Time course of recovery from gustatory adaptation to NaCl

Recovery from adaptation to NaCl was tested by comparing some relevant parameters of response to the adapting and test stimuli separated by different recovery intervals. The time course of response was determined using magnitude estimations and using the flow chamber for stimulus delivery. The course of recovery for all parameters used was a negatively accelerated function of the rest time, but the recovery rate of different parameters did not prove to be equal. Recovery was fastest for the initial maximum taste magnitude, followed by the time needed for the taste to disappear. The taste effect summed over time and the time required for the taste magnitude to decrease to 30% of its preadapted maximum were the slowest to recover. Although the recovery process proceeded at a rapid rate during the initial period, all parameters remained depressed over a rather long period.     

Psychological effects of deep-breathing: the impact of expectancy-priming

Outcome expectancy could mediate the psychological effects of exercise-related interventions, which implies that part of the psychological benefits of physical activity could be ascribed to placebo effects. In this framed field-experiment, 89 healthy participants were studied in three groups, (1) breathing-primed (deep-breathing with an exercise-related expectancy), (2) breathing-unprimed (deep-breathing with no exercise-related expectancy), and (3) control (no intervention). Deep-breathing lasted for three minutes. Before and after deep-breathing, or sitting quietly in the control group, participants completed two questionnaires assessing their positive- and negative affect (NA) and subjective well-being (WB). In contrast to the control group, both the breathing-primed and breathing-unprimed groups showed decreased NA and increased subjective WB. The breathing-primed group reported larger changes in WB than the breathing-unprimed group, in addition to also exhibiting significant increases in positive affect. These findings support the hypothesis of the work that expectations mediate the psychological effects of deep-breathing beyond the intervention’s specific effects. Therefore, future research should control for expectations related to an intervention when gauging psychological changes.     

Effects of a Carbohydrate Supplement upon Resting Brain Activity

Glucose is a major energy source for the brain, and along with several monosaccharide derivatives as components of brain gangliosides, they play important roles in neurologic function. However, there is little information available on the role of glucose and other monosaccharides on resting brain activity. This study was designed to evaluate the effects of a single dose of a carbohydrate supplement containing glucose and several of its derivatives on resting brain activity in 20 healthy male college students. The supplement provided an insignificant amount of carbohydrate (3.9 g), protein (0.28 g), fat (0 g), and calories (14 kcal). The amount of glucose in the supplement was 0.5 g (1% the amount of glucose used in adult studies of cognitive functioning and memory). We hypothesized that the glyconutrient supplement would enhance brain activity associated with alertness and attention. The study design was double blind, with subjects randomly assigned to one of two orders, either carbohydrate supplement week one followed by placebo a week later, or the opposite. Electrical brain activity was monitored by 15 electrodes positioned at nine standard international 10-20 system locations, including three bilateral pairs at frontal, parietal, and occipital sites. Thirty minutes following ingestion of a placebo or carbohydrate supplement drink, EEG activity was recorded for 10-mins while subjects focused on a stationary visual target. Spectral power of resting brain activity was computed and analyzed contrasting the placebo and supplement groups. Relative to placebo, the carbohydrate supplement significantly enhanced power in three brain wave frequencies (theta, alpha, and beta) that are known to be associated with attention and arousal. Since changes were observed in the supplement but not placebo group, our study suggests that additional sugars in the glyconutritional supplement facilitate enhancement of brain electrical activity. Whether the apparent enhancement of arousal in baseline recordings is associated with improved task performance remains to be determined.     

Perception of the form of stimulus increment as a method in assessment of the psychophysical relationship

Among numerous procedures for determination of the psychophysical relation, one approach has seldom been applied. Essential in this method is to present a set of stimuli whose intensity increases in fixed time following different forms. The objective stimulus increment, which the subjects perceive as linear growth directly, represents the inverse psychophysical relation. In this paper the method was tested in the fields of click frequency and sound pressure. This procedure was named "Perception of the Form of Stimulus Increment in Time". In comparison to other psychophysical approaches, this one has several advantages. The principal ones are the following: (1) In assessing the psychophysical relation it is not necessary to try to measure the perceptual magnitude; and (2) the psychophysical relation is directly determined by its dynamic pattern. In this paper modifications to the method are reported which facilitate the subject's task and avoid some differences in subjects' individual approaches to the task. The modified procedure leads to results satisfactory independent of the influence of the factors irrelevant to the psychophysical relationship.     

Interaction between stimuli with different taste qualities evaluated by reaction time

The influence of adaptation to taste stimuli of 1 quality on tastants with other qualities was investigated by comparing the reaction time (RT) to a test solution after adapting-solution flow with the RT to the same test solution after water flow. Adapting solutions were strong concentrations of NaCl, HCl, QHCl, and sucrose; test solutions were the same compounds but in lower concentrations. Adaptation to sucrose significantly shortened RT to NaCl and HCl, and to a lesser degree to QHCl. A similar cross-enhancement was found in sucrose when other compounds served as adapting solutions, In all other taste combinations, only a cross-adaptation effect was observed. Results are discussed in relation to some adaptation phenomena, water taste data, and magnitude-estimation data.     

Effect of catatoxic steroids upon lidocaine intoxication

Various steroids have been shown to influence the activity of psychotropic hormones and drugs. Among these, we distinguish “syntoxic” steroids which act by inhibiting excessive reactions to various agents and “catatoxic” steroids which actually destroy certain toxicants and hormones often through the induction of hepatic microsomal enzymes. Thus, the liver can play a decisive role in psychosomatic interrelations by regulating the blood clearance of agents affecting the nervous system. To illustrate these principles, new observations are presented which show that certain catatoxic steroids offer considerable protection against lidocaine, an anesthetic, analgesic drug. These findings may serve as an example showing how modern research techniques may help us to analyze the possible relationships between the liver and the mind, which were intuitively suspected since Hippocrates created the term “melancholia.”     

Data on the role of the frontal cortex in vegetative behavior

A homeostatic conditional reflex (CR) was elaborated to the effect of repeated inhalations in rats of a gas mixture containing 8 per cent oxygen. The effect of the conditional response was opposite to that of the unconditional one. After ablation of the frontal cortex, the conditional reaction disappeared. The repeated administration of 40 mg/kg of histamine resulted in a tolerance to the temperature lowering effect of histamine similar to the habituation. An injection of distilled water brought about dishabituation. Tolerance was not influenced by the ablation of the frontal cortex, but the dishabituating effect of distilled water was absent.     

The legacy of Hans Selye and the origins of stress research: A retrospective 75 years after his landmark brief "Letter" to the Editor(#) of Nature

Hans Selye's single author short letter to Nature (1936, 138(3479):32) inspired a huge and still growing wave of medical research. His experiments with rats led to recognition of the "general adaptation syndrome", later renamed by Selye "stress response": the triad of enlarged adrenal glands, lymph node and thymic atrophy, and gastric erosions/ulcers. Because of the major role of glucocorticoids (named by Selye), he performed extensive structure-activity studies in the 1930s-1940s, resulting in the first rational classification of steroid hormones, e.g. corticoids, testoids/androgens, and folliculoids/estrogens. During those years, he recognized the respective anti- and pro-inflammatory actions of gluco- and mineralocorticoids in animal models, several years before demonstration of anti-rheumatic actions of cortisone and adrenocorticotrophic hormones in patients. Nevertheless, Selye did not receive a Nobel Prize, which was awarded in 1950 to the clinician Hench and the two chemists who isolated and synthesized some of the glucocorticoids. Nonetheless, Selye was internationally recognized as a world authority in endocrinology, steroid chemistry, experimental surgery, and pathology. He wrote over 1500 original and review articles, singly authored 32 books, and trained 40 PhD students, one of whom (Roger Guillemin) won a Nobel Prize for isolating the hypothalamic releasing factors/hormones. Here, we consider the main implications of his first article launching the biological stress concept and the key ideas and problems that occupied him. Selye considered "Stress in heath and disease is medically, sociologically, and philosophically the most meaningful subject for humanity that I can think of".     

Response of the norepinephrine system to antidepressant drugs

Environmental stimuli and drugs affect the norepinephrine (NE) system and may be linked to the manifestation and treatment of anxiety and affective disorders. The activity of locus ceruleus NE neurons in the brainstem can alter the function of forebrain structures associated with several psychiatric disorders. In particular, NE neurons send and receive projections from sensory afferents, limbic areas, and cortical areas implicated in higher-order brain malfunctions and the symptomatology of anxiety and affective disorders. In turn, anxiolytic and antidepressant drugs are able to offset perturbations of NE activity and forebrain structures with a time course congruent with their therapeutic action. All antidepressants, even the agents selective for other biogenic amines or peptides, act on the NE system. In the present review, the effects of antidepressants on NE neurons are summarized and applied to the treatment of neuropsychiatric disorders, with emphasis placed on mechanisms of action.