Association between glucose dips and the feeling of hunger in a dietary intervention study among students with early and late chronotype-secondary analysis of a randomized cross-over nutrition trial.

Consumption of foods with high glycaemic index (GI) can cause hyperglycemia, thus increasing postprandial hunger. Since circadian rhythm differs inter-individually, we describe glucose dips after breakfast/dinner with high/medium estimated meal GI among students with early (n = 22) and late chronotype (n = 23) and examine their relation to the feeling of hunger in a secondary analysis of a randomized cross-over nutrition trial. Glucose dips reflect the difference between the lowest glucose value recorded 2-3 h postprandially and baseline, presented as percentage of average baseline level. Associations between glucose dips and the feeling of hunger were analyzed using multilevel linear models. Glucose dips were lower after medium GI meals than after high GI meals among both chronotype groups (p = 0.03). Among early chronotypes, but not among late chronotypes, glucose dip values were lower after breakfast than after dinner (-4.9 % vs. 5.5 %, p = 0.001). Hunger increased throughout the day among both chronotypes but glucose dips were not related to the feeling of hunger at the meal following breakfast. Interestingly, lower glucose dip values 2-3 h postprandially occurred particularly after medium GI meals and were seen after breakfast among early chronotypes. These glucose dips did not predict hunger at meals after breakfast.

Source connectivity patterns in the default mode network differ between elderly golf-novices and non-golfers.

Learning to play golf has high demands on attention and therefore may counteract age-related changes of functional brain networks. This cross-sectional study compared source connectivity in the Default Mode Network (DMN) between elderly golf novices and non-golfers. Four-minute resting-state electroencephalography (128 channels) from 22 elderly people (mean age 67 ± 4.3 years, 55% females) were recorded after completing a 22-week golf learning program or after having continued with normal life. Source connectivity was assessed after co-registration of EEG data with native MRI within pre-defined portions of the DMN in the beta band (14-25 Hz). Non-golfers had significantly higher source connectivity values in the anterior DMN compared to non-golfers. Exploratory correlation analyses did not indicate an association to cognitive performance in either group. Inverse correlations between a marker of external attention with source connectivity of the anterior DMN may suggest a trend in the golf group only, but have to be replicated in future studies. Clinical relevance of these findings remains to be elucidated, but the observed difference in the anterior DMN may provide a starting point to further investigate if and how learning golf may have an impact on physiological age-related cognitive changes.

Classification characteristics of fine motor experts based on electroencephalographic and force tracking data.

The application of machine learning techniques provides a data-driven approach for a deeper understanding of the development and expressions of expertise. In extension to the common procedure of comparing experts' and novices' performances in expertise-domain-related tasks we applied conventional classification algorithms. We distinguished between tasks for each participant and between groups, i.e., experts or novices, based on electroencephalographic (EEG) activity patterns and force output variables during four different force modulation tasks. The tasks under investigation involved sinusoidal and steady force tracking tasks, which were performed with the left and right hand. Classification of tasks based on EEG patterns as well as force output was possible with high accuracy in novices and experts, whereas classification of group membership, i.e., experts or novices, was at chance level. In follow-up analyses, we found a high degree of individuality in the EEG patterns of the experts, implying the long-term development of specialized central processing during fine motor tasks in fine motor experts. Taken together, the results suggest that continuous practice in the work context leads to the development of a highly individual and task-specific central control pattern.

Classification of visuomotor tasks based on electroencephalographic data depends on age-related differences in brain activity patterns.

Classification of physiological data provides a data driven approach to study central aspects of motor control, which changes with age. To implement such results in real-life applications for elderly it is important to identify age-specific characteristics of movement classification. We compared task-classification based on EEG derived activity patterns related to brain network characteristics between older and younger adults performing force tracking with two task characteristics (sinusoidal; constant) with the right or left hand. We extracted brain network patterns with dynamic mode decomposition (DMD) and classified the tasks on an individual level using linear discriminant analysis (LDA). Next, we compared the models' performance between the groups. Studying brain activity patterns, we identified signatures of altered motor network function reflecting dedifferentiated and compensational brain activation in older adults. We found that the classification performance of the body side was lower in older adults. However, classification performance with respect to task characteristics was better in older adults. This may indicate a higher susceptibility of brain network mechanisms to task difficulty in elderly. Signatures of dedifferentiation and compensation refer to an age-related reorganization of functional brain networks, which suggests that classification of visuomotor tracking tasks is influenced by age-specific characteristics of brain activity patterns. In addition to insights into central aspects of fine motor control, the results presented here are relevant in application-oriented areas such as brain computer interfaces.

Automating Interictal Spike Detection: Revisiting A Simple Threshold Rule.

Interictal spikes (IIS) are bursts of neuronal depolarization observed electrographically between periods of seizure activity in epilepsy patients. However, IISs are difficult to characterize morphologically and their effects on neurophysiology and cognitive function are poorly understood. Currently, IIS detection requires laborious manual assessment and marking of electroencephalography (EEG/iEEG) data. This practice is also subjective as the clinician has to select the mental threshold that EEG activity must exceed in order to be considered a spike. The work presented here details the development and implementation of a simple automated IIS detection algorithm. This preliminary study utilized intracranial EEG recordings collected from 7 epilepsy patients, and IISs were marked by a single physician for a total of 1339 IISs across 68 active electrodes. The proposed algorithm implements a simple threshold rule that scans through iEEG data and identifies IISs using various normalization techniques that eliminate the need for a more complex detector. The efficacy of the algorithm was determined by evaluating the sensitivity and specificity of the detector across a range of thresholds, and an approximate optimal threshold was determined using these results. With an average true positive rate of over 98% and a false positive rate of below 2%, the accuracy of this algorithm speaks to its use as a reliable diagnostic tool to detect IISs, which has direct applications in localizing where seizures start, detecting when seizures start, and in understanding cognitive impairment due to IISs. Furthermore, due to its speed and simplicity, this algorithm can be used for real-time detection of IIS that will ultimately allow physicians to study their clinical implications with high temporal resolution and individual adaptation.

Language lateralization represented by spatiotemporal mapping of magnetoencephalography.

BACKGROUND AND PURPOSE: Determination of hemispheric language dominance is critical for planning epilepsy surgery. We assess the usefulness of spatiotemporal source analysis of magnetoencephalography for determining language laterality. MATERIALS AND METHODS: Thirty-five patients with epilepsy were studied. The patients performed a semantic word-processing task during MEG recording. Epochs containing language-related neuromagnetic activity were averaged after preprocessing. The averaged data between 250 and 550 ms after stimulus were analyzed by using dynamic statistical parametric mapping. ROIs were obtained in the opercular and triangular parts of the inferior frontal gyrus, superior temporal gyrus, and supramarginal gyrus in both hemispheres. We calculated laterality indices according to 1) dSPM-amplitude method, based on the amplitude of activation in the ROIs, and 2) dSPM-counting method, based on the number of unit dipoles with activation over a threshold in the ROIs. The threshold was determined as half of the maximum value in all ROIs for each patient. A LI ≥0.10 or ≤-0.10 was considered left- or right-hemisphere dominance, respectively; a LI between -0.10 and 0.10 was considered bilateral. All patients underwent an intracarotid amobarbital procedure as part of presurgical evaluation. RESULTS: The dSPM-counting method demonstrated laterality consistent with the IAP in 32 of 35 patients (91.4%), the remaining 3 (8.6%) demonstrated bilateral language representation, whereas the dSPM-amplitude method showed 18 (51.4%) concordant and 17 (48.6%) bilateral. No laterality opposite to the IAP was found. CONCLUSIONS: Spatiotemporal mapping of language lateralization with the dSPM-counting method may reduce the necessity for an IAP in as many as 90% of patients.

Autonomic changes with seizures correlate with postictal EEG suppression.

OBJECTIVE: Sudden unexpected death in epilepsy (SUDEP) poses a poorly understood but considerable risk to people with uncontrolled epilepsy. There is controversy regarding the significance of postictal generalized EEG suppression as a biomarker for SUDEP risk, and it remains unknown whether postictal EEG suppression has a neurologic correlate. Here, we examined the profile of autonomic alterations accompanying seizures with a wrist-worn biosensor and explored the relationship between autonomic dysregulation and postictal EEG suppression. METHODS: We used custom-built wrist-worn sensors to continuously record the sympathetically mediated electrodermal activity (EDA) of patients with refractory epilepsy admitted to the long-term video-EEG monitoring unit. Parasympathetic-modulated high-frequency (HF) power of heart rate variability was measured from concurrent EKG recordings. RESULTS: A total of 34 seizures comprising 22 complex partial and 12 tonic-clonic seizures from 11 patients were analyzed. The postictal period was characterized by a surge in EDA and heightened heart rate coinciding with persistent suppression of HF power. An increase in the EDA response amplitude correlated with an increase in the duration of EEG suppression (r = 0.81, p = 0.003). Decreased HF power correlated with an increase in the duration of EEG suppression (r = -0.87, p = 0.002). CONCLUSION: The magnitude of both sympathetic activation and parasympathetic suppression increases with duration of EEG suppression after tonic-clonic seizures. These results provide autonomic correlates of postictal EEG suppression and highlight a critical window of postictal autonomic dysregulation that may be relevant in the pathogenesis of SUDEP.

Focal hand dystonia: lack of evidence for abnormality of motor representation at rest.

OBJECTIVE: To examine whether the corticospinal system emanating from the primary motor cortex may be organized to facilitate generation of dystonic movements. METHODS: In this cross-sectional observational study, finger movement (FM) representations were assessed in 10 patients with focal hand dystonia (FHD) and 10 matched healthy controls by transcranial magnetic stimulation during rest. Evoked finger movements of the right hand were recorded using an instrumented data glove. Patterns of finger joint movements were analyzed using cluster analysis. Principal component analysis and centers of gravity for finger movement representations and motor evoked potentials recorded from the abductor pollicis brevis and abductor digiti minimi muscles were computed. For comparison, high-resolution somatosensory evoked potentials (SSEP) were recorded after electrical stimulation of the thumb (D1) or little finger (D5) in the same patients. Source reconstruction for the N20 SSEP component was performed using a dual-dipole model. RESULTS: Stimulation of the resting motor cortex did not reveal overt abnormalities in FHD, neither with respect to finger joint movement patterns nor with respect to the topologic organization of finger movements or intrinsic hand muscle representations. However, in line with previous reports, the distance between the dipole sources of D1 and D5 in the somatosensory cortex (S1) was smaller in patients with FHD, suggesting disruption of homuncular finger representations in S1. CONCLUSIONS: Our findings may imply that abnormality of motor organization in focal hand dystonia arises principally only during activation, when abnormal somatosensory representations are functionally integrated.

Electroconvulsive therapy resolves cortical inhibition and manneristic omissions in a chronic catatonic patient.

We investigated a patient with severe catatonic schizophrenia (manneristic catatonia according to Karl Leonhard) treated with electroconvulsive therapy (ECT) after pharmacological approaches did not result in any clinical improvement. Before and after nine ECT sessions a double-pulse transcranial magnetic stimulation (TMS) paradigm was used to measure intracortical inhibition (ICI) which has been shown to be reduced in a significant proportion of patients with schizophrenia. Although the patient showed no remission regarding some psychomotor aspects after ECT, we found an increase in ICI and a remarkable clinical improvement of catatonic omissions which might be due to changes in the GABAergic system.

Dose-dependent melanonychia by mitoxantrone.

We report an unusual case of a 43-year old female patient suffering from multiple sclerosis, who was treated with mitoxantrone. Few weeks after treatment initiation a hyperpigmentation of the patient's left thumb and index was noted. Following dose-reduction (from 12 to 10 mg/m(2)) and over the further course of mitoxantrone treatment the discoloration slightly faded. Although mitoxantrone is known to cause hyperpigmentation of various tissues this is the first report of melanonychia without hyperpigmentation of other tissue. Albeit speculative, pathogenesis of selective melanonychia by mitoxantrone could involve selective activation of nail matrix melanocytes or endocrine disturbances involving melanocyte stimulating hormone.

[Preclinical diagnosis of traumatic paraplegia or tetraplegia -- a prospective study in 100 patients]. / Die präklinische Diagnose der traumatischen Querschnittlähmung -- eine prospektive Studie an 100 Patienten.

OBJECTIVE: To avoid neurological deterioration, traumatic spinal cord injury has to be recognized as early as possible. Aim of the study was to analyze alterations of the neurological level of injury in the preclinical interval. METHODS: In a prospective observational study the clinical diagnoses of 100 patients referred to the Swiss Paraplegic Centre in Nottwil, Switzerland, were compared to the preclinical diagnoses. RESULTS: In 12 patients we observed neurological deterioration for more than 2 spinal segments. Six of these patients had been diagnosed preclinically with paraplegia at a neurological level of T4 or T5, whereas the evaluation in the hospital showed cervical spinal cord injury and tetraplegia. CONCLUSION: Possible reasons for this neurological deterioration can be secondary damages of the nervous tissue due to vascular, metabolic or biochemical mechanisms, transportation trauma or insufficient preclinical diagnostics. There is no evidence for a higher risk of secondary tissue damage for patients with cervical spinal cord injury. None of the six patients had additional injuries of the spinal cord or the vertebral column in the thoracic region, therefore transportation trauma is also unlikely. It is more likely that preclinical diagnoses were incorrect, what could have been avoided by consequent sensory and motor testing at the upper extremities.