Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course.

The effects of the amino acid tyrosine on cognitive task performance were studied on a group of 21 cadets during a demanding military combat training course. In addition, the effects on mood, blood pressure and the norepinephrine metabolite MHPG were determined. Ten subjects received five daily doses of a protein-rich drink containing 2 g tyrosine, and 11 subjects received a carbohydrate rich drink with the same amount of calories (255 kcal). Assessments were made both immediately prior to the combat course and on the 6th day of the course. The group supplied with the tyrosine-rich drink performed better on a memory and a tracking task than the group supplied with the carbohydrate-rich drink. In addition, the supplementation of tyrosine decreased systolic blood pressure. No effects on mood were found. These findings suggest that supplementation with tyrosine may, under operational circumstances characterized by psychosocial and physical stress, reduce the effects of stress and fatigue on cognitive task performance.

Influence of drive and timing mechanisms on breathing pattern and ventilation during mental task performance.

Assessment of multiple respiratory measures may provide insight into how behavioral demands affect the breathing pattern. This is illustrated by data from a study among 44 subjects, in which tidal volume, respiration rate, minute ventilation and indices of central drive and timing mechanisms were assessed via inductive plethysmography, in addition to end-tidal PCO2. After a baseline, three conditions of a memory comparison task were presented. The first two conditions differed only with regard to the presence or absence of feedback of performance (NFB and FB). In the third 'all-or-nothing' (AON) condition, subjects only received a monetary bonus, if their performance exceeded that of the previous two conditions. Minute ventilation increased from baseline to all task conditions, and from NFB and FB to AON. Respiration rate increased in all task conditions, but there were no differences between task conditions. Tidal volume decreased during NFB, but was equal to baseline during FB and AON. Of the respiratory control indices, inspiratory flow rate covaried much more closely with minute ventilation than duty cycle. The task performance induced a minor degree of hyperventilation. The discussion focusses on how behavioral demands affect respiratory control processes to produce alterations in breathing pattern and ventilation.

Highlights of the annual meeting of the International Society for the Advancement of Respiratory Psychophysiology and the 14th International Symposium on Respiratory Psychophysiology.

This article provides a review of selected presentations and events that highlighted the annual meeting of the International Society for the Advancement of Respiratory Psychophysiology (ISARP) and the 14th International Symposium on Respiratory Psychophysiology, Toronto, Ontario, Canada, October 1995. The meeting, which was scheduled as a satellite to the 35th annual meeting of the Society for Psychophysiological Research, included two workshops (Diana M. Innocenti on "Identification of Individual Breathing Patterns and Introduction to the Reeducation of Dysfunctional Patterns in Hyperventilation, Asthma, and Emphysema" and Richard N. Gevirtz on "Respiratory and Psychophysiological Factors in the Diagnosis and Treatment of Functional Cardiac and Panic Disorders"), two symposia (one on "Breathing Retraining: Issues and Applications" and one on "Capnography and Hyperventilatory Hemodynamics"), three invited addresses (Hans Folgering on "Rehabilitation of Patients with Exercise Hypoxemia"; David Stubbing on "Assessing Impairment, Disability, and Handicap in Chronic Lung Disease"; and Robert Banzett on "Hypercapnia-Induced Air Hunger"), three panel sessions (one on "Respiratory Psychophysiology of Airway Obstruction," one on "Applied Respiratory Psychophysiology," and one on "Hyperventilation and Panic: Psychological Aspects"), and a poster session.

Cardiovascular and respiratory responses during a complex decision-making task under prolonged isolation.

Self-administered psychophysiological assessment during a mission is not only feasible, but yields reliable data that can be related to mission demands in a meaningful way. The unique methodology that has been employed during the EXEMSI campaign, may be of great promise for the development of techniques that provide daily monitoring of physiological cost of mission demands. This approach can thus be used for obtaining a better understanding of problems that can arise with regard to the functioning of individual crew members. The response profiles of the individual crew members showed remarkable quantitative and qualitative differences during isolation. Due to the limitations of this study, these differences could by no means all be explained in terms of mission demands, operator workload or other relevant parameters. However, the findings do seem to permit some tentative conclusions. In subjects B and D the cardiovascular response profiles suggested that cumulative stress effects emerged, in particular during the second part of the mission. It is important to note that both subjects carried specific responsibilities for the success of the mission, and that there was evidence for a conflict between them. Concerning the question which physiological measures are most appropriate for in-mission psychophysiological assessment, these results can appear to imply that cardiovascular measures yield more valid information about the effects of mission demands that respiratory measures. However, it should be noted that important aspects of respiratory activity, namely, respiratory volume measures and ventilation, could not be reliably determined in this study. Therefore, definitive conclusions concerning the choice of measures wait until the validity of the measures has been more extensively evaluated. Although the methodology that was developed for this study appears to be promising, it is obvious that its value can only be properly assessed when the physiological findings are correlated with behavioral, performance and subjective data. An extensive analysis of the covariation of the daily variations in physiological response, performance measures, and subjective assessments of workload and mood, is currently in progress in collaboration with Hockey and Sauer. Finally, if the usefulness and validity of this type of in-mission self-administered psychophysiological assessment are confirmed in ongoing and future studies (e.g., the 1994 HUBES mission), protocols will have to be worked out for practical implementation during actual spaceflights. In this regard, it has been advocated that psychophysiological monitoring techniques should include feedback and support policies, make crew members aware of potential risks for breakdown, and enable them to take appropriate measures when necessary. Initially, this can perhaps best be realized by procedures which include a data-link between the spacecraft and ground mission control. On the basis of ground-based analysis and evaluation of the data, psychologists at mission control may decide to provide information to the crew concerning potential individual or intragroup overload or stress problems, and to implement specific supportive measures. The effectiveness of the supportive activities should be closely monitored by mission control. Future work should also be aimed at developing expert-systems, which will enable the crew to maintain an appropriate degree of inflight biobehavioral self-regulation by providing a range of support techniques, like biofeedback, coping techniques against individual and group stressors, work/rest and sleep/wake schedules, and emergency procedures.

The relation between event-related brain potential, heart rate, and blood pressure responses in an S1-S2 paradigm.

Event-related brain potential (ERP), heart rate (HR), and blood pressure (BP) responses were examined during the 6 s foreperiod of a choice-reaction task. Low and high trait-anxious males were required to make same/different judgements based on the similarity of two successively presented visual patterns. The pitch of a warning tone, presented at the beginning of the foreperiod, indicated whether speed or accuracy was to be emphasized on that trial. In different conditions, subjects received either a monetary reward or aversive noise, depending on their performance. Two clusters of parallel variations were observed in the foreperiod: (1) speed/accuracy instructions affected the amplitude of the CNV and, in interaction with anxiety group, the initial decreases in HR and diastolic BP; (2) type of reward, in interaction with speed/accuracy instructions, affected the amplitude of the P300 and PSW, the mid-interval HR acceleration, and subsequent increases in diastolic and systolic BP. A correlational analysis showed a close relationship between changes in HR and BP, whereas no relationship was evident between changes in ERPs and changes in HR and BP.

Overreactivity of the psyche or the soma? Interindividual associations between psychosomatic symptoms, anxiety, heart rate, and end-tidal partial carbon dioxide pressure.

Current research has all but refuted previous suggestions about the role of hyperventilation as a proximal, common cause of psychosomatic symptoms. As an alternative, it has been proposed that the experience of psychosomatic symptoms is primarily associated with psychological mechanisms, i.e., with enhanced tendencies of distressed individuals to focus their attention on bodily sensations and to evaluate these in a catastrophic manner. Although this hypothesis has received considerable empirical support, physiological influences on symptom reporting have not, as yet, been fully explored. In this study, contributions of psychological and physiological factors were studied among a group of 83 normal healthy male subjects by an assessment of the interindividual relationships between symptom experience in daily life, situational and dispositional anxiety, baseline end-tidal partial carbon dioxide pressure (PCO2), and heart rate. Trait anxiety and end-tidal PCO2 each contributed separately to the prediction of the psychosomatic symptom score. Trait anxiety explained nearly one third of the symptom variance, and an additional 4% was explained by PCO2. Psychological symptoms were more strongly associated with anxiety and somatic symptoms, more strongly with PCO2. Heart rate only tended to be correlated with symptom reporting. Analysis of covariance among subgroups of extreme-symptom reporters supported the correlational findings by demonstrating that the association between hyperventilation and symptom reporting remained intact when psychological influences were factored out. The findings suggest that reports of psychosomatic symptoms represent two distinct components: one that is primarily psychological (and is unrelated to physiological factors) and a second that reflects objective variance in physiological functioning. The influence of the first component is probably greater than that of the second.

Emotions and respiratory patterns: review and critical analysis.

The literature on emotions and respiration is reviewed. After the early years of experimental psychology, attention to their relationship has been sparse, presumably due to difficulties in adequate measurement of respiration. The available data suggest nevertheless that respiration patterns reflect the general dimensions of emotional response that are linked to response requirements of the emotional situations. It is suggested that the major dimensions are those of calm-excitement, relaxation-tenseness, and active versus passive coping. Research on the emotion-respiration relationships has been largely restricted to the correlates of respiration rate, amplitude, and volume. Finer distinctions than those indicated may well be possible if a wider range of parameters, such as the form of the respiratory cycle, is included in the investigation.

Respiration in psychophysiology: methods and applications.

With the use of advanced equipment, respiratory measures can unobtrusively and reliably be assessed in a variety of psychophysiological research settings. New computerized analysis techniques can break down respiration into a number of components that provide valid estimates of variations in respiratory control mechanisms in the brain stem. Thus analysed, respiratory responses may vary in at least two dimensions: (A) with regard to drive and timing aspects, and (B) with regard to the metabolic appropriateness of the respiratory response. Assessment of respiratory responses may be relevant for a broad variety of research areas, including studies of the physiological effects of mental load and stress, investigations of physiological correlates of emotions and affect, and research linking physiological responses to subjective distress and psychosomatic disorders.

Type A behaviour, borderline hyperventilation and psychological, psychosomatic and neuroendocrine responses to mental task load.

Psychological, psychosomatic and neuroendocrine (in blood) responses to mental task load were investigated in relation to Type A behaviour and borderline hyperventilation. For this purpose 32 apparently healthy, male volunteers were classified on the basis of their scores on the Jenkins Activity Survey (JAS) and on a questionnaire assessing hyperventilation related symptoms (HRS). The subjects performed a memory search task in which a monetary bonus could be won or lost. At rest higher HRS scores were related to increased acute psychosomatic symptom scores and higher JAS scores to higher prolactin levels. Task performance caused an increase of state anxiety, acute psychosomatic symptoms, adrenaline and cortisol, whereas prolactin decreased. Higher JAS scores were related to greater cortisol responses and higher HRS scores to smaller adrenaline responses.