86,606 research outputs found
Exposure to an enriched environment accelerates recovery from cerebellar lesion
No full textThe exposure to enriched environments allows the maintenance of normal cognitive functioning even in the presence of brain pathology. Up until now, clinical and experimental studies have investigated environmental effects mainly on the symptoms linked to the presence of neuro-degenerative diseases, and no study has yet analyzed whether prolonged exposure to complex environments allows modifying the clinical expression and compensation of deficits of cerebellar origin. In animals previously exposed to complex stimulations, the effects of cerebellar lesions have been analyzed to verify whether a prolonged and intense exposure to complex stimulations affected the compensation of motor and cognitive functions following a cerebellar lesion. Hemicerebellectomized or intact animals housed in enriched or standard conditions were administered spatial tests. Postural asymmetries and motor behavior were also assessed. Exposure to the enriched environment almost completely compensated the effects of the hemicerebellectomy. In fact, the motor and cognitive performances of the enriched hemicerebellectomized animals were similar to those of the intact animals. The plastic changes induced by enhanced mental and physical activity seem to provide the development of compensatory responses against the disrupting motor and cognitive consequences of the cerebellar damage. © 2010 Springer Science+Business Media, LLC
Cognitive performances of cholinergically depleted rats following chronic donepezil administration.
No full textCognitive performance of healthy young rats following chronic donepezil administration.
No full textRATIONALE:
Experimental studies have investigated the effects of chronic donepezil treatment on the behavioral deficits elicited by reduced activity or the loss of cholinergic neurons that occurs in aging or in models of dementia. However, few studies have analyzed the effects of chronic donepezil treatment on the cognitive functions of intact animals.
OBJECTIVES:
The cognitive functions of healthy young rats treated chronically with the acetylcholinesterase inhibitor donepezil were evaluated using a wide behavioral test battery.
RESULTS:
Chronic treatment with donepezil ameliorated memory functions and explorative strategies, speeded up the acquisition of localizing knowledge, augmented responsiveness to the context, and reduced anxiety levels. However, it did not affect spatial span, modify motivational levels, or influence associative learning.
CONCLUSIONS:
The present findings show the specific profile of donepezil action on cognitive functions in the presence of unaltered cholinergic neurotransmission systems
Lesion-induced and activity-dependent structural plasticity of Purkinje cell dendritic spines in cerebellar vermis and hemisphere
No full textNeuroplasticity allows the brain to encode experience and learn behaviors, and also to re-acquire lost functions after damage. The cerebellum is a suitable structure to address this topic because of its strong involvement in learning processes and compensation of lesion-induced deficits. This study was aimed to characterize the effects of a hemicerebellectomy (HCb) combined or not with the exposition to environmental enrichment (EE) on dendritic spine density and size in Purkinje cell proximal and distal compartments of cerebellar vermian and hemispherical regions. Male Wistar rats were housed in enriched or standard environments from the 21st post-natal day (pnd) onwards. At the 75th pnd, rats were submitted to HCb or sham lesion. Neurological symptoms and spatial performance in the Morris water maze were evaluated. At the end of testing, morphological analyses assessed dendritic spine density, area, length, and head diameter on vermian and hemispherical Purkinje cells. All hemicerebellectomized (HCbed) rats showed motor compensation, but standardreared HCbed animals exhibited cognitive impairment that was almost completely compensated in enriched HCbed rats. The standard-reared HCbed rats showed decreased density with augmented size of Purkinje cell spines in the vermis, and augmented both density and size in the hemisphere. Enriched HCbed rats almost completely maintained the spine density and size induced by EE. Both lesion-induced and activity-dependent cerebellar plastic changes may be interpreted as ‘‘beneficial’’ brain reactions, aimed to support behavioral performance rescuing
Bihemispheric tDCS enhances language recovery but does not alter BDNF levels in chronic aphasic patients
No full textThe neuroprotective effects of experience on cognitive functions: evidence from animal studies on the neurobiological bases of brain reserve
No full textBrain plasticity is the ability of the nervous system to change structurally and functionally in response to experience. By shaping brain structure and function, experience leads to the creation of a protective reserve that accounts for differences among individuals in susceptibility to age-related brain modifications and pathology. This review is aimed to address the biological bases of the experience-dependent "brain reserve" by describing the results of animal studies that focused on the neuroanatomical and molecular effects of environmental enrichment. More specifically, the effects at the cellular level are considered in terms of changes in neurogenesis, gliogenesis, angiogenesis, and synaptogenesis. Moreover, the effects at the molecular level are described, highlighting gene- and protein-level changes in neurotransmitter and neurotrophin expression. The experimental evidence for the basic biological consequences of environmental enrichment is described for healthy animals. Subsequently, by discussing the findings for animal models that mimic age-related diseases, the involvement of such plastic changes in supporting an organism as it copes with normal and pathological age-related cognitive decline is considered. On the whole, studies of the structural and molecular effects of environmental enrichment strongly support the neuroprotective action of a particularly stimulating lifestyle on cognitive functions. Our current level of understanding of these effects and mechanisms is such that additional and novel studies, systematic reviews, and meta-analyses are necessary to investigate the specific effects of the different components of environmental enrichment in both healthy and pathological models. Only in this way can comprehensive recommendations for proper life habits be developed
Activity-dependent structural plasticity of Purkinje cell spines in cerebellar vermis and hemisphere.
No full textThe environmental enrichment (EE) paradigm is widely used to study experience-dependent brain plasticity. In spite of a long history of research, the EE influence on neuronal morphology has not yet been described in relation to the different regions of the cerebellum. Thus, aim of the present study was to characterize the EE effects on density and size of dendritic spines of Purkinje cell proximal and distal compartments in cerebellar vermian and hemispherical regions. Male Wistar rats were housed in an enriched or standard environment for 3.5 months from the 21st post-natal day onwards. The morphological features of Purkinje cell spines were visualized on calbindin immunofluorescence-stained cerebellar vermian and hemispherical sections. Density, area, length and head diameter of spines were manually (ImageJ) or automatically (Imaris) quantified. Results demonstrated that the Purkinje cell spine density was higher in enriched rats than in controls on both proximal and distal dendrite compartments in the hemisphere, while it increased only on distal compartment in the vermis. As for spine size, a significant increase of area, length and head diameter was found in the distal dendrites in both vermis and hemisphere. Thus, the exposure to a complex environment enhances synapse formation and plasticity either in the vermis involved in balance and locomotion and in the hemisphere involved in complex motor adaptations and acquisition of new motor strategies. These data highlight the importance of cerebellar activity-dependent structural plasticity underling the EE-related high-level performances
Bihemispheric tDCS enhances language recovery but does not alter BDNF levels in chronic aphasic patients
No full textSeveral studies have shown that transcranial direct current stimulation (tDCS) is a useful tool to enhance language recovery in aphasia. It has also been suggested that modulation of the neurotrophin brain-derived neurotrophic factor (BDNF) might be part of the mechanisms involved in tDCS effects on synaptic connectivity. However, all language studies have previously investigated the effects using unihemispheric stimulation. The purpose of the present study is to investigate the role of bihemispheric tDCS on language recovery and BDNF serum levels
Effects of chronic donepezil treatment and cholinergic deafferentation on parietal pyramidal neuron morphology.
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