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This study was aimed to explore the sleep/wake states related cortico-pontine theta carrier frequency phase shift following a systemically induced chemical axotomy of the monoaminergic afferents within a brain of the freely moving rats. Our experiments were performed in 14 adult, male Sprague Dawley rats, chronically implanted for sleep recording. We recorded sleep during baseline condition, following sham injection (saline i.p. 1 ml/kg), and every week for 5 weeks following injection of the systemic neurotoxins (DSP-4 or PCA; 1 ml/kg, i.p.) for chemical axotomy of the locus coeruleus (LC) and dorsal raphe (DR) axon terminals. After sleep/wake states identification, FFT analysis was performed on 5 s epochs. Theta carrier frequency phase shift (Delta Phi) was calculated for each epoch by averaging theta Fourier component phase shifts, and the Delta Phi values were plotted for each rat in control condition and 28 days following the monoaminergic lesions, as a time for permanently established DR or LC chemical axotomy. Calculated group averages have shown that Delta Phi increased between pons and cortex significantly in all sleep/wake states (Wake, NREM and REM) following the monoaminergic lesions, with respect to controls. Monoaminergic lesions established the pontine leading role in the brain theta oscillations during all sleep/wake states. Serbian Ministry of Education and Science [OI173022]; NIH [AG016303]

We applied a combination of fractal analysis and Independent Component Analysis (ICA) method to detect the sources of fractal complexity in snail Br neuron activity induced by static magnetic field of 2.7 mT. The fractal complexity of Br neuron activity was analyzed before (Control), during (MF), and after (AMF) exposure to the static magnetic field in six experimental animals. We estimated the fractal dimension (FD) of electrophysiological signals using Higuchi's algorithm, and empirical FD distributions. By using the Principal Component Analysis (PCA) and FastICA algorithm we determined the number of components, and defined the statistically independent components (ICs) in the fractal complexity of signal waveforms. We have isolated two independent components of the empirical FD distributions for each of three groups of data by using FastICA algorithm. ICs represent the sources of fractal waveforms complexity of Br neuron activity in particular experimental conditions. Our main results have shown that there could be two opposite intrinsic mechanisms in single snail Br neuron response to static magnetic field stimulation. We named identified ICs that correspond to those mechanisms - the component of plasticity and the component of elasticity. We have shown that combination of fractal analysis with ICA method could be very useful for the decomposition and identification of the sources of fractal complexity of bursting neuronal activity waveforms. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Ministry of Education and Science, Republic of Serbia [OI 173027, OI 173022]

The complexity, entropy and other non-linear measures of the electroencephalogram ( EEG), such as Higuchi fractal dimension (FD), have been recently proposed as the measures of anesthesia depth and sedation. We hypothesized that during unconciousness in rats induced by the general anesthetics with opposite mechanism of action, behaviorally and poligraphically controlled as appropriately achieved stable anesthesia, we can detect distinct inter-structure brain dynamic using mean FDs. We used the surrogate data test for nonlinearity in order to establish the existence of nonlinear dynamics, and to justify the use of FD as a nonlinear measure in the time series analysis. The surrogate data of predefined probability distribution and autocorrelation properties have been generated using the algorithm of statically transformed autoregressive process (STAP). FD then is applied to quantify EEG signal complexity at the cortical, hippocampal and pontine level during stable general anesthesia (ketamine/xylazine or nembutal anesthesia). Our study showed for the first time that global neuronal inhibition caused by different mechanisms of anesthetic action induced distinct brain inter- structure complexity gradient in Sprague Dawley rats. EEG signal complexities were higher at cortical and hippocampal level in ketamine/ xylazine vs. nembutal anesthesia, with the dominance of hippocampal complexity. In nembutal anesthesia the complexity dominance moved to pontine level, and ponto- hippocampocortical decreasing complexity gradient was established. This study has proved the Higuchi fractal dimension as a valuable tool for measuring the anesthesia induced inter- structure EEG complexity. Serbian Ministry of Science and Technological Development [173022]; NIH [AG16303]

We have decided to detect the seizure brain activity induced by camphor essential oil in rats, as there are still reports of severe intoxication in humans by camphor. The experiments were performed on adult Wistar male rats. The surgery and the acute electrophysiological recordings were done under pentobarbital sodium anesthesia. Local field potentials of cerebral parietal cortex were recorded. The rats were injected by camphor essential oil (150-675 μl/kg b.w., in 1 ml of saline, i.p). We analyzed by Fast Fourier Transform the digitized electrocortical signals before and up 2-3 h after essential oil administration at the sampling rate of 256 Hz. There was a great increase of the mean total power spectra, a relative increase of the power in delta range and decreases of theta and beta ranges when seizural activity with spikes and waves of large amplitude occurred at the level of cerebral cortex 5-30 min after administration of camphor oil at doses >300 μl/kg b.w. It is necessary to investigate further the dose dependent effectiveness of each terpenoid constituent of camphor essential oil on brain activity in order to elucidate the relative safety of the usage of essential oils with these terpenoids. Odlučili smo se za istraživanje pojave epileptičnih napada kod pacova izazvanih kamforovim esencijalnim uljem jer se još uvek pojavljuju slučajevi teške intoksikacije kamforom u ljudi. Eksperimenti su izvedeni na odraslim pacovima muškog pola Wistar soja. Operativni zahvati i akutna registrovanja elektrofizioloških signala su obavljeni pod Nembutal anestezijom. Registrovani su lokalni potencijali polja parijetalnog dela kore velikog mozga. Kamforovo esencijalno ulje je pacovima intraperitonealno ubrizgavano (150-675 μl/kg, t.m. u l ml fiziološkog rastvora, i.p). Pomoću brze Furijeove transformacije analizirali smo elektrokortikalne signale pre i oko 2-3 h posle intraperitonealnog ubrizgavanja kamforovog ulja, pri frekvenciji semplovanja od 256/s. Pojavio se veliki porast ukupne snage i relativno povećanje snage u delta opsegu, a smanjenje u teta i beta opsegu kada se pojavila epileptična aktivnost kore velikog mozga - šiljci i talasi potencijala velike amplitude i to tek pri dozi kamforovog ulja većoj od 300 μl/kg, a 5-30 min po ubrizgavanju ulja. Neophodno je dalje ispitivati doznu zavisnost efekta svake od glavnih terpenskih komponenti kamforovog ulja na aktivnost mozga pacova kako bi se obezbedila relativna sigurnost upotrebe esencijalnih ulja. Projekat ministarstva br. 143021

The aim of our study was to investigate the electrophysiological effects of aluminium neurotoxicity. This animal model of neurodegenerative dementia was induced by chronic treatment of Wistarrats with aluminum chloride for 4 weeks - 2mg Al/kg, i.p, per day. Electrophysiological recordings of left and right somatosensory cortical areas of animals treated by aluminium and the control rats were done under Nembutal anesthesia. Analog to the digital one conversion of the recorded signals was performed at the sampling rate of 256 Hz. Spectral analysis of electrocortical activity during sequences of 120 s (divided in epochs of 8s) was obtained by Fast Fourier Transformation while fractal dimension (FD) of these signals was calculated by Higuchi's algorithm. The relative power spectra of cerebral activity were increased in delta frequency range and decreased in (8.1-32.0 Hz) range in aluminium treated animals compared to the controls. The average fractal dimension of electrocortical activity in aluminium treated animals was lower - 1.290 than the average fractal dimension of electrocortical activity in the control rats - 1.377. Spectral and fractal characteristics of brain activity could bean electrophysiological sign of developing neurodegenerative process similar to the Alzheimer's dementia. Predmet ovog istraživanja je bio da se elektrofiziološki prouče efekti aluminijumske neurotoksičnosti. Animalni model neurodegenerativne demencije postignut je hroničnim tretmanom Wistar pacova sa aluminium hloridom u toku 4 nedelje u dozi od 2 mg/kg aluminijuma dnevno. Elektrofiziološko registrovanje levog i desnog somatosenzornog korteksa pacova tretiranih aluminijumom i kontrolnih pacova je vršeno pod Nembutalskom anestezijom. Analogno-digitalna konverzija registrovanih signala je izvršena pri frekvenciji semplovanja 256Hz. Spektralna analiza elektrokortikalne aktivnosti u trajanju od 120s (podeljena u epohe od 8s) je izvršena Furijeovom transformacijom, a fraktalna dimenzija ovih signala je izračunata Higučijevim algoritmom. Relativni spektri snage cerebralne aktivnosti u delta frekventnom opsegu su bili povećani, a u (8.1-15.0 Hz) frekventnom opsegu su bili smanjeni kod aluminijumom tretiranih životinja u odnosu na kontrolne. Srednja fraktalna dimenzija elektrokortikalne aktivnosti kod tretiranih pacova je manja - 1,290 u odnosu na srednju fraktalnu dimenziju elektrokortikalne aktivnosti kontrolnih pacova - 1,377. Spektralne i fraktalne karakteristike mogu biti elektrofiziološki znak razvitka neurodegenerativnih procesa kao kod Alchajmerove bolesti. Projekat ministarstva br. 143021

We recorded electrocortical activity in anesthetized rats and constructed kmax new self-similar time series, applying Higuchi's algorithm. The aim of this study was to estimate value of the parameter k(max). in order to obtain fractal dimension values as an optimum measure of biosignal change. After our analysis, electrocortical activity recordings resulted in a family of curves f(k(max)). Three regions could be distinguished 2 = 30, with a smaller slope quasilinear increase. We suggest the optimum region for k(max): 8 < k(max) < 18, specifically k(max) = 8. null

Simple, complex action potentials (AP) and interspike recorded background activity (RBA) were detected and extracted from 12 rat cerebellar cortical recordings. For each recording, an averaged simple action potential (SAP) was formed. Fourier amplitude spectra of SAP and RBA were similar in all recordings. For one of the recordings, a series of RBA simulations (SBA) was generated, superimposing random SAPs, varying the superposition frequency (fsup). Average Fourier amplitude, Amp(SBA), was calculated, in order to use Amp(SBA)=f(fsup) as a calibration line for reading fsup of RBA, which is a measure of the population activity. A probability distribution for SAP intensities was derived and a family of calibration lines constructed. As all lines were linear and parallel (slope S) in log-log plots, a population activity change could be calculated as fsup2/fsup1=[Amp2(RBA)/Amp(RBA)]1/S. Jednostavni, složeni akcioni potencijali (AR) i međuspajkovna osnovna aktivnost (MOA) detektovani su i izdvojeni iz 12 registrovanih signala kore malog mozga pacova. Za svaku registraciju, formiran je usrednjeni jednostavni AR (JAR). Spektri Furijeovih amplituda JAR i MOA signala bili su slični kod svih registracija. Za jednu od registracija, superponiranjem slučajnih usrednjenih jednostavnih akcionih potencijala formiran je niz simulacija međuspajkovne osnovne aktivnosti (SOA), pri čemu je varirana frekvencija superpozicije (fsup). Izračunavana je srednja Furijeova amplituda, Amp(SBA), u cilju korišćenja Amp(SBA)=f(fsup) kao kalibracione linije za očitavanje fsup od MOA, što je mera za aktivnost populacije. Izvedena je raspodela verovatnoća za intenzitete JAR, pomoću koje je konstruisana familija kalibracionih linija. Kako su sve linije linearne i paralelne u log-log dijagramu, sa nagibom S, promena aktivnosti populacije može se izračunati kao fsup2/fsup1 =[Amp2(RBA)/Amp(RBA)]1/S. null