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Potent Stimulus (potent + stimulus)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Electromagnetic brain activity evoked by affective stimuli in schizophrenia

PSYCHOPHYSIOLOGY, Issue 5 2006
Brigitte Rockstroh
Abstract Schizophrenia is typically associated with cognitive deficits, but symptoms also point to alterations in the processing of affective material, with potential impact on behavioral performance. This impact may unfold on multiple time scales, but initial processing of rapidly unfolding social cues may be particularly important. MEG-assessed regional brain activity associated with the capacity to process the emotional content of rapid visual stimuli (3/s) was examined in 12 individuals with schizophrenia and 12 matched controls. Patients showed less differentiation of emotional versus neutral stimuli 90,300 ms following picture onset. Together with group differences in the lateral topography of valence effects, these results are discussed as evidence of deficient automatic processing of emotionally potent stimuli in schizophrenia. [source]

Oestrogen Receptor ,: Role in Neurohypophyseal Neurones

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2004
C. D. Sladek
Abstract The robust expression of oestrogen receptor , (ER-,) in magnocellular vasopressin neurones has focused attention on the role of this receptor and the gonadal steroids in the regulation of vasopressin secretion. Although the effects of gonadal steroids on vasopressin secretion have been the subject of many studies, there is no consensus in the literature as to their role. Possible reasons for the diverse findings are discussed, including diversity in the types, site and level of expression of steroid receptors across species, gender and physiological conditions. The physiological regulation of expression is of particular interest because ER-, mRNA expression in vasopressin neurones is inversely correlated to the osmotic state of the animal. Chronic hyperosmolality inhibits ER-, mRNA expression in magnocellular vasopressin neurones, while chronic hypo-osmolality enhances expression. This is consistent with an inhibitory role for ER-, because hyperosmolality is a potent stimulus for vasopressin secretion, whereas vasopressin secretion is maximally inhibited by chronic hypo-osmolality. An inhibitory role is also indicated by in vitro experiments demonstrating inhibition of osmotically stimulated vasopressin secretion by oestrogen and testosterone, and ER-, mediated inhibition of NMDA-stimulated vasopressin secretion. The challenge remains to elucidate the mechanism of this inhibition, and to understand its significance for maintenance of whole-body fluid and electrolyte homeostasis. [source]

No place like home: Testosterone responses to victory depend on game location

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2009
Justin M. Carré
Several studies have demonstrated that a variety of factors influence testosterone responses to competitive interactions. This study examined the extent to which game location would influence testosterone responses to human competition. Male amateur ice hockey players (n = 10) provided saliva samples before and after competing against the same opponent on two separate occasions (one game at home and one game away). Although both games resulted in similar victories, the home victory was associated with a significantly larger rise in testosterone concentrations relative to the away victory. The factors responsible for the different testosterone responses are not known, however, it is possible that a rise in status in front of the home crowd is more rewarding to athletes, and thus, a more potent stimulus for the endocrine system. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source]

Mechanical and neural stretch responses of the human soleus muscle at different walking speeds

THE JOURNAL OF PHYSIOLOGY, Issue 13 2009
Neil J. Cronin
During human walking, a sudden trip may elicit a Ia afferent fibre mediated short latency stretch reflex. The aim of this study was to investigate soleus (SOL) muscle mechanical behaviour in response to dorsiflexion perturbations, and to relate this behaviour to short latency stretch reflex responses. Twelve healthy subjects walked on a treadmill with the left leg attached to an actuator capable of rapidly dorsiflexing the ankle joint. Ultrasound was used to measure fascicle lengths in SOL during walking, and surface electromyography (EMG) was used to record muscle activation. Dorsiflexion perturbations of 6 deg were applied during mid-stance at walking speeds of 3, 4 and 5 km h,1. At each walking speed, perturbations were delivered at three different velocities (slow: ,170 deg s,1, mid: ,230 deg s,1, fast: ,280 deg s,1). At 5 km h,1, fascicle stretch amplitude was 34,40% smaller and fascicle stretch velocity 22,28% slower than at 3 km h,1 in response to a constant amplitude perturbation, whilst stretch reflex amplitudes were unchanged. Changes in fascicle stretch parameters can be attributed to an increase in muscle stiffness at faster walking speeds. As stretch velocity is a potent stimulus to muscle spindles, a decrease in the velocity of fascicle stretch at faster walking speeds would be expected to decrease spindle afferent feedback and thus stretch reflex amplitudes, which did not occur. It is therefore postulated that other mechanisms, such as altered fusimotor drive, reduced pre-synaptic inhibition and/or increased descending excitatory input, acted to maintain motoneurone output as walking speed increased, preventing a decrease in short latency reflex amplitudes. [source]