Respiratory Control: Central and Peripheral Mechanisms

Understanding of the respiratory control system has been greatly improved by technological and methodological advances. This volume integrates results from many perspectives, brings together diverse approaches to the investigations, and represents important additions to the field of neural control of breathing. Topics include membrane properties of respiratory neurons, in vitro studies of respiratory control, chemical neuroanatomy, central integration of respiratory afferents, modulation of respiratory pattern by peripheral afferents, respiratory chemoreception, development of respiratory control, behavioral control of breathing, and human ventilatory control. Forty-seven experts in the field report research and discuss novel issues facing future investigations in this collection of papers from an international conference of nearly two hundred leading scientists held in October 1990. This research is of vital importance to respiratory physiologists and those in neurosciences and neurobiology who work with integrative sensory and motor systems and is pertinent to both basic and clinical investigations. Respiratory Control is destined to be widely cited because of the strength of the contributors and the dearth of similar works. The four editors are affiliated with the University of Kentucky: Dexter F. Speck is associate professor of physiology and biophysics, Michael S. Dekin is assistant professor of biological sciences, W. Robert Revelette is research scientist of physiology and biophysics, and Donald T. Frazier is professor and chairman of physiology and biophysics. Experts in the field report current research and discuss novel issues facing future investigations. —SciTech Book Newshttps://uknowledge.uky.edu/upk_biology/1002/thumbnail.jp

The effect of decerebrate rigidity on intracranial pressure in man and animals

Patients with decerebrate rigidity frequently also show intracranial hypertension. The factors responsible for this effect and their inter -relationships were explored in cats and in patients with head injuries.Animals: The factors examined, separately and in combination, were elevation of central venous, intrathoracic, intra- abdominal and systemic arterial pressures. The baselines thus established were used for the investigation of the effects of these factors on the intracranial pressure (ICP) in cats which had been rendered decerebrate by focal stereotactic mesencephalic lesions.Little or no change occurred in the ICP when: 1) Rigidity was mainly unilateral. 2) Bilateral limb rigidity was extreme.Persistent elevation of ICP occurred when 1) Truncal rigidity resulted in the simultaneous elevation of the intrathoracic and intra- abdominal pressures 2) Elevation of the systemic arterial pressure occurred in the presence of defective cerebrovascular homeostasis.Human: The dynamics and management of the complex clinical problem posed by decerebrate rigidity were investigated in patients with head injuries who exhibited well -developed bi- lateral rigidity under conditions of altered cerebral elastance.Rigidity was quantified by measuring the resonant frequency of the wrist induced by a printed- circuit motor. The brain elastance, ICP, intrathoracic and blood pressures were measured throughout the study. The effect of pharmacological muscle paralysis on the ICP and rigidity was examined.It appeared that well- developed decerebrate rigidity increased the ICP. The relationship was direct; the greater the rigidity or cerebral elastance, the greater the rise in ICP and vice versa. The two factors mainly responsible were muscle hypertonicity and cerebral elastance. The rises in ICP were caused by the rigidity and although it may not always be possible to reduce the abnormally increased elastance, the rigidity can certainly be abolished. As long as the cerebral vascular homeostatic mechanisms were intact, spontaneous waning of the rigidity or its abolition by muscle relaxants returned the ICP to its previous resting level. Pancuronium produced much deeper and more lasting relaxation than either diazepam or chlorpromazine.During the period of mechanical ventilation, alterations in ICP were of prognostic value as regards the outcome of the injuries

INTRODUCTION TO HUMAN PHYSIOLOGY FOR MEDICAL STUDENTS

With recent advances in the fielded of human physiology, it has become urgent to provide an up to date review in the subject of human physiology.This book to help medical student in understanding modern human physiology. It presents the whole subject in brief comprehensive and up to date form.I hope this book will be a real help to undergraduate medical students, as well as to postgraduate and candidates of higher degree, in the field of human physiology

Central and peripheral autonomic influences : analysis of cardio-pulmonary dynamics using novel wavelet statistical methods

The development and implementation of novel signal processing techniques, particularly with regard to applications in the clinical environment, is critical to bringing computer-aided diagnoses of disease to reality. One of the most confounding factors in the field of cardiac autonomic response (CAR) research is the influence of the coupling of respiratory oscillations with cardiac oscillations. This research had three objectives. The first was the assessment of central autonomic influence over heart rate oscillations when the pulmonary system is damaged. The second was to assess the link between peripheral and central autonomic control schema by evaluating the heart rate variability (HRV) of people who were able or unable to adapt to the use of integrated lenses for vision, specifically acconrrmodation, correction (adaptive and non-adaptive presbyopes). The third objective was the development of a wavelet-based toolset by which the first two objectives could be achieved. The first tool is a wavelet based entropy measure that quantifies the level of information by assessing not only the entropy levels, but also the distribution of the entropy across frequency bands. The second tool is a wavelet source separation (WayS) method used to separate the respiratory component from the cardiac component, thereby allowing for analysis of the dynamics of the cardiac signal without the confounding influence of the respiratory signal that occurs when the body is perturbed. With regard to hypothesis one, the entropy method was used to separate the COPD study populations with 93% classification accuracy at rest, and with 100% accuracy during exercise. Changes in COPD and control autonomic markers were evident after respiration is removed. Specifically, the LF/HF ratio slightly decreased on average from pre to post reconstruction for controls, increased on average for COPD. In healthy controls, respiration frequency is distributed across multiple bandwidths, causing large decreases in both LF and HF when removed. With respiration effect removed from COPD population, LE dominates autonomic response, indicating that the frequency is concentrated in the HF autonomic region. Decrease in variance of data set increases probability tat smaller changes can be detected in values. The theory set forth in hypothesis two was validated by the quantification of a correlation between peripheral and central autonomic influences, as evidenced by differences in oculomotor adaptability correlating with differences in HRV. Standard Deviation varies with grouping, not with age. Increasing controlled respiration frequencies resulted in adaptive presbyopes and controls displaying similar sympathetic responses, diverging from non-adaptive group. WayS reduced frequency content in ranges concurrent with breathing rate, indicating a robust analysis. The outcome of hypothesis three was the confirmation that wavelet statistical methods possess significant potential for applications in HRV. Entropy can be used in conjunction with cluster analysis to classify patient populations with high accuracy. Using the WayS analysis, the respiration effect can be removed from HRV data sets, providing new insights into autonomic alterations, both central and peripheral, in disease

Respiratory influences on pupil size dynamics and visual recognition memory

Breathing, a fundamental rhythm of life, has traditionally been associated with the exchange of oxygen and carbon dioxide. However, recent research in both animal models and humans has unveiled additional roles of respiration in modulating cortical neuronal activity, influencing sensory, motor, emotional, and cognitive processes. This dissertation aims to explore the impact of respiration on pupil size dynamics and visual recognition memory in humans. In Study I, we synthesized the research conducted on respiratory influences on pupil size dynamics in humans by conducting a systematic literature review. We discovered that the evidence for respiratory influences on pupil size dynamics in humans is less solid and extensive than previously believed. After more than 50 years of research, only 12 studies have directly investigated this topic. Not only was the underlying evidence for an effect of breathing phase, depth, and rate on pupil size dynamics weak, but the influence of breathing route (oral or nasal breathing) had not been investigated at all. In Study II, we conducted an experimental study to answer the outstanding questions identified in Study I. We collected pupil size data from participants during periods of rest while they breathed through their nose and mouth, on separate occasions. We demonstrated small but significant effects of breathing phase on pupil size and a spurious correlation and phase synchronization between the breathing and the pupil signal that is largely driven by breathing rate. After accounting for this spurious correlation and phase synchronization, we show that a small but significant interaction between the breathing and the pupil signal remains. Importantly, we show that, contrary to common belief, pupil size does not increase during inhalation, but rather during exhalation. Furthermore, we did not find any changes in pupil size in the time around inhalation and exhalation, and our results were not affected by the breathing route. In conclusion, we confirmed the influence of breathing on pupil size dynamics, while uncovering a more complex and intricate relationship than previously conceived. In Study III, we investigated the influence of breathing phase and breathing route on performance in a visual recognition memory task with a within-subject design and with stimuli presentation phase-locked to the inhalation or exhalation onset. We show that neither breathing phase nor breathing route affect memory performance. However, we did find an effect of breathing phase on response bias, with participants using a more conservative response bias during exhalation. Furthermore, we found that breathing route and breathing phase shape the Late Parietal Effect (LPE), but not the Frontal Negative Component (FN400), amplitude during encoding. Additionally, during recognition, both the LPE and FN400 component amplitudes were not, or only to a small extent, affected by breathing route and phase. While we demonstrated that breathing does not shape visual recognition memory performance, we also showed that breathing influences brain activity related to memory functions. Therefore, we highlight the importance of further research to elucidate the extent of respiratory influence on perception, cognition, and behavior. In Study IV, we further investigated the impact of breathing on visual memory performance by investigating the effects of nasal breathing phase on memory of repeated images presented in a rapid serial visual presentation (RSVP) task. In two separate, high-powered experiments, we did not find an effect of breathing phase on task performance. An exploratory analysis in the first experiment discovered a potential performance increase for stimuli presented approximately one second after inhalation. However, this was not replicated in the second, larger, and pre-registered study. Thus, we find no effect of breathing phase on performance in this RSVP task and urge for caution regarding the notion that visual memory is broadly affected by the breathing phase. Finally, in Study V, we investigated whether oral hormonal contraceptives (OC) affect chemosensory sensitivity and perception. Whereas previous research focused nearly exclusively on olfaction, we expanded this to also study the taste and trigeminal sense. Making use of Bayesian statistics, we evaluated the performance differences between a group of women taking OC, and a control group of normal cycling women. Our results indicated that the use of OC does not affect odor, trigeminal, or taste detection thresholds. Furthermore, neither odor nor taste perception were affected, with Bayes factors weighing the evidence in favor of the null hypothesis. We therefore conclude it to be unlikely that OC affect chemosensory perception to a degree that is of behavioral relevance. Collectively, this doctoral thesis challenges prevailing myths while paving the way for a more intricate understanding of the relationship between respiration and pupil size, and perceptual and cognitive processes. Importantly, it underscores the importance of implementing rigorous methodological paradigms in future research

Evaluation of Brainstem auditory evoked potential and serum Interleukin-1beta levels in patients with generalized tonic clonic seizures

BACKGROUND: Epilepsy is a neurological disorder characterized by abnormal changes in the brain’s electrical potentials. Brainstem Auditory Evoked Potential (BAEP) is an important clinical tool in studying the electrophysiological phenomena of neural excitation, conduction and transmission across the auditory pathway. It has been widely used for the early detection of neural conduction irregularities in auditory pathway. Using BAEP, we can easily detect the early changes occurring in the auditory pathway in Generalized Tonic Clonic Seizure (GTCS) patients even before the clinical manifestation of hearing impairment occurs so that proper measures to intervene the disease process at the earliest possible is achieved to provide a better quality of life for GTCS patients. AIM OF THE STUDY: 1. To determine the functional integrity of auditory pathway in patients with GTCS by recording brainstem auditory evoked potential. 2. To assess serum Interleukin -1 beta levels in these patients. 3. To find the correlation between serum Interleukin-1 beta level and Brainstem auditory evoked potential in patients with GTCS. MATERIALS AND METHODS: 30 patients with GTCS of both sexes in the age group 20-40 years without any clinical evidence of hearing impairment were included in the study. Controls were age, sex and BMI matched healthy population. Both the controls and GTCS patients were subjected to BAEP and serum interleukin-1beta levels were also measured. The data were analyzed by Student ‘t’ test. RESULT: GTCS patients showed significant differences in wave III, V absolute latency and I-III, I-V IPL of BAEP. The interleukin-1β levels were significantly prolonged in GTCS patients as compared to control population suggesting the contribution of this cytokine in epileptogenesis. CONCLUSION: There was significant prolongation of central conduction time in GTCS patients even though there was no clinical evidence of hearing impairment assessed by pure tone audiogram prior to the study. Hence BAEP can be utilized as an objective electrophysiological tool to evaluate the functional integrity of auditory pathway from the external ear to lower brainstem

The transmission of music into the human uterus and the response to music of the human fetus and neonate

The aim of this study was to investigate whether music influences human life before birth. In order to determine the existence and character of music in the uterine acoustic environment, a study was conducted involving the insertion of a hydrophone through the cervix, next to the fetal head. The investigation was conducted on eight women in early labour. The average residual uterine sound of the eight subjects was measured at 65 dBA (A-weighted) re 20 µ.Pa in a 1 O KHz band, RMS averaged over 32-second records. Above this emerged the maternal voice, an external female voice and a male voice presented at approximately 65 dB (linear weighted). Pure tones between 50 Hz and 1 O KHz and orchestral music, all presented at 80 dB (linear weighted), were also shown to emerge above the residual uterine sound. Attenuation of external sound was observed to vary as a function of frequency, with less attenuation of lower frequencies. It was determined that the music was transmitted into the uterus without sufficient distortion to significantly alter the recognisable characteristics of the music. The fetal heart rate (FHA) response to a music stimulus (MS) and a vibroacoustic stimulus (VS) was measured in 40 subjects. Gestational age of the fetuses ranged from 32 to 42 weeks. The study included a control period with no acoustic stimulation; a period with the presentation of 5 music stimuli; and a period with the presentation of 5 vibroacoustic stimuli. A change in the FHA of 15 beats per minute or greater, lasting 15 seconds and occurring within 15 seconds of at least 2 of the 5 stimuli (or a tachycardia of greater than 15 beats per minute above the resting baseline, sustained for one minute or longer) was considered to be a positive response. The MS elicited a positive response in 35 of the fetuses (the 5 non-responses occurring in a period of low FHA variability) and all 40 fetuses responded to the VS (regardless of arousal state). In the third study, mothers attending childbirth education classes volunteered to listen to a prescribed music excerpt twice daily from the 34th week of pregnancy. Ten neonates (all clinically normal) were tested betw~en the 2nd and 5th day after birth. Investigators observed the effect of two music sti:Tiuli, the prescribed stimulus and a non-prescribed stimulus, on neonatal sucking of a non-nutritive nipple. A five-minute control period with no stimulation was compared with a ten-minute period during which two music stimuli were presented. By random allocation, either the prescribed music stimulus (PM) or the nonprescribed music (NM) was presented contingent upon sucking pressure. If a sucking burst was initiated, the PM stimulus was activated. On cessation of sucking, the NM stimulus was activated. Randomly, the procedure would be reversed for some of the subjects, where initiation of sucking activated the NM stimulus and cessation of sucking activated the PM stimulus. It was determined that the inter-burst intervals during the music period were significantly extended when coinciding with the PM stimulus and significantly shortened when coinciding with the NM stimulus.The studies indicated that music is transmitted into the uterus with insufficient distortion to alter the character of the music; that the normal fetus responds to a music stimulus from at least the 32nd week of gestation; and that the neonate alters the normal sucking pattern to activate longer periods of a music stimulus which has been repeatedly presented during the intrauterine stage and shorter periods of a novel music stimulus