Changes In Mean Frequency Research Articles

Change in Mean Frequency of Resting-State Electroencephalography after Transcranial Direct Current Stimulation.

Transcranial direct current stimulation (tDCS) is proposed as a tool to investigate cognitive functioning in healthy people and as a treatment for various neuropathological disorders. However, the underlying cortical mechanisms remain poorly understood. We aim to investigate whether resting-state electroencephalography (EEG) can be used to monitor the effects of tDCS on cortical activity. To this end we tested whether the spectral content of ongoing EEG activity is significantly different after a single session of active tDCS compared to sham stimulation. Twenty participants were tested in a sham-controlled, randomized, crossover design. Resting-state EEG was acquired before, during and after active tDCS to the left dorsolateral prefrontal cortex (15 min of 2 mA tDCS) and sham stimulation. Electrodes with a diameter of 3.14 cm2 were used for EEG and tDCS. Partial least squares (PLS) analysis was used to examine differences in power spectral density (PSD) and the EEG mean frequency to quantify the slowing of EEG activity after stimulation. PLS revealed a significant increase in spectral power at frequencies below 15 Hz and a decrease at frequencies above 15 Hz after active tDCS (P = 0.001). The EEG mean frequency was significantly reduced after both active tDCS (P < 0.0005) and sham tDCS (P = 0.001), though the decrease in mean frequency was smaller after sham tDCS than after active tDCS (P = 0.073). Anodal tDCS of the left DLPFC using a high current density bi-frontal electrode montage resulted in general slowing of resting-state EEG. The similar findings observed following sham stimulation question whether the standard sham protocol is an appropriate control condition for tDCS.

Variability and stability in the McGurk effect: contributions of participants, stimuli, time, and response type.

In the McGurk effect, pairing incongruent auditory and visual syllables produces a percept different from the component syllables. Although it is a popular assay of audiovisual speech integration, little is known about the distribution of responses to the McGurk effect in the population. In our first experiment, we measured McGurk perception using 12 different McGurk stimuli in a sample of 165 English-speaking adults, 40 of whom were retested following a one-year interval. We observed dramatic differences both in how frequently different individuals perceived the illusion (from 0 % to 100 %) and in how frequently the illusion was perceived across different stimuli (17 % to 58 %). For individual stimuli, the distributions of response frequencies deviated strongly from normality, with 77 % of participants almost never or almost always perceiving the effect (≤10 % or ≥90 %). This deviation suggests that the mean response frequency, the most commonly reported measure of the McGurk effect, is a poor measure of individual participants' responses, and that the assumptions made by parametric statistical tests are invalid. Despite the substantial variability across individuals and stimuli, there was little change in the frequency of the effect between initial testing and a one-year retest (mean change in frequency = 2 %; test-retest correlation, r = 0.91). In a second experiment, we replicated our findings of high variability using eight new McGurk stimuli and tested the effects of open-choice versus forced-choice responding. Forced-choice responding resulted in an estimated 18 % greater frequency of the McGurk effect but similar levels of interindividual variability. Our results highlight the importance of examining individual differences in McGurk perception instead of relying on summary statistics averaged across a population. However, individual variability in the McGurk effect does not preclude its use as a stable measure of audiovisual integration.

Spatial and Frequency Compounding in Application to Attenuation Estimation in Tissue

Abstract The soft tissue attenuation is an interesting parameter from medical point of view, because the value of attenuation coefficient is often related to the state of the tissue. Thus, the imaging of the attenuation coefficient distribution within the tissue could be a useful tool for ultrasonic medical diagnosis. The method of attenuation estimation based on tracking of the mean frequency changes in a backscattered signal is presented in this paper. The attenuation estimates are characterized by high variance due to stochastic character of the backscattered ultrasonic signal and some special methods must be added to data processing to improve the resulting images. The following paper presents the application of Spatial Compounding (SC), Frequency Compounding (FC) and the combination of both. The resulting parametric images are compared by means of root-mean-square errors. The results show that combined SC and FC techniques significantly improve the quality and accuracy of parametric images of attenuation distribution.

'Tamsulosin and Darifenacin' Versus 'Tamsulosin Monotherapy' for 'BPH with Accompanying Overactive Bladder'.

To evaluate the efficacy/safety of 'tamsulosin and darifenacin' (TD) vs. 'tamsulosin and placebo' (TP) for patients with symptomatic benign prostrate hyperplasia (BPH) with accompanying overactive bladder (OAB) symptoms. This study included symptomatic patients of BPH with one or more of the following OAB symptoms; micturition frequency >8, nocturnal frequency > 2, urgency > 1 per 24 hour between November 2012 and February 2014. After protocol approval by ethics committee and obtaining informed consent, patients were randomly assigned to receive tamsulosin 0.4mg plus placebo (TP) (n=30) or tamsulosin 0.4 mg plus darifenacin 7.5 mg (TD) (n=30) for 8 weeks. The mean change from baseline in urinary frequency and incontinence episodes/24 hour (primary end points), and nocturnal frequency; mean change in PVR and changes in IPSS (secondary end points) were compared between groups at 0/eight week using voiding diary and ultrasonography. The mean change in frequency, incontinence, nocturnal frequency/24 hour and IPSS (International prostrate symptom score) were (-4.83 vs. -3.93, p=0.023), (-1.50 vs. 1.08, p=0.001), (-2.20 vs. -1.87, p<0.001) and (-7.90 vs. -6.27, p<0.001) in the TD/TP group respectively (significant). Apart from some minor side effects (12 vs. 9) all interventions appeared to be safe and well tolerated. The mean change in the PVR (Postvoid residual) was marginal (+10.84ml and -16.93) and the incidence of urinary retention was 13% and 3% in the TD and TP groups respectively (p=0.35). Treatment with tamsulosin and darifenacin for 8 weeks is an effective and safe treatment modality in select patients of BPH with accompanying OAB symptoms.

EEG mean frequency changes in healthy subjects during prefrontal transcranial direct current stimulation

In this pilot study we evaluated electroencephalographic (EEG) mean frequency changes induced by prefrontal transcranial direct current stimulation (tDCS) and investigated whether they depended on tDCS electrode montage. Eight healthy volunteers underwent tDCS for 15 min during EEG recording. They completed six tDCS sessions, 1 wk apart, testing left and right direct current (DC) dipole directions with six different montages: four unipolar montages (one electrode on a prefrontal area, the other on the opposite wrist) and two bipolar montages (both electrodes on prefrontal areas), and a single sham session. EEG power spectra were assessed from four 1-min EEG epochs, before, during, and after tDCS. During tDCS the outcome variable, brain rate (fb), changed significantly, and the changes persisted for minutes after tDCS ended. With the DC dipole directed to the left (anode on the left prefrontal area or wrist), fb increased, and with the DC dipole directed to the right (anode on the right prefrontal area or wrist), fb decreased, suggesting asymmetric prefrontal cortex functional organization in the normal human brain. Anodal and cathodal effects were opposite but equally large. Gender left these effects unchanged.

Acupuncture and traditional Chinese medicine for hot flushes in menopause: a randomized trial.

To evaluate the effect of acupuncture on hot flushes and other menopause-related symptoms used in an integrated system, including such therapeutic techniques as diet therapy and Tuina self-massage. Randomized trial. Outpatient center. One hundred women in spontaneous menopause with at least three episodes of hot flushes daily were randomly allocated to two treatment groups (50 per group): Women in group A were given diet, self-massage training, and treatment with acupuncture, and women in group B (the control group) were given the same diet and self-massage training, but treatment with acupuncture started 6 weeks after they were enrolled into the study. Acupuncture treatments were scheduled twice weekly for 6 consecutive weeks. Mean change in frequency and/or intensity in menopause-related symptoms were estimated by questionnaire after treatment at week 4. Treatment with acupuncture significantly reduced the occurrence of hot flushes and sudden sweating (p<.001). Other symptoms (sleep disorders, tightness in the chest, irritability, bone pain, feeling depressed) significantly improved. Acupuncture in an integrated system that includes therapeutic techniques such as diet therapy and Tuina self-massage can be used to treat hot flushes and selected symptoms in postmenopausal women.

Role of nitric oxide-containing factors in the ventilatory and cardiovascular responses elicited by hypoxic challenge in isoflurane-anesthetized rats.

Exposure to hypoxia elicits changes in mean arterial blood pressure (MAP), heart rate, and frequency of breathing (fR). The objective of this study was to determine the role of nitric oxide (NO) in the cardiovascular and ventilatory responses elicited by brief exposures to hypoxia in isoflurane-anesthetized rats. The rats were instrumented to record MAP, heart rate, and fR and then exposed to 90 s episodes of hypoxia (10% O2, 90% N2) before and after injection of vehicle, the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), or the inactive enantiomer D-NAME (both at 50 μmol/kg iv). Each episode of hypoxia elicited a decrease in MAP, bidirectional changes in heart rate (initial increase and then a decrease), and an increase in fR. These responses were similar before and after injection of vehicle or D-NAME. In contrast, the hypoxia-induced decreases in MAP were attenuated after administration of L-NAME. The initial increases in heart rate during hypoxia were amplified whereas the subsequent decreases in heart rate were attenuated in L-NAME-treated rats. Finally, the hypoxia-induced increases in fR were virtually identical before and after administration of L-NAME. These findings suggest that NO factors play a vital role in the expression of the cardiovascular but not the ventilatory responses elicited by brief episodes of hypoxia in isoflurane-anesthetized rats. Based on existing evidence that NO factors play a vital role in carotid body and central responses to hypoxia in conscious rats, our findings raise the novel possibility that isoflurane blunts this NO-dependent signaling.

MP75-03 A PROSPECTIVE RANDOMIZED OPEN-LABEL CLINICAL OBSERVATIONAL STUDY TO ASSESS THE EFFECTIVENESS OF ADDING TAMSULOSIN IN WOMEN TREATED WITH SOLIFENACIN FOR OVERACTIVE BLADDER

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Female Urology II1 Apr 2014MP75-03 A PROSPECTIVE RANDOMIZED OPEN-LABEL CLINICAL OBSERVATIONAL STUDY TO ASSESS THE EFFECTIVENESS OF ADDING TAMSULOSIN IN WOMEN TREATED WITH SOLIFENACIN FOR OVERACTIVE BLADDER Changhee Yoo, Sun Il Kim, Jae Hyun Bae, Jung Hwan Son, Cheol Young Oh, Dong Hee Yoon, Seoung Yul Lee, Seoung-Ju Lee, Sung Jin Chung, Young Kwon Hong, Jong Bo Choi, and Woo Jin Bang Changhee YooChanghee Yoo More articles by this author , Sun Il KimSun Il Kim More articles by this author , Jae Hyun BaeJae Hyun Bae More articles by this author , Jung Hwan SonJung Hwan Son More articles by this author , Cheol Young OhCheol Young Oh More articles by this author , Dong Hee YoonDong Hee Yoon More articles by this author , Seoung Yul LeeSeoung Yul Lee More articles by this author , Seoung-Ju LeeSeoung-Ju Lee More articles by this author , Sung Jin ChungSung Jin Chung More articles by this author , Young Kwon HongYoung Kwon Hong More articles by this author , Jong Bo ChoiJong Bo Choi More articles by this author , and Woo Jin BangWoo Jin Bang More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2376AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To verify additional effect of alpha-blocker to anticholinergics in women with overactive bladder (OAB). METHODS 144 women (age¡Ã18 years) were enrolled. They complained OAB symptoms with International Prostate Symptom Score ¡Ã 8 and OAB short symptom score (OABSS) ¡Ã 2 in Q3 with over 3 of total OABSS and frequency more than 8 a day on voiding diary. Any subjects with neurogenic bladder, previous pelvic operation history and urinary tract infection were excluded. They were randomly assigned to solifenacin monotherapy (Mono) group (n=71) or solifenacin and tamsulosin combination therapy (Comb) group (n=73). The primary end points were change of frequency and urgency episode in voiding diary at 4 and 12 weeks after treatment. RESULTS In the Mono group, 65 and 56 women completed the protocol at 4 and 12 weeks respectively. And, in the Comb group, 56 and 49 women completed the protocal at 4 and 12 weeks respectively. At 4 weeks, the change of mean frequency, and the change of mean urgency episode were significantly larger in the Comb group.(p=0.027, and p=0.048 respectively). However, at 12 weeks, only the change of mean urgency episode was significantly larger in the Comb group (p=0.046). (Table 1) CONCLUSIONS Tamsulosin and solifenacin combination treatment improved OAB symptoms more rapidly than solifenacin monotherapy. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e874 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Changhee Yoo More articles by this author Sun Il Kim More articles by this author Jae Hyun Bae More articles by this author Jung Hwan Son More articles by this author Cheol Young Oh More articles by this author Dong Hee Yoon More articles by this author Seoung Yul Lee More articles by this author Seoung-Ju Lee More articles by this author Sung Jin Chung More articles by this author Young Kwon Hong More articles by this author Jong Bo Choi More articles by this author Woo Jin Bang More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Digital Photography as an Educational Food Logging Tool in Obese Patients With Type 2 Diabetes

The purpose of this pilot study is to investigate the utility of, and areas of refinement for, digital photography as an educational tool for food logging in obese patients with type 2 diabetes (T2DM). Thirty-three patients aged 18 to 70 with T2DM, body mass index at least 30 kg/m(2), and A1C 7.5% to 9% were recruited from an endocrinology clinic and randomized to a week of food logging using a digital camera (DC) or paper diary (PD), crossing over for week 2. Patients then viewed a presentation about dietary effects on blood glucose, using patient DC and blood glucose entries. Outcomes of adherence (based on number of weekly entries), changes in mean blood glucose and frequency of blood glucose checks, and patient satisfaction were compared between methods. Patient feedback on the DC intervention and presentation was also analyzed. Thirty patients completed the study. Adherence was identical across methods. The mean difference in number of entries was not significant between methods. This difference increased and neared statistical significance (favoring DC) among patients who were adherent for at least 1 week (21 entries, with 2 entries per day for 5 of 7 days, n = 25). Mean blood glucose did not significantly decrease in either method. Patient satisfaction was similar between interventions. Feedback indicated concerns over photograph accuracy, forgetting to use the cameras, and embarrassment using them in public. Although the DC method was comparable to PD in adherence, blood glucose changes, and patient satisfaction in this pilot trial, patient feedback suggested specific areas of refinement to maximize utility of DC-based food logging as an educational tool in T2DM.

Stochastic Generation of Gamma-Band Activity in Primary Visual Cortex of Awake and Anesthetized Monkeys

Oscillatory neural activity within the gamma band (25-90 Hz) is generally thought to be able to provide a timing signal for harmonizing neural computations across different brain regions. Using time-frequency analyses of the dynamics of gamma-band activity in the local field potentials recorded from monkey primary visual cortex, we found identical temporal characteristics of gamma activity in both awake and anesthetized brain states, including large variability of peak frequency, brief oscillatory epochs (<100 ms on average), and stochastic statistics of the incidence and duration of oscillatory events. These findings indicate that gamma-band activity is temporally unstructured and is inherently a stochastic signal generated by neural networks. This idea was corroborated further by our neural-network simulations. Our results suggest that gamma-band activity is too random to serve as a clock signal for synchronizing neuronal responses in awake as in anesthetized monkeys. Instead, gamma-band activity is more likely to be filtered neuronal network noise. Its mean frequency changes with global state and is reduced under anesthesia.

Upper Airway Dimensions in Snoring: Acoustical and MRI Findings

Objective: OSA is caused by soft tissue collapse of the upper airway; treatment strategies can be determined depending on accurately localizing the obstruction sites. Acoustic analysis of snoring might provide a valuable way to localize the obstruction, if the association between the acoustics and the dynamics of the upper airway during OSA can be identified. Method: Nine PSG OSA patients were enrolled. Dynamics of upper airway and the acoustic manifestations of snore events during natural sleep were recorded with dynamic MRI and a fiber-optic microphone simultaneously. The Gabor/wavelet transformation was applied to extract the acoustic representation of OSA events by removing the repeated-appearing MRI scanning background noises. Results: All of the 9 patients were men (mean age, 48.3 ± 9.9 years, mean BMI, 25.1 ± 1.9). The snore events were categorized into typical (velopharyngeal) and mixed (combined with hypopharyngeal) obstructions. The mean frequency (161 ± 17.4 vs 188 ± 24.1 Hz; P &lt; 10-16) and high (151~350 Hz)/low(80~150 Hz) frequency power ratio (1.08 ± 0.31 vs 1.55 ± 0.42 Hz; P &lt; 10-16) of the snore sounds were significantly higher in mixed obstructions. However, the dynamic patterns of the frequency modulation varied with structural changes identified by dMRI. During the snore events, different characteristics of shifts in frequency were found (mean frequency changes: −28.3 ± 21.4 in typical obstruction vs 12.5 ± 22.9 Hz for mixed obstruction; P &lt; 10-32), which gives better discrimination power. Conclusion: The dynamics of acoustic patterns derived by Gabor spectrogram are unique and characteristics in different types of obstruction with the advantage of low cost and easy availability. Therefore, the dynamics of acoustic patterns warrants further investigation in combination with instantaneous structural changes of the obstruction sites in OSA patients through dMRI.

Neural Contributions to Concentric vs. Eccentric Exercise–Induced Strength Loss

The purpose of this study was to examine the strength, electromyographic (EMG), and mechanomyographic (MMG) responses after workouts designed to elicit fatigue and muscle damage vs. only fatigue. Thirteen men (mean ± SD age = 23.7 ± 2.2 years) performed 6 sets of 10 maximal concentric isokinetic (CONexercise) or eccentric isokinetic (ECCexercise) muscle actions of the dominant forearm flexors on 2 separate days. Before (PRE) and after (POST) these workouts, peak torque (PT), surface EMG, and MMG signals were measured during maximal concentric isokinetic, eccentric isokinetic, and isometric muscle actions of the forearm flexors. The subjects also visited the laboratory for a control (CTL) visit with quiet resting between the PRE and POST measurements, rather than performing the CONexercise or ECCexercise. The results showed that there were significant 26 and 25% decreases in PT after the CONexercise and ECCexercise, respectively, and these decreases were statistically equivalent for the concentric, eccentric, and isometric muscle actions. There were also 19 and 23% reductions in normalized EMG amplitude after the CONexercise and ECCexercise, respectively, but no changes in EMG mean frequency (MNF), MMG amplitude, or MMG MNF. These findings demonstrated a neural component(s) to the strength decrement after CONexercise and ECCexercise. It is possible that after these 2 types of exercise, activation of free nerve endings that are sensitive to muscle damage and pH changes resulted in inhibition of alpha motor neurons, causing decreased muscle activation and torque. These findings suggest that training programs designed to minimize strength loss during competition should consider the fact that at least some of this loss is because of neural factors.

The Impacts of ACE Activity according to ACE I/D Polymorphisms on Muscular Functions of People Aged 65.

ObjectiveTo investigate associations between angiotensin-converting enzyme (ACE) polymorphisms and muscle fatigability in 65-year-old Koreans.MethodThe study participants were 49 Koreans aged 65 years. ACE insertion/deletion (I/D) polymorphisms were determined by polymerase chain reaction and serum ACE activity, by spectrophotometry. Body mass index (BMI), body fat mass (BFM), and lean body mass (LBM) were determined. To evaluate muscle fatigability, dynamic Electromyography was used to measure maximum voluntary isometric contractions (MVICs) of ankle plantar flexor muscles. Patients were seated with their hips flexed at 90°, knees fully extended, and ankles at 0°. Continuous submaximal VICs (40% MVIC) were then performed, and contraction duration and EMG frequency changes during the initial 2 min were measured. A self-reported physical activity questionnaire was used to evaluate effects of ACE activity levels on muscle fatigability.ResultsAmong the 49 volunteers, 15 showed II genotype; 22, ID genotype; and 12, DD genotype. Serum ACE activity levels were significantly higher in DD genotype subjects than in II genotype subjects (p<0.05). Furthermore, the duration of submaximal isometric contractions was longer in II and ID genotype subjects than in DD genotype subjects (p<0.05). Dynamic EMG showed significantly lower mean frequency changes in II genotype subjects than in DD genotype subjects (p<0.05). However, LBM, BFM, and BMI were independent of ACE genotypes.ConclusionACE II genotype subjects showed significantly higher resistant to muscle fatigue than that by DD genotype subjects. However, body composition and BMI showed no correlations with ACE I/D polymorphisms.

Back extensor muscle fatigue at submaximal workloads assessed using frequency banding of the electromyographic signal

Background Changes in the mean or median frequency of the electromyographic (EMG) power spectrum are often used to assess skeletal muscle fatigue. A more global analysis of the spectral changes using frequency banding may provide a more sensitive measure of fatigue than changes in mean or median frequency. So, the aim of the present study was to characterize changes in different power spectrum frequency bands and compare these with changes in median frequency. Methods Twenty male subjects performed isometric contractions of the back muscles in an isometric dynamometer at 30%, 40%, 50% and 60% of maximum voluntary contraction. During each contraction, surface EMG signals were recorded from the right and left longissimus thoracis muscles, and endurance time was measured. The EMG power spectra were divided into four frequency bands (20–50 Hz; 50–80 Hz; 80–110 Hz; 110–140 Hz) and changes in power in each band with fatigue were compared with changes in median frequency. Findings The percentage changes in 20–50 Hz band were greater than in all other and the rate of change in power, indicated by the slope, was also greatest in 20–50 Hz band. Also, 20–50 Hz band had a greater change in power than the median frequency. Interpretation Power in the low frequency part of the EMG power spectrum increases with fatigue in a load-dependent manner. The rate of change in low frequency power may be a useful indicator of fatigue rate or “fatigability” in the back muscles. Also, changes in low frequency power are more evident than changes in the median frequency.

Tissue Attenuation Estimation from Backscattered Ultrasound Using Spatial Compounding Technique - Preliminary Results

The pathological states of biological tissue are often resulted in attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion, is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the extraction of mean frequency trends. These trends were converted into attenuation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom (DFS, Denmark) with uniform echogenicity while attenuation coefficient underwent variation.

Oxygenation and EMG in the proximal and distal vastus lateralis during submaximal isometric knee extension

Muscle oxygenation responses are reportedly greater in the distal muscle region than in the proximal muscle region. We combined near infrared spectroscopy and electromyography (EMG) to determine whether regional differences in oxygenation are associated with differences in (1) muscle activation and/or (2) fatigue development. Nine males performed 2-min sustained isometric knee extensions at 15% and 30% maximum voluntary contraction during which oxygenation and EMG were recorded simultaneously from proximal and distal locations of the vastus lateralis muscle. Near infrared spectroscopy variables for oxygen saturation (StO2%) were initial slope at contraction onset, peak drop, and recovery slope at contraction end. Electromyography produced the root mean square to indicate muscle activation and mean power frequency changes over time (decreasing slope) to indicate fatigue development. For StO2%, significantly greater peak drop and steeper recovery slope were found for the distal muscle region than for the proximal muscle region. Root mean square, however, was not different between locations. Mean power frequency decreased throughout the contractions but changes were not different between locations. Our results indicate that for modest submaximal contractions, regional differences in oxygenation are not associated with differences in muscle activation or with fatigue development (as interpreted by changes in mean power frequency over time).

Topiramate modulates excitability of the occipital cortex when measured by transcranial magnetic stimulation

The aim of this study was to measure differences in occipital cortex excitability in migraineurs before and after administration of topiramate. We have previously demonstrated occipital cortex hyperexcitability in migraine using an objective technique of magnetic suppression of perceptual accuracy (MSPA). We hypothesized that a neuromodulator such as topiramate would demonstrate differences in MSPA in migraine compared with baseline. Ten migraine patients were recruited. To assess inhibitory function MSPA was measured using the following protocol. Timed transcranial magnetic stimulation were delivered at interstimulus intervals (ISI) varying from 40 to 190 ms (eight stimulations at each ISI) at 60% stimulus intensity. Subjects were asked to report letters projected at a fixed luminance on the screen. Visual suppression was calculated based on the number of errors the subjects made using automated analysis. This procedure was repeated at a minimum of two different dosages of topiramate when it was titrated for optimal migraine control. The interim dose was that at which an improvement in headache frequency was first observed, and the optimal dose was that at which the patient had a ≥ 50% reduction in headache frequency, or had reached a 100-mg dose. The mean [standard error (s.e.)] level of letters reported correct at baseline at 100-ms ISI was 91.6 (3.4) compared with 48.5 (6.0) (P = 0.001) at an optimal dose of topiramate. Dose ranged from 50 to 100 mg; the average dose was 75 mg. The interim dose for most patients was 50 mg; the mean (s.e.) percentage of letters reported correct at interim was 75.9 (6.2) compared with baseline (P = 0.01). Mean number of headaches at baseline was 27 per month, compared with eight headaches per month at interim dose and four headaches per month at optimal dose. There was no significant correlation between mean change in frequency of headache and mean change in inhibition from baseline to optimal dose (0.04, P = 0.89). Topiramate modulates occipital cortex excitability in chronic migraine possibly via mechanisms of cortical inhibition. Since there was not a strong correlation between the degree of inhibition and reduction of migraine frequency, it would appear that topiramate did have an independent effect on cortical excitability that was not dependent on reduction in migraine frequency.

Three Cycles of Recurrent Selection for Altered Recombination Frequency in Maize

The variability among progeny in a plant breeding population depends on the amount of recombination that occurs in meiosis preceding selection. The recombination arises either from the independent assortment of chromosomes or from crossing over during chromosome synapsis. Crossing over is not a constant value; it differs based on background genotype. This research determined the effectiveness of three cycles of recurrent selection for increased or decreased crossing over in Zea mays L. Testcrosses measured male recombination frequency on three chromosomes: 4, su1‐c2; 5, a2‐bt1‐pr1; and 9, sh1‐bz1‐wx1 Sixty plants from each of three populations (cycle 0 [C0], cycle 3 high recombination [C3HR], and cycle 3 low recombination [C3LR]) were evaluated. The mean recombination frequency changes between C0 and C3HR are significant at all chromosome regions (su1‐c2, +5%; a2‐pr1, +24%; sh1‐wx1, +8%). The mean recombination frequency changes between C0 and C3LR are significant at the chromosome 4 (su1‐c2,‐15%) and 5 (a2‐pr1,‐27%) linkage groups. The mean recombination frequency did not change significantly from C0 to C3LR at either of the chromosome 9 regions. Compared to the C0 population, the sum of the genetic distances at these chromosome regions increased 9.5% in the C3HR population and decreased 14.9% in the C3LR population. Selection for high or low recombination frequency successfully modified recombination frequency.

Randomized Controlled Trial on Single Dose Steroid Before Thyroidectomy for Benign Disease to Improve Postoperative Nausea, Pain, and Vocal Function

To evaluate the effects of a single preoperative dose of steroid on thyroidectomy outcomes. Nausea, pain, and voice alteration frequently occur after thyroidectomy. Because steroids effectively reduce nausea and inflammation, a preoperative administration of steroids could improve these thyroidectomy outcomes. Seventy-two patients (men = 20, women = 52) undergoing thyroidectomy for benign disease were included in this randomized, controlled, 2 armed (group D: 8 mg dexamethasone, n = 37; group C: 0.9% NaCl, n = 35), double-blinded study (clinical trial number NCT00619086). Anesthesia, surgical procedures, antiemetics, and analgesic treatments were standardized. Nausea (0-3), pain (visual analog scale), antiemetic and analgesic requirements, and digital voice recording were documented before and 4, 8, 16, 24, 36, and 48 hours after surgery. Patients were followed-up 30 days after hospital discharge. Baseline characteristics were similar among the 2 treatment groups. Nausea was pronounced in the first 16 hours postoperatively (scores were <0.3 and 0.8-1.0 for group D and C, respectively (P = 0.005)), and was significantly lower in group D compared with group C during the observation period (P = 0.001). Pain diminished within 48 hours after surgery (visual analog scale 20 and 35 in group D and C, respectively (P = 0.009)). Antiemetic and analgesic requirements were also significantly diminished. Changes in voice mean frequency were less prominent in the dexamethasone group compared with the placebo group (P = 0.015). No steroid-related complications occurred. A preoperative single dose of steroid significantly reduced nausea, vomiting, and pain, and improved postoperative voice function within the first 48 hours (most pronounced within 16 hours) after thyroid resection; this strategy should be routinely applied in thyroidectomies.

The Effect of Operating Time on Surgeons' Muscular Fatigue

A study was completed to determine if operating has an effect on a surgeon's muscular fatigue. Six head and neck surgery consultants, two ENT registrars, 20 normal controls from two tertiary referral centres in the West Midlands participated in the study. Electromyography (EMG) measurements were taken throughout a day of operating and fatigue indices were compared to controls performing desk work. The percentage changes in mean frequency of muscular contractions were examined; there was no significant difference in fatigue levels between consultants and registrars. Operating led to an increase in fatigue in all subjects, compared to no increase in controls performing desk work. It was also found that the brachioradialis muscle is used more than the mid-deltoid muscle and, hence, fatigues at a faster rate. Surgeons should be aware that their muscular fatigue levels will increase as an operation progresses; therefore, if possible, more complex parts of the operation should be performed as early as possible, or, in the case of a very long operation, a change in surgeon may be necessary.