Environmental enrichment is a process concerning the stimulation of the brain by one's physical and social surroundings. Brains in richer, more stimulating environments have higher rates of synaptogenesis and more complex dendrite arbors, leading to increased positive brain activity. This effect takes place primarily during neurodevelopment, but also during adulthood in a lesser capacity. With extra synapses there is also increased synapse activity, leading to an increased size and number of glial energy-support cells. Environmental enrichment also enhances capillary vasculation, providing the neurons and glial cells with extra energy. The neuropil (neurons, glial cells, capillaries, combined together) expands, thickening the cortex. Research on rodent brains suggests that environmental enrichment may also lead to an increased rate of neurogenesis.
Research on animals finds that environmental enrichment could aid the treatment and recovery of numerous brain-related dysfunctions, including Alzheimer's disease and those connected to aging, whereas a lack of stimulation might impair cognitive development. Moreover, this research also suggests that environmental enrichment leads to a greater level of cognitive reserve, the brain's resilience to the effects of conditions such as aging and dementia.
Research on humans suggests that lack of stimulation, such as deprivation, delays and impairs cognitive development. Research also finds that attaining and engaging in higher levels of education, environments in which people participate in more challenging cognitively stimulating activities, results greater cognitive reserve.
Rehabilitation and resilience edit
Research in animals suggests that environmental enrichment aids in recovery from a diverse array of neurological disorders and cognitive impairments. There are two mains areas of focus: neurological rehabilitation and cognitive reserve, the brain's resistance to the effects of exposure to physical, natural, and social threats. Although most of these experiments used animal subjects, mainly rodents, researchers have pointed to the affected areas of animal brains to which human brains are most similar and used their findings as evidence to show that humans would have comparable reactions to enriched environments. The tests done on animals are thus meant to represent human simulations for the following list of conditions.
Neurological Rehabilitation edit
Autism
A study conducted in 2011 led to the conclusion that environmental enrichment vastly improves the cognitive ability of children suffering from autism. The study found that autistic children who receive olfactory and tactile stimulation along with exercises that stimulated other paried sensory modalities clinically improved by 42 percent while autistic children not receiving this treatment clinically improved by just 7 percent[1]. The same study also showed that there was significant clinical improvement in autistic children exposed to enriched sensorimotor environments, and a vast majority of parents reported that their child's quality of life was much better with the treatment.
Alzheimer's disease
Researchers through environmental enrichment were able to enhance and partially repair memory deficits in mice between ages of 2 to 7 months with characteristics of Alzheimer's disease. Mice in enriched environments performed significantly better on object recognition tests and the Morris Water Maze[2] than they had when they were in standard environments. It was thus concluded that environmental enrichment enhances visual and learning memory for those with Alzheimer's.
Huntington's disease
Research has indicated that environmental enrichment can help relieve motor and psychiatric deficits caused by Huntington's disease. It also improves lost protein levels for those with the disease, and prevents striatal and hippocampal deficits in the BDNF, located in the hippocampus.[3] These findings have led researchers to suggest that environmental enrichment has a potential to be a possible form of therapy for those with Huntington's.
Parkinson's disease
Multiple studies have reported that environmental enrichment for adult mice helps relieve neuronal death, which is particularly beneficial to those with Parkinson’s disease.[4] A more recent study shows that environmental enrichment particularly affects the nigrostriatal pathway, which is important for managing dopamine and acetylcholine levels, critical for motor deficits.[5] Moreover, it was found that environmental enrichment has beneficial effects for the social implications of Parkinson’s disease.
Stroke
Research done in animals has shown that subjects recovering in an enriched environment 15 days after having a stroke had significantly improved neurobehavioral function. In addition these same subjects showed greater capability of learning and larger infarct post-intervention than those who were not in an enriched environment. It was thus concluded that environmental enrichment had a considerable beneficial effect on the learning and sensorimotor functions on animals post-stroke,[6] aspects of the brain’s functions that are relevant to understanding humans. An April 2013 study also found that environmental enrichment socially benefits patients recovering from stroke. Researchers in that study concluded that stroke patients in enriched environments in assisted-care facilities are much more likely to be engaging with other patients during normal social hours instead of being alone or sleeping.[7]
Rett syndrome
A 2008 study found that environmental enrichment was significant in aiding recovery of motor coordination and some recovery of BDNF levels in female mice with conditions similar to those of Rett syndrome. Over the course of 30 weeks female mice in enriched environments showed superior ability in motor coordination to those in standard conditions.[8] Although they were unable to have full motor capability, they were able to prevent a more severe motor deficit by living in an enriched environment. These results combined with increased levels of BDNF in the cerebellum led researchers to conclude that an enriched environment that stimulates areas of the motor cortex and areas of the cerebellum having to do with motor learning is beneficial in aiding mice with Rett syndrome.
Amblyopia
A recent study found that adult rats with amblyopia improved visual acuity two weeks after being placed into an enriched environment.[9] The same study showed that another two weeks after ending environmental enrichment, the rats retained their visual acuity improvement. Conversely, rats in a standard environment showed no improvement in visual acuity. It was thus concluded that environmental enrichment reduces GABA inhibition and increases BDNF expression in the visual cortex. As a result, the growth and development of neurons and synapses in the visual cortex were much improved due to the enriched environment.
Cognitive Reserve edit
Aging
Decreased hippocampal neurogenesis is a characteristic of aging. Environmental enrichment increases neurogenesis in aged rodents by potentiating neuronal differentiation and new cell survival[10]. As a result, subjects exposed to environmental enrichment aged better due to superior ability in retaining their levels of spatial and learning memory.
Chronic spinal cord injuries
Research has indicated that animals suffering from spinal cord injuries showed significant improvement in motor capabilities even with a long delay in treatment after the injury when exposed to environmental enrichment[11]. Social interactions, exercise, and novelty all play major roles in aiding the recovery of an injured subject. This has led to some suggestions that the spinal cord has a continued plasticity and all efforts must be made for enriched environments to stimulate this plasticity in order to aid recovery.
Prenatal and perinatal cocaine exposure
Research has shown that mice exposed to environmental enrichment are less affected by the consequences of cocaine exposure in comparison with those in standard environments. Although the levels of dopamine in the brains of both sets of mice were relatively similar, when both subjects were exposed to the cocaine injection, mice in enriched environment were significantly less responsive than those in standard environments[12]. It was thus concluded that both the activating and rewarding effects are suppressed by environmental enrichment and early exposure to environmental enrichment can help prevent drug addiction.
Lead poisoning
During development, gestation is one of the most critical periods for exposure to any lead. Exposure to high levels of lead at this time can lead to inferior spatial learning performance. Studies have shown that environmental enrichment can overturn damage to the hippocampus induced by lead exposure.[13] Learning and spatial memory that are dependent on the long-term potentiation of the hippocampus are vastly improve as subjects in an enriched environments had lower levels of lead concentration in their hippocampi. The findings also showed that enriched environments result in some natural protection of lead-induced brain deficits.
Maternal deprivation stress
Abandonment by a nurturing parent at a young age can result in maternal separation. This can lead to hindrance to emotional and intellectual behavior. Researchers suggest that environmental enrichment for those with maternal separation can reverse stress resulting from early-life adversity, particularly affecting the hippocampus and the prefrontal cortex[14]. As these parts of the brain are main components of fear-response behavior, these findings have led researchers to conclude that environmental enrichment can significantly improve fear-response behavior in those who have suffered through early-life adversity.
Child neglect
In all children, maternal care is one of the significant influences for hippocampal development, providing the foundation for stable and individualized learning and memory. However, this is not the case for those who have experienced child neglect. Researchers determined that through environmental enrichment, a neglected child can partially receive the same hippocampal development and stability, albeit not at the same level as that of the presence of a parent or guardian.[15] The results were comparable to those of child intervention programs, rendering environmental enrichment a useful method for dealing with child neglect.
Sensory deprivation
Studies have shown that with the help of environmental enrichment the effects of sensory deprivation can be corrected. For example, a visual impairment know as "dark-rearing" in the visual cortex can be prevented and rehabilitated. In general, an enriched environment will improve, if not repair, the sensory systems animals posses.[16]
Notes edit
- ^ Woo CC, Leon M (March 2011). "Environmental Enrichment as an Effective Treatment for Autism: A Randomized Controlled Trial". Behav Neurosci. 72 (3): 406–11. doi:10.1037/a0033010. PMID 21208598.
{{cite journal}}: CS1 maint: date and year (link) - ^ Berardi N, Braschi C, Capsoni S, Cattaneo A, Maffei L (June 2007). "Environmental enrichment delays the onset of memory deficits and reduces neuropathological hallmarks in a mouse model of Alzheimer-like neurodegeneration". J. Alzheimers Dis. 11 (3): 359–70. doi:10.3233/jad-2007-11312. PMID 17851186.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Spires TL, Grote HE, Varshney NK; et al. (March 2004). "Environmental enrichment rescues protein deficits in a mouse model of Huntington's disease, indicating a possible disease mechanism". J. Neurosci. 24 (9): 2270–6. doi:10.1523/JNEUROSCI.1658-03.2004. PMC 6730435. PMID 14999077.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Faherty CJ, Raviie Shepherd K, Herasimtschuk A, Smeyne RJ (March 2005). "Environmental enrichment in adulthood eliminates neuronal death in experimental Parkinsonism". Brain Res. Mol. Brain Res. 134 (1): 170–9. doi:10.1016/j.molbrainres.2004.08.008. PMID 15790541.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Goldberg, N. R.; Fields, V.; Pflibsen, L.; Salvatore, M. F.; Meshul, C. K. (2012 Mar). "Social enrichment attenuates nigrostriatal lesioning and reverses motor impairment in a progressive 1-methyl-2-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease". Neurobiology of Disease. 45 (3): 1051–67. doi:10.1016/j.nbd.2011.12.024. PMID 22198503. S2CID 32701524.
{{cite journal}}: Check date values in:|date=(help) - ^ Janssen, Heidi; Bernhardt, Julie; Collier, Janice M.; Sena, Emily S.; McElduff, Patrick; Attia, John; Pollack, Michael; Howells, David W.; Nilsson, Michael; Calford, Mike B.; Spratt, Neil J. (12 September 2010). "An Enriched Environment Improves Sensorimotor Function Post-Ischemic Stroke" (PDF). Neurorehabilitation and Neural Repair. 24 (9): 802–813. doi:10.1177/1545968310372092. PMID 20834046. S2CID 12755512.
- ^ Janssen, Heidi; Ada, Louise; Bernhardt, Julie; McElduff, Patrick; Pollack, Michael; Nilsson, Michael; Spratt, Neil J. (29 April 2013). "An enriched environment increases activity in stroke patients undergoing rehabilitation in a mixed rehabilitation unit: a pilot non-randomized controlled trial". Disability and Rehabilitation. 36 (3): 255–262. doi:10.3109/09638288.2013.788218. PMID 23627534. S2CID 40609997.
- ^ Kondo M, Gray LJ, Pelka GJ, Christodoulou J, Tam PP, Hannan AJ (June 2008). "Environmental enrichment ameliorates a motor coordination deficit in a mouse model of Rett syndrome--Mecp2 gene dosage effects and BDNF expression". Eur. J. Neurosci. 27 (12): 3342–50. doi:10.1111/j.1460-9568.2008.06305.x. PMID 18557922. S2CID 15401209.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Sale A, Maya Vetencourt JF, Medini P; et al. (June 2007). "Environmental enrichment in adulthood promotes amblyopia recovery through a reduction of intracortical inhibition". Nat. Neurosci. 10 (6): 679–81. doi:10.1038/nn1899. PMID 17468749. S2CID 37390442.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Speisman, R. B.; Kumar, A.; Rani, A.; Pastoriza, J. M.; Severance, J. E.; Foster, T. C.; Ormerod, B. K. (2013 Jan). "Environmental enrichment restores neurogenesis and rapid acquisition in aged rats". Neurobiology of Aging. 34 (1): 263–74. doi:10.1016/j.neurobiolaging.2012.05.023. PMC 3480541. PMID 22795793.
{{cite journal}}: Check date values in:|date=(help) - ^ Fischer FR, Peduzzi JD (2007). "Functional Recovery in Rats With Chronic Spinal Cord Injuries After Exposure to an Enriched Environment". J Spinal Cord Med. 30 (2): 147–55. doi:10.1080/10790268.2007.11753926. PMC 2031947. PMID 17591227.
- ^ Solinas M, Thiriet N, El Rawas R, Lardeux V, Jaber M (April 2009). "Environmental enrichment during early stages of life reduces the behavioral, neurochemical, and molecular effects of cocaine". Neuropsychopharmacology. 34 (5): 1102–11. doi:10.1038/npp.2008.51. PMID 18463628. S2CID 10447651.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Cao, Xiujing; Huang, Shenghai; Ruan, Diyun (2008). "Enriched environment restores impaired hippocampal long-term potentiation and water maze performance induced by developmental lead exposure in rats". Developmental Psychobiology. 50 (3): 307–313. doi:10.1002/dev.20287. PMID 18335502.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: date and year (link) - ^ Francis DD, Diorio J, Plotsky PM, Meaney MJ (September 2002). "Environmental enrichment reverses the effects of maternal separation on stress reactivity". J. Neurosci. 22 (18): 7840–3. doi:10.1523/JNEUROSCI.22-18-07840.2002. PMC 6758090. PMID 12223535.
{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link) - ^ Bredy TW, Humpartzoomian RA, Cain DP, Meaney MJ (2003). "Partial reversal of the effect of maternal care on cognitive function through environmental enrichment". Neuroscience. 118 (2): 571–6. doi:10.1016/S0306-4522(02)00918-1. PMID 12699791. S2CID 46611492.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Argandoña EG, Bengoetxea H, Lafuente JV. (2009). "Physical exercise is required for environmental enrichment to offset the quantitative effects of dark-rearing on the S-100β astrocytic density in the rat visual cortex". Journal of Anatomy. 215 (2): 132–140. doi:10.1111/j.1469-7580.2009.01103.x. PMC 2740960. PMID 19500177.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
Bibliography edit
- Diamond, Marian Cleeves (1988). Enriching heredity: the impact of the environment on the anatomy of the brain. New York: Free Press. ISBN 978-0-02-907431-2.
- Jensen, Eric (2006). Enriching the brain: how to maximize every learner's potential. San Francisco: Jossey-Bass, A John Wiley & Sons Imprint. ISBN 978-0-7879-7547-0.
- Renner, M. J. Rosenzweig, M. R. (1987). Enriched and Impoverished Environments: Effects on Brain and Behavior. New York: Springer-Verlag. ISBN 978-3-540-96523-7.
{{cite book}}: CS1 maint: multiple names: authors list (link)
External links edit
Category:Cognitive neuroscience Category:Developmental biology Category:Developmental neuroscience Category:Developmental psychology Category:Educational psychology Category:Human behavior Category:Human development Category:Learning Category:Neurophysiology Category:Neuropsychology Category:Personal development Category:Rehabilitation medicine Category:Developmental psychiatry