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How Enriched Environments Benefit The Brain (page 2)

By — John Wiley & Sons, Inc.
Updated on Jan 12, 2011

Enhanced Anatomical Structures

Scientific studies have shown that nearly every indicator of optimal brain functioning improves with successful enrichment. Enrichment involves changes in the physical brain, and these enhanced anatomical structures may provide the scaffolding necessary for increased cognitive tasks. In fact, enrichment pioneer Bill Greenough has shown that enrichment protocol efforts increase the brain's vascular system, which increases oxygen to the neurons.23 He also confirmed increases in the number of glial cells, which interact closely with neurons.24

Neuroscientist Marian Diamond has shown a number of enrichment effects, including a thicker cortex and increases in the size of neurons (Figure 3.4).25 Besides Diamond's studies showing increases in glial cells and in cortical depth, various researchers have found increased dendritic length, and more complex (higher order) branching on the dendrites, better enabling them to make more future connections.26 It sounds like all of these changes would add mass to the brain, and they do. Brain weights also increase with enrichment.27 These effects are robust and have correlated with overall brain weight increases of 7 to 10 percent after 60 days.28

Increased Connectivity

Enrichment studies show development of new circuitry in the brain. The evidence for increased connectivity comes from seeing changes as a result of neurons "talking" to each other, creating new synapses (Figure 3.5). First, there are studies showing changes in the necessary dendritic branching for connectivity in multiple areas of the brain, including the visual area.29 And more important, there is an increase in synapses from new connections and dendritic spine counts.30 More dendrites per neuron and more synapses per neuron are correlated with increased connectivity. This result occurs in animals given enrichment protocols compared with those raised in isolation or non-social environments.31 This increased connectivity and mapping may be important to cognition and processing.

Increased Connectivity

Connectivity is a tricky issue because there are competing models of how this occurs. Bill Greenough and his colleagues at the University of Illinois, Champagne-Urbana, have shown that motor learning induces the formation of new synapses in mouse models.32 But seven years later another study showed that associative learning changes the size of existing synapses, possibly facilitating neurotransmission. Yet it does not increase the number of synapses in the hippocampus.33 This contrasting set of data suggests there may be developmental phases in which the same stimulus produces altogether different results. It may also be a case of differences in brain geography; getting the effect in one area of the brain (versus another) may do the job better or in a more timely way.

Increased Connectivity

Responsiveness and Learning Efficiency

On each side of our heads, near our ears, are our temporal lobes. The hippocampus is buried deep within our temporal lobes, and we have two of these C-shaped structures. Studies suggest that the tissue in the hippocampus, an area associated with learning and memory, becomes better at electrical signal conduction points.34 The field potentials of synapses in the hippocampus increase with enrichment effects.35 Cells in enriched rats also showed an increased capacity for plasticity.36 These changes can influence our senses, too. Studies show an improvement in the capabilities of our auditory processing, and we can even spur the development of the visual system.37

Another astonishing factor of an enriched environment is that it influences protein synthesis and gene transcription. Rats show higher levels for the messenger RNA, which is essential for memory.38 After frequent stimulation, neurons change and become more responsive. An enriching environment may support the process of long-term potentiation, meaning it enhances the very processes by which learning takes place. It also improves memory.39 We see rats that perform mazes better, remember spatial cues better, and learn faster.40 Taken together, the electrophysiological data suggest that the brain can make activations easier and more often, a function associated with new learning and plasticity.

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