Lateralized and frequency-dependent effects of prefrontal rTMS on regional cerebral blood flow

Repetitive transcranial magnetic stimulation (rTMS) is a means to study the function and connectivity of brain areas. The present study addressed the question of hemispheric asymmetry of frontal regions and aimed to further understand the acute effects of high- and low-frequency rTMS on regional cerebral blood flow (rCBF). Sixteen healthy right-handed men were imaged using H(2)(15)O positron emission tomography (PET) immediately after stimulation. High (10 Hz)- and low (1 Hz)-frequency suprathreshold short-duration rTMS was applied over either the left or right dorsolateral prefrontal cortex (DLPFC). Slow and fast rTMS applied over the left DLPFC significantly increased CBF in the stimulated area. Compared to baseline, slow rTMS induced a significant increase in CBF contralateral to the stimulation site, in the right caudate body and in the anterior cingulum. Furthermore, slow rTMS decreased CBF in the orbitofrontal cortex (OFC, ipsilateral to stimulation side). Fast rTMS applied over the right DLPFC was associated with increased activity at the stimulation site, in the bilateral orbitofrontal cortex and in the left medial thalamus compared to 1-Hz rTMS. These results show that rCBF changes induced by prefrontal rTMS differ upon hemisphere stimulated and vary with stimulation frequency. These differential neurophysiological effects of short-train rTMS with respect to side and frequency suggest hemisphere-dependent functional circuits of frontal cortico-subcortical areas.

Assessment of bronchodilator responsiveness in preschool children using forced oscillations

BACKGROUND: The forced oscillation technique (FOT) requires minimal patient cooperation and is feasible in preschool children. Few data exist on respiratory function changes measured using FOT following inhaled bronchodilators (BD) in healthy young children, limiting the clinical applications of BD testing in this age group. A study was undertaken to determine the most appropriate method of quantifying BD responses using FOT in healthy young children and those with common respiratory conditions including cystic fibrosis, neonatal chronic lung disease and asthma and/or current wheeze. METHODS: A pseudorandom FOT signal (4-48 Hz) was used to examine respiratory resistance and reactance at 6, 8 and 10 Hz; 3-5 acceptable measurements were made before and 15 min after the administration of salbutamol. The post-BD response was expressed in absolute and relative (percentage of baseline) terms. RESULTS: Significant BD responses were seen in all groups. Absolute changes in BD responses were related to baseline lung function within each group. Relative changes in BD responses were less dependent on baseline lung function and were independent of height in healthy children. Those with neonatal chronic lung disease showed a strong baseline dependence in their responses. The BD response in children with cystic fibrosis, asthma or wheeze (based on both group mean data and number of responders) was not greater than in healthy children. CONCLUSIONS: The BD response assessed by the FOT in preschool children should be expressed as a relative change to account for the effect of baseline lung function. The limits for a positive BD response of -40% and 65% for respiratory resistance and reactance, respectively, are recommended.

Space-qualified laser system for the BepiColombo Laser Altimeter

The space-qualified design of a miniaturized laser for pulsed operation at a wavelength of 1064 nm and at repetition rates up to 10 Hz is presented. This laser consists of a pair of diode-laser pumped, actively q-switched Nd:YAG rod oscillators hermetically sealed and encapsulated in an environment of dry synthetic air. The system delivers at least 300 million laser pulses with 50 mJ energy and 5 ns pulse width (FWHM). It will be launched in 2017 aboard European Space Agency’s Mercury Planetary Orbiter as part of the BepiColombo Laser Altimeter, which, after a 6-years cruise, will start recording topographic data from orbital altitudes between 400 and 1500 km above Mercury’s surface.

Suppressing versus releasing a habit: frequency-dependent effects of prefrontal transcranial magnetic stimulation.

When subjects are required to generate a random sequence of numbers they typically produce too many forward and backward 'counts' (e.g. 5-6, 4-3). This counting bias is interpreted as the consequence of an interference by overlearned tendencies to arrange numbers according to their natural order. Inhibition of such well-learned routines is known to rely on frontal lobe functioning. We examined differential effects of slow (1 Hz) and fast (10 Hz) repetitive transcranial magnetic stimulation (rTMS) over the left or right dorsolateral prefrontal cortex (DLPFC) on random number generation (RNG) performance. Eighteen healthy men performed an RNG task. Those subjects stimulated over the left DLPFC showed a frequency-dependent rTMS effect: counting bias was significantly reduced after the 1 Hz stimulation compared with baseline, but significantly exaggerated after the 10 Hz stimulation compared with 1 Hz stimulation. In contrast, the sequences of the subjects stimulated over the right DLPFC showed the well-known excess of counting in all conditions (i.e. baseline, 1 Hz and 10 Hz). These findings confirm the functional importance of specifically the left DLPFC in sequential response production and show, for the first time, that rTMS affects cognitive processing in a frequency-dependent manner.

Development and validation of a novel pedometer algorithm to quantify extended characteristics of the locomotor behavior of dairy cows

Behavior is one of the most important indicators for assessing cattle health and well-being. The objective of this study was to develop and validate a novel algorithm to monitor locomotor behavior of loose-housed dairy cows based on the output of the RumiWatch pedometer (ITIN+HOCH GmbH, Fütterungstechnik, Liestal, Switzerland). Data of locomotion were acquired by simultaneous pedometer measurements at a sampling rate of 10 Hz and video recordings for manual observation later. The study consisted of 3 independent experiments. Experiment 1 was carried out to develop and validate the algorithm for lying behavior, experiment 2 for walking and standing behavior, and experiment 3 for stride duration and stride length. The final version was validated, using the raw data, collected from cows not included in the development of the algorithm. Spearman correlation coefficients were calculated between accelerometer variables and respective data derived from the video recordings (gold standard). Dichotomous data were expressed as the proportion of correctly detected events, and the overall difference for continuous data was expressed as the relative measurement error. The proportions for correctly detected events or bouts were 1 for stand ups, lie downs, standing bouts, and lying bouts and 0.99 for walking bouts. The relative measurement error and Spearman correlation coefficient for lying time were 0.09% and 1; for standing time, 4.7% and 0.96; for walking time, 17.12% and 0.96; for number of strides, 6.23% and 0.98; for stride duration, 6.65% and 0.75; and for stride length, 11.92% and 0.81, respectively. The strong to very high correlations of the variables between visual observation and converted pedometer data indicate that the novel RumiWatch algorithm may markedly improve automated livestock management systems for efficient health monitoring of dairy cows.

Peri-ictal correlation dynamics of high-frequency (80-200 Hz) intracranial EEG

To assess (1) how large-scale correlation of intracranial EEG signals in the high-frequency range (80-200Hz) evolves from the pre-ictal, through the ictal into the postictal state and (2) whether the contribution of local neuronal activity to large-scale EEG correlation differentiates epileptogenic from non-epileptogenic brain tissue.

Repetitive TMS over the human oculomotor cortex: comparison of 1-Hz and theta burst stimulation

The aim of the study was to compare the effect duration of two different protocols of repetitive transcranial magnetic stimulation (rTMS) on saccade triggering. In four experiments, two regions (right frontal eye field (FEF) and vertex) were stimulated using a 1-Hz and a theta burst protocol (three 30Hz pulses repeated at intervals of 100ms). The same number of TMS pulses (600 pulses) was applied with stimulation strength of 80% of the resting motor threshold for hand muscles. Following stimulation the subjects repeatedly performed an oculomotor task using a modified overlap paradigm, and saccade latencies were measured over a period of 60min. The results show that both 1-Hz and theta burst stimulation had inhibitory effects on saccade triggering when applied over the FEF, but not over the vertex. One-hertz rTMS significantly increased saccade latencies over a period of about 8min. After theta burst rTMS, this effect lasted up to 30min. Furthermore, the decay of rTMS effects was protocol-specific: After 1-Hz stimulation, saccade latencies returned to a baseline level much faster than after theta burst stimulation. We speculate that these time course differences represent distinct physiological mechanisms of how TMS interacts with brain function.