ABSTRACT
Research associates processes of fear conditioning and extinction with treatment of anxiety and stress-related disorders. Manipulation of these processes may therefore be beneficial for such treatment. The current study examines the effects of electrical brain stimulation on fear extinction processes in healthy humans in order to assess its potential relevance for treatment enhancement. Forty-five participants underwent a 3-day fear conditioning and extinction paradigm. Electrical stimulation targeting the medial prefrontal cortex was applied during the extinction-learning phase (Day 2). Participants were randomly assigned to three stimulation conditions: direct-current (DC) stimulation, aimed at enhancing extinction-learning; low-frequency alternating-current (AC) stimulation, aimed at interfering with reconsolidation of the activated fear memory; and sham stimulation. The effect of stimulation on these processes was assessed in the subsequent extinction recall phase (Day 3), using skin conductance response and self-reports. Results indicate that AC stimulation potentiated the expression of fear response, whereas DC stimulation led to overgeneralization of fear response to non-reinforced stimuli. The current study demonstrates the capability of electrical stimulation targeting the medial prefrontal cortex to modulate fear extinction processes. However, the stimulation parameters tested here yielded effects opposite to those anticipated and could be clinically detrimental. These results highlight the potential capacity of stimulation to manipulate processes relevant for treatment of anxiety and stress-related disorders, but also emphasize the need for additional research to identify delivery parameters to enable its translation into clinical practice. Clinical trial identifiers: Modulation of Fear Extinction Processes Using Transcranial Electrical Stimulation; https://clinicaltrials.gov/show/NCT02723188; NCT02723188 NCT02723188.
Subject(s)
Extinction, Psychological/physiology , Fear/physiology , Fear/psychology , Prefrontal Cortex/physiopathology , Transcranial Direct Current Stimulation , Adult , Conditioning, Classical/physiology , Female , Galvanic Skin Response/physiology , Generalization, Psychological/physiology , Humans , Male , Young AdultABSTRACT
A total of 1125 hens were used in 3 feeding and 20 hatching trials. The trials were performed to investigate the influence of different vitamin B6 levels on the reproduction characteristics of the hens (fertilization of eggs, hatchability of the chicks, development of progeny). The vitamin B6 requirements of the hens were fairly low for maintaining normal fertilization and hatching rates (approximately 1.5-2 mg per kg of feed). Chicks reared on low vitamin B6 diets (0-12 days) showed definitely improved rearing characteristics (Food consumption, liveweight gains, losses) if the diet of the hens had been supplemented with graded amounts of vitamin B6. These findings were, in the first instance, due to an increased rate of vitamin B6 deposition in the liver and in the yolk sac of the newly hatched chicks (vitamin B6 reserves), apart from the fact that the overall vitamin B6 content of the egg remained largely unchanged. Variations in the vitamin B6 reserves, on the other hand, did not exert any influence on the development of progeny if the chicks received adequate amounts of vitamin B6.
Subject(s)
Nutritional Physiological Phenomena , Nutritional Requirements , Pyridoxine , Animal Feed , Animals , Animals, Newborn , Breeding , ChickensABSTRACT
A total of 3426 broilers were used in 3 fattening trials. The birds received supplements of the antibiotic lamdbamycine in amounts of 30 or 40 mg per kg of feed added to adequately balanced fattening rations. OTC supplements (40 mg per kg) which were an obligatory food component at the time of the trial were used as controls. The results obtained may be summarized as follows: Supplements of neither lambdamycine nor oxytetracycline exerted any significant influence on food consumption. Lambdamycine improved the rate of liveweight gains by 2% (trial 1, alpha greater than 0.05) and 5% (trial 2 and 3; trial 2: alpha less than 0.05, trial 3: alpha greater than 0.05). The growth-promoting effect of OTC was less pronounced than usual (2-3%; alpha less than 0.05) or was completely absent (trial 2). Lambdamycine decreased the rate of food consumption per unit of weight gain in 2 trials (trial 2: alpha less than 0.01) OTC did not influence the rate of food consumption.
Subject(s)
Animal Feed , Anti-Bacterial Agents/pharmacology , Animals , Body Weight , Chickens , Food AdditivesABSTRACT
The present study included 2 trials which were performed to investigate in which way graded vitamin B6 supplies or vitamin B6 deficiency would influence the chemical composition of the whole body, the liver, pectoral muscle or the eggs of hens and in which way it might change the pattern of amino acid composition in the proteins of the pectoral muscle. The following results were obtained: No direct changes in the protein and fat content of the birds (total body, liver, pectoral muscle) were noted in trial 1 when graded amounts of vitamin B6 were supplied, whereas in trial 2 signifikant increases in the fat content of the body and decrases in the protein levels were observed when vitamin B6 supplements were added to a vitamin-deficient diet (pair-fed group) or fed to animals receiving increased amounts of food (controls). Variations in dietary vitamin B6 concentrations did not produce statistically significant changes in the protein and fat content of eggs, and in the pattern of amino acid composition of proteins in the pectoral muscle. However, with increasing vitamin B6 uptake, the serine to glycine ratio was narrowed.
