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BACKGROUND AND PURPOSE: Precise and timely diagnosis is crucial for the optimal use of emerging disease-modifying treatments for Alzheimer disease (AD). Electroencephalography (EEG), which is noninvasive and cost-effective, can capture neural abnormalities linked to various dementias. This study explores the use of individual alpha frequency (IAF) derived from EEG as a diagnostic and prognostic tool in cognitively impaired patients. METHODS: This retrospective study included 375 patients from the tertiary Memory Clinic of IRCCS San Raffaele Hospital, Milan, Italy. Participants underwent clinical and neuropsychological assessments, brain imaging, cerebrospinal fluid biomarker analysis, and resting-state EEG. Patients were categorized by amyloid status, the AT(N) classification system, clinical diagnosis, and mild cognitive impairment (MCI) progression to AD dementia. IAF was calculated and compared among study groups. Receiver operating characteristic (ROC) analysis was used to calculate its discriminative performance. RESULTS: IAF was higher in amyloid-negative subjects and varied significantly across AT(N) groups. ROC analysis confirmed IAF's ability to distinguish A-T-N- from the A+T+N+ and A+T-N+ groups. IAF was lower in AD and Lewy body dementia patients compared to MCI and other dementia types, with moderate discriminatory capability. Among A+ MCI patients, IAF was significantly lower in those who converted to AD within 2 years compared to stable MCI patients and predicted time to conversion (p < 0.001, R = 0.38). CONCLUSIONS: IAF is a valuable tool for dementia diagnosis and prognosis, correlating with amyloid status and neurodegeneration. It effectively predicts MCI progression to AD, supporting its use in early, targeted interventions in the context of disease-modifying treatments.
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PURPOSE: Visual evoked potentials (VEPs) are a powerful tool to evaluate nervous conduction along the visual pathways, both in humans and in animal models. Traditionally, epidural screw electrodes are used to record VEPs in preclinical research. Here we tested the feasibility in the preclinical setting of the same noninvasive technique used for clinical VEP acquisition, by using epidermal cup electrodes with no surgical procedures. METHODS: Monocular flash VEPs were recorded bilaterally under sevoflurane anesthesia once a week for 6 weeks in 14 dark Agouti rats, 7 with implanted epidural screws and 7 with epidermal 6 mm Ø Ag/AgCl cups. RESULTS: VEP traces obtained with the two techniques were morphologically comparable. There were no significant differences in latency of the main visual component between screw-recorded VEPs (sVEPs) and cup-recorded VEPs (cVEPs). Amplitude values with epidermal cups were significantly lower than those with epidural screws. Both techniques provided latencies and amplitudes which were stable over time. Furthermore, with regard to latency both methods ensured highly repeatable measurements over time, with epidermal cups even providing slightly better results. On the other hand, considering amplitudes, cVEPs and sVEPs provided fairly acceptable repeatability. CONCLUSIONS: Epidermal cup electrodes can provide comparable results to those obtained with the "gold standard" epidural screws, while representing a simpler and less invasive technique to test nervous conduction along the visual pathways in the preclinical setting.
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Epiderme/fisiologia , Potenciais Evocados Visuais/fisiologia , Vias Visuais/fisiologia , Anestésicos Inalatórios/administração & dosagem , Animais , Eletrodos , Eletrorretinografia , Feminino , Éteres Metílicos/administração & dosagem , Estimulação Luminosa/métodos , Ratos , SevofluranoRESUMO
Rac GTPases regulate the development of cortical/hippocampal GABAergic interneurons by affecting the early development and migration of GABAergic precursors. We have addressed the function of Rac1 and Rac3 proteins during the late maturation of hippocampal interneurons. We observed specific phenotypic differences between conditional Rac1 and full Rac3 knockout mice. Rac1 deletion caused greater generalized hyperactivity and cognitive impairment compared with Rac3 deletion. This phenotype matched with a more evident functional impairment of the inhibitory circuits in Rac1 mutants, showing higher excitability and reduced spontaneous inhibitory currents in the CA hippocampal pyramidal neurons. Morphological analysis confirmed a differential modification of the inhibitory circuits: deletion of either Rac caused a similar reduction of parvalbumin-positive inhibitory terminals in the pyramidal layer. Intriguingly, cannabinoid receptor-1-positive terminals were strongly increased only in the CA1 of Rac1-depleted mice. This increase may underlie the stronger electrophysiological defects in this mutant. Accordingly, incubation with an antagonist for cannabinoid receptors partially rescued the reduction of spontaneous inhibitory currents in the pyramidal cells of Rac1 mutants. Our results show that Rac1 and Rac3 have independent roles in the formation of GABAergic circuits, as highlighted by the differential effects of their deletion on the late maturation of specific populations of interneurons.
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Comportamento Animal/fisiologia , Neurônios GABAérgicos/fisiologia , Hipocampo/citologia , Rede Nervosa/metabolismo , Proteínas rac de Ligação ao GTP/deficiência , Proteínas rac1 de Ligação ao GTP/deficiência , Adaptação Ocular/genética , Animais , Condicionamento Clássico/fisiologia , Emoções/fisiologia , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Comportamento Exploratório/fisiologia , Regulação da Expressão Gênica/genética , Glutamato Descarboxilase/genética , Glutamato Descarboxilase/metabolismo , Técnicas In Vitro , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Células Piramidais/metabolismo , Sinapsinas/genética , Sinapsinas/metabolismo , Proteínas rac de Ligação ao GTP/genética , Proteínas rac1 de Ligação ao GTP/genéticaRESUMO
Onabotulinum toxin A (BT-A) is now one of the authorized prophylaxis treatments for chronic migraine (CM) thanks to previous clinical trials, which usually required a pharmacologic washout as a precondition for demonstrating its efficacy. Aim of our study was to assess the efficacy in daily clinical practice of BT-A injections in refractory CM patients, regardless of medication overuse without any standardized withdrawal protocol and without stopping the ongoing prophylaxis treatment as well. We treated 44 refractory CM patients (37 females and 7 males) trimonthly without any modification in symptomatic, or prophylactic drug therapy. Main efficacy variables included number of headache, or migraine days and episodes, total cumulative headache hours, MIDAS and HIT-6 scores; all items were assessed at baseline and at the 12-, 24-, and 36-week follow-up. All variables showed a statistically significant improvement at week 36. In general, more than 50 % of patients had a good clinical outcome (including all improved patients, either partial or full responder) and that the percentage of drug abuser patients significantly decreased from 75 to 50 %, thanks to a spontaneous reduction of the symptomatic drug intake. Adverse events were uncommon and did not require treatment discontinuation. Onabotulinum toxin A treatment in refractory CM patients with unsatisfactory prophylactic drug treatments and pharmacological abuse is effective in improving clinical outcome and quality of life. This result may be achieved through a flexible pharmacologic approach tailored to each patient's needs; moreover, the patient himself can be often expected to reduce drug consumption spontaneously.
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Toxinas Botulínicas Tipo A/uso terapêutico , Transtornos de Enxaqueca/tratamento farmacológico , Fármacos Neuromusculares/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Doença Crônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Índice de Gravidade de Doença , Fatores de Tempo , Adulto JovemRESUMO
BACKGROUND: Sensory tricks such as touching the face with fingertips often improve cervical dystonia [CD]. This study is to determine whether sensory tricks modulate motor cortex excitability, assessed by paired-pulse transcranial magnetic stimulation [p-pTMS]. METHODS: Eight patients with rotational CD underwent p-pTMS, at rest and when the sensory trick was applied. To test intracortical inhibition [ICI] and facilitation [ICF], the amplitude ratio between conditioned and unconditioned cortical motor evoked potentials was measured at several interstimulus intervals (ISI 1, 3, 15, and 20 ms) and compared with controls mimicking patients' sensory tricks. RESULTS: At rest, a significant ICF enhancement was found at ISIs 15 through 20 in patients compared with controls, whereas no significant ICI changes were observed. Sensory tricks significantly reduced the abnormal ICF in patients and did not induce any change in controls. CONCLUSIONS: In our CD patients, sensory tricks seem to improve dystonia through an inhibitory effect on motor cortex excitability.
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Encéfalo/fisiopatologia , Potencial Evocado Motor/fisiologia , Torcicolo/patologia , Tato/fisiologia , Estimulação Magnética Transcraniana , Adulto , Toxinas Botulínicas/uso terapêutico , Eletromiografia , Feminino , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Inibição Neural/fisiologia , Neurotoxinas/uso terapêutico , Torcicolo/tratamento farmacológicoRESUMO
INTRODUCTION: There are no data on quantitative electromyography (EMG) of the external urethral sphincter (EUS) in men. The aim of this study was to obtain reference data from a group of neurologically healthy continent men with prostate pathology using a standardized technique. METHODS: Sixty-six subjects without neurological disorders were included. Motor unit potential (MUP) and interference pattern (IP) analysis were performed using multi-MUP and turns/amplitude techniques, respectively. RESULTS: Of 66 patients, 51 (mean age, 65.17; SD, 6.70) had localized prostate cancer (PCa), and 15 (mean age 61.67, SD 6.25) had benign prostate hyperplasia (BPH). Descriptive MUP parameters and IP-clouds were obtained, respectively in the BPH and PCa groups. No group differences were found. CONCLUSIONS: This study provides quantitative EMG measures of EUS functionality in continent men with prostate pathology. The data could be used as reference values for patients undergoing prostate surgery to identify postoperative changes in EUS function possibly influencing continence.
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Músculo Esquelético/fisiopatologia , Neoplasias da Próstata/patologia , Uretra/inervação , Uretra/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Eletromiografia , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/cirurgia , Neoplasias da Próstata/cirurgiaRESUMO
BACKGROUND AND OBJECTIVES: Epileptic seizures pose challenges in emergency departments (ED), affecting up to 10% of admitted patients. This study aimed to assess emergency electroencephalogram (EmEEG) utilization, identifying factors predicting seizure detection and its influence on clinical decisions. METHODS: A retrospective review of 1135 EmEEGs on 1017 patients at a tertiary teaching hospital between June 2022 and June 2023 was conducted. Data included demographics, medical history, EmEEG indications, neuroimaging findings, and clinical outcomes. Statistical analyses utilized Fisher's exact tests and logistic regression models. RESULTS: EmEEG detected status epilepticus-related seizures in 5.40% of cases, seizures without status epilepticus in 3.05%, and status epilepticus without discrete seizures in 3.74%. Epileptiform abnormalities were noted in 22.12% of EmEEGs. EmEEG influenced initial diagnoses (21.24%), antiseizure medication changes (20.85%), and discharge decisions (39.04%). Predictors for seizures/status epilepticus included previous neurosurgery, seizures in the ED, and cognitive/behavioral impairment (p < 0.001). EmEEG significantly altered initial diagnoses based on witnessed seizures, involuntary movements, epileptiform abnormalities, and 1-2 Hz generalized periodic discharges (p < 0.001). Changes in antiseizure medications correlated with seizure occurrence, neuroimaging results, epileptiform abnormalities, and EEG background slowing (p < 0.001). Factors influencing discharge decisions included previous neurosurgery, consciousness impairment, acute neuroimaging pathology, EEG focal slowing, and EEG background slowing (p < 0.001). DISCUSSION: The study clarifies EmEEG's role in modifying initial diagnoses, treatment approaches, and discharge decisions. The study provides insights into the nuanced impact of EmEEG in different clinical scenarios, offering valuable guidance for clinicians in selecting patients for EmEEG, particularly in conditions of limited EEG availability.
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Eletroencefalografia , Serviço Hospitalar de Emergência , Convulsões , Centros de Atenção Terciária , Humanos , Eletroencefalografia/métodos , Masculino , Feminino , Estudos Retrospectivos , Pessoa de Meia-Idade , Adulto , Convulsões/diagnóstico , Convulsões/fisiopatologia , Idoso , Itália , Estado Epiléptico/diagnóstico , Estado Epiléptico/fisiopatologia , Adulto Jovem , Adolescente , Idoso de 80 Anos ou maisRESUMO
BACKGROUND AND OBJECTIVES: The 3 clinical presentations of primary progressive aphasia (PPA) reflect heterogenous neuropathology, which is difficult to be recognized in vivo. Resting-state (RS) EEG is promising for the investigation of brain electrical substrates in neurodegenerative conditions. In this study, we aim to explore EEG cortical sources in the characterization of the 3 variants of PPA. METHODS: This is a cross-sectional, single-center, memory center-based cohort study. Patients with PPA and healthy controls were consecutively recruited at the Neurology Unit, IRCCS San Raffaele Scientific Institute (Milan, Italy). Each participant underwent an RS 19-channel EEG. Using standardized low-resolution brain electromagnetic tomography, EEG current source densities were estimated at voxel level and compared among study groups. Using an RS functional MRI-driven model of source reconstruction, linear lagged connectivity (LLC) values within language and extra-language brain networks were obtained and analyzed among groups. RESULTS: Eighteen patients with logopenic PPA variant (lvPPA; mean age = 72.7 ± 6.6; % female = 52.4), 21 patients with nonfluent/agrammatic PPA variant (nfvPPA; mean age = 71.7 ± 8.1; % female = 66.6), and 9 patients with semantic PPA variant (svPPA; mean age = 65.0 ± 6.9; % female = 44.4) were enrolled in the study, together with 21 matched healthy controls (mean age = 69.2 ± 6.5; % female = 57.1). Patients with lvPPA showed a higher delta density than healthy controls (p < 0.01) and patients with nfvPPA (p < 0.05) and svPPA (p < 0.05). Patients with lvPPA also displayed a greater theta density over the left posterior hemisphere (p < 0.01) and lower alpha2 values (p < 0.05) over the left frontotemporal regions than controls. Patients with nfvPPA showed a diffuse greater theta density than controls (p < 0.05). LLC was altered in all patients relative to controls (p < 0.05); the alteration was greater at slow frequency bands and within language networks than extra-language networks. Patients with lvPPA also showed greater LLC values at theta band than patients with nfvPPA (p < 0.05). DISCUSSION: EEG findings in patients with PPA suggest that lvPPA-related pathology is associated with a characteristic disruption of the cortical electrical activity, which might help in the differential diagnosis from svPPA and nfvPPA. EEG connectivity was disrupted in all PPA variants, with distinct findings in disease-specific PPA groups. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that EEG analysis can distinguish PPA due to probable Alzheimer disease from PPA due to probable FTD from normal aging.
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Academias e Institutos , Afasia Primária Progressiva , Humanos , Feminino , Idoso , Pessoa de Meia-Idade , Masculino , Estudos de Coortes , Estudos Transversais , Afasia Primária Progressiva/diagnóstico por imagem , EletroencefalografiaRESUMO
BACKGROUND AND PURPOSE: Transcranial direct current stimulation is emerging as a promising tool for the treatment of several neurological conditions, including cerebral ischemia. The therapeutic role of this noninvasive treatment is, however, limited to chronic phases of stroke. We thus ought to investigate whether different stimulation protocols could also be beneficial in the acute phase of experimental brain ischemia. METHODS: The influence of both cathodal and anodal transcranial direct current stimulation in modifying brain metabolism of healthy mice was first tested by nuclear magnetic resonance spectroscopy. Then, mice undergoing transient proximal middle cerebral artery occlusion were randomized and treated acutely with anodal, cathodal, or sham transcranial direct current stimulation. Brain metabolism, functional outcomes, and ischemic lesion volume, as well as the inflammatory reaction and blood brain barrier functionality, were analyzed. RESULTS: Cathodal stimulation was able, if applied in the acute phase of stroke, to preserve cortical neurons from the ischemic damage, to reduce inflammation, and to promote a better clinical recovery compared with sham and anodal treatments. This finding was attributable to the significant decrease of cortical glutamate, as indicated by nuclear magnetic resonance spectroscopy. Conversely, anodal stimulation induced an increase in the postischemic lesion volume and augmented blood brain barrier derangement. CONCLUSIONS: Our data indicate that transcranial direct current stimulation exerts a measurable neuroprotective effect in the acute phase of stroke. However, its timing and polarity should be carefully identified on the base of the pathophysiological context to avoid potential harmful side effects.
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Isquemia Encefálica/fisiopatologia , Isquemia Encefálica/terapia , Terapia por Estimulação Elétrica/métodos , Estimulação Elétrica/métodos , Acidente Vascular Cerebral/fisiopatologia , Acidente Vascular Cerebral/terapia , Animais , Barreira Hematoencefálica , Encéfalo/patologia , Modelos Animais de Doenças , Eletrodos , Ácido Glutâmico/metabolismo , Inflamação , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
OBJECTIVE: This study assessed the long-term effect of the eversion technique for carotid endarterectomy (e-CEA) on arterial baroreflex and peripheral chemoreflex function. METHODS: The study included 13 patients who underwent, between 2001 and 2006, bilateral e-CEA and 16 who underwent bilateral standard CEA (s-CEA) to eliminate the complicating effects of intact contralateral carotid sinus function. Exclusion criteria were age >70 years, diabetes mellitus, chronic pulmonary disease, ischemic cardiac disease or medical therapy with ß-blockers, cardiac arrhythmia, neurologic deficits, carotid restenosis, and previous neck or chest surgery or irradiation. Young and aged-matched healthy individuals were recruited as controls. All patients underwent standard cardiovascular reflex tests, including lying-to-standing, orthostatic hypotension, deep breathing, and Valsalva maneuver. Autonomic cardiovascular modulation was indirectly evaluated by spectral analysis of heart rate variability and systolic arterial pressure variability. The chemoreflex sensitivity to hypoxia was obtained during classic rebreathing tests from the slopes of the linear regression of minute ventilation (VE) vs arterial oxygen saturation measured by pulse oximetry (SpO2%) and partial pressure of end-tidal oxygen (PetO2). RESULTS: Patients (16 men; age, 62.4 ± 8.0 years) were enrolled after a mean interval of 24 ± 17 months from the last CEA. All were asymptomatic, and results of standard tests were negative. Residual baroreflex performance was documented in both patient groups, although reduced, compared with young controls. Notably, baroreflex sensitivity (msec/mm Hg) was better maintained after e-CEA than after s-CEA at rest (young controls, 19.93 ± 9.50; age-matched controls, 7.75 ± 5.68; e-CEA, 13.85 ± 14.54; and s-CEA, 3.83 ± 1.15; analysis of variance [ANOVA], P = .001); and at standing (young controls, 7.83 ± 2.55; age-matched controls, 3.71 ± 1.59; e-CEA, 7.04 ± 5.62; and s-CEA 3.57 ± 3.80; ANOVA, P = .001). Similarly, chemoreflex sensitivity to hypoxia was maintained in both patient groups, which did not differ from each other, and was reduced compared with controls (controls vs patient groups ΔVE/ΔSpO2: -1.37 ± 0.33 vs -0.33 ± 0.08 and SpO2% -0.29 ± 0.13 L/min; P = .002; ΔVE/ΔPetO2: -0.20 ± 0.1 vs -0.01 ± 0.0 and -0.07 ± 0.02 L/min/mm Hg; P = .04, ANOVA with least significant difference correction for multiple comparisons). CONCLUSIONS: Our data show that e-CEA, even when performed on both sides, preserves baroreflexes and chemoreflexes and, therefore, does not confer permanent carotid sinus denervation. Also, e-CEA does not increase long-term arterial pressure variability, and this suggests that perioperative hemodynamic derangements can be attributed to the temporary effects of surgical trauma.
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Barorreflexo , Seio Carotídeo/inervação , Estenose das Carótidas/cirurgia , Células Quimiorreceptoras/metabolismo , Endarterectomia das Carótidas/métodos , Idoso , Análise de Variância , Pressão Arterial , Testes Respiratórios , Estenose das Carótidas/sangue , Estenose das Carótidas/diagnóstico , Estenose das Carótidas/fisiopatologia , Endarterectomia das Carótidas/efeitos adversos , Feminino , Testes de Função Cardíaca , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Oximetria , Oxigênio/sangue , Valor Preditivo dos Testes , Estudos Retrospectivos , Fatores de Tempo , Resultado do TratamentoRESUMO
OBJECTIVES: Despite the introduction of several adjuncts to improve spinal perfusion, spinal cord ischemia (SCI) remains a devastating complication of thoracoabdominal aortic aneurysm (TAAA) repair. Our aim was to assess the effects on clinical outcome of interventions triggered by motor evoked potentials (MEP) alerts. Furthermore, we want to assess whether a multimodal intraoperative neurophysiologic monitoring (IONM) protocol is helpful for stratifying patients according to the risk of SCI at the end of the vascular phase of surgery. METHODS: We prospectively studied one-hundred consecutive patients who underwent TAAA repair. We applied a multimodal IONM including MEP, somatosensory evoked potentials (SEP) and peripheral nerve monitoring techniques. Signal deteriorations were classified as reversible/irreversible according to whether they recovered or not at the end of monitoring (EOM), set at the end of the vascular phase of surgery. Significant MEP changes drove a series of corrective measures aimed to improve spinal perfusion. RESULTS: The rate of immediate postoperative motor deficits consistent with SCI was significantly higher with irreversible MEP deteriorations compared to reversible ones. The interpretation of MEP findings at the EOM led to the development of risk categories for SCI, based on the association between MEP results and motor outcome. CONCLUSIONS: Our data seem to justify interventions made to reverse MEP deterioration in order to improve the clinical outcome. A multimodal IONM protocol could improve MEP interpretation at the end of the vascular phase of surgery, supporting the surgeon in their decision-making, before concluding vascular maneuvers.
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Aneurisma da Aorta Torácica , Monitorização Neurofisiológica Intraoperatória , Isquemia do Cordão Espinal , Aneurisma da Aorta Torácica/complicações , Aneurisma da Aorta Torácica/cirurgia , Tomada de Decisões , Potencial Evocado Motor/fisiologia , Retroalimentação , Humanos , Monitorização Neurofisiológica Intraoperatória/efeitos adversos , Estudos Retrospectivos , Isquemia do Cordão Espinal/etiologia , Isquemia do Cordão Espinal/prevenção & controleRESUMO
BACKGROUND AND OBJECTIVES: To explore cognitive, EEG, and MRI features in COVID-19 survivors up to 10 months after hospital discharge. METHODS: Adult patients with a recent diagnosis of COVID-19 and reporting subsequent cognitive complaints underwent neuropsychological assessment and 19-channel-EEG within 2 months (baseline, N = 49) and 10 months (follow-up, N = 33) after hospital discharge. A brain MRI was obtained for 36 patients at baseline. Matched healthy controls were included. Using eLORETA, EEG regional current densities and linear lagged connectivity values were estimated. Total brain and white matter hyperintensities (WMH) volumes were measured. Clinical and instrumental data were evaluated between patients and controls at baseline, and within patient whole group and with/without dysgeusia/hyposmia subgroups over time. Correlations among findings at each timepoint were computed. RESULTS: At baseline, 53% and 28% of patients showed cognitive and psychopathological disturbances, respectively, with executive dysfunctions correlating with acute-phase respiratory distress. Compared to healthy controls, patients also showed higher regional current density and connectivity at delta band, correlating with executive performances, and greater WMH load, correlating with verbal memory deficits. A reduction of cognitive impairment and delta band EEG connectivity were observed over time, while psychopathological symptoms persisted. Patients with acute dysgeusia/hyposmia showed lower improvement at memory tests than those without. Lower EEG delta band at baseline predicted worse cognitive functioning at follow-up. DISCUSSION: COVID-19 patients showed interrelated cognitive, EEG, and MRI abnormalities 2 months after hospital discharge. Cognitive and EEG findings improved at 10 months. Dysgeusia and hyposmia during acute COVID-19 were related with increased vulnerability in memory functions over time.
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COVID-19 , Disfunção Cognitiva , Adulto , Anosmia , COVID-19/complicações , Cognição , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/patologia , Disgeusia , Eletroencefalografia , Humanos , Imageamento por Ressonância Magnética , Testes Neuropsicológicos , SobreviventesRESUMO
OBJECTIVE: We evaluated the value of resting-state EEG source biomarkers to characterize mild cognitive impairment (MCI) subjects with an Alzheimer's disease (AD)-like cerebrospinal fluid (CSF) profile and to track neurodegeneration throughout the AD continuum. We further applied a resting-state functional MRI (fMRI)-driven model of source reconstruction and tested its advantage in terms of AD diagnostic accuracy. METHODS: Thirty-nine consecutive patients with AD dementia (ADD), 86 amnestic MCI, and 33 healthy subjects enter the EEG study. All ADD subjects, 37 out of 86 MCI patients and a distinct group of 53 healthy controls further entered the fMRI study. MCI subjects were divided according to the CSF phosphorylated tau/ß amyloid-42 ratio (MCIpos: ≥ 0.13, MCIneg: < 0.13). Using Exact low-resolution brain electromagnetic tomography (eLORETA), EEG lobar current densities were estimated at fixed frequencies and analyzed. To combine the two imaging techniques, networks mostly affected by AD pathology were identified using Independent Component Analysis applied to fMRI data of ADD subjects. Current density EEG analysis within ICA-based networks at selected frequency bands was performed. Afterwards, graph analysis was applied to EEG and fMRI data at ICA-based network level. RESULTS: ADD patients showed a widespread slowing of spectral density. At a lobar level, MCIpos subjects showed a widespread higher theta density than MCIneg and healthy subjects; a lower beta2 density than healthy subjects was also found in parietal and occipital lobes. Evaluating EEG sources within the ICA-based networks, alpha2 band distinguished MCIpos from MCIneg, ADD and healthy subjects with good accuracy. Graph analysis on EEG data showed an alteration of connectome configuration at theta frequency in ADD and MCIpos patients and a progressive disruption of connectivity at alpha2 frequency throughout the AD continuum. CONCLUSIONS: Theta frequency is the earliest and most sensitive EEG marker of AD pathology. Furthermore, EEG/fMRI integration highlighted the role of alpha2 band as potential neurodegeneration biomarker.
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Doença de Alzheimer , Disfunção Cognitiva , Doença de Alzheimer/diagnóstico por imagem , Biomarcadores , Disfunção Cognitiva/diagnóstico por imagem , Eletroencefalografia , Humanos , Imageamento por Ressonância MagnéticaRESUMO
Shortly after the application of weak transcranial direct current stimulation (tDCS) to the animal and human brain, changes in corticospinal excitability, which mainly depend on polarity, duration and current density of the stimulation protocol, have been reported. In humans, anodal tDCS has been reported to enhance motor-evoked potentials (MEPs) elicited by transcranial brain stimulation while cathodal tDCS has been shown to decrease them. Here we investigated the effects produced by tDCS on mice motor cortex. MEPs evoked by transcranial electric stimulation were recorded from forelimbs of 12 C57BL/6 mice, under sevofluorane anaesthesia, before and after (0, 5 and 10 min) anodal and cathodal tDCS (tDCS duration 10 min). With respect to sham condition stimulation (anaesthesia), MEP size was significantly increased immediately after anodal tDCS, and was reduced after cathodal tDCS (approximately 20% vs. sham). Both effects declined towards basal levels in the following 10 min. Although the site and mechanisms of action of tDCS need to be more clearly identified, the directionality of effects of tDCS on mice MEPs is consistent with previous findings in humans. The feasibility of tDCS in mice suggests the potential applicability of this technique to assess the potential therapeutic options of brain polarization in animal models of neurological and neuropsychiatric diseases.
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Encéfalo/fisiologia , Estimulação Elétrica/métodos , Potencial Evocado Motor/fisiologia , Córtex Motor/fisiologia , Animais , Encéfalo/anatomia & histologia , Estimulação Elétrica/efeitos adversos , Feminino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Dark-Agouti rats were immunized with spinal cord homogenate to develop Experimental Autoimmune Encephalomyelitis, a model of multiple sclerosis. We assessed motor signs and recorded VEPs for five or eight weeks with epidural or epidermal electrodes, respectively, with final histopathology of optic nerves (ONs). Injected rats exhibited motor deficits a week after immunization. VEP delays arose from the 2nd to the 5th week, when a recovery occurred in epidermal-recorded rats. ON damage appeared in epidural-, but not in epidermal-recorded rats, probably due to a remyelination process. VEP could be exploited as neurophysiological marker to test novel treatments against neurodegeneration involving ONs.
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Encefalomielite Autoimune Experimental/imunologia , Potenciais Evocados Visuais/fisiologia , Nervo Óptico/imunologia , Medula Espinal/imunologia , Animais , Eletrodos Implantados , Encefalomielite Autoimune Experimental/patologia , Feminino , Imunização/efeitos adversos , Nervo Óptico/patologia , Neurite Óptica/imunologia , Neurite Óptica/patologia , Ratos , Medula Espinal/patologiaRESUMO
OBJECTIVE: Virtual reality (VR) has been proposed as a potentially useful tool for motor assessment and rehabilitation. The objective of this study was to investigate the usefulness of VR in the assessment of short-term motor learning in multiple sclerosis (MS). METHODS: Twelve right-handed MS patients and 12 control individuals performed a motor-tracking task with their right upper limb, following the trajectory of an object projected on a screen along with online visual feedback on hand position from a sensor on the index finger. A pretraining test (3 trials), a training phase (12 trials), and a posttraining test (3 trials) were administered. Distances between performed and required trajectory were computed. RESULTS: Both groups performed worse in depth planes compared to the frontal (x,z) plane (P < .006). MS patients performed worse than control individuals in the frontal plane at both evaluations (P < .015), whereas they had lower percent posttraining improvement in the depth planes only (P = .03). CONCLUSIONS: The authors' VR system detected impaired motor learning in MS patients, especially for task features requiring a complex integration of sensory information (movement in the depth planes). These findings stress the need for careful customization of rehabilitation strategies, which must take into account the patients' motor, sensory, and cognitive limitations.
Assuntos
Esclerose Múltipla Crônica Progressiva/reabilitação , Esclerose Múltipla Recidivante-Remitente/reabilitação , Desempenho Psicomotor , Terapia Assistida por Computador/instrumentação , Interface Usuário-Computador , Adulto , Percepção de Profundidade , Feminino , Dedos , Humanos , Masculino , Pessoa de Meia-Idade , Destreza Motora , Estimulação LuminosaRESUMO
BACKGROUND: Dysregulation of Ras-extracellular signal-related kinase (ERK) signaling gives rise to RASopathies, a class of neurodevelopmental syndromes associated with intellectual disability. Recently, much attention has been directed at models bearing mild forms of RASopathies whose behavioral impairments can be attenuated by inhibiting the Ras-ERK cascade in the adult. Little is known about the brain mechanisms in severe forms of these disorders. METHODS: We performed an extensive characterization of a new brain-specific model of severe forms of RASopathies, the KRAS12V mutant mouse. RESULTS: The KRAS12V mutation results in a severe form of intellectual disability, which parallels mental deficits found in patients bearing mutations in this gene. KRAS12V mice show a severe impairment of both short- and long-term memory in a number of behavioral tasks. At the cellular level, an upregulation of ERK signaling during early phases of postnatal development, but not in the adult state, results in a selective enhancement of synaptogenesis in gamma-aminobutyric acidergic interneurons. The enhancement of ERK activity in interneurons at this critical postnatal time leads to a permanent increase in the inhibitory tone throughout the brain, manifesting in reduced synaptic transmission and long-term plasticity in the hippocampus. In the adult, the behavioral and electrophysiological phenotypes in KRAS12V mice can be temporarily reverted by inhibiting gamma-aminobutyric acid signaling but not by a Ras-ERK blockade. Importantly, the synaptogenesis phenotype can be rescued by a treatment at the developmental stage with Ras-ERK inhibitors. CONCLUSIONS: These data demonstrate a novel mechanism underlying inhibitory synaptogenesis and provide new insights in understanding mental dysfunctions associated to RASopathies.
Assuntos
Encéfalo/fisiologia , Neurônios GABAérgicos/fisiologia , Deficiência Intelectual/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Sinapses/fisiologia , Animais , Ansiedade/metabolismo , Ansiedade/fisiopatologia , Comportamento Animal/fisiologia , Encéfalo/metabolismo , Modelos Animais de Doenças , Neurônios GABAérgicos/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiologia , Potenciais Pós-Sinápticos Inibidores , Potenciação de Longa Duração , Transtornos da Memória/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptores de GABA/metabolismo , Comportamento Social , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismoRESUMO
Schwann cells (SCs) generate the myelin wrapping of peripheral nerve axons and are promising candidates for cell therapy. However, to date a renewable source of SCs is lacking. In this study, we show the conversion of skin fibroblasts into induced Schwann cells (iSCs) by driving the expression of two transcription factors, Sox10 and Egr2. iSCs resembled primary SCs in global gene expression profiling and PNS identity. In vitro, iSCs wrapped axons generating compact myelin sheaths with regular nodal structures. Conversely, iSCs from Twitcher mice showed a severe loss in their myelinogenic potential, demonstrating that iSCs can be an attractive system for in vitro modelling of PNS diseases. The same two factors were sufficient to convert human fibroblasts into iSCs as defined by distinctive molecular and functional traits. Generating iSCs through direct conversion of somatic cells offers opportunities for in vitro disease modelling and regenerative therapies.
Assuntos
Reprogramação Celular/genética , Proteína 2 de Resposta de Crescimento Precoce/fisiologia , Fibroblastos/fisiologia , Fatores de Transcrição SOXE/fisiologia , Células de Schwann/fisiologia , Animais , Axônios/fisiologia , Linhagem Celular , Técnicas de Cocultura , Perfilação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Bainha de Mielina/metabolismo , Bainha de Mielina/ultraestrutura , Traumatismos dos Nervos Periféricos/terapia , Cultura Primária de Células , Ratos , Ratos Sprague-Dawley , Roedores , Células de Schwann/transplante , Células de Schwann/ultraestrutura , Nervo Isquiático/citologia , Nervo Isquiático/fisiologia , Pele/citologiaRESUMO
The neuronal mechanisms involved in brain plasticity after skilled motor learning are not completely understood. We aimed to study the short-term effects of keyboard training in music-naive subjects on the motor/premotor cortex activity and interhemispheric interactions, using electroencephalography and transcranial magnetic stimulation (TMS). Twelve subjects (experimental group) underwent, before and after a two week-piano training: (1) hand-motor function tests: Jamar, grip and nine-hole peg tests; (2) electroencephalography, evaluating the mu rhythm task-related desynchronization (TRD) during keyboard performance; and (3) TMS, targeting bilateral abductor pollicis brevis (APB) and abductor digiti minimi (ADM), to obtain duration and area of ipsilateral silent period (ISP) during simultaneous tonic contraction of APB and ADM. Data were compared with 13 controls who underwent twice these measurements, in a two-week interval, without undergoing piano training. Every subject in the experimental group improved keyboard performance and left-hand nine-hole peg test scores. Pre-training, ISP durations were asymmetrical, left being longer than right. Post-training, right ISPAPB increased, leading to symmetrical ISPAPB. Mu TRD during motor performance became more focal and had a lesser amplitude than in pre-training, due to decreased activity over ventral premotor cortices. No such changes were evidenced in controls. We demonstrated that a 10-day piano-training was associated with balanced interhemispheric interactions both at rest and during motor activation. Piano training, in a short timeframe, may reshape local and inter-hemispheric motor cortical circuits.
Assuntos
Potencial Evocado Motor/fisiologia , Lateralidade Funcional/fisiologia , Córtex Motor/fisiologia , Música , Rede Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Adulto , Estimulação Elétrica , Eletroencefalografia , Feminino , Humanos , Aprendizagem/fisiologia , Masculino , Córtex Motor/anatomia & histologia , Rede Nervosa/anatomia & histologia , Inibição Neural/fisiologia , Estimulação Magnética TranscranianaRESUMO
PURPOSE: The development of new drugs for the treatment of epilepsy is a major challenge for modern neurology and its first steps demand basic research. Preclinical studies on animal models of epilepsy are mainly based on the analysis of brain electrical activity to detect seizures, when they are not just limited to behavioral tests like the Racine scale. METHODS: In the present review, we discuss the importance of using time-locked video and EEG recordings (Video-EEG) coupled with behavioral tests as tools to monitor and analyze the effects of anti-epileptic drugs in pre-clinical research. Particularly, we focus on the utility of a multimodal approach based on EEG/behavioral analysis to study the beneficial effects of chronic rapamycin treatment as a potential anti-epileptogenic therapy for a broad spectrum of epilepsy, including both genetic (as in tuberous sclerosis complex) and acquired diseases. RESULTS: Changes and synchronization of neuronal activity of different areas have been correlated with specific behavior in both physiological and pathological conditions. In the epileptic brain, during a seizure there is an abnormal activation of many cells all at once, altering different networks. CONCLUSION: A multimodal approach based on video, EEG analysis and behavioral tests would be the best option in preclinical studies of epilepsy.