scholarly journals Supersaturation of VEP in Migraine without Aura Patients Treated with Topiramate: An Anatomo-Functional Biomarker of the Disease

2021 ◽  
Vol 10 (4) ◽  
pp. 769
Author(s):  
Ciro De Luca ◽  
Sara Gori ◽  
Sonia Mazzucchi ◽  
Elisa Dini ◽  
Martina Cafalli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Neurons ◽  
Migraine Without Aura ◽  
Inverse Correlation ◽  
Primary Headache ◽  
Contrast Gain ◽  
High Prevalence ◽  
Functional Pathway ◽  
Inhibitory Signaling ◽  
Potential Use

Migraine is a primary headache with high prevalence among the general population, characterized by functional hypersensitivity to both exogenous and endogenous stimuli particularly affecting the nociceptive system. The hyperresponsivity of cortical neurons could be due to a disequilibrium in the excitatory/inhibitory signaling. This study aimed to investigate the anatomo-functional pathway from the retina to the primary visual cortex using visual evoked potentials (VEP). Contrast gain protocol was used in 15 patients diagnosed with migraine without aura (at baseline and after 3 months of topiramate therapy) and 13 controls. A saturation (S) index was assessed to monitor the response of VEP’s amplitude to contrast gain. Non-linear nor monotone growth of VEP (S < 0.95) was defined as supersaturation. A greater percentage of migraine patients (53%) relative to controls (7%) showed this characteristic. A strong inverse correlation was found between the S index and the number of days separating the registration of VEP from the next migraine attack. Moreover, allodynia measured through the Allodynia Symptoms Check-list (ASC-12) correlates with the S index both at baseline and after 3 months of topiramate treatment. Other clinical characteristics were not related to supersaturation. Topiramate therapy, although effective, did not influence electrophysiological parameters suggesting a non-intracortical nor retinal origin of the supersaturation (with possible involvement of relay cells from the lateral geniculate nucleus). In conclusion, the elaboration of visual stimuli and visual cortex activity is different in migraine patients compared to controls. More data are necessary to confirm the potential use of the S index as a biomarker for the migraine cycle (association with the pain-phase) and cortical sensitization (allodynia).

Evoked Potential: Use in Screening of Hearing and Vision

1982 ◽  
Vol 4 (3) ◽  
pp. 81-98
Keyword(s):  
Visual Acuity ◽  
Visual Cortex ◽  
Evoked Potential ◽  
Light Flash ◽  
Electrical Response ◽  
Sensory Information ◽  
Occipital Cortex ◽  
Small Children ◽  
Refractive Correction ◽  
Potential Use

An evoked potential (EP) is the electrical response of the CNS to an external stimulus. Each EP may be represented as a sequence of waves, the amplitude and length of which reflect the conduction and processing of sensory information through the CNS. Visual, auditory, and somatic EP are used clinically in pediatrics. Visual evoked potentials are the responses recorded from the occipital cortex of the scalp near the primary visual cortex to a stroboscopic light flash. The occipital potential orginates in the retina. This study can be used to assess the functional integrity of the visual system. Visual acuity can be assessed using refractive correction to enhance the amplitude of the recorded response in small children.

scholarly journals Layer-dependent multiplicative effects of spatial attention on contrast responses in human early visual cortex

2020 ◽  
Author(s):  
Fanhua Guo ◽  
Chengwen Liu ◽  
Chencan Qian ◽  
Zihao Zhang ◽  
Kaibao Sun ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Middle Layer ◽  
Additive Effect ◽  
List Type ◽  
Strong Nonlinearity ◽  
Top Down ◽  
Contrast Gain ◽  
Early Visual Cortex ◽  
Deep Layers

AbstractAttention mechanisms at different cortical layers of human visual cortex remain poorly understood. Using submillimeter-resolution fMRI at 7T, we investigated the effects of top-down spatial attention on the contrast responses across different cortical depths in human early visual cortex. Gradient echo (GE) T2* weighted BOLD signal showed an additive effect of attention on contrast responses across cortical depths. Compared to the middle cortical depth, attention modulation was stronger in the superficial and deep depths of V1, and also stronger in the superficial depth of V2 and V3. Using ultra-high resolution (0.3mm in-plane) balanced steady-state free precession (bSSFP) fMRI, a multiplicative scaling effect of attention was found in the superficial and deep layers, but not in the middle layer of V1. Attention modulation of low contrast response was strongest in the middle cortical depths, indicating baseline enhancement or contrast gain of attention modulation on feedforward input. Finally, the additive effect of attention on T2* BOLD can be explained by strong nonlinearity of BOLD signals from large blood vessels, suggesting multiplicative effect of attention on neural activity. These findings support that top-down spatial attention mainly operates through feedback connections from higher order cortical areas, and a distinct mechanism of attention may also be associated with feedforward input through subcortical pathway.HighlightsResponse or activity gain of spatial attention in superficial and deep layersContrast gain or baseline shift of attention in V1 middle layerNonlinearity of large blood vessel causes additive effect of attention on T2* BOLD

scholarly journals Astrocytic modulation of information processing by layer 5 pyramidal neurons of the mouse visual cortex

2020 ◽  
Author(s):  
Dimitri Ryczko ◽  
Maroua Hanini-Daoud ◽  
Steven Condamine ◽  
Benjamin J. B. Bréant ◽  
Maxime Fougère ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Neurons ◽  
Calcium Binding ◽  
Pyramidal Neurons ◽  
Binding Protein ◽  
Contextual Information ◽  
Dendritic Tree ◽  
Cortical Layer ◽  
List Type ◽  
Ionic Environment

AbstractThe most complex cerebral functions are performed by the cortex which most important output is carried out by its layer 5 pyramidal neurons. Their firing reflects integration of sensory and contextual information that they receive. There is evidence that astrocytes influence cortical neurons firing through the release of gliotransmitters such as ATP, glutamate or GABA. These effects were described at the network and at the synaptic levels, but it is still unclear how astrocytes influence neurons input-output transfer function at the cellular level. Here, we used optogenetic tools coupled with electrophysiological, imaging and anatomical approaches to test whether and how astrocytic activation affected processing and integration of distal inputs to layer 5 pyramidal neurons (L5PN). We show that optogenetic activation of astrocytes near L5PN cell body prolonged firing induced by distal inputs to L5PN and potentiated their ability to trigger spikes. The observed astrocytic effects on L5PN firing involved glutamatergic transmission to some extent but relied on release of S100β, an astrocytic Ca2+-binding protein that decreases extracellular Ca2+ once released. This astrocyte-evoked decrease of extracellular Ca2+ elicited firing mediated by activation of Nav1.6 channels. Our findings suggest that astrocytes contribute to the cortical fundamental computational operations by controlling the extracellular ionic environment.Key Points SummaryIntegration of inputs along the dendritic tree of layer 5 pyramidal neurons is an essential operation as these cells represent the most important output carrier of the cerebral cortex. However, the contribution of astrocytes, a type of glial cell to these operations is poorly documented.Here we found that optogenetic activation of astrocytes in the vicinity of layer 5 in the mouse primary visual cortex induce spiking in local pyramidal neurons through Nav1.6 ion channels and prolongs the responses elicited in these neurons by stimulation of their distal inputs in cortical layer 1.This effect partially involved glutamatergic signalling but relied mostly on the astrocytic calcium-binding protein S100β, which regulates the concentration of calcium in the extracellular space around neurons.These findings show that astrocytes contribute to the fundamental computational operations of the cortex by acting on the ionic environment of neurons.

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.

Spatial Contrast Sensitivity of Migraine Patients Without Aura

Cephalalgia ◽  
2002 ◽  
Vol 22 (2) ◽  
pp. 142-145 ◽  
Author(s):  
K Benedek ◽  
J Tajti ◽  
M Janáky ◽  
L Vécsei ◽  
G Benedek
Keyword(s):  
Healthy Volunteers ◽  
Contrast Sensitivity ◽  
Migraine Without Aura ◽  
Marked Decrease ◽  
Primary Headache ◽  
Visual Pathway ◽  
Control Subjects ◽  
Spatial Frequencies ◽  
Spatial Contrast Sensitivity ◽  
Visual Disturbances

Visual disturbances are frequent symptoms in migraine. Since there is a possibility of separate damage in the magno- or parvo-cellular visual pathway in migraine patients, we performed a study including the measurement of static and dynamic spatial contrast sensitivity on 15 patients suffering from migraine without aura under photopic and scotopic conditions. Fifteen healthy volunteers without primary headache served as controls. The results revealed a marked decrease in contrast sensitivity at low spatial frequencies in the migraine patients. Spatial contrast sensitivity demonstrated some lateralization, as the sensitivity to low spatial frequencies obtained through separate eyes showed significantly larger side-differences in migraine patients than in control subjects. These findings suggest that the mechanisms responsible for vision at low spatial frequencies are impaired in migraine patients. This might indicate impaired function of the magnocellular pathways in this condition.

Contrast gain control in the cat visual cortex

Nature ◽  
1982 ◽  
Vol 298 (5871) ◽  
pp. 266-268 ◽  
Author(s):  
I. Ohzawa ◽  
G. Sclar ◽  
R. D. Freeman
Keyword(s):  
Visual Cortex ◽  
Gain Control ◽  
Contrast Gain ◽  
Contrast Gain Control ◽  
Cat Visual Cortex

scholarly journals Postnatal Development of Onset Transient Responses in Macaque V1 and V2 Neurons

2008 ◽  
Vol 100 (3) ◽  
pp. 1476-1487 ◽  
Author(s):  
Bin Zhang ◽  
Earl L. Smith ◽  
Yuzo M. Chino
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Primary Visual Cortex ◽  
Cortical Neurons ◽  
Newborn Infants ◽  
Neuronal Firing ◽  
Transient Responses ◽  
Visual Cortical ◽  
Better Than

Vision of newborn infants is limited by immaturities in their visual brain. In adult primates, the transient onset discharges of visual cortical neurons are thought to be intimately involved with capturing the rapid succession of brief images in visual scenes. Here we sought to determine the responsiveness and quality of transient responses in individual neurons of the primary visual cortex (V1) and visual area 2 (V2) of infant monkeys. We show that the transient component of neuronal firing to 640-ms stationary gratings was as robust and as reliable as in adults only 2 wk after birth, whereas the sustained component was more sluggish in infants than in adults. Thus the cortical circuitry supporting onset transient responses is functionally mature near birth, and our findings predict that neonates, known for their “impoverished vision,” are capable of initiating relatively mature fixating eye movements and of performing in detection of simple objects far better than traditionally thought.

scholarly journals Non-invasive methods for measuring vascular changes in neurovascular headaches

2017 ◽  
Vol 39 (4) ◽  
pp. 633-649 ◽  
Author(s):  
Henrik W Schytz ◽  
Faisal M Amin ◽  
Juliette Selb ◽  
David A Boas
Keyword(s):  
Migraine Without Aura ◽  
Near Infrared ◽  
Cerebral Blood Flow Velocity ◽  
Single Photon ◽  
Photon Emission ◽  
Primary Headache ◽  
Cerebral Vessels ◽  
Emission Tomography ◽  
Primary Headaches ◽  
Vascular Changes

Vascular changes during spontaneous headache attacks have been studied over the last 30 years. The interest in cerebral vessels in headache research was initially due to the hypothesis of cerebral vessels as the pain source. Here, we review the knowledge gained by measuring the cerebral vasculature during spontaneous primary headache attacks with the use of single photon emission tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRA) and transcranial Doppler (TCD). Furthermore, the use of near-infrared spectroscopy in headache research is reviewed. Existing TCD studies of migraine and other headache disorders do not provide solid evidence for cerebral blood flow velocity changes during spontaneous attacks of migraine headache. SPECT studies have clearly shown cortical vascular changes following migraine aura and the differences between migraine with aura compared to migraine without aura. PET studies have shown focal activation in brain structures related to headache, but whether the changes are specific to different primary headaches have yet to be demonstrated. MR angiography has shown precise changes in large cerebral vessels during spontaneous migraine without aura attacks. Future development in more precise imaging methods may further elucidate the pathophysiological mechanisms in primary headaches.

Disruption of binocularly correlated signals alters the postnatal development of spatial properties in cat striate cortical neurons

1991 ◽  
Vol 65 (4) ◽  
pp. 841-859 ◽  
Author(s):  
Y. M. Chino ◽  
E. L. Smith ◽  
H. Wada ◽  
W. H. Ridder ◽  
A. L. Langston ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Neural Development ◽  
Cortical Neurons ◽  
Rectus Muscle ◽  
Primary Objective ◽  
Lateral Rectus ◽  
Ocular Motility ◽  
Neural Basis ◽  
Contrast Gain ◽  
Optically Induced

1. Extracellular single-cell recording techniques were employed to investigate the effects of ocular misalignment on the postnatal development of the spatial response properties of striate cortical neurons. The primary objective of the study was to gain insight into the neural basis of strabismic amblyopia. 2. Two basic rearing strategies were used to study specific aspects of experimental strabismus in developing kittens. In one group, strabismus was optically induced by fitting kittens with goggles that held a 15-diopter base-in prism in front of one eye (MP) or both eyes (BP) between the ages of 4 wk and 4 mo. In the second group, a unilateral esotropia was surgically induced at 3 wks of age either by the simple resection of the lateral rectus muscle tendon (tenotomy) or by a more drastic procedure that involved removing sections of the lateral rectus and superior oblique muscles (myectomy). In addition, the eyelids of the nondeviating eyes of these kittens were sutured closed (ESO/MD). The first rearing paradigm isolated the effects of conflicting visual inputs on neural development, whereas the second procedure isolated the effects of anomalous ocular motility by producing a misalignment without putting the deviated eye at a competitive disadvantage. 3. The recording experiments were conducted when the animals were greater than or equal to 9 mo of age. A total of 445 striate cortical neurons were isolated and quantitatively studied in 17 cats (3 MPs, 3 BPs, 5 ESO/MDs, 3 goggle-reared controls, and 3 normals). In addition, we analyzed the distribution of preferred stimulus orientations of 1,205 single units that had been studied qualitatively in our previous investigation of 42 kittens reared with optically induced strabismus. 4. As expected, the proportion of binocularly driven units was reduced in both MP and BP cats. The great majority of units in ESO/MD animals were exclusively driven or highly dominated by the open deviating eye. 5. Prism-reared animals showed physiological deficits in spatial resolution, contrast sensitivity, contrast gain, and peak firing rate. These effects were manifest in both eyes, although there was always an interocular asymmetry in the deficits observed in the two eyes. In MP animals, the units dominated by the treated eye, which was contralateral to the recording hemisphere, were on the average more severely affected. The interocular asymmetry was smaller in BP cats; however, two of the three BP animals also showed a greater deficit in those units dominated by the contralateral eye.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Spatial Distribution of Contextual Interactions in Primary Visual Cortex and in Visual Perception

2000 ◽  
Vol 84 (4) ◽  
pp. 2048-2062 ◽  
Author(s):  
Mitesh K. Kapadia ◽  
Gerald Westheimer ◽  
Charles D. Gilbert
Keyword(s):  
Spatial Distribution ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Cortical Neurons ◽  
Receptive Fields ◽  
Human Perception ◽  
Spatial Arrangement ◽  
Orthogonal Axis ◽  
V1 Neurons ◽  
Contextual Interactions

To examine the role of primary visual cortex in visuospatial integration, we studied the spatial arrangement of contextual interactions in the response properties of neurons in primary visual cortex of alert monkeys and in human perception. We found a spatial segregation of opposing contextual interactions. At the level of cortical neurons, excitatory interactions were located along the ends of receptive fields, while inhibitory interactions were strongest along the orthogonal axis. Parallel psychophysical studies in human observers showed opposing contextual interactions surrounding a target line with a similar spatial distribution. The results suggest that V1 neurons can participate in multiple perceptual processes via spatially segregated and functionally distinct components of their receptive fields.

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