Dissociable distal and proximal motor components: Evidence from perseverative errors in three apraxic patients.

In the present study we analysed the perseverative behaviour of three apraxic patients (FG, CEO, and VCR) while they were pantomiming the use of common objects and during their real use. The three patients were found to perseverate from one trial to later ones aspects of a given action in the pantomiming and in real use tasks. In particular, our main result was a striking double dissociation between patients in perseverating hand and arm movements.

Effects of NMDA antagonists on memory processes in a novel two-trial swimming test.

Rats were placed in a circular swimming pool for two 3-min swims separated by 3 days. In the first swim control rats swam initially around the perimeter of the pool and later spent more time in the central region and swam more slowly. The time spent in the centre during min 1 was much higher in the second swim than in the first.

Effects of NMDA receptor antagonists on passive avoidance learning and retrieval in rats and mice.

The effects of NMDA antagonists on passive avoidance learning, shock sensitivity and locomotor activity were examined. Pre-training administration of the antagonists 3-((+-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) in mice and rats resulted in impaired performance in a retention test 24 h later. No such impairment resulted from immediate post-training administration of either compound in either species.

Effects of preweaning environmental enrichment on basilar dendrites of pyramidal neurons in occipital cortex: a Golgi study.

The effects of postnatal environmental stimulation on the branching patterns of cortical dendrites were measured in rats. Pups were exposed to 4 daily multisensory enrichment sessions from days 10-24, while littermates were maintained in standard conditions. At 25 days of age, the brains were stained using the Golgi-Cox-Sholl method.

Greater efficacy of preweaning than postweaning environmental enrichment on maze learning in adult rats.

In order to assess the behavioural effects of environmental stimulation at different stages of development, two groups of rats were exposed to multisensory enrichment on days 10-24 (preweaning) or 25-39 (postweaning). Both groups had four 25-min sessions per day in a large cage with a variety of stimuli, in addition to 3 min of handling before each session. The mother of the preweaning group remained in the home cage during the stimulation sessions.