Electroencephalographic correlates of paced breathing.

Multichannel EEG, respiration, blood pressure and ECG were recorded during paced breathing at five frequencies in 18 subjects in order to elucidate the effects of paced breathing on power changes in alpha, beta and theta bands, and on rhythmical variability of these parameters. Mean power in the beta band and low-frequency beta power variability (0.12-0.04 Hz) increased during paced breathing at frequencies of 0.25 and 0.20 Hz. The total variability of alpha power in the right parietal and occipital electrodes decreased during paced breathing at 0.1 Hz compared with initial rest. The results point to increased cortical excitability during paced breathing at eupnoeic frequencies and to diminished cortical sensitivity to desynchronizing influences during paced breathing at 0.1 Hz.

Periodic amplitude modulation of EEG.

Time variation of the EEG spectral parameters was analyzed during a 10 min resting period in 40 healthy subjects. Spectral band powers over the theta and alpha bands were calculated for each non-overlapping 2.5 s long EEG segment. The time variation of the band powers was further analyzed by computing the power spectra. The results showed that both theta and alpha band powers oscillate at an average frequency 0.024 Hz and 0.057 Hz. This indicates, that the background EEG activity is modulated by periodical slow components. We hypothesize that this modulation reflects spontaneous periodic changes of cortical excitability with control at the brainstem level.

Kapalabhati--yogic cleansing exercise. II. EEG topography analysis.

Topography of brain electrical activity was studied in 11 advanced yoga practitioners during yogic high-frequency breathing kapalabhati (KB). Alpha activity was increased during the initial five min of KB. Theta activity mostly in the occipital region was increased during later stages of 15 min KB compared to the pre-exercise period. Beta 1 activity increased during the first 10 min of KB in occipital and to a lesser degree in parietal regions. Alpha and beta 1 activity decreased and theta activity was maintained on the level of the initial resting period after KB. The score of General Deactivation factor from Activation Deactivation Adjective Checklist was higher after KB exercise than before the exercise. The results suggest a relative increase of slower EEG frequencies and relaxation on a subjective level as the after effect of KB exercise.

Kapalabhati--yogic cleansing exercise. I. Cardiovascular and respiratory changes.

We studied cardiovascular and respiratory changes during yogic breathing exercise kapalabhati (KB) in 17 advanced yoga practitioners. The exercise consisted in fast shallow abdominal respiratory movements at about 2 Hz frequency. Blood pressure, ECG and respiration were recorded continuously during three 5 min periods of KB and during pre- and post-KB resting periods. The beat-to-beat series of systolic blood pressure (SBP) and diastolic blood pressure (DBP), R-R intervals and respiration were analysed by spectral analysis of time series. The mean absolute power was calculated in three frequency bands--band of spontaneous respiration, band of 0.1 Hz rhythm and the low-frequency band greater than 15 s in all spectra. The mean modulus calculated between SBP and R-R intervals was used as a parameter of baroreceptor-cardiac reflex sensitivity (BRS). Heart rate increased by 9 beats per min during KB. SBP and DBP increased during KB by 15 and 6 mmHg respectively. All frequency bands of R-R interval variability were reduced in KB. Also the BRS parameter was reduced in KB. The amplitude of the high-frequency oscillations in SBP and DBP increased during KB. The low-frequency blood pressure oscillations were increased after KB. The results point to decreased cardiac vagal tone during KB which was due to changes in respiratory pattern and due to decreased sensitivity of arterial baroreflex. Decreased respiratory rate and increased SBP and low-frequency blood pressure oscillations after KB suggest a differentiated pattern of vegetative activation and inhibition associated with KB exercise.

Observations on respiratory and cardiovascular rhythmicities during yogic high-frequency respiration.

Yogic high-frequency respiration--kapalabhati (KB)--was studied in 24 subjects from a point of rhythmicity. Respiratory movements, blood pressure and R-R intervals of ECG were recorded in parallel and evaluated by spectral analysis of time series. Respiratory signals during KB were modulated by 0.1 Hz rhythm in 82% of experiments. This component was also present in R-R intervals and blood pressure during KB. Frequency (0.2-0.3 Hz) was observed in 67% of respiratory records. The presence of the component 0.2-0.3 Hz in respiration was dependent on resting respiratory frequency. This frequency component was reduced in R-R intervals but increased in blood pressure during kapalabhati as compared to that at rest. The occurrence of both frequency components in respiration during KB supports the hypothesis about the integrative role of cardiovascular and respiratory rhythms in physiological states characterized by altered respiratory frequency.

Hathayogic exercise jalandharabandha in its effect on cardiovascular response to apnoea.

Jalandharabandha (JB) is the important constituent of apnoea (kumbhaka) in hathayogic breathing exercises. It is performed by pressing the chin into the jugular notch and creating thus the positive pressure on the neck region. The influence of JB on the heart rate and vasomotor response was studied in relationship to different lung volumes. The course of R-R intervals is highly significantly different according to the type of apnoea. JB leads to the diminution of bradycardia, but does not change the position of the maximum and minimum in comparison to the apnoea without JB. Application of JB increases the number of vasodilatations and shortens the latencies of vasodilatations, duration and amplitude of reactions. JB during breath holding decreases the vagal reflex changes and may thus work as a stabilizing component in yogic breathing exercises.

Strictly simultaneous classical eyelid conditioning in man.

Strictly simultaneous eyelid conditioning in human Ss on the one hand and forward (ISI: 0.45 s), backward (ISI: -0.45 s), and pseudoconditioning on the other hand were compared in two different experimental situations: one-session experiment (100 reinforcements, 20 isolated CS randomly interspersed), and ten-sessions experiment (20 reinforcements, 4 isolated CS in each session), UCS was a light flash (0.5 J, 20 microseconds duration), CS a tone (1000 Hz, 50 ms, 73 dB). In both the experiments, strictly simultaneous conditioning was significantly different from pseudoconditioning, but significantly less effective than forward conditioning. In the ten-sessions experiment, it was also less effective than backward conditioning, while in the one-session experiment, it did not differ from backward conditioning. Statistical mixture decomposition method applied to the one-session- and the ten-sessions- experimental samples of individual acquisition curves resulted into the division of both samples into 4 subgroups according to the trend of acquisition curves. A significant positive association between the conditioning procedure and the distribution of individual curves into the four subgroups was found.

Spectral analysis of R-R interval variability in inspiratory breath holding in man at rest and during emotional strain.

30 young males performed inspiratory breath holdings during expectation of an aversive stimulus and at relative rest. The consecutive R-R intervals of the ECG from breath-hold trial were analysed via spectral analysis of time series. Following parameters were ascertained for each breath holding: mean R-R interval, total R-R interval variability, breath-hold time and relative variability in three spectral bands 3-8 s, 8-12 s and 12-18 s. Neither of these variables was influenced by expectation of an aversive stimulus. The data were subsequently analysed by means of multivariate analysis. Three distinct frequency components were selected according to both histogram data and multivariate analysis. Their modal periods were 5-6 s, 12 s and 16 s respectively. The 8-12 s component of R-R interval variability dominated during breath holdings. The 3-8 s band bore a negative relationship to breath-hold time.

Statistical mixture decomposition as a method for type analysis of learning curves.

A method for type analysis of learning curves, based on the statistical mixture decomposition, is described. Some critical points in current data-analytic techniques are discussed. The mathematical rationale of the new method is outlined in a brief sketch. The possibilities of the method are documented by two examples. In the first study, done on simulated lata of a known structure (N = 200, 2 classes), it was possible to distinguish, with an average performance of 82%, between two types, and to reproduce their original curves. In the second study data from experiments in classical eye-lid conditioning in man were analysed (N = 80). The decomposition procedure resulted into the classification into four groups, with pronounced inter-class differences in the course of respective learning curves. The variety of class curves ranges from a group with only few CRs (C1, N = 26), through a group with an initial increase and final decrease in CR frequency (C2, N = 16), a group with an apparently biphasic course of CR frequency (C3, N = 20), to a group with a rapid increase of CR and then stable course of CR frequency (C4, N = 18). The results are consistent with earlier findings concerning the existence of distinct types of learning curves. The problem of interpretation is briefly discussed. The method can be applied principally to any problems, where different types of time development trends of an alternative response are to be distinguished.

EEG patterns suggestive of shifted levels of excitation effected by hathayogic exercises.

Concurrent with the performance of hathayogic exercises such as Nauli, Bhastrika and Suryabhedana, three characteristic EEG patterns were identified: a "wicket" rhythm at a frequency wave of 12 to 17 Hz, recordable from para-Rolandic areas, which we have called Xi rhythm; a 26-33 Hz sinusoidal activity, confined to the mid-sagittal parietooccipital region; and paroxysmal activity localized in the lateral boundaries of parieto-temporo-occipital regions, bilaterally. - The expectation that hathayogic exercises would affect the electrical activity of circumscribed, relatively well defined areas of the brain was based on the fact that these exercises imply a strong stimulation of somatic and splanchnic receptors, the afferent impulses of which are fed into specific cortical representation areas localized for the most part around central and anterior parietal areas.

Description of an EEG pattern evoked in central--parietal areas by the Hathayogic exercise Agnisara.

Agnisara is a Hathayogic exercise consisting essentially in alternate, forceful retractions and protrusions of the abdominal wall, performed along a 20-30 s period of apnoea. In the course of series of Agnisars spindle bursts of a "wicket" EEG wave pattern developed over the para-Rolandic areas of the cerebral cortex, at frequencies around 12-13 Hz, with waxing and waning amplitudes in the range of 50 to 100 microV. These spindle-bursts, which occurred preferably during the phase of retraction of the abdominal wall, were named "Xi" rhythm (after the Greek letter X). It is the same as the one that regularly accompanies the performance on various other Hathayogic exercises. Xi spindles were recorded in linked earlobe reference derivations from areas located bilaterally midway between F-C, C-P, and P-O standard electrode positions of the 10-20 system. This EEG pattern would be considered as the expression of the central excitation, produced by the exercise's long-lasting and repeated stimulation of visceral, and somatic receptors. Thus, this activation affects mainly cortical structures with somato-visceral representation.

The course of aversive conditioning related to the excretion of catecholamines, DOPA and their oxidoreduction states.

Excretion of catecholamines, DOPA and their oxidoreduction states were studied during aversive conditioning in a 10-sitting experiment in man. Urinary samples in 3 intervals of 8 h. before respective sitting and 20, 80 and 200 minutes after the sitting. The initial unspecific phase of conditioning corresponds to an increase and decrease of catecholamine elimination characterized by a prevailing of adrenaline and noradrenaline (interpreted as the same change in level of unconditioned excitability). In the specific phase of conditioning more important participation of dopamine and probably DOPA and their metabolites were observed. The anticipatory conditioned reflex itself (manifested in urinary samples before resp. sittings) is characterized by surplus of adrenaline and noradrenaline. The results support our conception of two phases in conditioning (and generally learning) process.