Physiology & behavior
-
Physiology & behavior · Feb 2006
Clinical TrialRestrained eaters show altered brain response to food odor.
Do restrained and unrestrained eaters differ in their brain response to food odor? We addressed this question by examining restrained eaters' brain response to food (chocolate) and non-food (geraniol, floral) odors, both when odor was attended to and when ignored. Using olfactory event-related potentials (OERPs), we found that restrained eaters and controls responded similarly to the non-food odor; however, unlike controls, restrained eaters showed no increase in brain response to the food odor when they focused attention on it. Rather, restrained eaters showed attenuated OERP amplitudes to the food odor in both attended and ignored conditions, suggesting that the brain's response to attended food odor was abnormally suppressed.
-
Physiology & behavior · Feb 2006
Clinical TrialUnderstanding variety: tasting different foods delays satiation.
Variety stimulates intake by as much as 40% following both simultaneous and sequential presentations. Varying sensory and other characteristics of foods could sustain interest in eating and delay the development of satiation. Two experiments set out to explore this by investigating the effect of introducing different foods to taste and rate during intake of a snack. ⋯ FD (94 +/- 9.3 g) participants ate significantly more than FF (68 +/- 9.5 g) and in support of findings from Experiment 1 pleasantness ratings during eating declined more rapidly during FF than FD. Variety may stimulate food intake, in part, by delaying the development of satiation which extends eating and therefore amount consumed. Encouraging consumers to focus on eating should facilitate the normal decline in pleasantness of the food and serve to limit intake.
-
Physiology & behavior · Nov 2005
Audiogenic seizures associated with a cortical spreading depression wave suppress spike-wave discharges in rats.
To study the role of the cortex and sub-cortical structures in the generation of epileptic spike-wave discharges in more detail, cortical and striatal activity was eliminated by the induction of spreading depression in a non-invasive way. EEG and DC potentials were recorded from the cortex and striatum of WAG/Rij rats. Several of these rats show two forms of generalised epilepsy: spontaneously occurring non-convulsive absence seizures, together with convulsive audiogenic seizures. ⋯ It is suggested that cortical spreading depression, triggered by a short audiogenic seizure, induces a long-lasting suppression of spike-wave discharges. These results are in line with the concept that spike-wave discharges are originally initiated in the cortex, as proposed by the 'cortical focus' theory. The precise role of the striatum remains less clear, although this structure seems not to play a pivotal role in spike-wave generation.
-
Physiology & behavior · Sep 2005
Dopamine in disturbances of food and drug motivated behavior: a case of homology?
Highly palatable food and drugs of abuse share the ability to stimulate dopamine transmission in the shell of the nucleus accumbens. However, while in the case of food this property is adaptively regulated in a negative fashion upon repeated exposure to the reward, no such regulation is operative towards drugs of abuse. Dysadaptive stimulation of dopamine transmission in the accumbens shell is assigned an important role in the compulsive motivation for drugs typical of drug addiction. It is speculated that disturbances of feeding behavior are related to loss of adaptive regulation of food-stimulated release of dopamine in the shell of the accumbens.
-
Physiology & behavior · Jun 2005
Comparative StudyHeart rate variability in dairy cows-influences of breed and milking system.
Heart rate variability parameters in the time, frequency and nonlinear domains were investigated in two breeds of dairy cows (Austrian Simmental and Brown Swiss) milked either in an automatic milking system with partially forced cow traffic or in a herringbone milking parlour. Recordings were made of 24 cows (six of each breed and milking system) during lying, standing idle, and standing being milked, and analysed with linear mixed effects models taking the covariates time of day, live body weight, milk yield, stage of lactation and stage of pregnancy into account. ⋯ Differences in the linear and nonlinear domains during lying indicated an increased level of chronic stress in cows in the automatic milking system with partially forced cow traffic, compared to cows milked in the herringbone milking parlour. No effects of milking system were found during milking, indicating that the stressor in the automatic milking system was not the milking process itself.