The Benefits of a Complex and Enriched Housing Environment

The benefits of complex and enriched housing environments

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Complex housing refers to environments that offer diverse and stimulating conditions intended to promote and enhance holistic cognitive and physical development, alongside the benefits of social interaction (Nithianantharajah & Hannan, 2006; van Praag et al., 2000).

In an experiment involving rodents, Kimble (1992) established three conditions. One was an impoverished, non-stimulating environment where the rodents were housed in individual cages, lacking physical or social interaction. These rodents were isolated and alone.

Another group was placed in a complex, enriched environment. In this setting, the rodents could socialise with one another and explore and engage with the wheels, ladders, tunnels, and obstacles available to them according to their preferences.

In the third condition, according to Kimble (1992), this group of rodents was placed in a large single cage, similar to the second group, where they could socialise. However, this environment lacked any equipment. While it was not a complex environment, it remained a social one. At the end of the experiment, each rat’s brain was examined.

Thicker and Heavier Neocortex

Kimble found that rodents raised in an enriched, stimulating housing environment exhibited a thicker and heavier neocortex. According to Kimble (1992, p. 123), the neocortex of the rodents in the complex housing and exercise condition was “about 5 percent heavier than that of rodents in the impoverished environment, and about 2 percent heavier than that of rodents in the standard condition.”

Trillions of Extra Synapses

From a cognitive and learning perspective, Kimble (1992) noted that a 20-percent increase in synaptic connections could result in an additional 2,000 synapses per neuron, potentially leading to trillions of extra synapses when applied to the human brain.

This increase in synaptic connections would likely enhance the brain’s ability to transmit and store information, suggesting that environmental enrichment could significantly elevate cognitive and learning potential. Kimble (1992) also observed that this applied to juvenile and adult rodents in the experiment.

For Kimble, this was significant as it demonstrated that the complex environment offered overall neurological benefits, and perhaps more importantly, the physiological benefits observed in adult rodents indicated that adulthood was not a barrier to gaining neurological advantages in such an environment.

Subsequent research supported this finding, indicating that neurological benefits (regardless of age) can occur if one adheres to the principle of “use it or lose it” (Hickmott & Constantine-Paton, 1997; Hua & Smith, 2004; Stiles & Jernigan, 2010; Purnell, 2015). Suzuki (2015) reported similar findings.

Exercise, Complex and Enriched Housing and Myelin Production

Exercise and a complex, enriched housing environment also encourage myelin production, facilitating faster transmission of signals in the brain (Coyle, 2009). In a study that specifically examined myelin production, Coyle (2009) reported on research in which an unspecified number of rodents were divided into three groups.

One group had each individual rodent housed in its own separate cage; the second group of rodents was placed together in a spacious enclosure that encouraged social interaction; and the third group was kept in a complex and enriched environment (details of the complex and enriched environment were not provided).

When comparing the cortices of each rodent from the three groups at the end of the experiment, the brains of the complex-housed rodents exhibited increased weight and thickness. Myelin in the brain increased by 25% compared to the other two groups of rodents (Coyle, 2009).

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In another study by Arrowsmith-Young (2012), several rodents were placed in a complex, enriched housing environment. This environment featured tunnels, running wheels, ladders, and various unspecified toys. Upon evaluating what occurred in this setting, the brains of the rodents were examined, revealing neurological changes.

Every rodent brain examined appeared thicker and denser, suggesting a greater number of glial cells. Glial cells, also known as neuroglia, play a vital role in neurotransmission at the synaptic level. They provide physical support and maintenance for synapses while facilitating the formation of myelin. Furthermore, the capillaries in the brain seemed larger, indicating faster and more efficient blood flow within the brain (Arrowsmith-Young).

This increased blood flow would enhance the supply of oxygen, improve absorption efficiencies, and facilitate waste removal. This research, according to Arrowsmith-Young (2012, p. 29), also found “an increase in enzymes involved in the synthesis and breakdown of neurotransmitters.”

This study led Arrowsmith-Young (2012) to hypothesise that a complex and enriched environment not only altered the anatomical structure of rodents' brains but also enhanced neurotransmission efficiencies and improved chemical exchanges, thereby boosting cognitive potential. This may further enhance cognitive and learning capabilities, leading to overall mind-body benefits. Similar studies suggest that a stimulating and intricate living environment, combined with exercise, enhances both white and grey matter in the brains of rodents (Fares et al., 2013; Kobilo et al., 2011; Liu et al., 2021; Zhao & Franklin, 2018; Zhao, Rempe, & Blackband, 2016).

Increased Dendritic Branching and Complexity

Research indicates that an increase in grey matter is linked to a higher count of neurons, dendrites, axons, and synapses. Likewise, a rise in white matter results in a greater number of glial cells and improved myelination. Furthermore, studies show growth in both the quantity and density of synaptic connections, along with greater complexity in dendritic branching and an increased number of dendritic spines. All these elements enhance the overall potential of the brain and body (Arden, 2010; Arrowsmith-Young, 2012; Doidge, 2010, 2015; Fields, 2008; Giedd et al., 1999; Huttenlocher, 1990; Pakkenberg & Gundersen, 1997; Suzuki, 2015; Zatorre et al., 2012).

Cautious Encouragement

According to Teskey (2012), there exists a “genealogical relationship between all life forms.” Because of this phylogenetic connection, Teskey argues that all living species are interrelated, suggesting that findings from animal studies may theoretically be relevant to the human condition.

Research has also shown that enriched environments enhance cognitive functions, including learning, memory, and problem-solving skills (Nithianantharajah & Hannan, 2006). A study by Simpson and Kelly (2011) found that complex housing conditions increased neurogenesis, synaptic plasticity, and BDNF expression, contributing to improved brain health and resilience against neurological disorders.

Physical Health Benefits and Enhanced Mood States

Sale et al., (2014) noted that physical health benefits often arise in enriched, complex housing environments. This indicates a variety of activities in these settings encourages physical movement, thereby lowering the risks associated with issues connected to a sedentary lifestyle. Furthermore, van Praag et al. (2000) emphasise that individuals interacting in enriched and complex housing environments may also experience enhanced wellbeing, along with extended periods of improved mood and reduced stress levels.