EEG enhancement during electrosurgery using an optical fibre

The paper considers the limiting factors in EEG enhancement in the presence of electrosurgery interference and presents a design for a useful fibre-optic EEG monitoring instrument which is free from such problems as electrical shock (micro and macroshock), patient burns and susceptibility to electrosurgery interference associated with conventional EEG monitors.     

Effect on EEG responses of removing ocular artefacts by proportional EOG subtraction

Work undertaken to investigate the effect on EEG responses of ocular artefact removal by proportional electro-oculogram subtraction using the least-squares method is reported. The ocular artefact model and the least-squares approach to estimation of the model parameters and hence of the EEG waveform, including the response, are described. Results are presented to show that the response shapes become modified if ocular artefact removal is implemented recursively. This happens because the response is incorrectly treated as part of the random background EEG. The solution is to incorporate a model of the response within the ocular artefact removal algorithm. The results of tests on simulated data confirm these conclusions. The results of the incorporation of response models in removing ocular artefacts from CNV recordings are presented. Even with modelling recursive ocular artefact removal is found to modify the shape of the CNV, and so reliable results can only be obtained if the removal is implemented nonrecursively. Evidence is given that it is advisable to remove DC levels from the recorded data.     

90例小儿发热惊厥脑电图与临床预后关系

本文报告了90例发热惊厥(FC)患儿的脑电图检查结果,认为对FC患儿的脑电图检查时间应在退热至少2周后进行;FC起病年龄低者再发率高,且脑发育成熟前起病的FC患儿脑损伤轻严重;对于某些患者,引起FC的体温逐渐降低,这些患儿转为无热惊厥(癫痫)的可能性明显增高;家族史不仅会影响FC的发病倾向而且会影响FC的复发及转归。     

Potent depressant effects of adenosine analogs on hippocampal slow-wave activity in the unanesthetized rat

Summary Adenosine and its analogs have previously been shown to exert a depressant effect on several measures of hippocampal excitability in the hippocampal slice and intact anesthetized preparation. In the present report, we examined the effects of intraventricular injections of adenosine analogs on hippocampal slow-wave activity in the freely moving rat. Each of three adenosine analogs— 5-N-ethylcarboxamidoadenosine (NECA) and N⁶-(phenylisopropyl) adenosine (L- and D-PIA) — were found to strongly suppress hippocampal electroencephalographic (EEG) activity. For instance, low doses of NECA (0.5 g) produced an 80–90% decrease in the amplitude of the hippocampal EEG. NECA was approximately 20-fold more potent than L-PIA, and L-PIA was twice the potency of D-PIA. In separate experiments in the anesthetized rat, NECA and L-PIA were found to block completely the activation of the hippocampal theta rhythm elicited with brainstem stimulation. The effects of adenosine analogs on both the hippocampal EEG and theta rhythm were very effectively reversed with methylxanthine, 8-para-sulphophenyl-theophylline (8-PSPT). The present findings demonstrate that adenosine analogs exert a powerful depressant effect on the hippocampal EEG in the natural unanesthetized state, and suggest that changes in the levels of endogenous adenosine may play a significant role in modulating the normal activity and function of the hippocampus.This work was supported in part by National Science Foundation grant BNS-8403544 to RPV     

A statistical analysis and comparison of soma diameter spectra for classical neurones from different regions of the cat retinal ganglion cell layer

Multimodal soma diameter spectra for neurones of the cat retinal ganglion cell layer have been represented by three subpopulations of independent, normal diameter distribution. Recurrent computation according to the technique of Vibert and Caille (1978) has extracted best fit populations for samples from various regions of central and peripheral retina. The model subpopulations from all these regions did not differ significantly in their relative proportions or variance. Significant progressive variation between subpopulations representing different regions of retina were observed only in the mean diameter of the and mode cells. The parameters of the mode population were statistically uniform across the retina. The cat retina thus appears to be more homogeneously organized than has been suggested elsewhere.     

Sensation Seeking and Cortical Augmenting-Reducing

The experiment was designed to establish the relationship between the Sensation Seeking Scales (SSS) and cortical augmenting-reducing. Forty-nine male undergraduate Ss were used. Ss were presented with five intensities of light flashes in randomly presented blocks of trials at each intensity. Averaged evoked response (AER) amplitudes were measured at each intensity of light. Augmenting-reducing was measured for each S as the slope of the relationship between stimulus intensity and amplitude of response. This slope measure correlated very significantly (r= .59) with the Disinhibition subscale of the SSS and positively, but not significantly, with other subscales. Comparing the low and high scorers on the Disinhibition scale, a significant interaction between groups and stimulus intensities was found but no main effects of stimulus intensity or groups were found. The high Disinhibitors did not differ from the lows at the low stimulus intensities but did differ significantly at the highest intensity where the lows showed a marked reducing tendency. The results show an interesting convergence between the Disinhibition type of sensation seeking, manic tendencies, and the AER.     

Two Measures of Auditory Evoked Response Amplitude and Their Relationship to Background EEG

All-night sleep EEG and auditory evoked responses (AERs) were recorded in 8 children whose ages ranged from 27 to 60 months. EEG intensity was measured by means of a Drohocki-type integrator. Two measures of evoked response amplitude were calculated: the peak-to-peak amplitude of the P₂N₂ component, and a multiple-component amplitude measure of the first 500 msec of the response. Both amplitude measurements were found to correlate well with each other. Changes in EEG intensity between subjects were not correlated with changes in AER amplitude, but a number of correlations between AER amplitude and EEG intensity were found within individual subjects. Further analysis suggested the latter finding might be a result of the presence of “unaveraged’EEG in individual AER plots. It is concluded that little correlation exists between AER amplitude and EEG intensity in children during sleep.     

Localization of Somatosensory Evoked Potentials in Primary Somatosensory Cortex: A Comparison Between PCA and MUSIC

The aim of this study was to test source modeling strategies for EEC-data from a clinical group of amputees. The experimental conditions (measuring time, age and condition of the patients) resulted in low quality EEC-data. Noise reduction was achieved by a principal component analysis (PCA) and a multiple signal classification (MUSIC). A comparison of the results of these two methods with traditional signal handling yielded superior results for the MUSIC algorithm.