Patterns of excitability in human esophageal sensorimotor cortex to painful and nonpainful visceral stimulation

2002 ◽  
Vol 282 (2) ◽  
pp. G332-G337 ◽  
Author(s):  
Shaheen Hamdy ◽  
John C. Rothwell ◽  
Chris Fraser ◽  
Maxine Power ◽  
David Gow ◽  
...  
Keyword(s):  
Sensorimotor Cortex ◽  
Magnetic Stimulation ◽  
Cortical Plasticity ◽  
Visceral Pain ◽  
Random Order ◽  
Balloon Distension ◽  
Baseline Levels ◽  
The Right ◽  
The Relationship ◽  
Stimulation Of

To better understand the relationship between cortical plasticity and visceral pain, we developed a pain-induced model of altered esophageal corticobulbar excitability. In eight healthy volunteers, corticoesophageal electromyographic responses were recorded via an intraluminal catheter, following magnetic stimulation of the right sensorimotor cortex using perithreshold intensities. Corticothenar responses were used as control. Responses were assessed both before and for up to 1 h after either painful or nonpainful balloon distension of the esophagus (frequency = 1 Hz, dwell time = 200 ms, duration = 10 min), each being delivered to each subject in random order. Painful esophageal distension (mean volume = 11 ± 3 ml) induced a profound increase in esophageal responses compared with baseline levels (at 30 min: 141 ± 12 vs. 101 ± 9 μV, P < 0.01), whereas nonpainful esophageal distension (mean volume = 4 ± 2 ml) showed a decrease (at 30 min: 72 ± 8 vs. 88 ± 12 μV, P < 0.03). Thenar responses were unaffected. The results show that painful and nonpainful stimuli induce different patterns of esophageal corticobulbar excitability, suggesting a physiological link between cortical plasticity and visceral pain.

scholarly journals Magnetic Stimulation of the Right Visual Cortex Impairs Form-specific Priming

2007 ◽  
Vol 19 (6) ◽  
pp. 1013-1020 ◽  
Author(s):  
Gorana Pobric ◽  
Stefan R. Schweinberger ◽  
Michal Lavidor
Keyword(s):  
Magnetic Stimulation ◽  
Semantic Processing ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Brain Activity ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Object Form ◽  
The Right ◽  
Specific Priming ◽  
Stimulation Of

Recent evidence suggests that priming of objects across different images (abstract priming) and priming of specific images of an object (form-specific priming) are mediated by dissociable neural processing subsystems that operate in parallel and are predominantly linked to left and right hemispheric processing, respectively [Marsolek, C. J. Dissociable neural subsystems underlie abstract and specific object recognition. Psychological Science, 10, 111–118, 1999]. Previous brain imaging studies have provided important information about the neuroanatomical regions that are involved in form-specific and abstract priming; however, these techniques did not fully establish the functional significance of priming-related changes in cortical brain activity. Here, we used repetitive transcranial magnetic stimulation (rTMS) in order to establish the functional role of the right occipital cortex in form-specific priming [Kroll, N. E. A., Yonelinas, A. P., Kishiyama, M. M., Baynes, K., Knight, R. T., & Gazzaniga, M. S. The neural substrates of visual implicit memory: Do the two hemispheres play different roles? Journal of Cognitive Neuroscience, 15, 833–842, 2003]. Compared to no TMS and sham TMS, rTMS of the right occipital cortex disrupted immediate form-specific priming in a semantic categorization task. Left occipital rTMS, on the other hand, had no converse effect on abstractive priming. Abstract priming may involve deeper semantic processing and may be unresponsive to magnetic stimulation of a single cortical locus. Our TMS results show that form-specific priming relies on a visual word-form system localized in the right occipital lobe, in line with the predictions from divided visual field behavioral studies [Marsolek, 1999].

Hemispheric Asymmetry in Memory-Guided Pointing During Single-Pulse Transcranial Magnetic Stimulation of Human Parietal Cortex

2006 ◽  
Vol 96 (6) ◽  
pp. 3016-3027 ◽  
Author(s):  
Michael Vesia ◽  
Jachin A. Monteon ◽  
Lauren E. Sergio ◽  
J. D. Crawford
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Parietal Cortex ◽  
Magnetic Stimulation ◽  
Hemispheric Asymmetry ◽  
Posterior Parietal Cortex ◽  
Single Pulse ◽  
Pointing Movements ◽  
Posterior Parietal ◽  
The Right ◽  
Stimulation Of

Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. The present study examines the causal effect of single-pulse transcranial magnetic stimulation (TMS) over the left and right dorsal posterior parietal cortex during a memory-guided “reach-to-touch” movement task in six human subjects. Stimulation of the left parietal hemisphere significantly increased endpoint variability, independent of visual field, with no horizontal bias. In contrast, right parietal stimulation did not increase variability, but instead produced a significantly systematic leftward directional shift in pointing (contralateral to stimulation site) in both visual fields. Furthermore, the same lateralized pattern persisted with left-hand movement, suggesting that these aspects of parietal control of pointing movements are spatially fixed. To test whether the right parietal TMS shift occurs in visual or motor coordinates, we trained subjects to point correctly to optically reversed peripheral targets, viewed through a left–right Dove reversing prism. After prism adaptation, the horizontal pointing direction for a given visual target reversed, but the direction of shift during right parietal TMS did not reverse. Taken together, these data suggest that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. These results also suggest that a brief TMS pulse modifies the output of the right PPC in motor coordinates downstream from the adapted visuomotor reversal, rather than modifying the upstream visual coordinates of the memory representation.

Magnetic and electrical stimulation of the auditory cortex for intractable tinnitus

2004 ◽  
Vol 100 (3) ◽  
pp. 560-564 ◽  
Author(s):  
Dirk De Ridder ◽  
Gert De Mulder ◽  
Vincent Walsh ◽  
Neil Muggleton ◽  
Stefan Sunaert ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Auditory Cortex ◽  
Magnetic Stimulation ◽  
Cortical Plasticity ◽  
Cortical Reorganization ◽  
Complete Suppression ◽  
Content Type ◽  
Fine Print ◽  
Stimulation Of

✓ Tinnitus is a distressing symptom that affects up to 15% of the population for whom no satisfactory treatment exists. The authors present a novel surgical approach for the treatment of intractable tinnitus, based on cortical stimulation of the auditory cortex. Tinnitus can be considered an auditory phantom phenomenon similar to deafferentation pain, which is observed in the somatosensory system. Tinnitus is accompanied by a change in the tonotopic map of the auditory cortex. Furthermore, there is a highly positive association between the subjective intensity of the tinnitus and the amount of shift in tinnitus frequency in the auditory cortex, that is, the amount of cortical reorganization. This cortical reorganization can be demonstrated by functional magnetic resonance (fMR) imaging. Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Linked to a navigation system that is guided by fMR images of the auditory system, TMS can suppress areas of cortical plasticity. If it is successful in suppressing a patient's tinnitus, this focal and temporary effect can be perpetualized by implanting a cortical electrode. A neuronavigation-based auditory fMR imaging-guided TMS session was performed in a patient who suffered from tinnitus due to a cochlear nerve lesion. Complete suppression of the tinnitus was obtained. At a later time an extradural electrode was implanted with the guidance of auditory fMR imaging navigation. Postoperatively, the patient's tinnitus disappeared and remains absent 10 months later. Focal extradural electrical stimulation of the primary auditory cortex at the area of cortical plasticity is capable of suppressing contralateral tinnitus completely. Transcranial magnetic stimulation may be an ideal method for noninvasive studies of surgical candidates in whom stimulating electrodes might be implanted for tinnitus suppression.

scholarly journals Effectiveness of transcranial magnetic stimulation of the prefrontal cortex for the correction of autonomic disorders in miners with polyneuropathy

2021 ◽  
Vol 100 (7) ◽  
pp. 679-682
Author(s):  
Margarita O. Gidayatova ◽  
Ilya D. Martynov ◽  
Anastasia V. Yamshchikova ◽  
Arnold N. Fleishman
Keyword(s):  
Heart Rate ◽  
Prefrontal Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Right Hemisphere ◽  
Spectral Indices ◽  
Adaptive Capabilities ◽  
Autonomic Disorders ◽  
The Right ◽  
Stimulation Of

Introduction. Polyneuropathy is the most common occupational neurological pathology. Violation of the activity of the central links of autonomic regulation due to excessive afferent impulses from the receptors of the skin and other tissues of the extremities leads to sympathetic activation and angiospasm, the progression of polyneuropathy. A decrease in the parasympathetic influence is the cause of systemic trophic disturbances. The possibility of transcranial magnetic stimulation of the prefrontal cortex opens up new therapeutic opportunities to correct the autonomic disorders in occupationally caused polyneuropathy. The aim of the study was to evaluate the effect of transcranial magnetic stimulation of the dorsolateral zone in the prefrontal cortex of the right hemisphere for the correction of neuroautonomic disorders in miners with polyneuropathy. Material and methods. Forty-two miners of the Kuzbass coal mines with a proven diagnosis of upper extremity polyneuropathy were examined. To identify autonomic dysregulation, the “Questionnaire for revealing the signs of autonomic changes”, spectral and nonlinear indices of cardio rhythm were used. Low-frequency (1 Hz) transcranial magnetic stimulation of the dorsolateral zone of the prefrontal cortex of the right hemisphere was performed in the course of 5 procedures according to a specially elaborated methodology. Results. In the examined miners, a decrease in the nonlinear and spectral indices of heart rate variability was initially determined, which indicated reducing adaptive capabilities, an increase in sympathetic influence. After the magnetic stimulation course, there was an improvement in general well-being and normalization of autonomous regulation according to the questionnaire. An increase in the spectral indices of the heart rate variability, more pronounced in the range of very low frequencies, indicated the activation of suprasegmental autonomic centers and an increase in parasympathetic influence. Conclusions. Transcranial magnetic stimulation of the prefrontal cortex effectively corrects autonomic disorders in miners with polyneuropathy and promotes an increase in adaptive capabilities due to the activation of suprasegmental autonomic centres.

Mathematics and TMS

2012 ◽  
Author(s):  
Elena Rusconi ◽  
Carlo Umiltà
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Right Hemisphere ◽  
Parietal Lobe ◽  
Brain Activation ◽  
Number Line ◽  
Mathematical Cognition ◽  
Mental Number Line ◽  
The Right ◽  
The Relationship

This article introduces the relationship between mathematical cognition and transcranial magnetic stimulation (TMS). The mental number line is located in the parietal lobe. Studies employing TMS have explored issues related to the mental number line. This article reviews the studies centered on the magnitude code. The results show that even though the parietal activation is nearly always present in both hemispheres, it is often asymmetric, being greater in the right hemisphere when quantification of nonverbal and nonsymbolic material is required. Neuropsychological studies confirm the relation between the magnitude code and the parietal lobe. The extent to which number-related processes are number specific, and the extent to which they overlap with other aspects of spatial or magnitude representation, is currently a burgeoning area of research. Current work is aimed to disrupt numerical processes and observe concomitant changes in brain activation.

Effects of acidosis on Ca2+sensitivity of contractile elements in intact ferret myocardium

1998 ◽  
Vol 274 (1) ◽  
pp. H147-H154 ◽  
Author(s):  
Kimiaki Komukai ◽  
Tetsuya Ishikawa ◽  
Satoshi Kurihara
Keyword(s):  
Muscle Length ◽  
Length Change ◽  
Troponin C ◽  
Tetanic Contraction ◽  
Twitch Contraction ◽  
Intracellular Ca ◽  
The Right ◽  
The Hill ◽  
The Relationship ◽  
Stimulation Of

We investigated the effects of acidosis on the intracellular Ca2+ concentration ([Ca2+]i) and contractile properties of intact mammalian cardiac muscle during tetanic and twitch contractions. Aequorin was injected into ferret papillary muscles, and the [Ca2+]iand tension were simultaneously measured. Acidosis was attained by increasing the CO2 concentration in the bicarbonate (20 mM)-buffered Tyrode solution from 5% (pH 7.35, control) to 15% (pH 6.89, acidosis). Tetanic contraction was produced by repetitive stimulation of the preparation following treatment with 5 μM ryanodine. The relationship between [Ca2+]iand tension was measured 6 s after the onset of the stimulation and was fitted using the Hill equation. Acidosis decreased the maximal tension to 81 ± 2% of the control and shifted the [Ca2+]i-tension relationship to the right by 0.18 ± 0.01 pCa units. During twitch contraction, a quick shortening of muscle length from the length at which developed tension became maximal ( L max) to 92% L maxproduced a transient change in the [Ca2+]i(extra Ca2+). The magnitude of the extra Ca2+ was dependent on the [Ca2+]iimmediately before the length change, suggesting that the extra Ca2+ is related to the amount of troponin-Ca complex. Acidosis decreased the normalized extra Ca2+ to [Ca2+]iimmediately before the length change, which indicates that the amount of Ca2+ bound to troponin C is less when [Ca2+]iis the same as in the control. The decrease in the Ca2+ binding to troponin C explains the decrease in tetanic and twitch contraction, and mechanical stress applied to the preparation induced less [Ca2+]ichange in acidosis.

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