(c) 2008 Elsevier Ireland Ltd. All rights reserved.”
“In three experiments with rat subjects, we examined the effects of trial spacing

in appetitive conditioning. Previous research in this preparation suggests that self-generated priming of the conditional stimulus (CS) and/ or unconditional stimulus (US) in short-term memory is a cause of the trial-spacing effect that occurs with intertrial intervals (ITIs) of less than 240 sec. Experiment I nonetheless showed that a trial-spacing effect still occurs when ITIs are increased beyond 240 sec, and that the effect of ITI over 60-1,920 sec on conditioned responding is best described as a linear function. In Experiment 2, some subjects were removed from the context click here during the buy 5-Fluoracil ITIs, preventing extinction of the context. Removal abolished the advantage of the long ITI, suggesting the importance of exposure to the context during the long ITI. Experiment 3 still produced a trial-spacing effect in a within-subjects design that controlled for the level of context conditioning and reinforcement rate in the absence of the CS. Overall, the results are most consistent with the idea that adding time to the ITI above 240 sec facilitates conditioning by extinguishing context-CS associations-and possibly context-US associations-that otherwise interfere with CS-US learning through retrieval-generated

priming (see, e.g., Wagner, 1981).”
“Repetitive transcranial magnetic stimulation (5 Hz-rTMS, 10 stimuli, 120% resting motor threshold intensity, RMT) produces in healthy subjects a progressive facilitation of motor-evoked potential (MEP) amplitude probably through a short-term enhancement of cortical excitatory interneurones. We had the opportunity to investigate the effect of 5 Hz-rTMS delivered over the right and left primary motor www.selleck.cn/products/jnj-64619178.html cortex (M1) in a patient with limb-kinetic apraxia of the left hand and fingers and reduced cerebral perfusion in the fronto-parietal

Cortex of the right hemisphere documented by single-photon emission computed tomography scans. Changes in the MEP size during the trains and the RMT were measured and compared between the hemispheres. 5 Hz-rTMS was also delivered in a group of healthy subjects over both hemispheres in order to compare changes in the MEP size from the right and left M1. In the patient, 5 Hz-rTMS delivered over the left hemisphere elicited normal MEN that progressively increased in size during the trains whereas 5 Hz-rTMS delivered over the right affected hemisphere failed to facilitate the MEP size. RMT was similar in both hemispheres. In healthy subjects, 5 Hz-rTMS delivered over either hemisphere elicited a similar, significant MEP size facilitation. Despite the limitations of a single case, our findings suggest an altered response to 5 Hz-rTMS over the M1 of the affected hemisphere.