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1.
Medicina (Kaunas) ; 57(12)2021 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-34946308

RESUMO

Background and Objectives: The most prevalent dementia are Alzheimer's disease and vascular dementia. There is evidence that cortical synaptic function may differ in these two conditions. Habituation of cortical responses to repeated stimuli is a well-preserved phenomenon in a normal brain cortex, related to an underlying mechanism of synaptic efficacy regulation. Lack of habituation represents a marker of synaptic dysfunction. The purpose of this study was to assess the habituation of somatosensory evoked potentials (SEPs) in 29 patients affected by mild-to-moderate Alzheimer's disease (AD-type) or vascular (VD-type) dementia. Materials and Methods: All patients underwent a clinical history interview, neuropsychological evaluation, and neuroimaging examination. SEPs were elicited by electrical stimulation of the right median nerve at the wrist. Six-hundred stimuli were delivered, and cortical responses divided in three blocks of 200. Habituation was calculated by measuring changes of N20 amplitude from block 1 to block 3. SEP variables recorded in patients were compared with those recorded in 15 age- and gender-matched healthy volunteers. Results: SEP recordings showed similar N20 amplitudes in AD-type and VD-type patients in block 1, that were higher than those recorded in controls. N20 amplitude decreased from block 1 to block 3 (habituation) in normal subjects and in VD-type patients, whereas in AD-type patients it remained unchanged (lack of habituation). Conclusions: The findings suggest that neurophysiologic mechanisms of synaptic efficacy that underneath habituation are impaired in patients with AD-type dementia but not in patients with VD-type dementia. SEPs habituation may contribute to early distinction of Alzheimer's disease vs. vascular dementia.


Assuntos
Doença de Alzheimer , Demência Vascular , Potenciais Somatossensoriais Evocados , Habituação Psicofisiológica , Humanos , Nervo Mediano
2.
J Neural Eng ; 18(5)2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34725311

RESUMO

A brain-computer interface (BCI) aims to derive commands from the user's brain activity in order to relay them to an external device. To do so, it can either detect a spontaneous change in the mental state, in the so-called 'active' BCIs, or a transient or sustained change in the brain response to an external stimulation, in 'reactive' BCIs. In the latter, external stimuli are perceived by the user through a sensory channel, usually sight or hearing. When the stimulation is sustained and periodical, the brain response reaches an oscillatory steady-state that can be detected rather easily. We focus our attention on electroencephalography-based BCIs (EEG-based BCI) in which a periodical signal, either mechanical or electrical, stimulates the user skin. This type of stimulus elicits a steady-state response of the somatosensory system that can be detected in the recorded EEG. The oscillatory and phase-locked voltage component characterising this response is called a steady-state somatosensory-evoked potential (SSSEP). It has been shown that the amplitude of the SSSEP is modulated by specific mental tasks, for instance when the user focuses their attention or not to the somatosensory stimulation, allowing the translation of this variation into a command. Actually, SSSEP-based BCIs may benefit from straightforward analysis techniques of EEG signals, like reactive BCIs, while allowing self-paced interaction, like active BCIs. In this paper, we present a survey of scientific literature related to EEG-based BCI exploiting SSSEP. Firstly, we endeavour to describe the main characteristics of SSSEPs and the calibration techniques that allow the tuning of stimulation in order to maximise their amplitude. Secondly, we present the signal processing and data classification algorithms implemented by authors in order to elaborate commands in their SSSEP-based BCIs, as well as the classification performance that they evaluated on user experiments.


Assuntos
Interfaces Cérebro-Computador , Encéfalo , Eletroencefalografia , Potenciais Somatossensoriais Evocados , Processamento de Sinais Assistido por Computador
3.
Elife ; 102021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34609278

RESUMO

Perception of sensory information is determined by stimulus features (e.g., intensity) and instantaneous neural states (e.g., excitability). Commonly, it is assumed that both are reflected similarly in evoked brain potentials, that is, larger amplitudes are associated with a stronger percept of a stimulus. We tested this assumption in a somatosensory discrimination task in humans, simultaneously assessing (i) single-trial excitatory post-synaptic currents inferred from short-latency somatosensory evoked potentials (SEPs), (ii) pre-stimulus alpha oscillations (8-13 Hz), and (iii) peripheral nerve measures. Fluctuations of neural excitability shaped the perceived stimulus intensity already during the very first cortical response (at ~20 ms) yet demonstrating opposite neural signatures as compared to the effect of presented stimulus intensity. We reconcile this discrepancy via a common framework based on the modulation of electro-chemical membrane gradients linking neural states and responses, which calls for reconsidering conventional interpretations of brain potential magnitudes in stimulus intensity encoding.


Assuntos
Estimulação Elétrica , Córtex Motor/fisiologia , Nervos Periféricos/fisiologia , Córtex Somatossensorial/fisiologia , Adulto , Eletroencefalografia , Potenciais Somatossensoriais Evocados/fisiologia , Humanos , Masculino , Percepção , Adulto Jovem
4.
Artigo em Inglês | MEDLINE | ID: mdl-34705650

RESUMO

Current medical care lacks an effective functional evaluation for the spinal cord. Magnetic resonance imaging and computed tomography mainly provide structural information of the spinal cord, while spinal somatosensory evoked potentials are limited by a low signal to noise ratio. We developed a non-invasive approach based on near-infrared spectroscopy in dual-wavelength (760 and 850 nm for deoxy- or oxyhemoglobin respectively) to record the neurovascular response (NVR) of the peri-spinal vascular network at the 7th cervical and 10th thoracic vertebral levels of the spinal cord, triggered by unilateral median nerve electrical stimulation (square pulse, 5-10 mA, 5 ms, 1 pulse every 4 minutes) at the wrist. Amplitude, rise-time, and duration of NVR were characterized in 20 healthy participants. A single, painless stimulus was able to elicit a high signal-to-noise ratio and multi-segmental NVR (mainly from Oxyhemoglobin) with a fast rise time of 6.18 [4.4-10.4] seconds (median [Percentile 25-75]) followed by a slow decay phase for about 30 seconds toward the baseline. Cervical NVR was earlier and larger than thoracic and no left/right asymmetry was detected. Stimulus intensity/NVR amplitude fitted to a 2nd order function. The characterization and feasibility of the peri-spinal NVR strongly support the potential clinical applications for a functional assessment of spinal cord lesions.


Assuntos
Espectroscopia de Luz Próxima ao Infravermelho , Doenças da Medula Espinal , Potenciais Somatossensoriais Evocados , Humanos , Nervo Mediano , Medula Espinal
5.
Arq Neuropsiquiatr ; 79(9): 824-831, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34669817

RESUMO

The authors present a review of the current use of somatosensory evoked potentials (SSEPs) in neurological practice as a non-invasive neurophysiological technique. For this purpose we have reviewed articles published in English or Portuguese in the PubMed and LILACS databases. In this review, we address the role of SSEPs in neurological diseases that affect the central nervous system and the peripheral nervous system, especially in demyelinating diseases, for monitoring coma, trauma and the functioning of sensory pathways during surgical procedures. The latter, along with new areas of research, has become one of the most important applications of SSEPs.


Assuntos
Potencial Evocado Motor , Potenciais Somatossensoriais Evocados , Humanos
6.
Biol Psychol ; 165: 108177, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34478779

RESUMO

We examined how predictable and unpredictable punishment intensity contingent on error commission modulated ERN amplitudes. We recorded the ERN in 35 healthy volunteers performing the Eriksen flanker task. Errors were punished with predictable nonpainful, painful or unpredictable electrical stimulation. Furthermore, we investigated trait anxiety. We observed that ERN amplitudes did not differ across conditions, nor were there significant effects of anxiety. In contrast, we found that predictable painful punishments led to smaller Error Positivity (Pe). The effects of predictability and intensity were present in Somatosensory Evoked Potentials elicited by the punishments. N1 amplitudes were increased for painful compared to nonpainful stimulation, and P2/P3 amplitudes for painful compared to nonpainful, and for unpredictable compared to predictable stimulation. We suggest that unpredictability and increased painfulness of punishments enhance the potential motivational significance of the errors, but do not potentiate ERN amplitudes beyond the ones elicited by errors punished with predictable nonpainful stimulation.


Assuntos
Eletroencefalografia , Punição , Atenção , Potenciais Evocados , Potenciais Somatossensoriais Evocados , Humanos , Desempenho Psicomotor , Tempo de Reação
7.
Pediatr Neurosurg ; 56(6): 501-510, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34515213

RESUMO

OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of intraoperative neuromonitoring (IONM) in surgery for tethered cord in infants. MATERIALS AND METHODS: The study included 87 infants who underwent surgery for closed spinal dysraphism under IONM. Their preoperative neurological and urological statuses were compared with postoperative status clinically. The study design was prospective, and the study's duration was from January 2011 to February 2020. IONM was performed (TcMEP and direct mapping) with an Xltek Protektor 32 IOM system, Natus Neurology/medical Inc., Middleton, USA. Statistical analysis in the form of χ2 is conducted using SPSS. RESULTS: Overall, among 87 patients, clinical improvement was seen in 28 (28/29) patients with motor deficits, 17 (17/24) with bladder deficits, and 18 (18/24) with bowel deficits. The monitorability for motor and sphincter was 97.3% and 90.7%, respectively. The sensitivity of IONM in predicting new motor deficit was 100%, whereas the specificity was 100%. The negative predictive value of predicting motor deficit was 100%, with a diagnostic accuracy of 100%. There were no complications in this cohort related to the IONM. CONCLUSIONS: The study has highlighted that the use of IONM is sensitive in identifying motor injury in infants with reliable outcome correlation. Assessment, monitoring, and outcome correlation of bladder and sphincteric functions are a challenge in this cohort.


Assuntos
Monitorização Neurofisiológica Intraoperatória , Potencial Evocado Motor , Potenciais Somatossensoriais Evocados , Humanos , Lactente , Procedimentos Neurocirúrgicos , Estudos Prospectivos , Estudos Retrospectivos
8.
J Stroke Cerebrovasc Dis ; 30(10): 106007, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34407498

RESUMO

OBJECTIVES: During carotid artery stenting (CAS), hemodynamics may be affected by the carotid sinus reflex in some cases. Although general anesthesia has been reported to stabilize intraoperative hemodynamics, the patient's neurological condition must be assessed indirectly. Therefore, we investigated the changes in intraoperative hemodynamics and perioperative complications of CAS under general anesthesia and evaluated the efficacy of somatosensory evoked potential (SEP) monitoring in detecting a reduction in perfusion during CAS. MATERIALS AND METHODS: From April 2011 to August 2016,57 consecutive patients who underwent CAS under general anesthesia were evaluated. The follow-up period ranged from 3 to 8 years. During CAS, anesthesiologists monitored and managed the hemodynamics. SEP monitoring was performed during the CAS procedure in all patients. RESULTS: Intraoperative hypotension (systolic blood pressure ≤ 100 mmHg) was evident in 16 patients (28.1%), and 13 patients (22.8%) experienced intraoperative bradycardia; however, all of these cases were promptly managed under general anesthesia. None of the patients showed systolic blood pressure < 50 mmHg from baseline. Regarding perioperative complications, none of the patients exhibited myocardial infarction or postoperative hyperperfusion symptoms, and there was no mortality. Among 21 patients (36.8%) with a decrease in the intraoperative SEP, 3 (5.3%) exhibited transient ischemic symptoms and 1 (1.8%) had postoperative infarction. CONCLUSIONS: CAS under general anesthesia is a safe and effective management option in terms of intraoperative hemodynamic stability. In addition, our findings indicate that SEP monitoring could be helpful in evaluating transient postoperative cerebral ischemia or cerebral infarction after CAS.


Assuntos
Anestesia Geral , Doenças das Artérias Carótidas/terapia , Seio Carotídeo/inervação , Procedimentos Endovasculares/instrumentação , Potenciais Somatossensoriais Evocados , Hemodinâmica , Monitorização Neurofisiológica Intraoperatória , Stents , Idoso , Idoso de 80 Anos ou mais , Doenças das Artérias Carótidas/diagnóstico , Doenças das Artérias Carótidas/fisiopatologia , Procedimentos Endovasculares/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Reflexo , Estudos Retrospectivos , Fatores de Risco , Resultado do Tratamento
11.
J Rehabil Med ; 53(9): jrm00223, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34435643

RESUMO

OBJECTIVE: To test whether the presence of N30 somatosensory evoked potentials, generated from the supplementary motor area and premotor cortex, correlate with post-stroke spasticity, motor deficits, or motor recovery stage. DESIGN: A cross-sectional study. PATIENTS: A total of 43 patients with stroke hospitalized at Maoming People's Hospital, Maoming, China. METHODS: Forty-three stroke patients underwent neurofunctional tests, including Modified Ashworth Scale (MAS), Brunnstrom stage, manual muscle test and neurophysiological tests, including N30 somatosensory evoked potentials, N20 somatosensory evoked potentials, motor evoked potentials, H-reflex. The results were compared between groups. Correlation and regression analyses were performed as well. RESULTS: Patients with absence of N30 somatosensory evoked potential exhibited stronger flexor carpi radialis muscle spasticity (r = -0.50, p < 0.05) and worse motor function (r = 0.57, p < 0.05) than patients with presence of N30 somatosensory evoked potential. The generalized linear model (GLM) including both N30 somatosensory evoked potentials and motor evoked potentials (Akaike Information Criterion (AIC) = 121.99) better reflected the recovery stage of the affected proximal upper limb than the models including N30 somatosensory evoked potentials (AIC = 125.06) or motor evoked potentials alone (AIC = 127.45). CONCLUSION: N30 somatosensory evoked potential status correlates with the degrees of spasticity and motor function of stroke patients. The results showed that N30 somatosensory evoked potentials hold promise as a biomarker for the development of spasticity and the recovery of proximal limbs.


Assuntos
Espasticidade Muscular , Acidente Vascular Cerebral , Estudos Transversais , Potencial Evocado Motor , Potenciais Somatossensoriais Evocados , Humanos , Espasticidade Muscular/etiologia , Acidente Vascular Cerebral/complicações
13.
Clin Neurophysiol ; 132(10): 2351-2356, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34454261

RESUMO

OBJECTIVE: The present study investigated the effects of the stimulus polarity and location of motor evoked potential (MEP) to establish a stimulation protocol. METHODS: Nineteen patients who intraoperatively underwent MEP in bipolar direct cortical stimulation were enrolled in the present study. Somatosensory evoked potentials (SEP) of the contralateral median nerve stimulation were recorded to determine stimulation sites. MEP was performed under two settings in all patients: 1. Anodal bipolar stimulation: an anode on the precentral gyrus and a cathode on the postcentral gyrus, 2. Cathodal bipolar stimulation: a cathode on the precentral gyrus and an anode on the postcentral gyrus. MEP amplitudes and the coefficient of variation (CV) at a stimulation intensity of 25 mA and the thresholds of induced MEP were compared between the two settings. RESULTS: An electrical stimulation at 25 mA induced a significantly higher amplitude in cathodal bipolar stimulation than in anodal bipolar stimulation. Cathodal bipolar stimulation also showed significantly lower thresholds than anodal stimulation. CV did not significantly differ between the two groups. CONCLUSIONS: These results indicate that cathodal bipolar stimulation is superior to anodal bipolar stimulation for intraoperative MEP monitoring. SIGNIFICANCE: MEP in cathodal bipolar cortical stimulation may be used in a safe and useful evaluation method of motor fiber damage that combines sensitivity and specificity.


Assuntos
Eletrodos Implantados , Potencial Evocado Motor/fisiologia , Potenciais Somatossensoriais Evocados/fisiologia , Monitorização Neurofisiológica Intraoperatória/métodos , Córtex Motor/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Estimulação Elétrica/instrumentação , Estimulação Elétrica/métodos , Feminino , Humanos , Monitorização Neurofisiológica Intraoperatória/instrumentação , Masculino , Pessoa de Meia-Idade
14.
Clin Neurophysiol ; 132(10): 2357-2364, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34454262

RESUMO

OBJECTIVES: To investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents. METHODS: SEPs were recorded in 6 patients suffering from Parkinson's disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed. RESULTS: After median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts. CONCLUSIONS: Stimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential. SIGNIFICANCE: Our results shed light on the subcortical processing of the somatosensory input of different modalities.


Assuntos
Eletrodos Implantados , Potenciais Somatossensoriais Evocados/fisiologia , Nervo Mediano/fisiologia , Doença de Parkinson/fisiopatologia , Núcleo Tegmental Pedunculopontino/fisiologia , Idoso , Estimulação Elétrica/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/diagnóstico
15.
Clin Neurophysiol ; 132(10): 2431-2439, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34454270

RESUMO

OBJECTIVE: The purpose of this investigation was to better understand the effects of concussions on the ability to selectively up or down-regulate incoming somatosensory information based on relevance. METHODS: Median nerve somatosensory-evoked potentials (SEPs) were elicited from electrical stimulation and recorded from scalp electrodes while participants completed tasks that altered the relevance of specific somatosensory information being conveyed along the stimulated nerve. RESULTS: Within the control group, SEP amplitudes for task-relevant somatosensory information were significantly greater than for non-relevant somatosensory information at the earliest cortical processing potentials (N20-P27). Alternatively, the concussion history group showed similar SEP amplitudes for all conditions at early processing potentials, however a pattern similar to controls emerged later in the processing stream (P100) where both movement-related gating and facilitation of task-relevant information were present. CONCLUSIONS: Previously concussed participants demonstrated impairments in the ability to up-regulate relevant somatosensory information at early processing stages. These effects appear to be chronic, as this pattern was observed on average several years after participants' most recent concussion. SIGNIFICANCE: Given the role of the prefrontal cortex in relevancy-based facilitation during movement-related gating, these findings lend support to the notion that this brain area may be particularly vulnerable to concussive forces.


Assuntos
Concussão Encefálica/fisiopatologia , Potenciais Somatossensoriais Evocados/fisiologia , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Córtex Somatossensorial/fisiologia , Adulto , Concussão Encefálica/diagnóstico , Estimulação Elétrica/métodos , Feminino , Humanos , Masculino , Nervo Mediano/fisiologia , Movimento/fisiologia , Fatores de Tempo , Adulto Jovem
16.
J Neurosci ; 41(33): 7148-7159, 2021 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-34210784

RESUMO

Following stroke, the survival of neurons and their ability to reestablish connections is critical to functional recovery. This is strongly influenced by the balance between neuronal excitation and inhibition. In the acute phase of experimental stroke, lethal hyperexcitability can be attenuated by positive allosteric modulation of GABAA receptors (GABAARs). Conversely, in the late phase, negative allosteric modulation of GABAAR can correct the suboptimal excitability and improves both sensory and motor recovery. Here, we hypothesized that octadecaneuropeptide (ODN), an endogenous allosteric modulator of the GABAAR synthesized by astrocytes, influences the outcome of ischemic brain tissue and subsequent functional recovery. We show that ODN boosts the excitability of cortical neurons, which makes it deleterious in the acute phase of stroke. However, if delivered after day 3, ODN is safe and improves motor recovery over the following month in two different paradigms of experimental stroke in mice. Furthermore, we bring evidence that, during the subacute period after stroke, the repairing cortex can be treated with ODN by means of a single hydrogel deposit into the stroke cavity.SIGNIFICANCE STATEMENT Stroke remains a devastating clinical challenge because there is no efficient therapy to either minimize neuronal death with neuroprotective drugs or to enhance spontaneous recovery with neurorepair drugs. Around the brain damage, the peri-infarct cortex can be viewed as a reservoir of plasticity. However, the potential of wiring new circuits in these areas is restrained by a chronic excess of GABAergic inhibition. Here we show that an astrocyte-derived peptide, can be used as a delayed treatment, to safely correct cortical excitability and facilitate sensorimotor recovery after stroke.


Assuntos
Inibidor da Ligação a Diazepam/uso terapêutico , Agonistas de Receptores de GABA-A/uso terapêutico , Neurônios/efeitos dos fármacos , Neuropeptídeos/uso terapêutico , Fragmentos de Peptídeos/uso terapêutico , Receptores de GABA-A/efeitos dos fármacos , Acidente Vascular Cerebral/tratamento farmacológico , Adulto , Animais , Astrócitos/metabolismo , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Inibidor da Ligação a Diazepam/deficiência , Inibidor da Ligação a Diazepam/fisiologia , Implantes de Medicamento , Potenciais Somatossensoriais Evocados , Feminino , Agonistas de Receptores de GABA-A/farmacologia , Humanos , Hidrogéis , Infarto da Artéria Cerebral Média/tratamento farmacológico , Trombose Intracraniana/tratamento farmacológico , Trombose Intracraniana/etiologia , Luz , Camundongos , Camundongos Endogâmicos C57BL , N-Metilaspartato/toxicidade , Neurônios/fisiologia , Neuropeptídeos/deficiência , Neuropeptídeos/fisiologia , Técnicas de Patch-Clamp , Fragmentos de Peptídeos/deficiência , Fragmentos de Peptídeos/fisiologia , Ratos , Rosa Bengala/efeitos da radiação , Rosa Bengala/toxicidade , Método Simples-Cego , Acidente Vascular Cerebral/etiologia
17.
Exp Brain Res ; 239(9): 2803-2819, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34279670

RESUMO

The cerebral integration of somatosensory inputs from multiple sources is essential to produce adapted behaviors. Previous studies suggest that bilateral somatosensory inputs interact differently depending on stimulus characteristics, including their noxious nature. The aim of this study was to clarify how bilateral inputs evoked by noxious laser stimuli, noxious shocks, and innocuous shocks interact in terms of perception and brain responses. The experiment comprised two conditions (right-hand stimulation and concurrent stimulation of both hands) in which painful laser stimuli, painful shocks and non-painful shocks were delivered. Perception, somatosensory-evoked potentials (P45, N100, P260), laser-evoked potentials (N1, N2 and P2) and event-related spectral perturbations (delta to gamma oscillation power) were compared between conditions and stimulus modalities. The amplitude of negative vertex potentials (N2 or N100) and the power of delta/theta oscillations were increased in the bilateral compared with unilateral condition, regardless of the stimulus type (P < 0.01). However, gamma oscillation power increased for painful and non-painful shocks (P < 0.01), but not for painful laser stimuli (P = 0.08). Despite the similarities in terms of brain activity, bilateral inputs interacted differently for painful stimuli, for which perception remained unchanged, and non-painful stimuli, for which perception increased. This may reflect a ceiling effect for the attentional capture by noxious stimuli and warrants further investigations to examine the regulation of such interactions by bottom-up and top-down processes.


Assuntos
Potenciais Somatossensoriais Evocados , Potenciais Evocados por Laser , Encéfalo , Mapeamento Encefálico , Eletroencefalografia , Mãos , Humanos
18.
J Clin Neurosci ; 90: 359-362, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34275575

RESUMO

Vagus somatosensory evoked potentials (VSEP) and ultrasonography can be used to detect functional and structural changes of the vagus nerve (VN) that are hypothesized to be associated with neurodegenerative diseases. However, it has not yet been established whether age-related changes in the VN occur in the healthy population. In this pilot study we included healthy volunteers in the 26-30 and 51-55 age range who comprised the younger (n = 20) and older (n = 20) groups, respectively. VSEP were recorded separately for stimulation of the auricular branch of the left and right VN. The VN CSA was measured in the transverse plane proximal to the carotid bifurcation, at the level of the distal end of the common carotid artery. No differences were found between the younger and older groups when comparing the average VN CSA (2.01 ± 0.20 vs 2.05 ± 0.20, mm2; p = 0.570) or the CSA of the right (2.08 ± 0.19 vs 2.17 ± 0.24, mm2; p = 0.233) or left VN (1.94 ± 0.26 vs 1.93 ± 0.24, mm2; p = 0.911). The right VN was larger than the left in 95% (n = 19) of older participants and in 65% (n = 13) of younger participants (p = 0.055). In comparison with the younger group, older participants showed significantly longer VSEP latencies of all wave components for electrodes C4-F4 and Fz-F3, of P1 for electrodes C3-F3 and of N1 and P2 for electrodes Fz-F4. The results of this study indicate that older age is associated with longer VSEP latencies but not with changes in VN CSA.


Assuntos
Envelhecimento/fisiologia , Potenciais Somatossensoriais Evocados/fisiologia , Nervo Vago/diagnóstico por imagem , Nervo Vago/fisiologia , Adulto , Artérias Carótidas/diagnóstico por imagem , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Bainha de Mielina/fisiologia , Ultrassonografia
19.
Clin Neurophysiol ; 132(9): 2003-2011, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34284234

RESUMO

OBJECTIVE: A large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS. METHODS: A total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis. RESULTS: Patients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively). CONCLUSIONS: The HFO amplitude in ALS is increased, but does not predict survival. SIGNIFICANCE: The enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons.


Assuntos
Esclerose Amiotrófica Lateral/fisiopatologia , Potenciais Somatossensoriais Evocados/fisiologia , Nervo Mediano/fisiopatologia , Córtex Somatossensorial/fisiopatologia , Idoso , Esclerose Amiotrófica Lateral/diagnóstico por imagem , Esclerose Amiotrófica Lateral/mortalidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Somatossensorial/diagnóstico por imagem , Taxa de Sobrevida/tendências
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