Who you really are; the default mode network

The default mode network has a crucial but poorly understood role in how meditation influences brain structure and function. This paper sets out some of the current thinking regarding self-generated thought.

Meditation and the defaulyt mode network.
What is your brain doing when you are day dreaming?

Authors: Andrews‐Hanna, J. R., Smallwood, J., & Spreng, R. N.

Year: 2014

Title: The default network and self‐generated thought: component processes, dynamic control, and clinical relevance

Summary: It is frequently suggested that neuroscience is still in its infancy, this becomes patently clear when you start to consider how little we know about the default mode network (DMN). The DMN, also known as the default network (DN) or the task-negative network (TNN) is most active when humans are in a resting state. In short, the DMN is the network that takes over when we are not actively engaged in a specific task. Surprisingly it was assumed that the brain was resting when not engaged in an externally focussed activity. This assumption was surprising because scientists know that their brains are capable of complex processes such as mind wandering when they are not reacting to the external environment. However, only when it was demonstrated that functional brain activity could reach similar levels in task and non-task modes did the investigation into the DMN begin in earnest. This has particular relevance for meditators and contemplative science, as the DMN is often the direct and indirect target for meditation methods.

Andrews‐Hanna,  Smallwood and Spreng produced a review of the leading findings linked to the DMN, which they describe as an anatomically diffuse global network.  Their primary focus is the DMN and self-generated thought, thought that arise without external sensory stimulus. Describing much of the recent research in the field they conclude that the DMN plays an integrated role in a wide range of neurological functions. Thus both normal and abnormal mental health is dependent on activity and functional connectivity within the DMN and links to other neural networks. The paper provides a useful background to contemplative scientists looking for an understanding of how meditation might influence human behaviour.

Link:  www.ncbi.nlm.nih.gov

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

How much does science know about meditation?

Scientific understanding of meditation and mindfulness

Science and meditation
Science and meditation

Blogging about a related issue at Meditation for Health prompted me to think about how much does science really know about meditation and mindfulness. Leading scientists in the field state that empirical meditation research is at a relatively early stage. But relative to what? Surely not the efforts of the scientific community, thousands of scientific studies have already been published that explored meditation and/or its presumed operationalised components. It should also be considered that there is a vast body of traditional texts available, documenting many aspects of contemplative sciences over the last two thousand years. Contemporary research should also have benefited from the millions of current practitioners, including meditation masters with great experience of practice and underlying theoretical frameworks. It is hard to imagine more auspicious conditions for the study of meditation, so why is the research struggling to make significant progress?

After I had been meditating for five years I asked a traditional meditation teacher what the goal of my particular practice was. She stripped away the esoteric imagery in which the practice was framed and explained the likely result of my efforts. In particular, she emphasized the importance of my motivation. The idea that the method alone is not the practice is central to many forms of meditation and contemplation. In fact, traditional literature from Tibetan Buddhism makes it clear that progress in a particular method may require the application of significant levels of compassion or non-attachment. It is not my suggestion that a western scientific approach cannot fully understand the processes engaged in different forms of meditation. But rather it might be time to start to think about the phenomena underpinning meditation in a more complete way, even within cognitive psychology or neuropsychology. In some traditional schools, meditators are discouraged from evaluating the progress of others. But when you meditate cheek by jowl in a community of meditators for years, you may inevitably observe differences in the effects of the same meditation practice on different people.

Whilst the capacity of practitioners (individual differences) is a known factor in the experience of meditation. An individual’s motivation is also central to the benefits of a practice. This is a paradigm for all meditators and mindful practitioners in all settings. Unless a scientist can integrate the enthusiasm, scepticism and goals of the meditator into the input part of the equation, great uncertainty regarding the output is inevitable.  In a survey of meditators and mindfulness practitioners (Morris, 2017) that included both types of practice and reasons for commencement. The motivation of practitioners was very varied. Among the cited reasons for beginning meditation or mindfulness were:        

Motive %
To improve my health 12
To improve my general well-being 43
For spiritual/religious reasons 22
As a lifestyle choice 6
Because of the influence of others 3
Any other reasons 14

There are reasons to suppose that the motivation of a meditator is a significant influencer on the results of a practice. The empirical approach has a great deal to offer the investigation of meditation, it can help to construct reductionist models able to identify the elements contemplative practice. But we are perhaps at a point when a fuller understanding of meditation and meditators needs to evolve.

 

References

Morris, S. (2017), An exploration of the relationship between wellbeing and meditation experience amongst meditators and mindfulness practitioners. The Open University, Milton Keynes. Unpublished

Investigating the Phenomenological Matrix of Mindfulness-Related Practices from a Neurocognitive Perspective

The experience of the meditator in meditation research

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Title: Investigating the Phenomenological Matrix of Mindfulness-Related Practices from a Neurocognitive Perspective

Authors: Antoine Lutz, Amishi P. Jha, John D. Dunne, Clifford D. Saron

Year: 2015

Summary: This review of research into mindfulness summarises a significant amount of recent nonclinical investigation into the subject. It presents mindfulness as a series of different but related practices which cover diverse phenomena. It highlights the broad spectrum of mindfulness and how it is understood from both spiritual and secular perspectives. This paper expresses the complex nature of mindfulness meditation within ‘a multidimensional phenomenological matrix which itself can be expressed in a neurocognitive framework’. Opportunities and approaches for new research in the general area of mindfulness are suggested. Several important and under researched concerns are raised in this investigation, and calls for a greater understanding of the ethical and axiological contexts are particularly welcome. This work may in due course prove to be an important milestone in the research of meditation in general and mindfulness in particular.

Perspective: Neurocognitive, phenomenological, cognitive psychology

Link: https://www.upaya.org/uploads/pdfs/DunneSaron.pdf

 

Challenges in Researching Mindfulness

Problems in the scientific research of meditation and mindfulness.

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Authors: Richard J. Davidson, Alfred W. Kaszniak

Year: 2015

Title: Conceptual and Methodological Issues in Research on Mindfulness and Meditation

Summary: As western psychological investigation into meditation and mindfulness increases, concerns are being raised about how to understand and integrate the wide ranging findings that are being published. Mindfulness is a very general term for one meditative approach which can include a number of distinct psychological phenomena. This paper discusses the conceptual and methodological difficulties in researching this area. Addressing the challenges of creating and subsequently evaluating findings, which by their very nature may only be fully appreciated in the first person.

Perspective: Cognitive psychology, neuroscience

Link: http://centerhealthyminds.org/assets/files-publications/DavidsonConceptualAP.pdf

 

Mindfulness Practice Leads To Increases in Regional Brain Grey Matter Density

Mindfulness increases some brain matter dentsity

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Authors: Hölzel, B. K., Carmody, J., Vangel, M., Congleton, C., Yerramsetti, S. M., Gard, T., & Lazar, S. W

Year: 2011

Title: Mindfulness practice leads to increases in regional brain grey matter density

Summary: An investigation into the neural mechanisms that may be impacted by the Mindfulness Based Stress Reduction (MBSR) form of mindfulness meditation.  16 participants with no prior experience of meditation were put through an eight week MSBR training programme. Any changes to grey matter concentration within the MBSR group were investigated and compared to the control group. Analyses indicated the MBSR group experienced increased grey matter in the left hippocampus, posterior cingulate cortex, the temporo-parietal junction and the cerebellum. The findings suggest a potential relationship between the practice of MBSR and changes to concentration of grey matter in parts of the brain connected to learning and memory processes, emotion regulation, self-referential processing, and perspective taking.

Perspective: Neuroscience

Link: http://www.ncbi.nlm.nih.gov/pubmed/21071182