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A method of ERA using the Vertex potential is presented which is entirely objective. The result is given by means of a statistical evaluation which is derived automatically. The method is based on pattern analysis of the V-potential, the technique relying essentially on analysis of the phase spectrum of the appropriate Fourier components.
A statistical test of the brain stem auditory-evoked potential (BAEP) detection is presented. The data were collected by averaging groups of 200 sweeps in order to obtain a set of group averages. The synchrony measure (SM), which represents the degree of reproducibility for group averages, is used as a statistical measure and is calculated from the phase variance for selected Fourier components of the group averages. The sensitivity of the test was demonstrated on 375 normal BAEPs with different stimulus intensities (45, 60, 75 dB SL) from both the ipsilateral and contralateral recordings, and on 82 BAEP recordings in the absence of stimulus. In all 375 cases of normal BAEPs the SM exceeds the threshold level while in the absence of stimulation the SM was below the threshold level. The clinical usefulness of the test was demonstrated on 22 patients with tumors of the posterior fossa. The absence of the BAEP was detected in 21 patients. In 12 out of 13 patients with lateralized tumors (acoustic neuromas), absence of the BAEP was noted for stimulation of the affected ear.
In this study, twenty four albino rats, weighing between 180 and 200 g were tested. One half was fed with a diet containing 1% cholesterol for 12 weeks and the other half was fed with a normal lab diet for the same period. After the experimental period, the plasma cholesterol level in the diet group was 134.04 +/- 21.11 mg/dl compared with the control group 72.72 +/- 10.5 mg/dl. In the two groups, SEPs were recorded from central (Cz) referenced to frontal (Fz) following left posterior tibial nerve (PTN) stimulation. Amplitude spectra of SEPs were computed by Fast Fourier Transform (FFT) algorithm. Their amplitude maxima were found to occupy the frequency bands of 1-3.5, 4-5, 6-7, 8-10, 11-12, 13-20, 20.5-36 and 36 Hz and above. The decibel (dB) values of the maxima were statistically lower for hypercholesterolemia than for the normals in the all the frequency bands.
EEG recordings during spontaneous sleep were obtained in 50 children from 18-30 months of age (27 boys, 23 girls). Twenty five children were classified as high risk (HR) and twenty five as low risk (LR), taking into account social and cultural disadvantages. Absolute power (AP) and relative power (RP) for delta, theta, alpha and beta bands were computed. ANOVAS assessing the main effects of risk and sex as well as their interactions were performed. HR showed significantly more delta AP than LR, while LR had higher values of alpha AP than HR. Values of RP were significantly different in alpha and beta bands in Fp1, Fp2, O1 and O2. LR with more alpha and beta RP. Risk/sex interactions were only observed in delta AP in T5 and T6. Differences were more prominent in HR boys. These results suggest a maturational lag of the brain in high risk children.
Visual event-related potentials (ERPs) were studied in twenty hypercholesterolemic (HC) patients and twenty age-matched healthy controls. ERPs were recorded in two different experimental conditions that the target stimulus (red light) was counted (Test 1) or uncounted (Test 2). Amplitude spectra of ERPs were computed by transient response-frequency characteristics (TRFC) method. Their maxima were found to occupy the frequency bands of 1-2, 3-4, 5-7, 8-12, 13-20, 20.5-32 Hz. The amplitude mean (decibel) of 1-2 and 3-4 frequency bands were decreased in Test 2 compared to Test 1 in the control group, but no significant amplitude differences were found between Test 1 and Test 2 in the HC group.
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A practical and portable method is described to analyze the sound spectra of coughs. The system is based upon a personal computer and simultaneously collects the sounds of cough heard both at the mouth and through the chest wall together with the airflow at the mouth produced during the cough. Subsequent analysis produce spectrographs of the cough sound linked to the corresponding airflow. The system will be used initially to examine the effects of exercise on the sound of cough in asthma. Further study of cough spectra in this way may be useful in the management of asthma either diagnostically or in the assessment of therapeutic interventions.
In the past two years the above computerisations have been applied as a routine in over 2500 EEG recordings in our department. From the experience gained with this type of registration, processing and presentation of the EEG signals it appears that the scope of electro-encephalographic examination has been considerably extended. This is evident from the following examples 1. Communication between EEG specialists and non-EEG specialists over electro-encephalographic examination is improved considerably by means of this way of data reduction and topographical presentation. 2. As far as the discriminating power is concerned, it appears that, for example, small differences in frequency of cerebral activities in for example slight unilateral or local disorders of the circulation in the brain can be indicated by the computer analysis, even if it is invisible to the naked eye [10]. 3. Further statistical analysis of various parameters has become possible by distinguishing between normal and abnormal importance in distinguishing between normal and abnormal EEG's of one and the same patient, the difference can be indicated both objectively and quantitatively. 4. By means of electrical filing of EEG signals simultaneous with the usual paper filing, there is the possibility of applying newly developed statistical and mathematical computer programs to the stored EEG data of patients whose brain disorders have been definitively diagnosed.
The 'in vivo' impulse response of long bones was investigated with the object of assessing the reliability of data taken under various conditions. The ultimate goal of the research is to develop a non-invasive method of monitoring the healing of long bones. A spectrum analyser was developed specifically for this investigation and is presented here.
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The contents of plant vacuoles vary in different organs and with the health of the plant, but little is known of the cell-to-cell distribution of soluble organic compounds within plant tissues. Soluble fluorescent phenolic compounds can be immobilized in plant tissues using an anhydrous freeze-substitution and resin embedment process. The vacuolar fluorescence can be characterized in fluorescence photomicrographs for variations in color and intensity, or more quantitatively with spectra obtained using a microspectrofluorometer. This is demonstrated here in freeze-substituted roots and leaves of soybean. Excitation and emission spectra of individual vacuoles can be compared with spectra of pure compounds to form profiles of the varied phenolic contents of plant vacuoles. Such analyses will add an important anatomical dimension to the study of plant defense and stress responses.
The cardiovascular reactivation to a recently described videogame task i.e. a maze test was evaluated in the time and frequency-domain using finger blood pressure (BP) measurement in 25 subjects on no medication, including 6 subjects with mild hypertension. Prior to BP measures subjects completed the items of the State-Trait Anger Expression Inventory questionnaire corresponding to the trait anger and anger expression scales. The BP recording session was divided into resting, test and recovery periods. A detrending procedure was applied to each recording prior to the fast Fourier transform. Systolic BP (SBP) and heart rate (HR) were increased during the test. The mid-frequency (MF, 0.1 Hz) components of SBP and HR variability were also elevated during the stressful period. In resting conditions SBP levels of subjects with low trait anger was lower than in subjects with high trait anger (128 +/- 4 mmHg, n = 14 versus 148 +/- 4 mmHg, n = 11, P < 0.01, Student t test). Nevertheless the average SBP increase due to the stress was of similar magnitude in these two subgroups (14 mmHg). A significant negative relationship was observed between anger-out expression score and the MF SBP variation (r = 0.46, P < 0.05). A significant negative relation was found between anger-in mode of expression and the HR peak during the test (r = 0.43, P < 0.05). In conclusion, our data suggest that individuals who are often in anger-provoking situations (high trait anger) should have heightened BP. Two different patterns of cardiovascular responses (SBP variability and HR levels) were observed for the outward and inward mode of expression of anger. This may reflect a different psychological control of HR levels and BP variability.
Bone mineral density (BMD) and bone structure are very important indices for prevention of fracture. However, it is very difficult to quantify bone structure, and only a few indices for structural quantification of bone have been reported. The purpose of this research was to investigate a new index for bone structure. The subjects were 52 women aged from 20 to 85 years. Directivity index (DI) is a new index of bone structure calculated by directivity of power spectrum from radiographs of metacarpal bone using fast Fourier transform (FFT). DI was obtained by subtracting the integral power value at 0 and 90 degree directions on the x-y plane of the two-dimensional power spectrum of bone from the integral power value at a direction of 45 degrees. A significant relationship between BMD and DI was indicated by correlation coefficient. However, no significant relationship between BMD and the first moment of the Fourier power spectrum or the fractal dimension was found. There is a possibility that DI estimates a slight deformation of bone structure. In the future, we will apply DI to the prevention of fractures and osteoarthritis.
An exact diagnosis of osteoarthritis is very important to prevent deterioration of ADL (activities of daily living) of the elderly. However, it is very difficult to diagnose the stage of osteoarthritis, and only a few indices for structural quantification of osteoarthritis have been reported. The purpose of this research is to investigate a new index for the bone structure in osteoarthritis. We examined right knees of 41 women aged from 34 to 85 years. Directivity index (DI) is a new index of bone structure calculated by directivity of the power spectrum from radiographs of tibial bone using fast Fourier transform (FFT). DI was obtained by subtracting the integral power value at 0 and 90 degree directions on the x-y plane of the two-dimensional power spectrum of tibial bone from the integral power value at a direction of 45 degrees. A significant relationship between the state of the knee joint by X-ray inspection and DI was indicated by evaluation of the correlation coefficient. However, no significant relationship was found between the state of the knee joint by X-ray inspection and the first moment of the Fourier power spectrum or the fractal dimension. There is a possibility that DI can estimate slight deformation of bone structure in osteoarthritis. In the future, we will apply DI to the prevention of osteoarthritis and a deterioration of ADL in the elderly.
AIM: To evaluate the myoelectric manifestations of peripheral fatigability in patients with primary biliary cirrhosis in comparison to healthy subjects. METHODS: Sixteen women with primary biliary cirrhosis without comorbidity and 13 healthy women matched for age and body mass index (BMI) completed the self-reported questionnaire fatigue impact scale. All subjects underwent surface electromyography assessment of peripheral fatigability. Anterior tibial muscle isometric voluntary contraction was executed for 20 s at 80% of maximal voluntary isometric contraction. During the exercise electromyographic signal series were recorded and root mean square (expression of central drive) as well as mean and median of electromyographic signal frequency spectrum (estimates of muscle fatigability) were computed. Each subject executed the trial two times. EMG parameters were normalized, then linear regression was applied and slopes were calculated. RESULTS: Seven patients were fatigued (median fatigue impact scale score: 38, range: 26-66) and 9 were not fatigued (median fatigue impact scale score: 7, range: 0-17). The maximal voluntary isometric contraction was similar in patients (82, 54-115 N) and controls (87, 74-101 N), and in patients with high (81, 54-115 N) and low fatigue impact scale scores (86, 65-106 N). Root mean square as well as mean and median of frequency spectrum slopes were compared with the Mann-Whitney U test, and no significant difference was found between fatigued and non-fatigued patients and controls. CONCLUSION: No instrumental evidence of peripheral fatigability can be found in women with primary biliary cirrhosis but no comorbidity, suggesting that fatigue in such patients may be of central origin.
PURPOSE: In the aging lens, two different structural changes become progressively apparent: loss of accommodation and formation of cataract. These changes are due to different alterations in lens structure taking place on a molecular scale. METHODS: For the characterization of liquids, gels, elastic bodies and solids, dynamic mechanical analysis (DMA) represents a non-destructive macroscopic analysis method with considerable sensitivity to microscopic structural changes. Spectra of the shear compliance (reciprocal shear modulus) of human lenses at different ages were measured in a wide frequency range (1 mHz to 1 kHz). By means of computer analysis, the parameters of the involved relaxation processes and the viscous flow were determined. RESULTS: The increase in cross-linking density was correlated with the disappearance of viscous flow in the measured spectra. The accumulation of high-molecular-weight aggregates was held responsible for the shift of the lower frequency relaxation process to lower frequencies with increasing stiffness, which is likely to be correlated with a prolonged accommodation time. CONCLUSION: Dynamic mechanical analysis represents a useful method for the spectroscopic characterization and quantification of the changes in the macroscopic viscoelastic properties caused by molecular changes in cataract formation and loss of accommodation.
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