Limbic autonomic arousal: its physiological classification and review of the literature

Immediate effect of chandra nadi pranayama (left unilateral forced nostril breathing) on cardiovascular parameters in hypertensive patients

Introduction:

Recent studies have reported differential physiological and psychological effects produced by exclusive right and left nostril breathing and clinical research is required to prove immediate and sustained efficacy of these techniques in various psychosomatic conditions such as hypertension (HT). The present study was designed to determine immediate effects of 27 rounds of exclusive left nostril breathing, a yogic pranayama technique known as chandra nadi pranayama (CNP) on cardiovascular parameters in patients of essential HT.

Materials and Methods:

Twenty two patients of essential HT under regular standard medical management were individually taught to perform CNP by a qualified yoga instructor with a regularity of 6 breaths/min throughout a performance of 27 rounds of CNP. Pre and post intervention heart rate (HR) and blood pressure (BP) measurements were recorded using non-invasive semi-automatic BP monitor and Students t test for paired data used to determine significant differences.

Results:

Twenty seven rounds of CNP produced an immediate decrease in all the measured cardiovascular parameters with the decrease in HR, systolic pressure (SP), pulse pressure, rate-pressure product and double product being statistically significant. Further, gender-based sub-analysis of our data revealed that our male participants evidenced significant reductions in HR and SP with an insignificant decrease in diastolic pressure, while in female participants only HR decreased significantly with an insignificant decrease in SP.

Discussion and Conclusion:

It is concluded that CNP is effective in reducing HR and SP in hypertensive patients on regular standard medical management. To the best of our knowledge, there are no previously published reports on immediate effects of left UFNB in patients of HT and ours is the first to report on this beneficial clinical effect. This may be due to a normalization of autonomic cardiovascular rhythms with increased vagal modulation and/or decreased sympathetic activity along with improvement in baroreflex sensitivity. Further studies are required to enable a deeper understanding of the mechanisms involved as well as determine how long such a BP lowering effect persists. We recommend that this simple and cost effective technique be added to the regular management protocol of HT and utilized when immediate reduction of BP is required in day-to-day as well as clinical situations.

Retino-hypothalamic-pineal hypothesis in the pathophysiology of primary headaches

Primary headaches include migraine, tension, cluster headaches, paroxysmal hemicrania and miscellaneous headaches unassociated with structural lesions. A putative role of the retino-hypothalamic-pineal (RHP) axis in the pathophysiology of primary headaches is reviewed in terms of (1) retinal dysfunction, (2) hypothalamic dysfunction and human circadian desynchrony, (3) pineal melatonin dysfunction and (4) rostral limbic dysfunction mediating the human stress response. Unified RHP hypothesis is proposed, suggesting that an acute, periodic or chronic, circadian desynchrony and dysfunction of the whole or part of the RHP axis is implicated in the pathophysiology of primary headaches. Supportive evidence for the RHP hypothesis, including recent PET studies showing changes in dorsal pons, hypothalamus and rostral limbic structures, is presented.

Brain electrocortical activity during and after exercise: A quantitative synthesis

Investigators of brain electrocortical responses to exercise have interpreted increased activity, or frontal hemispheric asymmetry, in the alpha frequency band as indicative of relaxation or a change in affect. However, few studies compared alpha activity with other frequencies and within or across hemispheres. To clarify the cumulative evidence in this area, we provide a quantitative review of the effects of exercise on brain electrocortical activity according to frequency bands and recording sites. Fifty-eight effects from 18 studies and 282 participants were retrieved. The mean effect size was moderately large (0.54 SD, 95% CI: 0.43 to 0.65) but heterogeneous. Compared to before exercise, alpha activity was greater immediately after and during exercise when expressed as absolute power but not as relative to power in other frequency bands; delta, theta, and beta activity also increased (0.38 to 0.75 SD). Effects did not differ significantly by recording sites. The cumulative evidence does not indicate that change in brain electrocortical activity after exercise is specific to alpha activity or hemispheric site.

Physiological classification of sleep-wake states: based on tri-vesicular (3V) model of the brain

A new physiological classification of sleep-wake states, based on a novel Tri-Vesicular (3V) model of the brain is proposed. The 3V model consists of an interconnected network of three primal brain vesicles, namely, right and left Arch-Encephalon (Mesencephalon + Diencephalon + Telencephalon) and one DeuterEncephalon (Metencephalon + Myelencephalon). Nine sleep-wake states are defined on the basis of the central activational index (activation and/or inhibition of the 3 brain vesicles), and the level of global arousal. Four sleep states I-IV, four wake states I-IV, and one transitional sleep-wake state, are characterized. The four sleep states correspond with the four non-REM sleep stages, the transitional sleep-wake state correlates with REM sleep, and four wake states are defined in terms of minimal, low, moderate, and high, global behavioral arousal. Three sets of data in the form of polysomnographic and aerobic exercise studies in five adult subjects, and 30 days' data of self-monitored arousal and oro-nasal breathing patterns, are provided in support of this physiological classification of sleep-wake states and the 3V brain model.