2. Meditation and Learning and Plasticity

The Benefits of Meditation on Learning and Plasticity
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This article entails some differential benefits associated with meditation and neuronal plasticity
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The act of meditation has been practiced by our ancestors for centuries and only recently have scientists started to understand and explore its vast benefits. A specific topic sparking more interest is the understanding of how meditation influences learning and overall neuroplasticity. It has been shown that both short-term and long-term meditation practices have had beneficial effects on learning, through physiological brain alterations. Tested short-term practices include experiments where participants are gathered for a few months at meditation retreat and their ability to perform tasks prior and post-meditation had been monitored [1]. Long-term meditators had also been observed, such as Tibetan Buddhists, whom demonstrate alterations in their brain physiology [2]. Neurological structures involved in meditation, with specific correlation to learning include; increase in amount of grey matter in the brain, at the location of the hippocampus and an overall larger hippocampal and parahippocampal gyrus [3] which plays a significant role in memory, growth of white matter tracts, increase in gamma waves and activation of prefrontal cortex for example. Scientists have started integrating meditation as a more holistic approach to medical practices, such as for depression, pain perception and even addiction, but it is also able to elucidate the vast benefit into other areas of the human brain and allow for overall heightened learning and plasticity.

2.1 Experimental Studies

There has been an growing interest on the topic of Meditation in the field of Neuroscience and the different functional roles that may be involved in learning and plasticity, which include the heightened ability to concentrate on a task, expanded capability in retaining information and overall less brain activity in correlation with outside distractors. Both short-term and long-term practices have shown to be quite advantageous in overall neuroplasticity, far greater than the non-practitioner, which kindled interest towards further studies.

a. Short-Term Meditation

Short-Term meditation plays an important role in learning, and have shown beneficial towards increasing attention [4]. A study conducted gathered undergraduate students and had them practice integrative body mind training for a short period of five weeks, focusing their attentions on being aware of their body and different sensory modalities while in a state of relaxation verses a control group that followed solely a relaxation regiment for a duration of twenty minutes per day [4]. Examination had followed, observing the ability of the participants to perform attentional focused tests prior and post-meditation [4]. Before training, there was not much difference between either of the groups however, as predicted, five weeks after practice the meditation group had shown some improvement in comparison to that of the control [4]. Therefore, even a short amount of time spent towards the act of meditation has proven to be effective in increasing the individuals learning skills and allowing for neuroplasticity.

b. Long-Term Meditation

Although short-term mediation can induce some minor physiological changes and benefit in neuroplasticity, the benefits are not as vast as those observed in long-term practitioners. Tibetan Monks whom have dedicated a majority of their lives to meditation, including 10,000 to 54,000 hours towards this art, have shown activation in attention related brain structures. Focusing their practices on a concentrative forms of meditation, putting all their attention on an object or a task that is usually unconsciously executed, such as breathing [5]. Even in comparative tests with incentive induced novice meditators, whom were trying with all their might to perform to their optimum and received the best results on the learning tests, were not able to exceed the amount and rapidity of brain activation of the Buddhist monks [5]. There was also evidence in decreased brain activity in response to external sound distractors, promoting better concentration and learning for the practitioners [5]. In response to the tests, these monks in fact show concrete evidence of structural brain changes. Some examples include a decrease in activity of the Amygdala, which inversely correlated with a better concentration, as reactions to certain types of emotions are less prevalent. These long-term practitioners also demonstrate increase post-meditation gamma waves, which is directly related to increase in memory and overall focus [6]. These findings, along with the benefits of even short-term practices have really brought to question the neurological effects meditation may impose on the brain, bringing to light the benefits of increased neuroplasticity through a more effortless form of learning, attention and concentrating to the task at hand.

2.2 Neurological Evidence

a. Growth in Grey Matter

i. The hippocampus

Figure 1. Growth GM
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Source; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705194/figure/F1/

The hippocampus plays one of the most important functional components in learning, as it is responsible for consolidation of short-term learnt memory into long-term plasticity [10]. Rat model groups where the hippocampus has been lesioned has proven to obstruct their ability of memory and spatial and contextual learning [11], further elucidating some of the hippocampus’ involved responsibilities. It is through meditation that the hippocampus, and other nearby surrounding areas all involved in some way to learning, increase in size and grey matter [9].
Figure 1 demonstrates growth in hippocampal grey matter through Voxel-based morphometry , a source of neuroimaging, linked to practitioners with approximately 20 years of meditation in comparison to the control non-meditating group [7]. Other imaging sources, such as Magnetic resonance imaging (MRI), have been shown to exhibit again, growth in grey matter of other experimental studies performed [8]. Prior studies bring validation that meditation, more specifically long-term practice, is able to show increase in size of hippocampus, and areas such as parahippocampal, thalamus and inferior temporal gyrus[8]. Some researchers have speculated that growth may be the result of focused attention on both external and internal stimuli through focusing attention on visualization, or induced through neurogenesis that occurs through meditation [8]. Other experimental data, independent of meditation, but all involving the hippocampus, have been able to increase size of grey matter through learnt motor tasks and various forms or technique to which induces hippocampal growth, showing evidence of increased memory and learning [12].

b. Growth of White Matter

Figure 2. Increase FA
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Source; http://www.pnas.org/content/109/26/10570/F1.large.jpg

Meditation also seems to play an important part in changing the physiological role of white matter in the brain [13]. Measurement of white matter plasticity can be achieved in vivo through, a technique known as diffusor tensor imaging (DTI), a form of MRI [13]. The higher the index indicated by fractional anisotropy the better the brain function [13]. Fractional anisotropy is determined based on numerous aspects; myelination of the tracts, their diffusion and axon density [13]. Other similar studies, capable of inducing similar changes in white matter through other forms of training, such as increased reading or abacus training have also showed the result of increased fractional anisotropy [13]. It is believed that this increase is induced by more myelination of the tracts, as more neuronal firings is proportional to myelination, therefore strengthening the delivery of information between synapses of cortical areas [13]. Figure 2 is able to show evidence of this increase in fractional anisotropy and decrease in axial and radial diffusivity having an overall beneficial effect towards performance.

i. The Anterior Cingulate Cortex

Figure 3. Increase FA
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Source; http://www.pnas.org/content/107/35/15649/F2.large.jpg

The role of the anterior cingulate cortex is a key player in problem solving, and thus a fundamental part in the process of learning [14]. Through short-term meditation, which can involve as little as six hours of integrative-body mind training, can lead to increase in white matter tracts from the corona radiata found to connect and cross the anterior cingulate cortex [14].

Figure 4. Growth CC
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Source; http://www.pnas.org/content/107/35/15649/F3.large.jpg

As demonstrated in figure 3, a slight increase in fractional anisotropy activity is observed, in individuals that perform integrative body mind training from values of about 0.5 to close to 0.6 when contrasted to the control group of merely relaxation training. Other increases of white matter tracts include growth in the corpus callosum, found in the genu and body [14], as seen evident in figure 4. Through the progression of age, from maturation of a child the anterior cingulate cortex is a dynamic and changing structure, that allows altering of behaviour [14]. A lesion at this area can prove to cause deficits in attention, showing its extensive importance in learning [14]. To show specific relation between the two, reading skills have been proven to be best in those with increased activity of white matter [15]. This can be similarly related to the changes induced by meditation in the brain, though the activation of increase fractional anisotropy previously observed. This is achieved as the white matter tracts integrates different sensory modalities together; incorporates visual cues, auditory and language processes together, allowing for the ability to read [15].

c. Gamma Waves

Changes in gamma waves has been observed through the practice of meditation [16], and also much involved in learning and attention as sensory input is responsible for the modulation of gamma waves, involved in memory and attention [17]. Methods to best observe brain wave oscillations has been conducted through electroencephalogram (EEG), and recorded activity of long-term meditative practitioners have demonstrated increased in gamma oscillations, in relation to meditative states not observed in baseline brain activity of a control novice group [16]. Other factors that may have been contributed to such high-amplitudes of gamma activity have been tested against, such as age, culture of origin or diet and sleep. The data indicates that attention and affective processes, which is represented in electroencephalogram synchronization can be altered and a trained process. Gamma activity is abundant in numeral cortical areas including subcortical structure [17]. Increase in its activity can be driven through the increase of sensory modality located in the sensory cortex, as well through other cognitive phenomena such as attention [17]. Neurodegenerative disorders such as Alzheimer’s, Parkinson’s or schizophrenia show irregularities in gamma activity, but elevated in levels during fully functional and working memory and learning [17]. Other studies have also been successful in demonstrating that fast and high amplitude and oscillation is linked to the functional role of learning and neuronal plasticity. These findings, are able to clearly illustrate the functional role of meditation in learning, through the increased levels of gamma brain waves after continual practice of long-term meditation [18].

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