scholarly journals Visual cortex cTBS increases mixed percept duration while a-tDCS has no effect on binocular rivalry

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0239349
Author(s):  
Dania Abuleil ◽  
Daphne McCulloch ◽  
Benjamin Thompson
Keyword(s):  
Visual Cortex ◽  
Binocular Rivalry ◽  
Gamma Aminobutyric Acid ◽  
Gaba Concentration ◽  
Excitatory Neurotransmitter ◽  
Inhibitory Neurotransmitter ◽  
Before And After ◽  
Visual Cortices ◽  
Cortical Excitation ◽  
Theta Burst

Neuromodulation of the primary visual cortex using anodal transcranial direct current stimulation (a-tDCS) can alter visual perception and enhance neuroplasticity. However, the mechanisms that underpin these effects are currently unknown. When applied to the motor cortex, a-tDCS reduces the concentration of the inhibitory neurotransmitter gamma aminobutyric acid (GABA), an effect that has been linked to increased neuroplasticity. The aim of this study was to assess whether a-tDCS also reduces GABA-mediated inhibition when applied to the human visual cortex. Changes in visual cortex inhibition were measured using the mixed percept duration in binocular rivalry. Binocular rivalry mixed percept duration has recently been advocated as a direct and sensitive measure of visual cortex inhibition whereby GABA agonists decrease mixed percept durations and agonists of the excitatory neurotransmitter acetylcholine (ACH) increase them. Our hypothesis was that visual cortex a-tDCS would increase mixed percept duration by reducing GABA-mediated inhibition and increasing cortical excitation. In addition, we measured the effect of continuous theta-burst transcranial magnetic stimulation (cTBS) of the visual cortex on binocular rivalry dynamics. When applied to the motor or visual cortex, cTBS increases GABA concentration and we therefore hypothesized that visual cortex cTBS would decrease the mixed percept duration. Binocular rivalry dynamics were recorded before and after active and sham a-tDCS (N = 15) or cTBS (N = 15). Contrary to our hypotheses, a-tDCS had no effect, whereas cTBS increased mixed percepts during rivalry. These results suggest that the neurochemical mechanisms of a-tDCS may differ between the motor and visual cortices.

scholarly journals Visual cortex cTBS increases mixed percept duration while a-tDCS has no effect on binocular rivalry

2020 ◽  
Author(s):  
Dania Abuleil ◽  
Daphne McCulloch ◽  
Benjamin Thompson
Keyword(s):  
Visual Cortex ◽  
Binocular Rivalry ◽  
Gamma Aminobutyric Acid ◽  
Gaba Concentration ◽  
Excitatory Neurotransmitter ◽  
Inhibitory Neurotransmitter ◽  
Before And After ◽  
Visual Cortices ◽  
Cortical Excitation ◽  
Theta Burst

AbstractNeuromodulation of the primary visual cortex using anodal transcranial direct current stimulation (a-tDCS) can alter visual perception and enhance neuroplasticity. However, the mechanisms that underpin these effects are currently unknown. When applied to the motor cortex, a-tDCS reduces the concentration of the inhibitory neurotransmitter gamma aminobutyric acid (GABA), an effect that has been linked to increased neuroplasticity. The aim of this study was to assess whether a-tDCS also reduces GABA-mediated inhibition when applied to the human visual cortex. Changes in visual cortex inhibition were measured using the mixed percept duration in binocular rivalry. Binocular rivalry mixed percept duration has recently been advocated as a direct and sensitive measure of visual cortex inhibition whereby GABA agonists decrease mixed percept durations and agonists of the excitatory neurotransmitter acetylcholine increase them. Our hypothesis was that visual cortex a-tDCS would increase mixed percept duration by reducing GABA-mediated inhibition and increasing cortical excitation. In addition, we measured the effect of continuous theta-burst transcranial magnetic stimulation (cTBS) of the visual cortex on binocular rivalry dynamics. When applied to the motor or visual cortex, cTBS increases GABA concentration and we therefore hypothesized that visual cortex cTBS would decrease the mixed percept duration. Binocular rivalry dynamics were recorded before and after active and sham a-tDCS (N=15) or cTBS (N=15). Contrary to our hypotheses, a-tDCS had no effect, whereas cTBS significantly increased mixed percepts during rivalry. These results suggest that the neurochemical mechanisms of a-tDCS may differ between the motor and visual cortices.

scholarly journals Relating excitatory and inhibitory neurochemicals to visual perception: a magnetic resonance study of occipital cortex between migraine events

2018 ◽  
Author(s):  
Yu Man Chan ◽  
Kabilan Pitchaimuthu ◽  
Qi-Zhu Wu ◽  
Olivia L Carter ◽  
Gary F Egan ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Magnetic Resonance ◽  
Visual Perception ◽  
Binocular Rivalry ◽  
Occipital Cortex ◽  
Individual Variability ◽  
Healthy Individuals ◽  
Magnetic Resonance Study ◽  
Gaba Concentration ◽  
Inhibitory Neurotransmitter

AbstractCertain perceptual measures have been proposed as indirect assays of brain neurochemical status in people with migraine. One such measure is binocular rivalry, however, previous studies have not measured rivalry characteristics and brain neurochemistry together in people with migraine. This study compared spectroscopy-measured levels of GABA and Glx (glutamine and glutamate complex) in visual cortex between 16 people with migraine and 16 non-headache controls, and assessed whether the concentration of these neurochemicals explains, at least partially, inter-individual variability in binocular rivalry perceptual measures. Mean Glx level was significantly reduced in migraineurs relative to controls, whereas mean occipital GABA levels were similar between groups. Neither GABA levels, nor Glx levels correlated with rivalry percept duration. Our results thus suggest that the previously suggested relationship between rivalry percept duration and GABAergic inhibitory neurotransmitter concentration in visual cortex is not strong enough to enable rivalry percept duration to be reliably assumed to be a surrogate for GABA concentration, at least in the context of healthy individuals and those that experience migraine.

scholarly journals GABA levels in ventral visual cortex decline with age and are associated with neural distinctiveness

2019 ◽  
Author(s):  
Jordan D. Chamberlain ◽  
Holly Gagnon ◽  
Poortata Lalwani ◽  
Kaitlin E. Cassady ◽  
Molly Simmonite ◽  
...  
Keyword(s):  
Older Adults ◽  
Visual Cortex ◽  
Magnetic Resonance ◽  
Aminobutyric Acid ◽  
Resonance Spectroscopy ◽  
Gamma Aminobutyric Acid ◽  
Younger Adults ◽  
Inhibitory Neurotransmitter ◽  
Neural Representations ◽  
Age Related

AbstractAge-related neural dedifferentiation – reduced distinctiveness of neural representations in the aging brain– has been associated with age-related declines in cognitive abilities. But why does neural distinctiveness decline with age? Based on prior work in non-human primates, we hypothesized that the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) declines with age and is associated with neural dedifferentiation. To test this hypothesis, we used magnetic resonance spectroscopy (MRS) to measure GABA and functional MRI (fMRI) to measure neural distinctiveness in the ventral visual cortex in a set of older and younger participants. Relative to younger adults, older adults exhibited lower GABA levels and less distinct activation patterns for faces and houses in the ventral visual cortex. Furthermore, individual differences in GABA within older adults predicted individual differences in neural distinctiveness even after controlling for gray matter volume and age. These results provide novel support for the view that age-related reductions of GABA contribute to age-related reductions in neural distinctiveness (i.e., neural dedifferentiation) in the human ventral visual cortex.Significance StatementNeural representations in the ventral visual cortex are less distinguishable in older compared to younger humans, and this neural dedifferentiation is associated with age-related cognitive deficits. Animal models suggest that reductions in the inhibitory neurotransmitter gamma aminobutyric acid (GABA) may play a role. To investigate this hypothesis, we combined functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) in a study of the human ventral visual cortex. We observed reduced distinctiveness of neural patterns and reduced GABA levels in older compared to younger adults. Furthermore, older adults with higher GABA levels tended to have more distinctive neural representations. These findings suggest that reduced GABA levels contribute to age-related declines in neural distinctiveness in the human ventral visual cortex.

scholarly journals The effects of multi-day rTMS and cardiorespiratory fitness on working memory and local GABA concentration

2020 ◽  
Author(s):  
Joshua Hendrikse ◽  
Sarah Thompson ◽  
Chao Suo ◽  
Murat Yucel ◽  
Nigel C. Rogasch ◽  
...  
Keyword(s):  
Working Memory ◽  
Cardiorespiratory Fitness ◽  
Cognitive Outcomes ◽  
Secondary Outcome ◽  
Gamma Aminobutyric Acid ◽  
Gaba Concentration ◽  
Novel Approach ◽  
Number Of Factors ◽  
Before And After ◽  
Left Parietal Cortex

AbstractWorking memory (WM) refers to the capacity to temporarily retain and manipulate finite amounts of information; a critical process in complex behaviours such as reasoning, comprehension, and learning. This cognitive function is supported by a parietal-prefrontal network and linked to the activity of key brain neurotransmitters, such as gamma-aminobutyric acid (GABA). Impairments in WM are seen in a range of psychiatric and neurological disorders, and there are currently no effective methods of remediating WM deficits. In this study, we analysed secondary outcome measures from a trial investigating the effects of multi-day rTMS on cognition. Participants received four days of 20 Hz rTMS to an individualised region of left parietal cortex in one week, and an individualised region of pre-supplementary motor area (pre-SMA) in a separate week. We assessed changes to WM function before and after each week of stimulation (N = 39), and changes to GABA concentration before and after stimulation in week one using MR spectroscopy (N = 18 per stimulation condition). We hypothesised that multi-day parietal rTMS would enhance WM and reduce GABA concentration, but this was not observed. Instead, we report some evidence of improved WM function and increased GABA concentration following pre-SMA rTMS, although this effect was variable across individuals. Additionally, we found that higher cardiorespiratory fitness was associated with greater WM improvement following pre-SMA stimulation. While there are a number of factors known to influence the response to rTMS, increasing cardiorespiratory fitness may provide a novel approach to enhance cognitive outcomes. Given the clinical utility of both exercise and rTMS, future studies are required to determine whether additive effects may be achieved when applied in tandem.

scholarly journals Dietary modulation of cortical excitation and inhibition

2017 ◽  
Vol 31 (5) ◽  
pp. 632-637 ◽  
Author(s):  
Anika K Smith ◽  
Alex R Wade ◽  
Kirsty EH Penkman ◽  
Daniel H Baker
Keyword(s):  
Dietary Intervention ◽  
Control Group ◽  
Gamma Aminobutyric Acid ◽  
Neural Responses ◽  
Dietary Interventions ◽  
Sensory Stimuli ◽  
Inhibitory Neurotransmitter ◽  
Clinical Benefits ◽  
Cortical Excitation ◽  
The Brain

The balance of excitatory and inhibitory neurotransmitters in the brain affects both neural responses and behaviour in humans and animals. Here we investigated whether dietary intervention aimed at increasing levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) can influence neural responses to basic sensory stimuli. Using a steady-state electroencephalography (EEG) paradigm, we found that the neural response to visual patterns was reduced in individuals who consumed a yeast extract product rich in substances associated with the production of GABA (glutamate and B vitamins), but not in a control group who consumed a placebo substance ( n = 14 per group). This demonstrates that the balance of excitation and inhibition in the brain can be influenced by dietary interventions, suggesting possible clinical benefits in conditions (e.g. epilepsy) where inhibition is abnormal.

Release of inhibitory neurotransmitters in response to anoxia in turtle brain

1991 ◽  
Vol 261 (1) ◽  
pp. R32-R37 ◽  
Author(s):  
G. E. Nilsson ◽  
P. L. Lutz
Keyword(s):  
Mammalian Brain ◽  
Intracerebral Microdialysis ◽  
Gamma Aminobutyric Acid ◽  
Excitatory Neurotransmitter ◽  
Inhibitory Neurotransmitter ◽  
Inhibitory Neurotransmitters ◽  
Extracellular Level ◽  
Inhibitory Amino Acids ◽  
Brain Striatum ◽  
Major Mediator

In mammals a massive release of the excitatory neurotransmitter glutamate, occurring within a few minutes of anoxia/ischemia, is thought to be a major mediator of anoxic brain damage. In contrast to the mammalian brain, the turtle brain is exceptionally anoxia tolerant. Using intracerebral microdialysis in turtle brain striatum, we have found a large increase in the extracellular level of the inhibitory neurotransmitter gamma-aminobutyric acid during anoxia, reaching 90 times the normoxic level after 240 min, whereas no substantial release of glutamate occurred. Moreover, the inhibitory neurotransmitters/neuromodulators glycine and taurine also displayed increased extracellular levels during anoxia. Increased extracellular levels of inhibitory amino acids may be one of the hitherto elusive mechanisms that underlie the decreased activity and energy consumption characterizing the anoxic turtle brain.

scholarly journals Melatonin Attenuates RVLM Neuro-inflammation and Sympathetic Activation in Stress-induced Hypertension Rats

2020 ◽  
Author(s):  
Shutian Zhang
Keyword(s):  
Blood Pressure ◽  
Stress Factors ◽  
Ventrolateral Medulla ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Concentration Dependent Manner ◽  
Excitatory Neurotransmitter ◽  
Inhibitory Neurotransmitter ◽  
M1 Polarization ◽  
Induced Hypertension

Background: Hypertension is a cardiovascular syndrome with the highest morbidity and mortality worldwide. Hypertension caused by various stress factors is called stress-induced hypertension (SIH). The rostral ventrolateral medulla (RVLM) "neuroinflammatory-sympathetic overactivation" is involved in SIH formation. Melatonin has anti-inflammatory, anti-oxidant and blood pressure lowering effects. The present study is to explore the antihypertensive effects and mechanism of central melatonin which based on microglia derived neuroinflammation. Methods: Stress-induced hypertension (SIH) was induced by electric foot-shock stressors with noise interventions in rats. Melatonin (0.01，0.1，1 mmol/L) was administered to RVLM and then blood pressure (BP) and serum norepinephrine (NE) were monitored to reflect sympathetic vasomotor activity in SIH rats. Excitatory neurotransmitter (Glutamate) and inhibitory neurotransmitter [γ-aminobutyric acid (GABA)] were measured using ELISA kits. Markers of microglia M1 polarization (CD86) and pro-inflammatory cytokines (PICs (IL-1β, TNF-α)) expression in the RVLM were measured by RT-qPCR. Results: (1) Stress-induced increase in blood pressure and serum NE concentration; RVLM microinjection melatonin attenuated the elevation of blood pressure and increase of plasma NE in SIH rats in a dose-dependent manner. (2) The expression of CD86, PICs (IL-1β, TNF-α) and c-fos were increased in SIH rats; RVLM injection melatonin attenuated RVLM neuroinflammation and its effect is concentration-dependent. (3). Stress-induced increase in glutamate concentration in RVLM; RVLM injection melatonin reduced glutamate level and increased GABA level in SIH rats in a concentration-dependent manner. Conclusion: RVLM injection of melatonin inhibits M1 polarization and has anti-hypertensive effects. Melatonin reduces M1 polarization in microglia might be a novel target and a new strategy for anti-stress induced-hypertension.

scholarly journals Alterations in the Excitatory and Inhibitory Coupling in Migraine: A Magnetic Resonance Study

2020 ◽  
Author(s):  
Yiwen Cai ◽  
Yingying Tang ◽  
Jijun Wang ◽  
Qinhui Fu ◽  
Min Hang Gan ◽  
...  
Keyword(s):  
Pain Modulation ◽  
Anterior Cingulate ◽  
Healthy Controls ◽  
Gamma Aminobutyric Acid ◽  
Excitatory Neurotransmitter ◽  
Inhibitory Neurotransmitter ◽  
Subgenual Anterior Cingulate Cortex ◽  
Inhibitory Coupling ◽  
The Right ◽  
Bilateral Thalamus

Abstract Background: There is evidence suggesting that an imbalance between the levels of the excitatory neurotransmitter, glutamate, and inhibitory neurotransmitter, gamma aminobutyric acid (GABA), leads to migraine attacks; however, the pathophysiology and specific diagnostic markers remain unknown. Methods: Twenty-one migraine patients (18 female, 3 male, mean age=40.63 14.23years) and 11 healthy controls (9 female, 2 male, mean age=39.78 15.31 years) were included in this study. We used 1H-MRS at 3 Tesla with voxels-of-interest located in the bilateral thalamus and subgenual anterior cingulate cortex (SG ACC) to quantify the GABA and GLX (glutamate-glutamine complex) concentrations measured via the Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence in migraineurs and healthy controls. Result: Statistical analyses revealed significantly decreased GLX/NAA (N-acetylaspartate) in the right thalamus of migraine patients compared to healthy controls. However, we found no group differences in GABA levels in the SG ACC and bilateral thalamus.Conclusion: The right thalamus may be involved in the pain modulation process of migraineurs through changes in the GLX levels. Decreased GLX levels within the right thalamus might be associated with the disruption of "excitation-inhibition" homeostasis in migraine.Trial registration: ClinicalTrials.gov, NCT02580968. Registered 30 October 2015, https://clinicaltrials.gov/ct2/show/study/NCT02580968

scholarly journals Cerebellar rTMS in PSP: a Double-Blind Sham-Controlled Study Using Mobile Health Technology

2021 ◽  
Author(s):  
Andrea Pilotto ◽  
Maria Cristina Rizzetti ◽  
Alberto Lombardi ◽  
Clint Hansen ◽  
Michele Biggi ◽  
...  
Keyword(s):  
Digital Technology ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Health Technology ◽  
Controlled Study ◽  
Double Blind ◽  
Non Invasive ◽  
Lower Back ◽  
Before And After ◽  
Double Blind Design ◽  
Theta Burst

AbstractThere are no effective treatments in progressive supranuclear palsy (PSP). The aim of this study was to test the efficacy of theta burst repetitive transcranial magnetic stimulation (rTMS) on postural instability in PSP. Twenty PSP patients underwent a session of sham or real cerebellar rTMS in a crossover design. Before and after stimulation, static balance was evaluated with instrumented (lower back accelerometer, Rehagait®, Hasomed, Germany) 30-s trials in semitandem and tandem positions. In tandem and semitandem tasks, active stimulation was associated with increase in time without falls (both p=0.04). In the same tasks, device-extracted parameters revealed significant improvement in area (p=0.007), velocity (p=0.005), acceleration and jerkiness of sway (p=0.008) in real versus sham stimulation. Cerebellar rTMS showed a significant effect on stability in PSP patients, when assessed with mobile digital technology, in a double-blind design. These results should motivate larger and longer trials using non-invasive brain stimulation for PSP patients.

scholarly journals Therapeutic Use of Cerebellar Intermittent Theta Burst Stimulation (iTBS) in a Sardinian Family Affected by Spinocerebellar Ataxia 38 (SCA 38)

2021 ◽  
Author(s):  
Angela Sanna ◽  
Paolo Follesa ◽  
Paolo Tacconi ◽  
Mariangela Serra ◽  
Maria Giuseppina Pisu ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Rating Scale ◽  
Clinical Symptoms ◽  
Therapeutic Use ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Motor Cortex Excitability ◽  
Before And After ◽  
Theta Burst ◽  
Serum Bdnf

AbstractSpinocerebellar ataxia 38 (SCA 38) is an autosomal dominant disorder caused by conventional mutations in the ELOVL5 gene which encodes an enzyme involved in the synthesis of very long fatty acids, with a specific expression in cerebellar Purkinje cells. Three Italian families carrying the mutation, one of which is of Sardinian descent, have been identified and characterized. One session of cerebellar intermittent theta burst stimulation (iTBS) was applied to 6 affected members of the Sardinian family to probe motor cortex excitability measured by motor-evoked potentials (MEPs). Afterwards, patients were exposed to ten sessions of cerebellar real and sham iTBS in a cross-over study and clinical symptoms were evaluated before and after treatment by Modified International Cooperative Ataxia Rating Scale (MICARS). Moreover, serum BDNF levels were evaluated before and after real and sham cerebellar iTBS and the role of BDNF Val66Met polymorphism in influencing iTBS effect was explored. Present data show that one session of cerebellar iTBS was able to increase MEPs in all tested patients, suggesting an enhancement of the cerebello-thalamo-cortical pathway in SCA 38. MICARS scores were reduced after ten sessions of real cerebellar iTBS showing an improvement in clinical symptoms. Finally, although serum BDNF levels were not affected by cerebellar iTBS when considering all samples, segregating for genotype a difference was found between Val66Val and Val66Met carriers. These preliminary data suggest a potential therapeutic use of cerebellar iTBS in improving motor symptoms of SCA38.

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