Better mental health through meditation?

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Photo by Oleksandr Pidvalnyi on Pexels.com

Authors: Kieran C.R. Fox, R. Nathan Spreng, Melissa Ellamil, Jessica R. Andrews-Hanna, Kalina Christoff

Year: 2015

Title: The wandering brain: Meta-analysis of functional neuroimaging studies
of mind-wandering and related spontaneous thought processes

Summary: Thinking about the most common effects on the brain from meditation will lead you into an area that psychologists call spontaneous thoughts. These are defined as thoughts and ideas that seem to come out of nowhere and don’t necessarily have any obvious relationship to a specific task you may be undertaking. Meditation scientists have long considered that the most popular forms of secular meditation lower activity in regions of the brain known as the Default Mode Network (DMN). The DMN is strongly connected with, self-reflection, thoughts about relationships with others, memories of the past and our ability to project into the future. It is also the home to our mind wandering or drifting.

Mind wandering can increase under certain conditions and has been linked to a number of long term mental health problems including anxiety and depression. Many forms of meditation reduce activity in the parts of the DMN known to support spontaneous thoughts and mind wandering. This can be a great help to people that have problems concentrating or are troubled by negative or challenging thoughts. The research by Fox and colleagues undertook a review of 24 functional neuroimaging studies looking into mind wandering/spontaneous thought. Results confirmed that well-established centres in the DMN (medial prefrontal cortex, posterior cingulate cortex, medial temporal lobe, and bilateral inferior parietal lobule) were associated with mind wandering. However, it was evident that a number of other brain regions were also engaged. The significance of the study was that spontaneous thought cannot be regarded as universally linked to a limited number of centres in the DMN. A range of regions in different networks appears to be instrumental to spontaneous thought and mind wandering.

The implication for meditation practitioners and researchers is that the apparent act of suppression or restriction of activity in the DMN cannot be seen in a narrow context and may have a broader implication for a number of interrelated processes.

Link: https://www.sciencedirect.com

Intelligence linked to brain size

Not a surprising headline until you consider that Dr Erhan Genç and Christoph Fraenz at Ruhr-Universität Bochum are reported as suggesting that people with higher scores on an intelligence test were found to have smaller brain structures. […]

Meditation changes brain size?
Meditation can change brain size, but not only in one direction

Not a surprising headline until you consider that Dr Erhan Genç and Christoph Fraenz at Ruhr-Universität Bochum are reported as suggesting that people with higher scores on an intelligence test were found to have smaller brain structures.

Brains are extremely complex organs and many aspects of their function and structure are not yet fully understood. However, we do know that neurons usually gather data from adjacent (presynaptic) neurons through complex tree-like structures containing many dendrites. The dendrites communicate with their own neuron’s cell body. Based on the messages received through the dendrites, a cell may fire (create an action potential) or not. When an action potential is generated, a message is then sent out to other neurons (postsynaptic) through the axon terminal. The reports of this study (I haven’t read the actual paper yet) is suggestive that people with fewer dendrites feeding into certain neurons in the cerebral cortex had higher IQ scores.

Dendrite (PSF)There are typically large numbers of dendrites communicating with each neuron in the cerebral cortex. There is a putative logic which could argue that smaller dendrite trees could be more efficient. Leading to a greater number of relevant action potentials being created more quickly. Given our limitations in understanding the mechanisms that lead to the generation and maintenance of dendrites, some caution needs to be expressed here. Without an appreciation of what the extra dendrites (in the participants with lower IQ scores) do, and why they are there, the picture is incomplete. Intelligence tests in general and IQ tests, in particular, are regarded by many experts as being reductive. It is possible that people with a history of IQ testing could have developed dendritic structures able to support this activity. But has anything been lost in the process? Are the extra dendrites in the lower IQ scored participants simply inefficient, and of no real benefit?

So what has this got to do with meditation? I wrote recently about structural changes in the brains of meditators. A conclusion from my own investigations was that increases and decreases in brain structures are likely to be the result of intense and sustained meditation practice. So the demonstration that neurological structures become bigger or smaller is probably an unhelpful oversimplification. The relationship between the alteration in structural size in different (interrelated) regions of the brain needs to be understood and then correlated to cognitive functionality if the understanding of the significance of changes is to be approached.

Rather than increasing or decreasing brain structures, meditators should probably think about their practice in terms of its deliverable goals in relation to behaviour. Brain imaging technology is still in its infancy and there are many significant problems still to overcome. We are probably decades away for being certain of the impact of complex human behaviours (like meditation) on brain structure, but we have for centuries been able to relate certain practices with behavioural changes. There are two obvious exceptions to these generalizations, age-related structural decline and changes due to neurodegeneration.

It should reiterate that I haven’t seen the full report of the Genç and Fraenz paper but a report is available at Eureka Alert.

Meditation can change the size of your brain

The brain is plastic, to what extend does it undergo structural changes during meditation?

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Authors: Kieran C.R. Fox, Savannah Nijeboer, Matthew L. Dixon, James L. Floman,
Melissa Ellamil, Samuel P. Rumak, Peter Sedlmeier, Kalina Christoff

Year: 2014

Title: Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners

Summary: Like almost every contemplative scientist will point out, our understanding of what meditation can do for us in its infancy. However, this investigation sets out the progress made in understanding meditation related to structural changes in the brain. The researcher identified 21 studies that imaged the brains of meditators, looking for structural changes. Although most of the research was cross-sectional in nature some ‘before and after’ examples are included.

This project reviewed research that used any of the six leading measures of structural changes in the brain (volumetry, concentration, thickness, fractional anisotropy (FA), diffusivity (axial and radial) and gyrification). The selected papers were qualitatively reviewed and also subject to an anatomical likelihood estimation (ALE) meta-analysis. Qualitative results highlighted nine brain areas that might have undergone structural alteration as a result of meditation practice. Seven areas of grey matter: anterior/mid-cingulate cortex, fusiform gyrus, hippocampus, inferior temporal gyrus, insular cortex, rostrolateral prefrontal cortex, somatomotor cortices and two white matter pathways: corpus callosum, superior longitudinal fasciculus.

Although Lazer et al. made efforts to link the results of morphometric neuroimaging to a range of functional studies there are a number of problems in this approach. There is little structure in how meditators and meditation methods are grouped together,  both in creating the meta-analysis and explanations for alterations in brain structures. This in part reflects the limitations of the 21 neuroimaging studies used, it is also linked to the widely documented problems in the theoretical frameworks used by contemplative science. For example, common features are looked for in diverse experiments using different forms of meditation, both secular and spiritual. Although the participants from the experimental groups cited in the studies had all meditated, they often differ significantly in the methods they use, frequency and duration of practice and time spent in intensive meditation retreat.

Despite the limitations, which are in large part symptomatic of meditation research in general, this remains an influential study fo0r both cognitive psychology and neuroscience.

Link: https://www.sciencedirect.com