputs are combined (i.e., trimodal vs. bimodal stimuli), the greater are the benefits on phosphene perception. Second, neuroelectrical activity changes induced by tDCS in the temporal and in the parietal cortices, but not in the occipital cortex, can further boost the multisensory enhancement of visual cortical excitability, by increasing the auditory and tactile inputs from temporal and parietal regions, respectively, to lower-level visual areas.

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Single Units and Visual Cortical Organization

Perception ◽

10.1068/p270889 ◽

1998 ◽

Vol 27 (8) ◽

pp. 889-935 ◽

Cited By ~ 162

Author(s):

Peter Lennie

Keyword(s):

Visual System ◽

Striate Cortex ◽

Occipital Cortex ◽

Relevant Information ◽

Hierarchical Organization ◽

Cortical Organization ◽

Visual Areas ◽

The World ◽

Visual Cortical ◽

Extrastriate Areas

The visual system has a parallel and hierarchical organization, evident at every stage from the retina onwards. Although the general benefits of parallel and hierarchical organization in the visual system are easily understood, it has not been easy to discern the function of the visual cortical modules. I explore the view that striate cortex segregates information about different attributes of the image, and dispatches it for analysis to different extrastriate areas. I argue that visual cortex does not undertake multiple relatively independent analyses of the image from which it assembles a unified representation that can be interrogated about the what and where of the world. Instead, occipital cortex is organized so that perceptually relevant information can be recovered at every level in the hierarchy, that information used in making decisions at one level is not passed on to the next level, and, with one rather special exception (area MT), through all stages of analysis all dimensions of the image remain intimately coupled in a retinotopic map. I then offer some explicit suggestions about the analyses undertaken by visual areas in occipital cortex, and conclude by examining some objections to the proposals.

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Acoustic Noise Improves Visual Perception and Modulates Occipital Oscillatory States

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00524 ◽

2014 ◽

Vol 26 (4) ◽

pp. 699-711 ◽

Cited By ~ 30

Author(s):

Stephanie Gleiss ◽

Christoph Kayser

Keyword(s):

Visual Perception ◽

Cortical Excitability ◽

Acoustic Noise ◽

Dependent Manner ◽

Beta Band ◽

Visual Contrast ◽

Continuous Background ◽

Multisensory Interactions ◽

Visual Cortical ◽

Task Irrelevant

Perception is a multisensory process, and previous work has shown that multisensory interactions occur not only for object-related stimuli but also for simplistic and apparently unrelated inputs to the different senses. We here compare the facilitation of visual perception induced by transient (target-synchronized) sounds to the facilitation provided by continuous background noise like sounds. Specifically, we show that continuous acoustic noise improves visual contrast detection by systematically shifting psychometric curves in an amplitude-dependent manner. This multisensory benefit was found to be both qualitatively and quantitatively similar to that induced by a transient and target synchronized sound in the same paradigm. Studying the underlying neural mechanisms using electric neuroimaging (EEG), we found that acoustic noise alters occipital alpha (8–12 Hz) power and decreases beta-band (14–20 Hz) coupling of occipital and temporal sites. Task-irrelevant and continuous sounds thereby have an amplitude-dependent effect on cortical mechanisms implicated in shaping visual cortical excitability. The same oscillatory mechanisms also mediate visual facilitation by transient sounds, and our results suggest that task-related sounds and task-irrelevant background noises could induce perceptually and mechanistically similar enhancement of visual perception. Given the omnipresence of sounds and noises in our environment, such multisensory interactions may affect perception in many everyday scenarios.

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Combined Activation and Deactivation of Visual Cortex During Tactile Sensory Processing

Journal of Neurophysiology ◽

10.1152/jn.00806.2006 ◽

2007 ◽

Vol 97 (2) ◽

pp. 1633-1641 ◽

Cited By ~ 84

Author(s):

Lotfi B. Merabet ◽

Jascha D. Swisher ◽

Stephanie A. McMains ◽

Mark A. Halko ◽

Amir Amedi ◽

...

Keyword(s):

Visual Cortex ◽

Sensory Processing ◽

Occipital Cortex ◽

Visual Modality ◽

Visual Areas ◽

Cortical Hierarchy ◽

Cortical Regions ◽

Visual Cortical ◽

Higher Visual Areas ◽

Significant Activation

The involvement of occipital cortex in sensory processing is not restricted solely to the visual modality. Tactile processing has been shown to modulate higher-order visual and multisensory integration areas in sighted as well as visually deprived subjects; however, the extent of involvement of early visual cortical areas remains unclear. To investigate this issue, we employed functional magnetic resonance imaging in normally sighted, briefly blindfolded subjects with well-defined visuotopic borders as they tactually explored and rated raised-dot patterns. Tactile task performance resulted in significant activation in primary visual cortex (V1) and deactivation of extrastriate cortical regions V2, V3, V3A, and hV4 with greater deactivation in dorsal subregions and higher visual areas. These results suggest that tactile processing affects occipital cortex via two distinct pathways: a suppressive top-down pathway descending through the visual cortical hierarchy and an excitatory pathway arising from outside the visual cortical hierarchy that drives area V1 directly.

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Visual cortical excitability in dementia with Lewy bodies

The British Journal of Psychiatry ◽

10.1192/bjp.bp.114.152736 ◽

2016 ◽

Vol 208 (5) ◽

pp. 497-498 ◽

Cited By ~ 7

Author(s):

John-Paul Taylor ◽

Michael Firbank ◽

John T. O'Brien

Keyword(s):

Visual System ◽

Dementia With Lewy Bodies ◽

Cortical Excitability ◽

Lewy Bodies ◽

Visual Hallucinations ◽

Double Dissociation ◽

Visual Areas ◽

Phosphene Threshold ◽

Visual Cortical ◽

The Relationship

SummaryAlterations in the visual system may underlie visual hallucinations in dementia with Lewy bodies (DLB). However, cortical excitability as measured by transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) activation of lower visual areas (V1–3) to visual stimuli appear normal in DLB. We explored the relationship between TMS-determined phosphene threshold and fMRI-related visual activation and found a positive relationship between the two in controls but a negative one in DLB. This double dissociation suggests a loss of inhibition in the visual system in DLB, which may predispose individuals to visual dysfunction and visual hallucinations.

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

Journal of Neurosurgery ◽

10.3171/2019.3.jns182774 ◽

2020 ◽

Vol 132 (6) ◽

pp. 2000-2007 ◽

Cited By ~ 3

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.

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Urban temporary housing environments—from a systematic comparison towards an integrated typology

Journal of Housing and the Built Environment ◽

10.1007/s10901-020-09812-x ◽

2021 ◽

Author(s):

Mirjam Stocker ◽

Gerda Schneider ◽

Julia Zeilinger ◽

Gloria Rose ◽

Doris Damyanovic ◽

...

Keyword(s):

Spatial Organization ◽

Housing Demand ◽

Economic Aspects ◽

Temporary Housing ◽

Open Spaces ◽

Systematic Comparison ◽

Human Needs ◽

Novel Approach ◽

Environmental Events ◽

First Time

AbstractHousing plays a central role in everyday life and the fulfillment of human needs. Temporary housing demand can occur due to migration, extreme environmental events or personal decisions, and is expected to increase in the upcoming years. This study aims to create a general understanding of temporary housing. We conducted an integrated comparison of 66 international temporary housing examples via tabulation (table work), in an interdisciplinary manner considering details regarding built structure, open spaces, area, infrastructure, organizational and socio-economic aspects. It is the first time that a systematic comparison via tabulation (based on the approach of Braun-Blanquet) is used to classify temporary housing environments. The process is described in detail. The application of the systematic comparison creates a detailed typology that allows extensions and further differentiations. The types that emerge from the tabulation have specific concepts regarding the structural-spatial organization, technical infrastructure, and organizational matters, among others. The typology was further examined in the context of previous groupings in published literature. This novel approach of analyzing and structuring temporary housing offers a comprehensive perspective that can work as a universal understanding and language for precise communication among different disciplines regarding temporary housing.

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Some Subcortical Determinants of Visual Cortical Excitability in the Cat

International Journal of Neuroscience ◽

10.3109/00207457309149444 ◽

1973 ◽

Vol 5 (1) ◽

pp. 1-13 ◽

Cited By ~ 4

Author(s):

Leo M. Chalupa ◽

William S. Battersby ◽

Thomas E. Frumkes

Keyword(s):

Cortical Excitability ◽

Visual Cortical

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Equal Degrees of Object Selectivity for Upper and Lower Visual Field Stimuli

Journal of Neurophysiology ◽

10.1152/jn.00462.2010 ◽

2010 ◽

Vol 104 (4) ◽

pp. 2075-2081 ◽

Cited By ~ 16

Author(s):

Lars Strother ◽

Adrian Aldcroft ◽

Cheryl Lavell ◽

Tutis Vilis

Keyword(s):

Visual Field ◽

Occipital Cortex ◽

Recognition System ◽

Blood Oxygen Level Dependent ◽

Lower Visual Field ◽

Blood Oxygen Level ◽

Visual Areas ◽

Bold Responses ◽

Cortical Regions ◽

Lateral Occipital Cortex

Functional MRI (fMRI) studies of the human object recognition system commonly identify object-selective cortical regions by comparing blood oxygen level–dependent (BOLD) responses to objects versus those to scrambled objects. Object selectivity distinguishes human lateral occipital cortex (LO) from earlier visual areas. Recent studies suggest that, in addition to being object selective, LO is retinotopically organized; LO represents both object and location information. Although LO responses to objects have been shown to depend on location, it is not known whether responses to scrambled objects vary similarly. This is important because it would suggest that the degree of object selectivity in LO does not vary with retinal stimulus position. We used a conventional functional localizer to identify human visual area LO by comparing BOLD responses to objects versus scrambled objects presented to either the upper (UVF) or lower (LVF) visual field. In agreement with recent findings, we found evidence of position-dependent responses to objects. However, we observed the same degree of position dependence for scrambled objects and thus object selectivity did not differ for UVF and LVF stimuli. We conclude that, in terms of BOLD response, LO discriminates objects from non-objects equally well in either visual field location, despite stronger responses to objects in the LVF.

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Neural correlates of motion processing through echolocation, source hearing, and vision in blind echolocation experts and sighted echolocation novices

Journal of Neurophysiology ◽

10.1152/jn.00501.2013 ◽

2014 ◽

Vol 111 (1) ◽

pp. 112-127 ◽

Cited By ~ 28

Author(s):

L. Thaler ◽

J. L. Milne ◽

S. R. Arnott ◽

D. Kish ◽

M. A. Goodale

Keyword(s):

Visual Motion ◽

Brain Activity ◽

Region Of Interest ◽

Occipital Cortex ◽

Neural Substrates ◽

Motion Processing ◽

Planum Temporale ◽

Show Evidence ◽

Visual Cortical ◽

Source Motion

We have shown in previous research (Thaler L, Arnott SR, Goodale MA. PLoS One 6: e20162, 2011) that motion processing through echolocation activates temporal-occipital cortex in blind echolocation experts. Here we investigated how neural substrates of echo-motion are related to neural substrates of auditory source-motion and visual-motion. Three blind echolocation experts and twelve sighted echolocation novices underwent functional MRI scanning while they listened to binaural recordings of moving or stationary echolocation or auditory source sounds located either in left or right space. Sighted participants' brain activity was also measured while they viewed moving or stationary visual stimuli. For each of the three modalities separately (echo, source, vision), we then identified motion-sensitive areas in temporal-occipital cortex and in the planum temporale. We then used a region of interest (ROI) analysis to investigate cross-modal responses, as well as laterality effects. In both sighted novices and blind experts, we found that temporal-occipital source-motion ROIs did not respond to echo-motion, and echo-motion ROIs did not respond to source-motion. This double-dissociation was absent in planum temporale ROIs. Furthermore, temporal-occipital echo-motion ROIs in blind, but not sighted, participants showed evidence for contralateral motion preference. Temporal-occipital source-motion ROIs did not show evidence for contralateral preference in either blind or sighted participants. Our data suggest a functional segregation of processing of auditory source-motion and echo-motion in human temporal-occipital cortex. Furthermore, the data suggest that the echo-motion response in blind experts may represent a reorganization rather than exaggeration of response observed in sighted novices. There is the possibility that this reorganization involves the recruitment of “visual” cortical areas.

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