scholarly journals α‐tACS over the somatosensory cortex enhances tactile spatial discrimination in healthy subjects with low alpha activity

2021 ◽  
Author(s):  
Kei Saito ◽  
Naofumi Otsuru ◽  
Hirotake Yokota ◽  
Yasuto Inukai ◽  
Shota Miyaguchi ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Healthy Subjects ◽  
Alpha Activity ◽  
Spatial Discrimination

Comparative study of electroencephalographic findings in patients with depression and schizophrenia

2019 ◽  
Vol 9 (8) ◽  
pp. 593-603
Author(s):  
Nitika Verma*,Gyanendra Kumar,B. D. Singh, Amit Kumar
Keyword(s):  
Healthy Subjects ◽  
Quantitative Eeg ◽  
Alpha Activity ◽  
Beta Activity ◽  
Quantitative Electroencephalography ◽  
Entire Sample ◽  
Qualitative And Quantitative ◽  
Clinical Diagnoses ◽  
Schizophrenic Patients ◽  
Study Participants

Introduction: Schizophrenia and depression are two major and very common mentaldisorders worldwide. Many clinical questionnaire and scales have been formulated todiagnose these cases. Standard (qualitative) electroencephalography (EEG) has alsobeen routinely employed in the diagnostic evaluation of patients of these disorders.However quantitative EEG (qEEG) has not been frequently used in evaluation of thesedisorders. Qualitative EEG (qEEG) findings differ between patients with schizophreniaand patients with depression, but results are not consistent. We performed this study todetermine the differences in EEG parameters(qualitative and quantitative) betweenpatients with schizophrenia, patients with depression, and healthy subjects.Materials and Methods: Our study included 69 patients with schizophrenia, 69patients with depression, and 138 healthy subjects. All patients and healthy subjectswere aged between 18-50 years. All clinical diagnoses were made according to DSM-IVdiagnostic criteria. Standard EEG was performed on all study participants and artefact-free 100-second epochs were selected from the recorded material and analysed withFast Fourier Transformation (FFT) analysis.Observations and Result: Of the entire sample of patients, 40.58% had abnormal EEG.Patients with schizophrenia when compared with healthy subjects showed increaseddelta, theta, and beta activity and decreased alpha activity. Patients with depression alsoshowed similar results, but in fewer regions. In patients with schizo-phrenia, deltapower over some frontal regions was increased in comparison with those in patientswith depression. Schizophrenic patients and healthy subjects showed interhemisphericasymmetry, but it was absent in patients with depression.Conclusion: Abnormal EEG findings in patients with schizophrenia and depression isnot very common. However, on qEEG, the patients with schizophrenia had in-creaseddelta power in comparison to patients with depression. Hence, qEEG may have a rolein clinical differentiation between these two mental disorders and it may be especiallyimportant in cases of negative-symptom schizophrenia.Key words: Schizophrenia, Depression, quantitative electroencephalography(qEEG).

scholarly journals Comparative analysis of electroencephalographic tests of alpha activity attenuation in evaluation of involuntary falling asleep in healthy adults

2010 ◽  
Vol 138 (3-4) ◽  
pp. 130-135
Author(s):  
Zvonko Sundric ◽  
Nenad Rajsic ◽  
Milan Lakocevic ◽  
Emilija Nikolic-Djoric
Keyword(s):  
Sleep Deprivation ◽  
Healthy Subjects ◽  
Traffic Accidents ◽  
Alpha Activity ◽  
Work Place ◽  
Optimal Method ◽  
Specific Test ◽  
Filter Width ◽  
Methods Of Evaluation ◽  
Falling Asleep

Introduction. Decrease of daily alertness is a common cause of accidents in the work place, especially traffic accidents. Therefore, an increasing interest exists to determine reliable indicators of a tendency to fall asleep involuntarily. Objective. To determine an optimal electroencephalographic (EEG) indicator of an involuntary tendency to fall asleep, we performed a study on neurologically healthy subjects, after one night of sleep deprivation. Total sleep deprivation was aimed at increasing daily sleepiness in healthy subjects, providing us with an opportunity to test different methods of evaluation. Methods. We applied a visual analogue scale for sleepiness (VASS), EEG registration with the specific test of alpha activity attenuation (TAA) in 87 healthy subjects. The test was performed in a standard way (sTAA) as well as in accordance with new modifications related to changes of EEG filter width in the range from 5 to 32 Hz (mTAA). Results. After sleep deprivation, we observed involuntary falling asleep in 54 subjects. The comparison of VASS results showed no differences, contrary to a more objective TAA. Between two variants of TAA, the modified test provided us with a better prediction for subjects who would fall asleep involuntarily. Conclusion. The application of a more objective EEG test in evaluation of daily alertness represents the optimal method of testing. Modified TAA attracts special attention, offering a simple solution for reliable testing of decreased daily alertness in medical services related to professional aircraft personnel.

S18.4 Glutamate-mediated primary somatosensory cortex excitability correlated with ceruloplasmin in healthy subjects

2011 ◽  
Vol 122 ◽  
pp. S42
Author(s):  
R. Squitti ◽  
G. Assenza ◽  
F. Zappasodi ◽  
L. Tomasevic ◽  
C. Porcaro ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Healthy Subjects ◽  
Primary Somatosensory Cortex

Somatosensory-evoked Fields for Gingiva, Lip, and Tongue

2004 ◽  
Vol 83 (4) ◽  
pp. 307-311 ◽  
Author(s):  
H. Nakahara ◽  
N. Nakasato ◽  
A. Kanno ◽  
S. Murayama ◽  
K. Hatanaka ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Healthy Subjects ◽  
Contralateral Hemisphere ◽  
Equivalent Current Dipole ◽  
Central Sulcus ◽  
Current Dipole ◽  
Somatosensory Evoked Fields ◽  
Left And Right ◽  
Evoked Fields ◽  
The Moment

To localize the oral primary somatosensory cortex, we measured somatosensory-evoked fields for the lip, gingiva, and tongue in six healthy subjects. The latency of the first peak of the posterior-oriented current in the contralateral hemisphere was 50.9 ± 8.3 ms for the gingiva, significantly shorter than those for the lip and tongue peaks. The equivalent current dipole was localized on the central sulcus. The gingival dipole was localized significantly inferior to the lip dipole but not different from the tongue dipole. The moment of the gingival dipole was significantly smaller than that of the lip dipole but not different from that of the tongue dipole. Differences in the above parameters were negligible between the left and right, anterior and posterior, and upper and lower locations within the same organ, except that the dipole location for the anterior upper tongue was significantly inferior to that for the lower tongue.

scholarly journals Effect of vibration characteristics and vibror arrangement on the tactile perception of the upper arm in healthy subjects and upper limb amputees

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Matthieu Guemann ◽  
Sandra Bouvier ◽  
Christophe Halgand ◽  
Florent Paclet ◽  
Leo Borrini ◽  
...  
Keyword(s):  
Upper Limb ◽  
Healthy Subjects ◽  
Longitudinal Axis ◽  
Vibration Characteristics ◽  
Spatial Discrimination ◽  
Sensory Substitution ◽  
Limb Amputation ◽  
Vibrotactile Stimulation ◽  
Upper Arm ◽  
Intensity Perception

Abstract Background Vibrotactile stimulation is a promising venue in the field of prosthetics to retrain sensory feedback deficits following amputation. Discrimination is well established at the forearm level but not at the upper arm level. Moreover, the effects of combining vibration characteristics such as duration and intensity has never been investigated. Method We conducted experiments on spatial discrimination (experiment 1) and tactile intensity perception (experiment 2), using 9 combinations of 3 intensities and 3 durations of vibror stimulations device. Those combinations were tested under 4 arrangements with an array of 6 vibrors. In both experiments, linear orientation aligned with the upper arm longitudinal axis were compared to circular orientation on the upper arm circumference. For both orientations, vibrors were placed either with 3cm space between the center of 2 vibrors or proportionally to the length or the circumference of the subject upper arm. Eleven heathy subjects underwent the 2 experiments and 7 amputees (humeral level) participated in the spatial discrimination task with the best arrangement found. Results Experiment 1 revealed that circular arrangements elicited better scores than the linear ones. Arrangements with vibrors spaced proportionally elicited better scores (up to 75% correct) than those with 3 cm spacing. Experiment 2, showed that the perceived intensity of the vibration increases with the intensity of the vibrors’ activation, but also with their duration of activation. The 7 patients obtained high scores (up to 91.67% correct) with the circular proportional (CP) arrangement. Discussion These results highlight that discrete and short vibrations can be well discriminated by healthy subjects and people with an upper limb amputation. These new characteristics of vibrations have great potential for future sensory substitution application in closed-loop prosthetic control.

Homeostatic Metaplasticity in the Human Somatosensory Cortex

2008 ◽  
Vol 20 (8) ◽  
pp. 1517-1528 ◽  
Author(s):  
Barbara Bliem ◽  
J. Florian M. Müller-Dahlhaus ◽  
Hubert R. Dinse ◽  
Ulf Ziemann
Keyword(s):  
Electrical Stimulation ◽  
Median Nerve ◽  
Somatosensory Cortex ◽  
Discrimination Threshold ◽  
Spatial Discrimination ◽  
High Frequency Stimulation ◽  
Human Motor Cortex ◽  
The Right ◽  
Stimulation Of

Long-term potentiation (LTP) and long-term depression (LTD) are regulated by homeostatic control mechanisms to maintain synaptic strength in a physiological range. Although homeostatic metaplasticity has been demonstrated in the human motor cortex, little is known to which extent it operates in other cortical areas and how it links to behavior. Here we tested homeostatic interactions between two stimulation protocols—paired associative stimulation (PAS) followed by peripheral high-frequency stimulation (pHFS)—on excitability in the human somatosensory cortex and tactile spatial discrimination threshold. PAS employed repeated pairs of electrical stimulation of the right median nerve followed by focal transcranial magnetic stimulation of the left somatosensory cortex at an interstimulus interval of the individual N20 latency minus 15 msec or N20 minus 2.5 msec to induce LTD- or LTP-like plasticity, respectively [Wolters, A., Schmidt, A., Schramm, A., Zeller, D., Naumann, M., Kunesch, E., et al. Timing-dependent plasticity in human primary somatosensory cortex. Journal of Physiology, 565, 1039–1052, 2005]. pHFS always consisted of 20-Hz trains of electrical stimulation of the right median nerve. Excitability in the somatosensory cortex was assessed by median nerve somatosensory evoked cortical potential amplitudes. Tactile spatial discrimination was tested by the grating orientation task. PAS had no significant effect on excitability in the somatosensory cortex or on tactile discrimination. However, the direction of effects induced by subsequent pHFS varied with the preconditioning PAS protocol: After PASN20-15, excitability tended to increase and tactile spatial discrimination threshold decreased. After PASN20-2.5, excitability decreased and discrimination threshold tended to increase. These interactions demonstrate that homeostatic metaplasticity operates in the human somatosensory cortex, controlling both cortical excitability and somatosensory skill.

scholarly journals EEG alpha activity increased in response to transcutaneous electrical nervous stimulation in young healthy subjects but not in the healthy elderly

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8330 ◽  
Author(s):  
Ebru Yıldırım ◽  
Bahar Güntekin ◽  
Lütfü Hanoğlu ◽  
Candan Algun
Keyword(s):  
Repeated Measures ◽  
Healthy Subjects ◽  
Alpha Activity ◽  
Elderly Subjects ◽  
Alpha Power ◽  
Nervous Stimulation ◽  
Healthy Elderly ◽  
Young Subjects ◽  
The Brain ◽  
Sensory Functions

Transcutaneous Electrical Nerve Stimulation (TENS) is used not only in the treatment of pain but also in the examination of sensory functions. With aging, there is decreased sensitivity to somatosensory stimuli. It is essential to examine the effect of TENS application on the sensory functions in the brain by recording the spontaneous electroencephalogram (EEG) activity and the effect of aging on the sensory functions of the brain during the application. The present study aimed to investigate the effect of the application of TENS on the brain’s electrical activity and the effect of aging on the sensory functions of the brain during application of TENS. A total of 15 young (24.2 ± 3.59) and 14 elderly (65.64 ± 4.92) subjects were included in the study. Spontaneous EEG was recorded from 32 channels during TENS application. Power spectrum analysis was performed by Fast Fourier Transform in the alpha frequency band (8–13 Hz) for all subjects. Repeated measures of analysis of variance was used for statistical analysis (p < 0.05). Young subjects had increased alpha power during the TENS application and had gradually increased alpha power by increasing the current intensity of TENS (p = 0.035). Young subjects had higher alpha power than elderly subjects in the occipital and parietal locations (p = 0.073). We can, therefore, conclude that TENS indicated increased alpha activity in young subjects. Young subjects had higher alpha activity than elderly subjects in the occipital and somatosensory areas. To our knowledge, the present study is one of the first studies examining the effect of TENS on spontaneous EEG in healthy subjects. Based on the results of the present study, TENS may be used as an objective method for the examination of sensory impairments, and in the evaluative efficiency of the treatment of pain conditions.

Reflex Responses in Upper Limb Muscles to Cutaneous Stimuli

1993 ◽  
Vol 20 (04) ◽  
pp. 271-278 ◽  
Author(s):  
R. Chen
Keyword(s):  
Stimulus Intensity ◽  
Upper Limb ◽  
Healthy Subjects ◽  
Voluntary Contraction ◽  
Cutaneous Reflexes ◽  
Focal Lesions ◽  
Normal Ranges ◽  
Conduction Velocities ◽  
Limb Muscles ◽  
Biphasic Responses

ABSTRACT:Cutaneous reflexes in the upper limb were elicited by stimulating digital nerves and recorded by averaging rectified EMG from proximal and distal upper limb muscles during voluntary contraction. Distal muscles often showed a triphasic response: an inhibition with onset about 50 ms (Il) followed by a facilitation with onset about 60 ms (E2) followed by another inhibition with onset about 80 ms (12). Proximal muscles generally showed biphasic responses beginning with facilitation or inhibition with onset at about 40 ms. Normal ranges for the amplitude of these components were established from recordings on 22 arms of 11 healthy subjects. An attempt was made to determine the alterent fibers responsible for the various components by varying the stimulus intensity, by causing ischemic block of larger fibers and by estimating the afferent conduction velocities. The central pathways mediating these reflexes were examined by estimating central delays and by studying patients with focal lesions

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