The influence of environment and experience on neural grafts

Abstract

An open field with moveable barriers that challenges the animal's learning and memory capabilities in locating a box from a given starting position. 872 | DECEMBER 2001 | VOLUME 2 www.nature.com/reviews/neuro R E V I E W S Cholinergic grafts in cortex and hippocampus. Grafts that are rich in cholinergic neurons derived from the embryonic basal forebrain can reverse various cognitive deficits that are associated with cholinergic depletion in the rat cortex and hippocampus, caused by ageing or explicit lesions 38,39 . In the first model system to be investigated under such conditions, cholinergic fibre outgrowth from basal forebrain tissues, implanted as dissociated cell suspension grafts into the dorsal neocortex, was greater in rats that were housed in an enriched environment than in rats kept in standard cages 40 . The difference was particularly marked at 4 weeks after grafting, but had waned by 10 weeks, indicating that the greatest effect might be on the initial stimulation of neurite growth, rather than asymptotic expansion of the grafts.Further studies analysed the effects of enriched or standard housing on the ability of basal forebrain grafts to alleviate maze-learning deficits in rats with hippocampal cholinergic lesions 41,42 . In the first study, only rats housed for 10 months in an enriched environment after receiving lesions and grafts showed significant attenuation of the profound lesion-induced deficit in relearning a HEBB-WILLIAMS MAZE task; neither the transplant nor enrichment was effective alone 41 . By contrast, a shorter period of enriched housing over 2 months was not sufficient to benefit even the grafted rats. In a second study, rats experienced standard housing alone, standard housing with daily handling and training in a water maze spatial navigation task, or environmental enrichment, before being retested in the Hebb-Williams mazes 42 . Again, neither enrichment nor graft alone was sufficient to sustain recovery over a shorter, 5-month post-surgery period, whereas the specific handling and spatial training did produce selective recovery in the grafted animals. This observation is akin to the finding

Physical activity and behaviour in dementia

“…Analysis of the various intervention parameters suggest that an exercise programme should be offered over at least a six-month period with an exercise duration session of one hour three times a week (Baum et al, 2003). All studies were carried out in care homes and rehabilitation is often driven by experience, in other words, environmental conditions and training (Döbrössy & Dunnett, 2001). Thus, in order to benefit the decrease in ADL that is characteristic for people with dementia (Avila, Bottino, Carvalho, Santos, Seral, & Miotto, 2004), the effects of an exercise intervention on ADL may be enhanced for care home residents when combined with training in maximizing functional skills.…”

Stem Cell Therapy for Parkinson’s disease: Are Double-Blind Randomized Control Trials the Best Design for Quantifying Therapy Outcomes?

“…Evidence from pre-clinical studies indicates that the host system as a whole and the cells constituting the graft respond to environmental stimuli, and have been shown to participate in learning processes [41][42][43]. It follows from this position that researchers addressing the safety and efficacy of cellular therapies need to take into optimise the psychosocial context for the recovery process following the grafting of the cells [43].…”

“…By combining both biological and psychosocial dimensions we will be in a position to develop and implement best practice cellular therapies for patients with brain disorders. Ultimately, the key requirement is to devise effective rehabilitation programs that target the needs of people adapting to their new intracerebral grafts [40,41].…”

Combined pharmacological and motor training interventions for recovery of upper limb function in subacute ischemic stroke

“…Compared with traditional simple motor exercises, task-specific training induces long-lasting motor learning and adaptative cortical reorganization by neural plasticity [5], [6]. Enriched environment should provide many opportunities for physical activity and for motivation [7]. The techniques used in motor learning-based rehabilitation strategies are: constraintinduced movement therapy (CIMT), body weight-supported treadmill training (BWSTT), robotic training, noninvasive brain stimulation (NIBS), transcutaneous neuromuscular electrical stimulation.…”