STUDIES OF SOLVENT EXTRACTION AND SUPPORTED LIQUID MEMBRANE WITH REACTIVE DYES FROM AQUEOUS SOLUTIONS USING ALIQUOT 336 AS CARRIER

The liquid-liquid extraction (LLE) and supported liquid membrane (SLM) studies of reactive dyes namely Gold Yellow (GYHE-R) and Reactive Green HE 4BD (RGHE-4BD) from aqueous solution using Aliquot 336 as the carrier has been investigated. Polytetrafluoroethylene (PTFE) membrane with 0.5 μm pore size has been used after impregnated with Aliquot 336 in dichloromethane. In liquid liquid extraction the following parameters had been optimized; pH of feed, diluent, carrier , strip and dye concentration and the same parameters have been applied to supported liquid membrane (SLM) study to transport dye from aqueous solution.The main advantages SLM study is; the extraction and stripping as single stage process and low consumption of carrier in the membrane phase compared to the solvent extraction process. The other parameters such as transport time, stirring speed and mechanism of dye transport has also studied by SLM. The percentage of transport of dye and flux rate increases with increasing time. The stability of membrane is satisfactory over 5 days

Relation between post-movement-beta-synchronisation and corticomuscular coherence [Abstract]

Objective: To analyse post-movement-beta-synchronisation in the EEG and EEG-EMG coherence simultaneously. Background: The mechanisms and function of EEG synchronistion in the beta-band after the end of a short movement is not clear. The corticomusucular coupling during isometric muscle contractions occurs in the same beta-band. It is unclear however, if these two features of cortical motor physiology are related. Methods: 64-channel EEG was measured simultaneously with surface EMG of the right FDI-muscle in 11 healthy volunteers. Subjects kept a constant medium strength contraction of the FDI-muscle during the entire experiment. Superimposed on this they performed repetitive self-paced brisk short contractions. Time-frequency analysis including coherence over time was performed with respect to the onset of the brisk movements and averaged for 40 contrcations in each subject. Results: Post-movement-beta synchronisation (PMBS) was found in the contralateral electrodes C1, C3 and C5 with a maximum 1-2.5sec. after the brisk movements in the frequency range between 16 and 27 Hz for all the subjects. In 9 of the subjects there was coherence between the EEG recorded from these electrodes and the FDI in the same frequency range as the PMBS and with the maximum occuring at the same time. The other two subjects did not show any corticomuscular coherence. Conclusions: Post-movement-beta-synchronisation coincides with corticomuscular coherence in the same frequency band. Thus PMBS is not merely a cortical phenomen but seems to involve the whole corticomuscular system, possibly reflecting recalibration after brisk movements

Network for parallel gamma synchronizations during upper limb movement [Abstract]

Objective: Our aim was to identify the sources of parallel gamma synchronizations (GS) and analyze the direction of information flow in their network, at the beginning of simple and combined upper limb movements. Background: GS at the onset of movements may promote the processing between functionally related cortico-subcortical neural populations. Methods: We measured 64-channel EEG in 11 healthy volunteers; surface EMG detected the movements of the dominant hand. In Task1 subjects kept a constant medium-strength contraction of the first dorsal interosseus muscle and superimposed on this they performed a repetitive voluntary self-paced brisk squeeze of an object. They executed brisk contraction in Task2 and constant contraction in Task3. Time-frequency analysis of the EEG signal was performed with multitaper method. GS sources were identified in five frequency bands (30-49Hz, 51-75Hz, 76-100Hz, 101-125Hz and 126-150Hz) with the beamformer inverse solution dynamic imaging of coherent sources by taking the EMG as the reference signal. The direction of information flow between the sources was estimated by renormalized partial directed coherence for each frequency band. To identify significant connections, the data driven surrogate test and the time reversal technique was performed. Results: The first three sources in consecutive order in each movement task, in every frequency band, were as follows: contralateral primary sensorimotor cortex (S1M1), dorsolateral prefrontal cortex (dPFC) and supplementary motor cortex (SMA). Gamma activity was detected in narrower low- and high-frequency bands in the contralateral thalamus (TH) and ipsilateral cerebellum (C), in all three tasks. In the combined Task1 additional low gamma activity appeared in the contralateral posterior parietal cortex (PPC). In every task, S1M1 had efferent information flow to the SMA and the dPFC; the latter had no afferent relation to the network. S1M1 and SMA had a bidirectional connection with the TH, and the C. Afferent information flow was detected from the PPC to the SMA and bidirectional flow between PPC and the TH, in the combined Task1. Conclusions: The same network could be identified for the parallel gamma synchronizations in the tasks; it was complemented by the PPC in the combined Task1. S1M1 drove the other cortical sources and had afferent activity from the TH and the C, which activated in variable frequency bands in the tasks

Cortical representation of voluntary and non-voluntary motor rhythms [Abstract]

Background: Coupled bilateral cortical activity seems to be the basis for intermanual coordination, but its direct relation to the peripheral bimanual movements is still unclear. Methods: We analyzed corticomuscular coherence between 64-channel EEG and bilateral hand/finger extensor and flexor EMG and intermuscular coherence between left and right muscle activity in 18 healthy subjects during unilateral and bilateral fast rhythmic hand/finger movements and isometric contractions on both sides. Results: Partial coherence between two separated coherent areas and muscle and corticomusuclar/cortico-cortical delays were calculated. Bilateral voluntary rhythms of each hand showed coherence with lateral cortical areas on both sides in 60-80% of the recordings and occasionally with the frontal midline region (10-30%). They were always coherent between both hands. Unilateral rhythmic movements were represented in the ipsilateral cortex in only 20%-30% of the recordings tending to be more frequent with the left hand, paralleled by more frequent left-right muscle coherence. Partial corticomuscular coherence was most often abolished (p� 0.05) when the cortical signal contralateral to the coherent muscle was used as the predictor indicating that the ipsilateral and occasional frontomesial connection with the muscle was mainly indirect via the contralateral cortex. Cortico-cortical delays showed mainly bidirectional interaction at the movement frequency and were bimodally distributed ranging between 1-10 ms and 15-30 ms indicating direct cortical and subcortical routes. Corticomuscular delays ranged mainly between 12-25 ms indicating fast corticospinal projections, and musculocortical feedback showed similar delays. These corticomuscular delays were not significantly different for the 15-30 Hz coherence encountered in 60-70% of the recordings during isometric contractions. However this involuntary corticomuscular rhythm was strictly unilaterally represented and did not show coherence between left and right muscles. Conclusions: We conclude that there is a fundamental difference between the complex bilateral cortical network representing and controlling a voluntary motor rhythm and the cortical representation of non-voluntary 15-30 Hz rhythm as well as pathological non-voluntary rhythms likeorganic tremors

Differentiating Parkinson's disease from advanced essential tremor using EMG [Abstract]

Objective: The primary objective of this study is to find out the appropriate spectral parameter from the electromyography (EMG) signals which quantitatively classify PD from ET tremor. Background: Essential tremor (ET) and the tremor in Parkinson's disease (PD) are the two most common pathological tremor forms encountered in clinical practice. Differential diagnosis between the two tremors is usually achieved clinically. There is a certain overlap in the presentation of these tremor forms while the clinical differentiation on purely clinical grounds might be challenging. Methods: EMG recordings on the more affected side of 194 age (60.84 ± 8.9 years) and sex matched (M=120; F=74) ET and PD patients were analyzed. Postural tremor was recorded from the more affected side, while subjects extended their hands and fingers actively to a 0 ° position with the resting forearm. This posture was held against gravity, and in this condition the tremor was recorded for a period of 30 seconds. The parameters from the power spectra of the EMG were tremor frequency, peak power, number of harmonic peaks, waveform asymmetry (autocorrelation decay), mean peak power of all harmonic peaks, coherence (antagonistic muscles), frequency-frequency coupling, phase-phase coupling and power-power coupling were estimated on the basic and harmonic frequencies. The reliable parameter for the classification was quantified with a support vector machine (SVM) classifier (50% training; 50% testing). Results: Tremor frequency, peak power, number of harmonic peaks showed less than 50% classification accuracy for the testing data. Whereas mean peak power of all harmonics showed 93% classification accuracy for the discrimination (PD>ET), frequency-frequency coupling showed 95% (ET>PD), phase-phase coupling showed 96% (ET>PD), power-power coupling showed 98% (PD>ET) respectively. Conclusions: The relation between the basic and harmonics peak frequencies play a major role in distinguishing ET from PD tremor. The mean peak power of all harmonics and the three coupling estimates are applicable measures to separate by the aid of artificial learning algorithms clinical difficult entities of ET from PD tremor cases with a very high reliability

Identifying seizure onset zone and epileptic networks with the dynamic imaging of coherent sources [Abstract]

Purpose: In the presurgical evaluation of children with refractory focalepilepsy the main difficulty is to locate the exact point of seizure onset.The aim of this study was to characterize the areas of seizure onset as wellas the epileptic network involved in seizure propagation usingDynamicimaging of coherent sources (DICS)of ictal EEGs. Method: DICS is an inverse solution in the frequency domain whichdescribes neuronal networks and coherence of oscillatory brain activityby applying a spatial filter (Gross et al. PNAS 2001; 98:694–699). In 15children with refractory focal epilepsy, typical seizures were selectedfrom the EEGs recorded during the presurgical evaluation. For every sei-zure, two data sets of 10 s duration were extracted: one EEG segmentcontained the seizure onset and the other segment included the middlepart of the seizure. For both segments, the frequency range was definedand analyzed with DICS. The brain area with the strongest power in thecorresponding frequency range was defined as a reference region and itscoherence with the entire brain was computed using DICS. The result ofthe reference region was compared with the electroclinical localizationof seizure onset as well as with the postoperative resection site to deter-mine concordance. Results: For the beginning of the seizure, a good concordance betweenresults of the DICS localization and postoperative outcome was achievedin all 15 patients. The analysis of seizure propagation revealed an epilep-tic network which resembled reverberation of epileptic activity betweendifferent brain areas. Conclusion: DICS may be a useful tool to define the seizure onset zoneand study epileptic networks

Effects of ON and OFF subthalamic nucleus-DBS on prefrontal cortex activation during a cognitive task: an fNIRS study

Subthalamic nucleus (STN) deep brain stimulation (DBS) therapy is an effective treatment for the appendicular motor symptoms of Parkinson’s disease (PD). The STN contains multiple segregated circuits subserving motor, cognitive and mood functions through distinct connectivity to cortical regions. Therefore, we examined prefrontal cortical (PFC) effects of “ON” and “OFF” STN-DBS on executive function (Go/NoGo) using functional near-infrared spectroscopy (fNIRS). Methods Out of 8 PD STN-DBS patients, we present here preliminary analysis of a male (62y) PD patient with bilateral STN-DBS (unipolar, 180Hz, 3.5V). The patient was tested after 12h withdrawal of dopamine medications in both an “OFF” and “ON” DBS session separated by 30min. The subject performed a computerised GoNoGo task with 3 alternating Go/NoGo blocks of 30s duration (20 trials/block) interspersed with 30s rest. Reaction time (RT) and accuracy (omission-Om and commission-Cm errors) results were the average of the 3 Go/NoGo blocks. During performance of the Go/NoGo blocks, changes in oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin concentrations were measured by a fNIRS system (Oxymon MkIII, Artinis Medical Systems) covering the bilateral PFC regions. Results/Discussion Clinical motor performance (UPDRSIII) improved from OFF (31) to ON (20). RT during Go and NoGo was ∼40ms faster in OFF (460 and 364ms) than ON (516 and 407ms). Furthermore, the NoGo condition increased misses (Om) in ON (7%) than OFF (0%); while false alarms (Cm) were similarly increased in ON (27%) and OFF (30%). The Go and NoGo conditions increased bilateral PFC activation (i.e., increase in O2Hb and decrease in HHb). However, there was a general decrease in PFC activation in OFF relative to ON, and this was more obvious in Go than NoGo (see Fig. 1) Conclusion These preliminary results indicate that STN-DBS modulates neurovascular responses in the bilateral PFC that are associated with response inhibition

Effective use of microelectrode recording for the implantation of deep brain electrodes into the nucleus subthalamicus in advanced Parkinson's disease [Abstract]

Objective: For electrode implantation into the STN in Parkin-son’s disease most DBS centers use microelectrode recording (MER)with multiple trajectories. The aim of the study is to identify MERpatterns to predict optimal electrode position and to keep clinicaltesting as short as possible in order to reduce operation time andadverse events. Background: There is an ongoing debate whether MER is associ-ated with higher operation risks and time-consuming or leading to asignificant better clinical outcome. Here, we focus on correlationsbetween background activity and firing rate to predict optimal elec-trode placement. Methods: 10 patients with advanced PD underwent bilateral STNDBS operation. Recording was done simultaneously for 3–5 micro-electrodes using a ben-gun for multiple trajectories. MER data wererecorded and analyzed postoperatively using spike2VRand wave_clusVRfor segmentation and spike sorting. The overall mean amplitude wasdetermined for each patient separately for firing rate and backgroundactivity to define an individual threshold and the needles with the fir-ing rate and background activity above this threshold was selected. Results: In 8 out of 10 patients the permanent electrode wasimplanted in the trajectory of the microelectrode with the highestbackground activity compared to all other microelectrodes, in the other 2 patients a neighbouring trajectory was chosen because of lowthresholds for side effects. The postoperatively chosen active contactof the permanent electrode was in 70% in the place of the highestfiring rate. Conclusions: MER in implantation of electrodes into the STN isvery helpful to predict the optimum stimulation place analysingbackground activity and firing rate. Finding a good ratio of effectand threshold for side effects at that place further clinical testingmight be useless and the permanent electrode could be implanteddirectly. This helps to save operation time and might reduce adverseevents, e.g. haemorrhage und infections

PB15. Neurophysiological biomarker for the clinical development of tuberous sclerosis [Abstract]

Aim To investigate the neuronal networks in children with tuberous sclerosis complex (TS) undergoing treatment with Everolimus. Methods Sleep and wake electroencephalography (EEG) before and one year after the start of the treatment with Everolimus were investigated in 13 patients with TS. To investigate functional and effective connectivity within the network generating the delta and theta activity in the background sleep and wake EEG, the methods of dynamic imaging of coherent sources (DICS) and renormalized partial directed coherence (RPDC) were applied. Results Sources before the treatment. Independent of location of the tubera and severity of epilepsy, delta activity in the background EEG pattern in patients with TS was associated with the sources in the medial prefrontal cortex, the supplementary motor area and the putamen during sleep. Theta waves during sleep were associated with sources in the prefrontal cortex, sensory cortex, hippocampus and the thalamus. The sources of delta frequency during wakefulness were identified at the posterior parietal cortex, the parahippocampal gyrus and the Broca area. Sources at theta frequency were found at the sensorymotor cortex, the prefrontal cortex, the primary visual cortex and the thalamus at awake state. Sources after the treatment. The sources one year after the start of the therapy, for both delta and delta frequencies were located in the same areas as before, however with a significantly weaker strength of coherence. The RPDC analysis at baseline showed strong bidirectional connections between described sources. The RPDC analyses after the one year of treatment showed significantly weaker unidirectional connections within the described network. At the follow up patients were grouped in two groups; group 1: five patients with >50% reduction of seizures and spike wave index, group 2: eight patients with <50% reduction of seizures and spike wave index. Interestingly, at follow up patients from the group 1 had decreased values in absolute power of the sources, coherence values and strength of connections. Whereas, patients from the group 2 had increased values in all above mentioned parameters. Conclusion The current study described the neuronal network in children with severe epilepsies due to TS. Regardless of the locations of the tubera the DICS analyses showed a complex network of cortical and subcortical sources with strong bidirectional connections. The described network was significantly weaker after one year under the treatment with Everolimus and appears to be characteristic for the children with TS and severe epilepsy