These experiments examined the effects of long-term instrumental training on subsequent radial arm maze performance and synaptic transmission within the hippocampal formation. In the first experiment, young (3 mo) and aged (18 mo) male rats underwent 12 weeks of appetitive instrumental conditioning; half were continually reinforced and the other half alternated between reinforcement and extinct...

This study was designed to determine (1) which brain area paces the theta rhythm in the medial entorhinal cortex (MEC) of rats and (2) the extent to which the behavioral effects of lesions in the medial septal area (MSA), which disrupt the cholinesterase-related pathway to the hippocampal formation, resemble the effects previously reported to result from fimbria-fornix lesions. MSA lesions abol...

Propofol is a general anesthetic widely used in surgical procedures, including those in pregnant women. Preclinical studies suggest that propofol may cause neuronal injury to the offspring of primates if it is administered during pregnancy. However, it is unknown whether those neuronal changes would lead to long-term behavioral deficits in the offspring. In this study, propofol (0.4 mg/kg/min, ...

A tumor suppressor gene, Adenomatous polyposis coli (Apc), is expressed in the nervous system from embryonic to adulthood stages, and transmits the Wnt signaling pathway in which schizophrenia susceptibility genes, including T-cell factor 4 (TCF4) and calcineurin (CN), are involved. However, the functions of Apc in the nervous system are largely unknown. In this study, as the first evaluation o...

Although the use of organophosphate (OP) insecticides has been restricted, sufficient exposure can occur to induce detrimental neurobehavioral effects. In this study, we measured physical and reflex development and spatial learning and memory in rats repeatedly exposed to incremental doses of chlorpyrifos (CPS) and methyl parathion (MPS) from postnatal day (PND) 1 to PND21. Other than decreased...

The aim of this work was to reveal a hypothetical improvement of cognitive abilities in animals acclimatized to altitude and performing under ground level conditions, when looking at submaximal performance, once seen that it was not possible when looking at maximal scores. We modified contrasted cognitive tasks (object recognition, operant conditioning, eight-arm radial maze, and classical cond...

The purpose of this study was to examine the effect on hippocampus morphology and learning behavior in rat pups following prenatal exposure to a 900 megahertz (MHz) electromagnetic field (EMF). Female Sprague Dawley rats weighing 180-250 g were left to mate with males. The following day, pregnant rats identified as such by the vaginal smear test were divided into two groups, control (n=3) and E...

Stress alters brain cell properties and then disturbs cognitive processes, such as learning and memory. In this study, we investigated the effect of postnatal treadmill exercise on hippocampal neurogenesis and spatial learning ability of rat pups following prenatal noise stress. The impact of exercise intensity (mild-intensity exercise vs heavy-intensity exercise) was also compared. The pregnan...

Brain-derived neurotrophic factor (BDNF) regulates both short-term synaptic functions and activity-dependent synaptic plasticity such as long-term potentiation. In the present study, we investigated the role of BDNF in the spatial reference and working memory in a radial arm maze test. The radial arm maze training resulted in a significant increase in the BDNF mRNA expression in the hippocampus...

The ketamine/midazolam association of a dissociative with a sedative agent is used for the induction and maintenance of anaesthesia in laboratory animals. Anaesthesia may interfere with research results through side-effects on the nervous system, such as memory impairment. It is known that ketamine and midazolam affect cognition; however, their effects have not been clarified when used in a con...