Electrophysiological Differences Research Articles

Electrophysiological investigation of the effects of Tai Chi on inhibitory control in older individuals.

The possibility that improved inhibitory control in older adults is associated with engagement in non-contact sporting activity, Tai Chi, was investigated. Three groups of participants were compared; a group who regularly took part in Tai Chi (TC), a regularly exercising (RE) group, and a sedentary group (SG). Concurrent electroencephalographic recordings were obtained while a stop-signal inhibitory control task, where speeded responses are needed for most trials, but these must occasionally be withheld when a 'stop signal' is displayed, was performed. The electrophysiological components P3, broadly related to decision making, and Pe, related to error monitoring, were analyzed. Both exercise groups performed better on the stop-signal task for the measure indicative of inhibitory control, as well as being generally better for other indices of performance. No significant effects were seen for post-error slowing. Electrophysiological differences were seen for the TC group, with a significantly larger P3 component related to the stop-signal and a larger Pe component when errors were made. This indicated that the TC group seemed to show better decision making and have better awareness of errors. Future work should investigate whether such effects are seen when this type of exercise is applied as an 'intervention' in non-exercising individuals.

Multilayer MEG functional connectivity as a potential marker for suicidal thoughts in major depressive disorder

Major depressive disorder (MDD) is highly heterogeneous in its clinical presentation. The present exploratory study used magnetoencephalography (MEG) to investigate electrophysiological intrinsic connectivity differences between healthy volunteers and unmedicated participants with treatment-resistant MDD. The study examined canonical frequency bands from delta through gamma. In addition to group comparisons, correlational studies were conducted to determine whether connectivity was related to five symptom factors: depressed mood, tension, negative cognition, suicidal thoughts, and amotivation. The MDD and healthy volunteer groups did not differ significantly at baseline when corrected across all frequencies and clusters, although evidence of generalized slowing in MDD was observed. Notably, however, electrophysiological connectivity was strongly related to suicidal thoughts, particularly as coupling of low frequency power fluctuations (delta and theta) with alpha and beta power. This analysis revealed hub areas underlying this symptom cluster, including left hippocampus, left anterior insula, and bilateral dorsolateral prefrontal cortex. No other symptom cluster demonstrated a relationship with neurophysiological connectivity, suggesting a specificity to these results as markers of suicidal ideation.

Quantitative EEG Differences in Subtypes of Frontotemporal Dementia

Frontotemporal dementia (FTD) is the second most common group of neurodegenerative disorder following Alzheimer’s Disease (AD); and characterized by degeneration of frontal and/or temporal lobes. FTD can be classified as behavioral variant FTD (bvFTD) and primary progressive aphasia (PPA). The aim of this study is to investigate electrophysiological differences in bvFTD and nonfluent/agrammatic PPA (naPPA), one of three forms of PPA. Twelve patients with bvFTD and 15 patients with naPPA were included in the study. EEG was recorded from 19 electrode sites based on international 10-20 system. Each participant's data were averaged across the recording epochs for each electrode, and the mean absolute power values were computed for delta, theta, beta and alpha frequency bands. For all frequency bands, inter-hemispheric and intrahemispheric coherence was calculated. In absolute power; decreased theta power at all regions was found in bvFTD group as compared to naPPA group. Regarding coherence; increased beta coherence at left centoparietal region and increased alpha coherence at inter-hemispheric frontal region was found in bvFTD as compared to naPPA group. Our findings suggests that subtypes of FTD vary in resting-state EEG especially indexed by the decreased theta power reflecting bvFTD.

Shoulder Double Crush Syndrome: A Retrospective Study of Patients With Concomitant Suprascapular Neuropathy and Cervical Radiculopathy.

Purpose:While the double crush phenomena (compression along two points on a nerve) has been established between median neuropathy and cervical radiculopathy, combined suprascapular neuropathy (SSN) and cervical C5/C6 radiculopathy—so-called shoulder double crush syndrome—has not been well examined. We aim to identify the incidence of shoulder double crush syndrome in patients undergoing arthroscopic suprascapular nerve release for SSN.Methods:One hundred consecutive patients >18 years of age who were positive for SSN on electromyography and motor nerve conduction studies (EMG/NCS) and underwent a suprascapular nerve release were included. Patients with evidence of shoulder double crush syndrome were identified based on x ray, cervical spine magnetic resonance imaging (MRI) and examination findings. Demographics, electrodiagnostics results, treatment courses, and clinical outcomes (visual analog scores and rotator cuff strength) following arthroscopic suprascapular nerve release were compared between patients with double crush syndrome versus isolated SSN.Results:Thirty one percent of patients had evidence of shoulder crush syndrome. Two significant electrophysiologic differences were noted in shoulder double crush patients compared to isolated SSN patients. Patients with double crush had an increased incidence of median neuropathy (51% vs 30%, P = .04). Double crush patients had less supraspinatus motor amplitude difference between the affected side and non-affected side compared to isolated SSN patients (2.62 mV vs 3.44 mV, P = .03). In general, most double crush patients were treated conservatively with regard to their cervical spine pathology.Conclusion:A significant percentage of patients with SSN have evidence of shoulder double crush syndrome. Patients with SSN and concomitant median neuropathy should have a detailed neck examination performed.

Monolinguals and bilinguals respond differently to a delayed matching-to-sample task: An ERP study

AbstractPrevious research examining whether bilinguals exhibit enhanced working memory (WM) compared to monolinguals has yielded mixed results. This inconsistency may be due to lack of sensitivity in behavioral and neuropsychological measures. The current study aimed to investigate the effects of bilingualism on WM by focusing on brain activity patterns (event-related potentials) in monolinguals and bilinguals during a WM task. We recorded brain activity while participants (26 monolingual English speakers and 28 English–French bilinguals) performed a delayed matching-to-sample task. Although performance measures were similar, electrophysiological differences were present across groups. Bilinguals exhibited larger P3b amplitudes than monolinguals, and smaller negative slow wave and N2b amplitudes during retrieval. These results suggest that bilinguals may have more cognitive resources available in WM to allocate to task completion, and that task completion may be less effortful for bilinguals than for monolinguals.

Supraventricular Tachyarrhythmias in Patients with Ebstein’s Anomaly

The paper analyzes the experience of catheter treatment of various types of supraventricular arrhythmias in patients with Ebstein’s abnormality (EA) – 19 consecutive cases of the elimination of additional atrioventricular connections (AAVC) and 5 cases of atrial macro-reentry. The elimination of AAVC, just like atrial macroreentry, was preceded by a stage of electrophysiological diagnosis. In a series of observations in 19 patients with EA, 25 AAVC were detected. The article reflects the main electrophysiological differences between “wide” AAVC from multiple ones. In the first procedure, the conduction in all AAVC was eliminated in 16 (84.2%) of 19 patients. 6 of 25 AAVC were qualified by us as “wide”; to eliminate them, a larger number of applications was required – 6 ± 2 (in typical cases – 3 ± 1). In 2 of 3 patients with an unsatisfactory result of the first procedure, AAVC were eliminated during the second procedure. In the long-term period(5.6 ± 3.6 years), recurrences of propagation through AAVC occurred in 2 (10.5%) of 19 patients. All AAVC were permanently eliminated during second procedure. In the group of patients with atrial tachycardia, 3 had a graph characteristic of a typical isthmus-dependent atrial flutter. In one patient with atypical graphics, macro-reentry with excitation circulation around the scar on the anterolateral wall of the right atrium was found. In 3 of 4 patients with isthmus-dependent atrial flutter after radiofrequency exposure, the sinus rhythm was restored and a block of passage through the cavotricuspid isthmus was created. In one case there were changes in the cycle of tachycardia and the morphology of wave P, applying applications between the scar and the tricuspid valve ring led to the creation of a block of passage through this area and to the cessation of arrhythmia. In a patient who initially had reentry with a circulation of excitement around the postoperative scar, arrhythmia was eliminated in a similar way (an additional block was created through the cavotricuspid isthmus). In the observation period of 5.2 ± 2.5 years, there were no recurrences of arrhythmia.

Temporal Discrimination is Altered in Patients With Isolated Asymmetric and Jerky Upper Limb Tremor

Unilateral or very asymmetric upper limb tremors with a jerky appearance are poorly investigated. Their clinical classification is an unsolved problem because their classification as essential tremor versus dystonic tremor is uncertain. To avoid misclassification as essential tremor or premature classification as dystonic tremor, the term indeterminate tremor was suggested. The aim of this study was to characterize this tremor subgroup electrophysiologically and evaluate whether diagnostically meaningful electrophysiological differences exist compared to patients with essential tremor and dystonic tremor. We enrolled 29 healthy subjects and 64 patients with tremor: 26 with dystonic tremor, 23 with essential tremor, and 15 patients with upper limb tremor resembling essential tremor but was unusually asymmetric and jerky (indeterminate tremor). We investigated the somatosensory temporal discrimination threshold, the short-interval intracortical inhibition, and the cortical plasticity by paired associative stimulation. Somatosensory temporal discrimination threshold was significantly increased in patients with dystonic tremor and indeterminate tremor, but it was normal in the essential tremor patients and healthy controls. Significant differences in short-interval intracortical inhibition and paired associative stimulation were not found among the three patient groups and controls. These results indicate that indeterminate tremor, as defined in this study, shares electrophysiological similarities with dystonic tremor rather than essential tremor. Therefore, we propose that indeterminate tremor should be considered as a separate clinical entity from essential tremor and that it might be dystonic in nature. Somatosensory temporal discrimination appears to be a useful tool in tremor classification. © 2019 International Parkinson and Movement Disorder Society.

Radiofrequency catheter ablation of ventricular arrhythmias arising from the region above pulmonary valve

BackgroundVentricular arrhythmias (VAs) arising from the origin above pulmonary valve lack comprehensive investigation. This study aimed to disclose the characteristics and radiofrequency catheter ablation (RFCA) outcomes for those VAs.MethodsOne hundred six VAs arising from the region above pulmonary valve treated with RFCA were included in this study.ResultsSeventy-five cases were identified in the pulmonary sinus cusps (PSCs, 32 in left sinus cusp (PLC), 15 in right (PRC), 28 in anterior (PAC)) and 31 cases were in the main stem of pulmonary artery (MSPA, 18 above PLC (LMSPA), 3 above PRC (RMSPA), 10 above PAC (AMSPA)). Compared with PSCs VAs, MSPA VAs exhibited a higher R wave amplitude in the inferior leads, a total inferior R amplitude > 5.1 mV predicting MSPA origins. LMSPA, RMSPA and AMSPA VAs resembled PLC, PRC and PAC VAs in electrocardiographic characteristics respectively. No electrophysiological differences were found between PSCs and MSPA VAs. The irrigated-up catheter and R0 Swartz long sheath were more utilized for ablation of PSCs VAs than for MSPA VAs. All these VAs were successfully eliminated by RFCA.ConclusionVAs arising from the origin above pulmonary valve were common. Based on certain electrocardiographic characteristics, they could be roughly located, which contributed to an effective RFCA.

Task switching and bilingualism in young and older adults: A behavioral and electrophysiological investigation

The current study investigated behavioral and electrophysiological (event-related potential; ERP) differences associated with task switching in a sample of young and older monolingual and bilingual adults. ERPs associated with task preparation (switch and mixing positivity) and task execution processes (N2 and P3b) were investigated. Participants performed a cued letter-number task switching paradigm that included single task and mixed task blocks, while their electroencephalography was recorded. Behavioral results revealed smaller switch and mixing costs in bilinguals relative to monolinguals, in both young and older participants. There were no ERP differences in the effect size of the cue-locked mixing and switch positivities, nor the target-locked mixing and switch N2 and P3b components. However, overall larger target-locked N2 amplitudes were observed in bilinguals relative to monolinguals. In addition, bilingual older adults exhibited smaller P3b amplitudes than monolingual older adults. The smaller behavioral mixing and switch costs observed in bilinguals suggest that bilinguals exhibit superior sustained attention and faster task-set reconfiguration processes compared to monolinguals. The ERP measures provide evidence for differences in brain processes between monolinguals and bilinguals and a reliance on different processing strategies in bilingual compared to monolingual older adults.

Sex Differences in QEEG in Psychopath Offenders.

Introduction. Functional brain differences related to sex in psychopathic behavior represent an important field of neuroscience research; there are few studies on this area, mainly in offender samples. Objective. The aim of this study was to investigate the presence of electrophysiological differences between male and female psychopath offenders; specifically, we wanted to assess whether the results in quantitative EEG, low-resolution electromagnetic tomography (LORETA), and changes in synchronous brain activity could be related to sex influence. Sample and Methods. The study included 31 male and 12 female psychopath offenders, according to the Hare Psychopathy Checklist-Revised criteria from 2 prisons located in Havana City. The EEG visual inspection characteristics and the use of frequency domain quantitative analysis techniques are described. Results. The resting EEG visual analyses revealed a high percentage of EEG abnormalities in both studied groups. Significant statistical differences between the mean parameters of cross spectral measures between psychopathic offender groups were found in the beta band at bilateral frontal derivation and centroparietal areas. LORETA showed differences especially in the paralimbic and parieto-occipital areas Synchronization likelihood revealed a significant group effect in the 26 to 30 Hz band. These results indicate that combining quantitative EEG, LORETA analysis, and synchronization likelihood may improve the neurofunctional differentiation between psychopath offenders of both sexes.

P wave indices, heart rate variability and anthropometry in a healthy South Asian population

BackgroundSouth Asians have a low prevalence of atrial fibrillation (AF) in comparison with White Europeans despite a higher burden of hypertension, diabetes mellitus and coronary artery disease. The reason for this disparity is unclear but may relate to electrophysiological or structural differences within the atria or variations in autonomic function. We aimed to assess these areas using a range of non-invasive cardiac investigations.MethodsA prospective cohort study was performed on 200 South Asian and 200 Caucasian healthy volunteers aged 18–40 years. All subjects underwent electrocardiography (ECG), echocardiography and anthropometric measurements. Eighty subjects in each cohort underwent 24 hour ambulatory ECG and fifty subjects in each cohort underwent exercise testing.ResultsCompared with White Europeans, South Asians were of a smaller height with lower lean body mass and smaller left atrial size. They had reduced P wave dispersion and P wave terminal force in lead V1. South Asians had a lower burden of supraventricular ectopy. They had a higher mean heart rate and South Asian males had lower heart rate variability, suggestive of sympathetic predominance. Exercise capacity was lower in South Asians.ConclusionsSouth Asians have differences in left atrial size, P wave indices, burden of supraventricular ectopy, heart rate, heart rate variability and anthropometric measurements. These differences may relate to variations in atrial morphology, atrial electrophysiology and autonomic function and might help to explain why South Asians are less susceptible to developing AF.

Self‐initiated learning reveals memory performance and electrophysiological differences between younger, older and older adults with relative memory impairment

Older adults display difficulties in encoding and retrieval of information, resulting in poorer memory. This may be due to an inability of older adults to engage elaborative encoding strategies during learning. This study examined behavioural and electrophysiological effects of explicit cues to self-initiate learning during encoding and subsequent recognition of words in younger adults (YA), older control adults (OA) and older adults with relative memory impairment (OD). The task was a variation of the old/new paradigm, some study items were preceded by a cue to learn the word (L) while others by a do not learn cue (X). Behaviourally, YA outperformed OA and OD on the recognition task, with no significant difference between OA and OD. Event-related potentials at encoding revealed enhanced early visual processing (70-140ms) for L- versus X-words in young and old. Only YA exhibited a greater late posterior positivity (LPP; 200-500ms) for all words during encoding perhaps reflecting superior encoding strategy. During recognition, only YA differentiated L- versus X-words with enhanced frontal P200 (150-250ms) suggesting impaired early word selection for retrieval in older groups; however, OD had enhanced P200 activity compared to OA during L-word retrieval. The LPP (250-500ms) was reduced in amplitude for L-words compared to both X- and new words. However, YA showed greater LPP amplitude for all words compared to OA. For older groups, we observed reduced left parietal hemispheric asymmetry apparent in YA during encoding and recognition, especially for OD. Findings are interpreted in the light of models of compensation and dedifferentiation associated with age-related changes in memory function.

Different paths, same destination: divergent action potential responses produce conserved cardiac fight-or-flight response in mouse and rabbit hearts.

Cardiac electrophysiology and Ca2+ handling change rapidly during the fight-or-flight response to meet physiological demands. Despite dramatic differences in cardiac electrophysiology, the cardiac fight-or-flight response is highly conserved across species. In this study, we performed physiological sympathetic nerve stimulation (SNS) while optically mapping cardiac action potentials and intracellular Ca2+ transients in innervated mouse and rabbit hearts. Despite similar heart rate and Ca2+ handling responses between mouse and rabbit hearts, we found notable species differences in spatio-temporal repolarization dynamics during SNS. Species-specific computational models revealed that these electrophysiological differences allowed for enhanced Ca2+ handling (i.e. enhanced inotropy) in each species, suggesting that electrophysiological responses are fine-tuned across species to produce optimal cardiac fight-or-flight responses. Sympathetic activation of the heart results in positive chronotropy and inotropy, which together rapidly increase cardiac output. The precise mechanisms that produce the electrophysiological and Ca2+ handling changes underlying chronotropic and inotropic responses have been studied in detail in isolated cardiac myocytes. However, few studies have examined the dynamic effects of physiological sympathetic nerve activation on cardiac action potentials (APs) and intracellular Ca2+ transients (CaTs) in the intact heart. Here, we performed bilateral sympathetic nerve stimulation (SNS) in fully innervated, Langendorff-perfused rabbit and mouse hearts. Dual optical mapping with voltage- and Ca2+ -sensitive dyes allowed for analysis of spatio-temporal AP and CaT dynamics. The rabbit heart responded to SNS with a monotonic increase in heart rate (HR), monotonic decreases in AP and CaT duration (APD, CaTD), and a monotonic increase in CaT amplitude. The mouse heart had similar HR and CaT responses; however, a pronounced biphasic APD response occurred, with initial prolongation (50.9±5.1ms at t=0s vs. 60.6±4.1ms at t=15s, P<0.05) followed by shortening (46.5±9.1ms at t=60s, P=NS vs. t=0). We determined the biphasic APD response in mouse was partly due to dynamic changes in HR during SNS and was exacerbated by β-adrenergic activation. Simulations with species-specific cardiac models revealed that transient APD prolongation in mouse allowed for greater and more rapid CaT responses, suggesting more rapid increases in contractility; conversely, the rabbit heart requires APD shortening to produce optimal inotropic responses. Thus, while the cardiac fight-or-flight response is highly conserved between species, the underlying mechanisms orchestrating these effects differ significantly.

Occipital Petalia and Albinism: A Study of Interhemispheric VEP Asymmetries in Albinism with No Nystagmus.

The purpose of this study was to assess chiasmal misrouting in a cohort of children with albinism with no nystagmus using hemifield visual evoked potentials (VEP) measures. Methods: Monocular VEPs were recorded and analyzed from three electrodes (O1, Oz, and O2 referred to Fz) from 16 children with albinism without nystagmus. Pattern reversal (full field and hemifield stimulation), full field pattern appearance and flash stimuli were used to evoke VEPs for each eye. Results: The amplitude of the pattern reversal VEPs to stimulation of the hemifield corresponding to the crossing pathways were as expected significantly larger than those to the non-crossing in each eye ((right eye p = 0.000004), (left eye p = 0.001)). Pattern reversal VEPs recorded from the left hemisphere were also larger than those from the right and most evident when comparing the crossing pathways of each eye (p = 0.004). Conclusions: This study has demonstrated electrophysiological differences in visual pathway function of the left and right hemisphere in subjects with albinism like that previously described in controls. Nasal field stimulation activated crossing and non-crossing pathways in patients with albinism and as a result, nasal hemifield VEPs in albinism are less lateralized compared to what is found in normal subjects.

Intracochlear Electrocochleography: Influence of Scalar Position of the Cochlear Implant Electrode on Postinsertion Results.

Electrocochleography (ECochG) recorded during cochlear implant (CI) insertion from the apical electrode in conjunction with postinsertion ECochG can identify electrophysiologic differences that exist between groups with and without a translocation of the array from the scala tympani (ST) into the scala vestibuli (SV). Translocation of the CI electrode from ST into SV can limit performance postoperatively. ECochG markers of trauma may be able to aid in the ability to detect electrode array-induced trauma/scalar translocation intraoperatively. Twenty-one adult CI patients were included. Subjects were postoperatively parsed into two groups based on analysis of postoperative imaging: 1) ST (n = 14) insertion; 2) SV (n = 7) insertion, indicating translocation of the electrode. The ECochG response elicited from a 500 Hz acoustic stimulus was recorded from the lead electrode during insertion when the distal electrode marker was at the round window, and was compared to the response recorded from a basal electrode (e13) after complete insertion. No statistically significant change in mean ECochG magnitude was found in either group between recording intervals. There was a mean loss of preoperative pure-tone average of 52% for the nontranslocation group and 94% for the translocation group. Intraoperative intracochlear ECochG through the CI array provides a unique opportunity to explore the impact of the CI electrode on the inner ear. Specifically, a translocation of the array from ST to SV does not seem to change the biomechanics of the cochlear region that lies basal to the area of translocation in the acute period.

Error processing in the adolescent brain: Age-related differences in electrophysiology, behavioral adaptation, and brain morphology

Detecting errors and adjusting behaviour appropriately are fundamental cognitive abilities that are known to improve through adolescence. The cognitive and neural processes underlying this development, however, are still poorly understood. To address this knowledge gap, we performed a thorough investigation of error processing in a Flanker task in a cross-sectional sample of participants 8 to 19 years of age (n = 98). We examined age-related differences in event-related potentials known to be associated with error processing, namely the error-related negativity (ERN) and the error positivity (Pe), as well as their relationships with task performance, post-error adjustments and regional cingulate cortex thickness and surface area. We found that ERN amplitude increased with age, while Pe amplitude remained constant. A more negative ERN was associated with higher task accuracy and faster reaction times, while a more positive Pe was associated with higher accuracy, independently of age. When estimating post-error adjustments from trials following both incongruent and congruent trials, post-error slowing and post-error improvement in accuracy both increased with age, but this was only found for post-error slowing when analysing trials following incongruent trials. There were no age-independent associations between either ERN or Pe amplitude and cingulate cortex thickness or area measures.

S119. Electrophysiological Differences Between Individuals With Remitted Bipolar Disorder and Major Depression Compared to Healthy Controls

S119. Electrophysiological Differences Between Individuals With Remitted Bipolar Disorder and Major Depression Compared to Healthy Controls

Interventricular Differences in Action Potential Duration Restitution Contribute to Dissimilar Ventricular Rhythms in ex vivo Perfused Hearts.

Background: Dissimilar ventricular rhythms refer to the occurrence of different ventricular tachyarrhythmias in the right and left ventricles or different rates of the same tachyarrhythmia in the two ventricles.Objective: We investigated the inducibility of dissimilar ventricular rhythms, their underlying mechanisms, and the impact of anti-arrhythmic drugs (lidocaine and amiodarone) on their occurrence.Methods: Ventricular tachyarrhythmias were induced with burst pacing in 28 Langendorff-perfused Sprague Dawley rat hearts (14 control, 8 lidocaine, 6 amiodarone) and bipolar electrograms recorded from the right and left ventricles. Fourteen (6 control, 4 lidocaine, 4 amiodarone) further hearts underwent optical mapping of transmembrane voltage to study interventricular electrophysiological differences and mechanisms of dissimilar rhythms.Results: In control hearts, dissimilar ventricular rhythms developed in 8/14 hearts (57%). In lidocaine treated hearts, there was a lower cycle length threshold for developing dissimilar rhythms, with 8/8 (100%) hearts developing dissimilar rhythms in comparison to 0/6 in the amiodarone group. Dissimilar ventricular tachycardia (VT) rates occurred at longer cycle lengths with lidocaine vs. control (57.1 ± 7.9 vs. 36.6 ± 8.4 ms, p < 0.001). The ratio of LV:RV VT rate was greater in the lidocaine group than control (1.91 ± 0.30 vs. 1.76 ± 0.36, p < 0.001). The gradient of the action potential duration (APD) restitution curve was shallower in the RV compared with LV (Control - LV: 0.12 ± 0.03 vs RV: 0.002 ± 0.03, p = 0.015), leading to LV-to-RV conduction block during VT.Conclusion: Interventricular differences in APD restitution properties likely contribute to the occurrence of dissimilar rhythms. Sodium channel blockade with lidocaine increases the likelihood of dissimilar ventricular rhythms.

Electrophysiological differences between typical and dense benign prostatic hyperplasia tissues retrieved after holmium laser enucleation of the prostate

Electrophysiological differences between typical and dense (beach ball) benign prostatic hyperplasia (BPH) tissues were investigated using a needle device with a micro-electrical impedance spectroscopy (µEIS) sensor. Ten pieces of typical BPH tissues and beach balls were collected from ten patients during the morcellation procedure of Holmium laser enucleation of the prostate. Their impedance was measured at a frequency range from 100 to 1 MHz using the µEIS-on-a-needle (µEoN). The impedance data (magnitude) were compared between the two tissue types and their correlation with the pathologic features was investigated. The mean magnitude of the beach balls tended to be larger than that of the typical BPH tissues at all investigated frequencies. Notably, significantly larger magnitudes were observed in the beach balls at the frequencies higher than 15.9 kHz (p ≤ 0.02). The variation of mean log-transformed magnitudes by frequency was significantly different between both tissue types (p < 0.001). The pathologic features of the beach balls presented pure stromal nodules of nodular hyperplasia, while the typical BPH tissues presented mixed epithelial-stromal nodules. The impedance difference between typical BPH tissues and beach balls is assumed to be attributed to the amount of their stromal content.

Electrophysiological differences between upper and lower limb movements in the human subthalamic nucleus

ObjectiveFunctional processes in the brain are segregated in both the spatial and spectral domain. Motivated by findings reported at the cortical level in healthy participants we test the hypothesis in the basal ganglia of Parkinson’s disease patients that lower frequency beta band activity relates to motor circuits associated with the upper limb and higher beta frequencies with lower limb movements. MethodsWe recorded local field potentials (LFPs) from the subthalamic nucleus using segmented “directional” DBS leads, during which patients performed repetitive upper and lower limb movements. Movement-related spectral changes in the beta and gamma frequency-ranges and their spatial distributions were compared between limbs. ResultsWe found that the beta desynchronization during leg movements is characterised by a strikingly greater involvement of higher beta frequencies (24–31 Hz), regardless of whether this was contralateral or ipsilateral to the limb moved. The spatial distribution of limb-specific movement-related changes was evident at higher gamma frequencies. ConclusionLimb processing in the basal ganglia is differentially organised in the spectral and spatial domain and can be captured by directional DBS leads. SignificanceThese findings may help to refine the use of the subthalamic LFPs as a control signal for adaptive DBS and neuroprosthetic devices.