Behavioural brain research
-
The corticospinal and rubrospinal systems are thought to collaborate in the production of skilled forelimb movements in primates. This study examined whether this relation holds in rodents. ⋯ Major findings were: (1) Unilateral red nucleus lesions did not influence subsequent development of limb preference in naive rats. (2) Unilateral red nucleus lesions in pretrained rats failed to affect the incidence of reaching (total reaches) and reaching success (hit percent) by either the contralateral or ipsilateral limb. (3) Whereas motor cortex lesions impaired subsequent use of the contralateral limb, additional red nucleus lesions did not change total reaches or hit percent, but did produce moderate qualitative changes in limb accuracy and paw opening during grasping. The results demonstrate that in the rat, the red nucleus is not essential for the ballistic component of reaching but may contribute to fine motor control.
-
Psychophysical procedures were used to investigate the effects observed by humans when two odorants were presented simultaneously through the same nostril (physical mixture) or separate nostrils (dichorhinic mixture). The odor pairs were (+)-limonene and alpha-pinene, (+)-limonene and propionic acid, alpha-pinene and propionic acid. With both types of mixtures subjects indicated the acid had no effect on the perception of the other odorants. ⋯ The magnitude of suppression with dichorhinic mixtures never exceeded that seen in physical mixtures, whilst suppression with physical mixtures was often significantly greater than in dichorhinic mixtures. The absence of suppression in dichorhinic mixtures in almost one-third of instances when suppression occurred with physical mixtures suggests that different mechanisms are involved in the perception of the two types of mixtures. A hypothesis that accounts for non-reciprocal suppression with both types of mixtures is proposed.
-
Rats were sleep deprived by the platform method to look for differential effects on light and deep slow wave sleep depending on platform size. Diameters of large and small platforms were 15 cm and 5.1 cm respectively. Sleep was recorded during a baseline light period (09.00-19.00 h), continuously during 48 h of sleep deprivation and during the first lights on recovery period (09.00-19.00 h). ⋯ The ratio SWS-2/SWS-1 was, however, significantly increased only in the small platform group recovery sleep. The results suggest that platform sleep deprivation deprives the animals of deep slow wave sleep in addition to REM sleep. This has implications for conclusions on REM sleep function based upon REM sleep deprivation.