Time, touch and temperature affect perceived finger position and ownership in the grasp illusion

Abstract

Perceived body position and ownership are fundamental to our ability to sense and interact with the world. Previous work indicates that temporally congruent, repetitive multisensory stimuli are needed to alter the sense of body ownership. In the present study 30 subjects passively grasped an artificial rubber finger with their left index and thumb while their right index finger, located 12 cm below, was lightly clamped. Fingers with varied physical characteristics were also passively grasped to determine how these characteristics influenced perceived body position and ownership. Subjects immediately felt their hands to be 5.3 cm [3.4 to 7.3] (mean [95%CI]) closer, a feeling that remained after 3 min (6.0 cm [4.5 to 7.5]). By the end of the trial, perceived ownership increased by 1.2 [0.6 to 1.9] points on a 7-point Likert scale, with the group average moving from 'neither agree or disagree' at the start to 'somewhat agree' at the end. Compared to grasping a control rubber finger, grasping a cold, rough, oddly shaped or rectangular shaped finger-like object reduced perceived ownership. These results provide new insights into the role of cutaneous sensory receptors in defining these aspects of proprioception, and the speed with which these effects occur. Static touch rapidly induces large, sustained changes in perceived body position and prolonged exposure to these cutaneous inputs, alone, can induce a sense of body ownership. Also, certain physical characteristics of grasped objects influence the sense of body ownership.

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2. Do repeated limbic seizures induce depression-like behavior in rats?

Publication date: November 2017
Source:Clinical Neurophysiology, Volume 128, Issue 11
Author(s): W. McIntyre Burnham, Brian W. Scott
It has been reported that rapid kindling of the hippocampus produces lasting depression-like behavior in rats, as evidenced by increased immobility in the forced swim test and a loss of preference for sweetened water (Mazarati et al., 2007). This might suggest that repeated limbic seizure activity could be the cause of the depression often seen in patients with temporal lobe epilepsy.Sixty-day old male Wistar rats were implanted with electrodes in the amygdala and ventral hippocampus and kindled (or sham kindled) daily to a criterion of 10 stage 5 seizures. Two weeks later subjects were tested in the forced swim and sweet taste preference tests. No differences were found between the kindled and sham kindled animals.Subsequently, twenty-one day old male Wistar rat pups were implanted and quick kindled (or sham kindled) in the ventral hippocampus. Kindling was accomplished in a single day by stimulating every 5min for 84 stimulations. Four days or two weeks later they were tested in the forced swim and sweet taste preference tests. No differences were found between the kindled and sham kindled animals.The present data do not support the idea that repeated limbic seizures induce depression-like behavior in rats.



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Machine-based classification of ADHD and nonADHD participants using time/frequency features of event-related neuroelectric activity

Publication date: December 2017
Source:Clinical Neurophysiology, Volume 128, Issue 12
Author(s): Hüseyin Öztoprak, Mehmet Toycan, Yaşar Kemal Alp, Orhan Arıkan, Elvin Doğutepe, Sirel Karakaş
ObjectiveAttention-deficit/hyperactivity disorder (ADHD) is the most frequent diagnosis among children who are referred to psychiatry departments. Although ADHD was discovered at the beginning of the 20th century, its diagnosis is still confronted with many problems.MethodA novel classification approach that discriminates ADHD and nonADHD groups over the time-frequency domain features of event-related potential (ERP) recordings that are taken during Stroop task is presented. Time-Frequency Hermite-Atomizer (TFHA) technique is used for the extraction of high resolution time-frequency domain features that are highly localized in time-frequency domain. Based on an extensive investigation, Support Vector Machine-Recursive Feature Elimination (SVM-RFE) was used to obtain the best discriminating features.ResultsWhen the best three features were used, the classification accuracy for the training dataset reached 98%, and the use of five features further improved the accuracy to 99.5%. The accuracy was 100% for the testing dataset. Based on extensive experiments, the delta band emerged as the most contributing frequency band and statistical parameters emerged as the most contributing feature group.ConclusionThe classification performance of this study suggests that TFHA can be employed as an auxiliary component of the diagnostic and prognostic procedures for ADHD.SignificanceThe features obtained in this study can potentially contribute to the neuroelectrical understanding and clinical diagnosis of ADHD.



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Interindividual variability in response to continuous theta-burst stimulation in healthy adults

Publication date: November 2017
Source:Clinical Neurophysiology, Volume 128, Issue 11
Author(s): Ali Jannati, Gabrielle Block, Lindsay M. Oberman, Alexander Rotenberg, Alvaro Pascual-Leone
ObjectiveWe used complete-linkage cluster analysis to identify healthy subpopulations with distinct responses to continuous theta-burst stimulation (cTBS).Methods21 healthy adults (age±SD, 36.9±15.2years) underwent cTBS of left motor cortex. Natural log-transformed motor evoked potentials (LnMEPs) at 5–50min post-cTBS (T5–T50) were calculated.ResultsTwo clusters were found; Group 1 (n=12) that showed significant MEP facilitation at T15, T20, and T50 (p's<0.006), and Group 2 (n=9) that showed significant suppression at T5–T15 (p's<0.022). LnMEPs at T10 and T40 were best predictors of, and together accounted for 80% of, cluster assignment.In an exploratory analysis, we examined the roles of brain-derived neurotrophic factor (BDNF) and apolipoprotein E (APOE) polymorphisms in the cTBS response. Val66Met participants showed greater facilitation at T10 than Val66Val participants (p=0.025). BDNF and cTBS intensity predicted 59% of interindividual variability in LnMEP at T10. APOE did not significantly affect LnMEPs at any time point (p's>0.32).ConclusionsData-driven cluster analysis can identify healthy subpopulations with distinct cTBS responses. T10 and T40 LnMEPs were best predictors of cluster assignment. T10 LnMEP was influenced by BDNF polymorphism and cTBS intensity.SignificanceHealthy adults can be sorted into subpopulations with distinct cTBS responses that are influenced by genetics.



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Effect of local cooling on excitation-contraction coupling in myasthenic muscle: Another mechanism of ice-pack test in myasthenia gravis

Publication date: November 2017
Source:Clinical Neurophysiology, Volume 128, Issue 11
Author(s): Daisuke Yamamoto, Tomihiro Imai, Emiko Tsuda, Takayoshi Hozuki, Rika Yamauchi, Shin Hisahara, Jun Kawamata, Shun Shimohama
ObjectiveThe ice-pack test is a convenient diagnostic testing procedure for myasthenia gravis (MG). We investigated the underlying mechanism of the ice-pack test performed on bilateral masseters.MethodsWe performed trigeminal repetitive nerve stimulation (RNS), excitation-contraction (E-C) coupling assessment (Imai's method) and bite force measurement before and after cooling of the masseters in MG patients and normal controls. After placing the ice-pack on the masseters for 3min, serial recordings of the three tests were performed at various time intervals during 10min after cooling.ResultsThe bite force increased significantly after cooling in ice-pack-positive MG patients. The acceleration and acceleration ratio (acceleration at a given time to baseline acceleration) of jaw movement increased significantly after cooling of the masseters in ice-pack-positive MG patients compared to ice-pack-negative patients and normal controls. The prolonged effect of cooling continued until the end of recording even though decremental response to RNS had returned to baseline value.ConclusionsCooling of myasthenic muscle may induce two effects. One is relatively short effect on electrical synaptic transmission at the endplate, and another is prolonged effect on E-C coupling in the muscle.SignificanceThe ice-pack test induces a prolonged effect of ameliorating impaired E-C coupling in MG.



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Reduced motor cortical inhibition in migraine: A blinded transcranial magnetic stimulation study

Publication date: December 2017
Source:Clinical Neurophysiology, Volume 128, Issue 12
Author(s): J.P. Neverdahl, P.M. Omland, M. Uglem, M. Engstrøm, T. Sand
ObjectiveTo investigate motor cortical excitability, inhibition, and facilitation with navigated transcranial magnetic stimulation (TMS) in migraine in a blinded cross-sectional study.MethodsResting motor threshold (RMT), cortical silent period (CSP), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) were compared in 27 interictal migraineurs and 33 controls. 24 female interictal migraineurs and 27 female controls were compared in subgroup analyses. Seven preictal migraineurs were also compared to the interictal group in a hypothesis-generating analysis. Investigators were blinded for diagnosis during recording and analysis of data.ResultsSICI was decreased in interictal migraineurs when compared to healthy controls (p=0.013), CSP was shortened in female interictal migraineurs (p=0.041). ICF was decreased in preictal compared to interictal migraineurs (p=0.023). RMT and ICF were not different between interictal migraineurs and controls.ConclusionCortical inhibition was decreased in migraineurs between attacks, primarily in a female subgroup, indicating an importance of altered cortical inhibition in migraine.SignificancePrevious studies on motor cortical excitability in migraineurs have yielded varying results. This relatively large and blinded study provides support for altered cortical inhibition in migraine. Measuring intracortical facilitation in the period preceding migraine attacks may be of interest for future studies.



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Intermittent theta-burst stimulation induces correlated changes in cortical and corticospinal excitability in healthy older subjects

Publication date: December 2017
Source:Clinical Neurophysiology, Volume 128, Issue 12
Author(s): Tamara Gedankien, Peter J. Fried, Alvaro Pascual-Leone, Mouhsin M. Shafi
ObjectiveWe studied the correlation between motor evoked potentials (MEPs) and early TMS-evoked EEG potentials (TEPs) from single-pulse TMS before and after intermittent Theta Burst Stimulation (iTBS) to the left primary motor cortex (M1) in 17 healthy older participants.MethodsTMS was targeted to the hand region of M1 using a MRI-guided navigated brain stimulation system and a figure-of-eight biphasic coil. MEPs were recorded from the right first dorsal interosseous muscle using surface EMG. TEPs were extracted from a 61-channel EEG recording. Participants received 90 single TMS pulses at 120% of resting motor threshold before and after iTBS.ResultsAcross all participants, the change in N15-P30 TEP and MEP amplitudes were significantly correlated (r=0.69; p<0.01). Average TEP responses did not change significantly after iTBS, whereas MEP amplitudes showed a significant increase.ConclusionsChanges in corticospinal reactivity and cortical reactivity induced by iTBS are related. However, the effect of iTBS on TEPs, unlike MEPs, is not straightforward.SignificanceOur findings help elucidate the relationship between changes in cortical and corticospinal excitability in healthy older individuals. Going forward, TEPs may be used to evaluate the effects of theta-burst stimulation in non-motor brain regions.



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