Cortical correlates of the basic and first harmonic frequency of Parkinsonian tremor

Objective It has been hypothesized that the basic and first harmonic frequency of Parkinsonian tremor are somewhat independent oscillations the biological basis of which remains unclear. Methods We recorded 64-channel EEG in parallel with EMG of the forearm muscles most affected by rest tremor in 21 PD patients. EMG power spectrum, corticomuscular coherence spectra and EEG power spectra for each EEG electrode were calculated. The dynamics of the coherence and relative EMG and EEG power at the basic (tremor) frequency were calculated by a sliding, overlapping window analysis. Corticomuscular delays and direction of interaction were analysed by the maximizing coherence method for narrow band signals. Results The contralateral EEG electrodes with maximal coherence were different for the basic and first harmonic frequency. The dynamical coherence curves showed non-parallel time courses for the two frequencies. The mean EEG-EMG and EMG-EEG delays were all around 15–20 ms but significantly longer for the first harmonic than for the basic frequency. Conclusions Our data indicate different cortical representations and corticomuscular interaction of the basic and first harmonic frequencies of Parkinsonian tremor. Significance Separate central generators seem to contribute to the tremor via different pathways. Further studies on this complex tremor network are warranted

Cortical representation of different motor rhythms during bimanual movements

The cortical control of bimanual and unimanual movements involves complex facilitatory and inhibitory interhemispheric interactions. We analysed the part of the cortical network directly related to the motor output by corticomuscular (64 channel EEG–EMG) and cortico-cortical (EEG–EEG) coherence and delays at the frequency of a voluntarily maintained unimanual and bimanual rhythm and in the 15–30-Hz band during isometric contractions. Voluntary rhythms of each hand showed coherence with lateral cortical areas in both hemispheres and occasionally in the frontal midline region (60–80 % of the recordings and 10–30 %, respectively). They were always coherent between both hands, and this coherence was positively correlated with the interhemispheric coherence (p < 0.01). Unilateral movements were represented mainly in the contralateral cortex (60–80 vs. 10–30 % ipsilateral, p < 0.01). Ipsilateral coherence was more common in left-hand movements, paralleled by more left–right muscle coherence. Partial corticomuscular coherence most often disappeared (p < 0.05) when the contralateral cortex was the predictor, indicating a mainly indirect connection of ipsilateral/frontomesial representations with the muscle via contralateral cortex. Interhemispheric delays had a bimodal distribution (1–10 and 15–30 ms) indicating direct and subcortical routes. Corticomuscular delays (mainly 12–25 ms) indicated fast corticospinal projections and musculocortical feedback. The 15–30-Hz corticomuscular coherence during isometric contractions (60–70 % of recordings) was strictly contralaterally represented without any peripheral left–right coherence. Thus, bilateral cortical areas generate voluntary unimanual and bimanual rhythmic movements. Interhemispheric interactions as detected by EEG–EEG coherence contribute to bimanual synchronization. This is distinct from the unilateral cortical representation of the 15–30-Hz motor rhythm during isometric movements

Cerebral pressure passivity in newborns with encephalopathy undergoing therapeutic hypothermia

We extended our recent modification of the power spectral estimation approach to quantify spectral coherence. We tested both the standard and the modified approaches on simulated data, which showed that the modified approach was highly specific and sensitive to the coupling introduced in the simulation while the standard approach lacked these features. We also applied the modified and standard approaches to quantify the pressure passivity in 4 infants receiving therapeutic hypothermia. This was done by measuring the coupling between continuous cerebral hemoglobin differences and mean arterial blood pressure. Our results showed that the modified approach identified a lower pressure passivity index (PPI, percent time the coherence was above a predefined threshold) than the standard approach (P = 0.0027)

Mitigating the effect of non-stationarity in spectral analysis-An application to neonate heart rate analysis

In order to mitigate the effect of non-stationarity in frequency domain analysis of data, we propose a modification to the power spectral estimation, a widely used technique to characterize physiological signals. Spectral analysis requires partitioning data into smaller epochs determined by the desired frequency resolution. The modified approach proposed here involves dividing the data within each epoch by the standard deviation of the data for that epoch. We applied this modified approach to cardiac beat-to-beat interval data recorded from a newborn infant undergoing hypothermia treatment for birth asphyxia. The critically ill infant had episodes of tachyarrhythmia, distributed sporadically throughout the study, which affected the stationarity of the heart rate. Over the period of continuous heart rate recording, the infant’s clinical course deteriorated progressively culminating in death. Coinciding with this clinical deterioration, the heart rate signal showed striking changes in both low-frequency and high-frequency power indicating significant impairment of the autonomic nervous system. The standard spectral approach failed to capture these phenomena because of the non-stationarity of the signal. Conversely, the modified approach proposed here captured the deteriorating physiology of the infant clearly

The effect of respiratory oscillations in heart rate on detrended fluctuation analysis

Characterization of heart rate using detrended fluctuation analysis (DFA) is impeded by respiratory oscillations. In particular, the short-term exponent measured from 15 to 30 beats is compromised in the DFA. We reconstruct respiratory signal from electrocardiograms and attenuate the respiratory oscillation in the heart rate using a frequency-dependent subtraction approach. We validate this method by applying it to an electrocardiogram signal simulated using a coupled differential equation with the respiratory oscillation modelled using a sine function. The exponent estimated using the proposed approach agreed with the exponent incorporated in the model within a narrow range. In contrast, the exponent obtained from the raw data deviated from the expected value. Furthermore, the exponents obtained for the raw heart rate are smaller than the exponents obtained for the respiration oscillation attenuated heart rate. We apply this approach to heart rate measured from 12 preterm infants that were being treated for prematurity related complications. As observed in the simulated data, we show that compared to the raw heart rate, the respiratory oscillation attenuated heart rate shows higher short-term exponent (p < 0.001)

Effects of globalization on geography education in universities in Turkey

Küreselleşme en basit tanımıyla uluslararası ilişkilerin, iletişim ve ulaşım teknolojilerinin gelişmesiyle mal, hizmet, bilgi ve insanın dünya çapındaki hareketliliğinde meydana gelen yaygınlaşmadır. Yer ile ilgili ilk genellemelerin yapılması (ilk dünya haritasının çizilmesi, coğrafi keşifler vb.) ile küreselleşmenin başladığı ve sanayi devrimi ile ivme kazandığı söylenebilir. Ancak küreselleşmeyi asıl önemli yapan 1980?li yılların başlarından beri uluslar arası ilişkilerin (ekonomik, siyasi kültürel vb.) gelişmesi, üretim, ulaşım ve iletişim teknolojilerinde meydana gelen hızlı gelişmelerin sonucunda küresel boyutta yaşanan değişimdir._x000B_Küreselleşmenin en fazla etkili olduğu alanlardan biri de eğitim sektörüdür. Yetiştirilecek bireylerin küresel etkilere ayak uydurması gereklidir. Küresel değerleri kavrayabilen, ulusal değerleri koruyan bireylerin yetiştirilmesi eğitim faaliyetleri ile gerçekleştirilebilmektedir._x000B_Küreselleşmenin üniversitelerimizdeki coğrafya eğitimi üzerinde de kaçınılmaz etkileri olmuştur. Osmanlı Devletinde cılız da olsa başlayan bu etkiler Cumhuriyetin kurulması ve İkinci Dünya Savaşının başlamasıyla ilerlemeye başlamıştır. Küresel boyutta 1980?li yıllardan itibaren uygulanan siyasi ve ekonomik politikalar küreselleşmenin coğrafya bölümlerimiz üzerindeki etkilerini daha da arttırmıştır. 1990?lı yıllardan günümüze soğuk savaşın sona ermesi ve ülkemizin Avrupa Birliğine girme çalışmalarının hız kazanması ile yeni bir boyut kazanmıştır._x000B_Ülkemiz üniversitelerinde coğrafyanın tarihsel gelişimi ve kuruluşu, eğitim programları, akademik personel, akademik coğrafya yayınları, ders araç gereçleri, coğrafya eğitim ve öğretiminde internet kullanımı, yabancı dil öğrenimi, yabancı üniversitelerin coğrafya bölümleri ile işbirliği gibi alanlarda küreselleşmenin etkilerinin daha fazla olduğu görülmektedir. Ancak coğrafya bölümlerinin yapısı, akademik coğrafya dergileri, coğrafya mesleği gibi alanlarda küreselleşmenin daha az etkili olduğu anlaşılmaktadır._x000B_Küreselleşmenin etkilerinden üniversitelerimizin her bir coğrafya bölümü kendilerine özgü koşuları ile etkilenmektedir. Küreselleşmenin üniversitelerimizdeki coğrafya eğitimi üzerine etkilerine odaklanarak gerçekleştirilen bu çalışma ile küreselleşmenin üniversitelerimizdeki coğrafya eğitimi üzerine etkileri ortaya konulmaya çalışılmaktadır. The simplest definition of globalization of international relations, communications and transportation technology to the progress of goods, services, informations and human commonly occurring in the worldwide mobility. The first place to make generalizations of (the first to draw the world map, geographical discoveries, etc..) And globalization and the industrial revolution began with the impetus it can be said. However, globalization actually makes important since the early 1980s, international relations (economic, political, cultural, etc..) Development, production, transportation and communication technologies developments occurring as a result of rapid changes in global dimension is._x000B_The most effective area of globalization is one of the education sector. Individuals will be trained to keep pace with global effects is required. Global values can comprehend, national values that protect individuals' upbringing and education activities can be carried out. Therefore, inter-university cooperation and student exchange programs, development of teaching staff has been implemented. Thus, our education system to provide global integration and global minimization of adverse effects has been to provide._x000B_Effects of Globalization had an inevitable impact on our universities geography education. Although the Ottoman Empire at the beginning of this puny impact on the establishment of the Republic and the start of the Second World War began to increase. Applied at a global level since the 1980s political and economic policies of globalization and the impact of geography departments has further increased. 1990s to today the end of the cold war and our country's entry into the European Union to accelerate efforts gained a new dimension._x000B_At the universities of our country's geography and historical development organizations, educational programs, academic personnel, academic geography publications, course tools, geography education and training in the use of the internet, foreign language learning, foreign universities with geography departments cooperate in areas such as effects of globalization is more than can be seen. However, part of the structure of geography, geography of the academic journals, professional areas such as geography of globalization is understood to be less effective._x000B_Effects of globalization on the our universities geography departments each with its own specific conditions are affected. Effects of globalization on education geography by focusing in our universities conducted this study in our universities and globalization effects on geography education is trying to reveal