Neurophysiological Investigations Research Articles

Relation of local window size in a model of modules with estimation of the size of visual images and their segmentation

Subject of study. The fundamental mechanisms of visual image processing, such as size estimation and segmentation, are considered. The possibility of describing these mechanisms using the model of modules proposed by V. D. Glezer and based on electrophysiological data from studies of the receptive fields of neurons in the visual cortex was investigated. Aim of study. This study aimed to investigate mechanisms of size estimation and the segmentation processes by comparing the experimental data obtained by the authors with modeling results. Methods. Psychophysical methods were used for the experimental part. Two different paradigms were used for size estimation: a modified Ebbinghaus illusion with different surroundings of the test stimuli or a comparison of the sizes of upright and oblique crosses previously used in experiments on segmentation. Spatial-frequency filtering of images in local areas of the visual field was performed during modeling using a finite set of filters. Main results. The dependence of the size estimate on the distance between images and on their shape and the relationship of those estimates with segmentation was demonstrated for the first time to our knowledge. Another new result shows that images with different shapes are perceived as equal in size if the modules that optimally describe these images (i.e., maximum energy is preserved in images when filtered with a limited number of filters) are of equal sizes. The obtained results demonstrate that the model of modules can describe to a first approximation the mechanisms performing the estimation of the sizes of the images and their segmentation. Correspondence between the data of neurophysiological, psychophysical, and modeling investigations was shown for the first time to our knowledge. The conclusions were supported by a comparison of the experimental results, and the modeling, with patterns of traditional Byzatntine icon paintings, as well as Russian avant-garde paintings of the early 20th century, which were inspired by the former. Practical significance. Application and further enhancement of the model of modules as an artificial neural network that ensures the segmentation, image size estimation, and recognition of visual objects can be of practical significance.

Peripheral neuropathy in severe iron deficiency anemia: A case report

Anemia is a global health problem that need medical attention. Iron deficiency anemia (IDA), in particular is the most common nutritional deficiency anemia prevalent in India. Iron essential for effective myelination of peripheral nervous system.1 Nerve conduction studies are one of the neurophysiological investigations that can quantitatively detect peripheral nerve dysfunction.2 In this case report, we present findings of nerve conduction studies performed on a case of severe iron deficiency anemia and the associated peripheral neurodeficit observed in the case study. Nerve conduction study (NCS) was performed in bilateral median and ulnar motor and sensory nerves. CMAP (compound muscle action potential) and SNAP(sensory nerve action potential) and motor and sensory NCV (nerve conduction velocity) was decreased and the distal latency was prolonged in both ulnar and median nerves. These observations indicate a sensorimotor demyelinating and axonal peripheral neuropathy in the patient due to iron deficiency.

Electrodiagnostic findings in facial onset sensory motor neuronopathy (FOSMN)

ObjectiveTo determine the electrodiagnostic characteristics of facial onset sensory and motor neuronopathy (FOSMN). MethodsElectrophysiological data from 10 FOSMN patients in Newcastle-upon-Tyne and Sydney were reviewed. Relevant literature was reviewed. ResultsFindings on standard electrophysiological assessment were in broad agreement with those published: blink reflexes were abnormal in all but one patient; sensory nerve action potentials were reduced but compound muscle action potentials preserved; mixed acute and chronic neurogenic change was identified on needle electromyography in bulbar and cervico-thoracic muscles in approximately 50% of patients.Upper limb somatosensory evoked potential (SEP) central conduction times were increased (n = 4) and progressed on repeat testing (n = 3). Upper motor neuron dysfunction was revealed by several measures [ipsilateral motor evoked potentials (MEPs) (n = 1); reduced short interval intra-cortical inhibition on threshold-tracking transcranial magnetic stimulation (n = 2); absent beta-band intermuscular coherence (n = 3)]. ConclusionsElectrodiagnostic investigation of FOSMN should include blink reflex testing, SEPs and tests of upper motor neuron function. The combination of progressive lower motor neuron disease and upper motor neuron disease on neurophysiological investigation provides further support for the contention that FOSMN is a rare variant of motor neurone disease. SignificanceThese findings will aid the neurologist and neurophysiologist in making a confident diagnosis of FOSMN, thus expediting appropriate care.

Diagnostic value of clinical examination for identifying patients with large- and small-fibre neuropathy.

The diagnosis of polyneuropathy usually requires neurophysiological investigation, necessitating specialised testing and interpretation thereby increasing the time to final diagnosis. To investigate the predictive value of the clinical examination in patients with potential neuropathies. Patients were recruited based on their referral requesting neurophysiological testing. Two examiners tested ankle jerk reflexes and gradient to temperature sensation prior to the patient undergoing neurophysiology investigations, blinded to subsequent testing results. The neurophysiology investigations were either standard nerve conduction study (NCS) or thermal threshold testing (TTT) or both. These data were then analysed to determine the Kappa between examiners as well as sensitivity, specificity, and positive and negative likelihood ratios. There was a modest level of agreement between examiners for ankle jerk testing (Kappa=0.6) but poor agreement for gradient temperature testing (Kappa=0.3). Bilateral absence of ankle jerk reflexes was moderately associated with abnormal NCS, with the following characteristics: sensitivity 72%, specificity 91%, positive likelihood ratio 7.6 and negative likelihood ratio 0.3. The presence of a temperature gradient was poorly diagnostic for abnormal TTT: sensitivity 87%, specificity 14%, with positive and negative likelihood ratios close to 1. The absence of ankle jerks performed moderately well in identifying patients likely to have large-fibre neuropathy and could potentially be used to help decide who should be sent for NCS. Gradient temperature testing was much more subjective and did not change the likelihood of abnormal TTT.

Multicolor labeling of airway neurons and analysis of parasympathetic heterogeneity

We report subpopulations of airway parasympathetic neurons expressing substance P, neuronal nitric oxide synthase, and tyrosine hydroxylase, highlighting unexplored heterogeneity in this population. These neurotransmitter-specific subpopulations did not form intraganglionic interneurons, but rather, extended outside the ganglia, into the airways, to distant innervation targets. Our experiments demonstrate the utility of multicolor labeling to characterize airway innervation, allowing us to confirm the extensive heterogeneity of postganglionic parasympathetic neurons. These methods will facilitate future investigations of neurophysiology and neural contributions to airway disease.

Scalable Thousand Channel Penetrating Microneedle Arrays on Flex for Multimodal and Large Area Coverage BrainMachine Interfaces.

The Utah array powers cutting-edge projects for restoration of neurological function, such as BrainGate, but the underlying electrode technology has itself advanced little in the last three decades. Here, advanced dual-side lithographic microfabrication processes is exploited to demonstrate a 1024-channel penetrating silicon microneedle array (SiMNA) that is scalable in its recording capabilities and cortical coverage and is suitable for clinical translation. The SiMNA is the first penetrating microneedle array with a flexible backing that affords compliancy to brain movements. In addition, the SiMNA is optically transparent permitting simultaneous optical and electrophysiological interrogation of neuronal activity. The SiMNA is used to demonstrate reliable recordings of spontaneous and evoked field potentials and of single unit activity in chronically implanted mice for up to 196 days in response to optogenetic and to whisker air-puff stimuli. Significantly, the 1024-channel SiMNA establishes detailed spatiotemporal mapping of broadband brain activity in rats. This novel scalable and biocompatible SiMNA with its multimodal capability and sensitivity to broadband brain activity will accelerate the progress in fundamental neurophysiological investigations and establishes a new milestone for penetrating and large area coverage microelectrode arrays for brain-machine interfaces.

Fact retrieval or compacted counting in arithmetic—A neurophysiological investigation of two hypotheses.

There is broad consensus on the assumption that adults solve single-digit multiplication problems almost exclusively by fact retrieval from memory. In contrast, there has been a long-standing debate on the cognitive processes involved in solving single-digit addition problems. This debate has evolved around two theoretical accounts. Proponents of a fact-retrieval account postulate that these are also solved through fact retrieval, whereas proponents of a compacted-counting account propose that solving very small additions (with operands between 1 and 4) involves highly automatized and unconscious compacted counting. In the present electroencephalography (EEG) study, we put these two accounts to the test by comparing neurophysiological correlates of solving very small additions and multiplications. Forty adults worked on an arithmetic production task involving all (nontie) single-digit additions and multiplications. Afterward, participants completed trial-by-trial strategy self-reports. In our EEG analyses, we focused on induced activity (event-related synchronization/desynchronization, ERS/ERD) in three frequency bands (theta, lower alpha, upper alpha). Across all frequency bands, we found higher evidential strength for similar rather than different neurophysiological processes accompanying the solution of very small addition and multiplication problems. In the alpha bands, evidence for similarity was even stronger when operand-1-problems were excluded. In two additional analyses, we showed that ERS/ERD can differentiate between self-reported problem-solving strategies (retrieval vs. procedure) and between very small n × 1 and n + 1 problems, demonstrating its high sensitivity to cognitive processes in arithmetic. The present findings support a fact-retrieval account, suggesting that both very small additions and multiplications are solved through fact retrieval. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

MScanFit motor unit number estimation of human anconeus muscle.

Motor unit number estimation (MUNE) studies of the anconeus muscle are very limited, although the information they provide is useful for neurophysiological investigations. The objective of this study was to estimate the number of motor units in the anconeus muscle. Compound muscle action potential scans of the anconeus muscle were recorded from 11 healthy participants, all of whom were tested on two occasions. MUNE was determined from the MScanFit program. The average MUNE of the anconeus muscle was 55.09 ± 3.27 (mean ± standard error of the mean) for the first test and 54.64 ± 3.70 for the retest, demonstrating excellent measurement reliability, with an intraclass correlation coefficient of 0.90. A relatively low motor unit number is found in the anconeus, a muscle not comprehensively studied in literature.

Segment-Wise Decomposition of Surface Electromyography to Identify Discharges Across Motor Neuron Populations.

The surface electromyography (EMG) decomposition techniques have shown promising results in neurophysiologic investigations, clinical diagnosis, and human-machine interfacing. However, current decomposition methods could only decode a limited number of motor units (MUs) because of the local convergence. The number of identified MUs remains similar even though more muscles or movements are involved, where multiple motor neuron populations are activated. The objective of this study was to develop a segment-wise decomposition strategy to increase the number of MU decoded from multiple motor neuron populations. The EMG signals were divided into several segments depending on the number of involved movements. The motor neurons, activated during each movement, were regarded as a population. The convolution kernel compensation (CKC) method was applied individually for each segment to decode the motor unit discharges from each motor neuron population. The MU filters were obtained in each segment and filtrated to estimate the MU spike trains (MUSTs) from the global EMG signals. The decomposition performance was validated on synthetic and experimental EMG signals. From synthetic EMG signals generated by two motor neuron populations, the proposed segment-wise CKC (swCKC) decoded significantly more MUs during low and medium excitation levels, with an increased rate of 16.3% to 75.4% compared with the conventional CKC. From experimental signals recorded during ten motor tasks, 133±24 MUs with the pulse-to-noise ratio of 36.6±6.5 dB were identified for each subject by swCKC, whereas the conventional CKC identified only 43±12 MUs. These results indicate the feasibility and superiority of the proposed swCKC to decode MU activities across motor neuron populations, extending the potential applications of EMG decomposition for neural decoding during multiple motor tasks.

Acute Spinal Cord Dysfunction Following COVID-19 Infection: A Case Report

Here, we describe a 44-year-old female that developed abrupt symptomatology, including lower-limb paralysis with sensory involvement at the T12 level, two weeks after the resolution of COVID-19 bilateral pneumonia. Based on the neurological symptoms and the neurophysiological investigations, a clinical diagnosis of thoracic spinal cord dysfunction was made. However, all the complementary tests performed showed normal results. In particular, repeated MRIs showed no alterations; the cerebrospinal fluid analysis showed normal results: the CT scan of the brain was normal and the CT scan of the abdominal and thoracic aorta showed a normal size and course. Cases of spinal cord involvement have rarely been described, in which the MRIs never revealed cord signaling changes. We hypothesize that a small vessel spinal cord stroke might explain the pathogenesis and the absence of changes detectable on an MRI along with the patient's modest recovery during the long follow up. However, it cannot be excluded that the severe clinical course of SARS-CoV-2 infection, may suggest other different etiologies that could be related to prolonged hospitalization.

The additional diagnostic benefits of performing both video-polysomnography and prolonged video-EEG-monitoring: When and why

ObjectiveVideo-polysomnography (VPSG) and prolonged video-EEG-monitoring (pVEEG-M) are neurophysiological investigation modalities. Depending on indication either is performed, but occasionally patients undergo both (during the same or separate stays). We sought to assess the reasons and potential benefits of dual diagnostic assessments with both modalities. MethodsA retrospective chart-review was performed to identify patients who underwent both VPSG and pVEEG-M during the 10 year period between 2007 and 2017. One-hundred-nine patients were identified who had undergone both studies. Patients were grouped according to indication and outcome. ResultsOne-hundred-nine patients had both, a VPSG and pVEEG-M, in 62 (56.9%) the studies were performed because of separate diagnoses independent from each other. In 47 patients (43.1%) investigation with both modalities was needed to clarify the suspected diagnosis or to refute differential diagnoses. Out of these 47, 11 (10.1% of the whole group) arrived a new final diagnosis whereas in 36 (33%) the primary diagnosis was corroborated with the second modality. ConclusionsIn the majority of cases VPSG plus pVEEG-M were indicated to diagnose or monitor different comorbid diseases (e.g. sleep-related breathing disorder and epilepsy). In the other cases, performing both modalities was useful to achieve a higher diagnostic accuracy or to refute differential diagnoses. SignificanceVPSG and pVEEG-M are neurophysiological investigations which complement each other, especially in case of two different comorbid diseases in a single patient, to rule out differential diagnosis or when a higher diagnostic certainty is seeked.

The Neurophysiology of the Cerebellum in Emotion.

Neuroscientific investigation of the detailed neurophysiology of emotion processing is a rapidly progressing field, which has opened discussion on key findings regarding the timing characteristics of the neuronal networks involved. Study designs incorporating quantitative electroencephalography (EEG) and event-related potentials (ERP) have mapped neuronal representations at various stages of emotion processing, identifying early and late stages corresponding to cerebral activity in attention and in appraisal of emotion. Interestingly, in addition to confirming aspects of cerebral cortex involvement, these investigations have also implicated the cerebellum in emotion processing. This has led to research aimed at distinguishing the contributions of cerebellar and cerebral networks and how these may interrelate. With respect to underlying neurophysiological mechanisms, ERP studies confirm that the cerebellum is involved in both early and late stages of processing of salient emotion cues, and also in capturing emotions in facial expressions. Topological analyses indicate direct connections between the vermis, Crus I, and Crus II areas of the cerebellum and the cerebral area of lateral prefrontal cortex. This suggests a broad evolutionary development of large-scale cerebral networks in emotion. In this chapter, we highlight findings to date of neurophysiological activity related to cerebellar participation in emotion processing. The neurophysiological findings, which by inference represent underlying neural activity, emphasize an integrative role of the cerebellum in emotion.

First afebrile seizures: Clinical and radiological view with emergent testing.

The first afebrile seizures in children are an important and common reason for emergency department admissions. We aim to examine the presentation, laboratory/neurodiagnostic investigation, and emergency management of children with first afebrile seizures. The retrospective study included 333 patients aged 1 month to 18 years admitted with a first afebrile seizure to the pediatric emergency department of Prof. Dr. Cemil Taşcıoğlu City Hospital between January 2017 and January 2020. Age, gender, seizure duration and type, treatments for seizures, laboratory, neurophysiological, and radiological investigations, ward or intensive care unit hospitalizations, and antiepileptic drugs on discharge were recorded. The average age of the patients was 81.6 ± 62.9 months; 187 (56.2%) were male and 146 (43.8%) were female. Two hundred and sixty-one (78.4%) patients had only one seizure. In 45 (13.5%) of the patients, the seizure recurred in the emergency department. Hypoglycemia, hyponatremia, and hypocalcemia were detected in 13 (3.9%) patients. Patients with clinically significant cranial computed tomography results were at an increased risk for seizures lasting longer than 5 min. Patients with focal seizures had more recurrences, were given more antiepileptic drugs during the emergency, had better known etiology, more intensive care unit hospitalization, and greater post-discharge antiepileptic drug prescription. Biochemical abnormalities remain in the background in the etiology of afebrile seizures. Patients with abnormal neuroimaging on cranial tomography tended to have longer seizures. Patients with focal seizures followed a more complicated course as they had more recurrences and more hospitalization in the intensive care unit.

Classification of Cognitive Impairment and Healthy Controls Based on Transcranial Magnetic Stimulation Evoked Potentials.

Backgrounds: Nowadays, risks of Cognitive Impairment (CI) [highly suspected Alzheimer's disease (AD) in this study] threaten the quality of life for more older adults as the population ages. The emergence of Transcranial Magnetic Stimulation-Electroencephalogram (TMS-EEG) enables noninvasive neurophysiological investi-gation of the human cortex, which might be potentially used for CI detection.Objectives: The aim of this study is to explore whether the spatiotemporal features of TMS Evoked Potentials (TEPs) could classify CI from healthy controls (HC).Methods: Twenty-one patients with CI and 22 HC underwent a single-pulse TMS-EEG stimulus in which the pulses were delivered to the left dorsolateral prefrontal cortex (left DLPFC). After preprocessing, seven regions of interest (ROIs) and two most reliable TEPs' components: N100 and P200 were selected. Next, seven simple and interpretable linear features of TEPs were extracted for each region, three common machine learning algorithms including Support Vector Machine (SVM), Random Forest (RF), and K-Nearest Neighbor (KNN) were used to detect CI. Meanwhile, data augmentation and voting strategy were used for a more robust model. Finally, the performance differences of features in classifiers and their contributions were investigated.Results: 1. In the time domain, the features of N100 had the best performance in the SVM classifier, with an accuracy of 88.37%. 2. In the aspect of spatiality, the features of the right frontal region and left parietal region had the best performance in the SVM classifier, with an accuracy of 83.72%. 3. The Local Mean Field Power (LMFP), Average Value (AVG), Latency and Amplitude contributed most in classification.Conclusions: The TEPs induced by TMS over the left DLPFC has significant differences spatially and temporally between CI and HC. Machine learning based on the spatiotemporal features of TEPs have the ability to separate the CI and HC which suggest that TEPs has potential as non-invasive biomarkers for CI diagnosis.

Rhythmic sampling revisited: Experimental paradigms and neural mechanisms.

Sampling of information is thought to be an important aspect of explorative behaviour. Evidence for it has been gained in behavioural assessments of a variety of overt and covert cognitive domains, including sensation, attention, memory, eye movements and dexterity. A common aspect across many findings is that sampling tends to exhibit a rhythmicity at low frequencies (theta, 4-8 Hz; alpha, 9-12 Hz). Neurophysiological investigations in a wide range of species, including rodents, non-human primates and humans have demonstrated the presence of sampling related neural oscillations in a number of brain areas ranging from early sensory cortex, hippocampus to high-level cognitive areas. However, to assess whether rhythmic sampling represents a general aspect of exploratory behaviour one must critically evaluate the task parameters, and their potential link with neural oscillations. Here we focus on sampling during attentive vision to present an overview on the experimental conditions that are used to investigate rhythmic sampling and associated oscillatory brain activity in this domain. This review aims to (1) provide guidelines to efficiently quantify behavioural rhythms, (2) compare results from human and non-human primate studies and (3) argue that the underlying neural mechanisms of sampling can co-occur in both sensory and high-level areas.

Transcutaneous spinal cord stimulation and motor responses in individuals with spinal cord injury: A methodological review.

Transcutaneous spinal cord stimulation (tSCS) is a non-invasive modality in which electrodes can stimulate spinal circuitries and facilitate a motor response. This review aimed to evaluate the methodology of studies using tSCS to generate motor activity in persons with spinal cord injury (SCI) and to appraise the quality of included trials. A systematic search for studies published until May 2021 was made of the following databases: EMBASE, Medline (Ovid) and Web of Science. Two reviewers independently screened the studies, extracted the data, and evaluated the quality of included trials. The electrical characteristics of stimulation were summarised to allow for comparison across studies. In addition, the surface electromyography (EMG) recording methods were evaluated. A total of 3753 articles were initially screened, of which 25 met the criteria for inclusion. Studies were divided into those using tSCS for neurophysiological investigations of reflex responses (n = 9) and therapeutic investigations of motor recovery (n = 16). The overall quality of evidence was deemed to be poor-to-fair (10.5 ± 4.9) based on the Downs and Black Quality Checklist criteria. The electrical characteristics were collated to establish the dosage range across stimulation trials. The methods employed by included studies relating to stimulation parameters and outcome measurement varied extensively, although some trends are beginning to appear in relation to electrode configuration and EMG outcomes. This review outlines the parameters currently employed for tSCS of the cervicothoracic and thoracolumbar regions to produce motor responses. However, to establish standardised procedures for neurophysiological assessments and therapeutic investigations of tSCS, further high-quality investigations are required, ideally utilizing consistent electrophysiological recording methods, and reporting common characteristics of the electrical stimulation administered.

Dystonia

Dystonia is a complex movement disorder characterized by irregular and involuntary movement patterns and contractions leading to twisted postures with or without a tremulous component. Focal dystonia is the most frequent form of adult-onset dystonia. The current pathophysiological model posits focal dystonia as a network disorder. Neurophysiological and neuroimaging investigations have identified functional abnormalities in two networks involved in movement control: the basal ganglia sensorimotor network and the cerebello-thalamo-cortical network, with the basal ganglia and thalamus playing a central role.

Axonal polineuropathy associated with Sars-CoV 2 infection: a case report.

World healthcare systems are dealing with the pandemic of the severe Coronavirus disease 19 (Covid-19). Covid-19 neurological manifestations affecting both central and peripheral nervous systems have been reported. We describe the case of 44-year-old patient, who was admitted to our Rehabilitation Unit after discharge from intensive care unit for severe Covid-19 related respiratory failure. Neurophysiological investigation revealed an axonal polineuropathy with impairment both of sensory and motor component. He underwent a comprehensive rehabilitation treatment, including breathing exercises and motor rehabilitation. Despite rapid and effective diagnosis and customized progressive rehabilitation treatment, significant improvement in sensory-motor abnormalities has begun but distal complete recovery was not achieved. Indeed, complete indipendence during walking has been partially reached: patient constantly needs two sticks and wears two ankle-foot orthosis during ambulatory function. Nowadays, exploring the neurologic manifestations of Covid-19 may represent a step towards better understanding the virus, preventing longterm sequela and rehabilitation concerns.

A Commentary on “Can Neuroscience Provide a New Foundation for the Rorschach Variables?” (Jimura et al., 2021)

A Commentary on “Can Neuroscience Provide a New Foundation for the Rorschach Variables?” (Jimura et al., 2021)

WS3.4. Electrodiagnostic Approach to Motor Neuron Disease: Split Hand in ALS

Amyotrophic lateral sclerosis (ALS) is characterized by involvement of both upper and lower motor neurons. Electrophysiologic approach includes EMG (denervation potentials and fasciculation potentials) and nerve conduction studies (NCS; low CMAP, decreased motor unit number, and axonal hyperexcitability on nerve excitability testing) for lower motor neuron involvement, and transcranial magnetic stimulation with threshold tracking (decreased short- latency intracortical inhibition) for upper motoneuronal hyperexcitability. Of these, routine NCS can detect the “split hand” pattern, which is a very important indicator for diagnosis, because this symptom has been recognized as being specific to ALS; the thenar and first dorsal interosseous (FDI) muscles are preferentially affected. In contrast, the hypothenar muscle (abductor digiti minimi, ADM) is relatively preserved. FDI and ADM muscles are innervated by the same C8/Th1 spinal segments and the same ulnar nerve. The split hand indicates a potentially specific pathological mechanism, suggesting hyperexcitability of both upper and lower motor neuron/axons. Along with this symptom, wide-spread fasciculations are prominent clinical features in patients with ALS, specifically seen in ALS among disorders with neurogenic muscle atrophy. Fasciculations frequently arise from the motor nerve terminals, and the hyperexcitability of motor axons appears to constitute the pathophysiology of the disease. Neurophysiologic investigations of the upper and lower motor neurons/axons have shown increased excitability. The altered excitability is supposed to relate to motor neuron death.