The nervous system has enough complexity underlying in the vasteness of neural and connecting settings. Stressful responses originally exists evolutionarily being part of the general adaptation syndrome, named by Hans Selye. But the lifestyle is originating an enormous burst of stress to each individual. There are some interventions known from ancient times, including several types of meditation, which were re-discovered by scholar researchers during the last decades of the last century, which were re-inforced in its impact on the nervous system, by many of the techniques intensely researched during the previous decade of the brain. The mindfulness is a well-proven intervention demonstrating evidence in controlling functional states of several structures of nervous system, namely prefrontal cortex, hippocampal structures, cyngulate cortex, thalamus, and the resulting attention not only controls the stressful response, but improves cognition and cognitive abilities. And the amigdala, the nucleus in the forebrain linked to fear and stressful responses, diminish in size, and in function, improving conditions such as chronic pain, pos-traumatic stress disorders, to mention some. The value of mindfulness as described by the investigator Jon Kavatt Zin is of big value when taking in consideration the new definition of health, namely the abilities to face and to adapt to stressful situations in a physical, social or mental challenges.
Brief introduction to the brain.
The human brain is the most complex object in universe, is a reddish grey mass, with the consistency of firm jelly, which weighs on average 1200 grams and contains nearly 100 billion cells called neurones. Each neurone has a cell body which houses its processor, the nucleus and a lot of batteries providing energy, the mithochondria. Branching from the bodies are numerous processes or extension called collectively neurites, classified as dendrites or axons. Dendrytes branch and re-branch, are tree like structures that intertwingle with another dendritic trees of other neurones, while axon allows the transmission of electrical impulses to target tissues or another neurons. Each neurone makes up to 1000 different connections with its neighbours and different areas of the brain. This extensive connectivity allows electrical signals, and thus information to travel from one brain processing centre to another in a matter of milliseconds.
The human brain is organised in a hierarchical manner: the oldest core parts controlling the more primitive, instinctual behavioural reflexes; the newest parts enveloping the new ones, are controlling the more sophisticated cognitive, sensory and motor functions. The human brain is made up of three main blocks: the forebrain, the midbrain and the hindbrain.
The brain is made of three main parts: the forebrain, midbrain, and hindbrain. The forebrain consists of the cerebrum, thalamus, and hypothalamus (part of the limbic system). The midbrain consists of the tectum and tegmentum. The hindbrain is made of the cerebellum, pons and medulla. Often the midbrain, pons, and medulla are referred to together as the brainstem, which is the oldest part, evolved more than 500 million years ago. It closely resembles the brain of a modern reptile. It is responsible for automatic physiological reflexes that control in example breathing, heart rate and digestion, and coordinate movement and sense perception.
The midbrain contains neurones responsible for temperature control and the fine tuning of movement. It relays sensory information from the bodies sensory organs to the forebrain, while the hindbrain is made of the cerebellum, pons and medulla.
The most evolved part is the forebrain which is composed of cerebral hemispheres, and is what we most commonly think of as the brain, and the hypothalamus and thalamus. It also plays an important part of the limbic system, a group of brain structures associated with the expression of emotion. In the last 100,000 years, the weight of the human brain has almost tripled, and most of this growth has been mainly by the cerebral hemispheres. The neurones of the forebrain control cognitive, sensory and motor function, as well as regulating reproductive functions, eating, sleeping and the display of emotion. (http://serendip.brynmawr.edu/bb/kinser/Structure1.html)
Neuroscience behind emotions
Emotions are triggered in the brain by thoughts, which are often unconscious. When we are confronted by a potential threat, this can trigger the best known feelings of fear, anger or the urge to flee (sometimes called “amygdala hyjack“). The reaction is often disproportionate to the actual provocation.
Stress is thought to be an important factor in many health problems. Early stress researchers found that regardless of the environmental stressor, a generalized physiological response was activated in the organism called the “fight or flight,” or stress response and termed the General Adaptation Syndrome by Hans Selye. When an individual encounters a stressor, the body part that first notes the stimulus passes the signal to the brain. The physical problems related to chronic stress include the lowering of the immune response, chronic muscle tension, and increased blood pressure.These problems can eventually lead to serious life-threatening illnesses such as heart attacks, kidney disease, and cancer (http://www.indiana.edu/~engs/hints/stress1.htm)
Makes absolute sense in the lifestyle we live in, the mastering of these stressful emotions, so then the enhancement of the own´s abilities for higher “rational brain” thinking favours the person, being likely to avoid the automatically behaviour stored in the basal ganglia.
MRI scans show that after an eight-week course of mindfulness practice, the brain’s “fight or flight” center, the amygdala, appears to shrink. This primal region of the brain, associated with fear and emotion, is involved in the initiation of the body’s response to stress.
As the amygdala shrinks, the pre-frontal cortex – associated with higher order brain functions such as awareness, concentration and decision-making – becomes thicker.
The practice of mindfulness helps us to recognise and observe our thought patterns. Practitioners develop the ability to recognise when thoughts arise, and observe them in a detached manner, without the need to become involved in them, in the way described by professor Jon Kavatt-Zim Ph.D. (thus not triggering an emotional or “automatic” reaction).
The basic and classic conflict between reason and emotion is between the amygdala, or the emotional and fearful part of the brain, and the frontal cortex, which can calm the amygdala and sort things out rationally. Curiously, there is a limit to what the rational brain can handle, and the neuroanatomy can explain why. Projections from the amygdala to the brainstem, via the hypothalamus, regulate the expression of autonomic reactions to social signals, affecting the prefrontal cortex (PFC). In the same way, the control of the amygdala (AMY) arises from the anterior cingulate cortex (ACG) and affects the ventral medial prefrontal cortex (vmPFC) (http://mindblog.dericbownds.net/2010/10/serotonin-regulates-our-moral.html)
Right Brain and Left Brain?
The theory of right brain vs. left brain dominance originates with Nobel Prize winning neurobiologist and neuropsychologist Roger Sperry. Sperry discovered that the left hemisphere of the brain usually functions by processing information in rational, logical, sequential, and overall analytical ways. The right hemisphere tends to recognize relationships, integrate and synthesize information, and arrive at intuitive thoughts. By working together as a team, sharing logical and creative information, the two hemispheres can generate a more complete description. A study conducted at the University of Utah has debunked the myth. Neuroscientists analyzed over 1,000 brain scans from people between the ages of seven and 29. The brain scans did not show any evidence that people use one side of the brain more than the other. Essentially, the brain is interconnected, and the two hemispheres support each other in its processes and functions (http://www.diffen.com/difference/Left_Brain_vs_Right_Brain)
Kavat- Zimm describes mindfulness as “the awareness that emerges through paying attention on purpose, in the present moment, and non-judgmentally to the unfolding of experience moment by moment”. This general understanding is echoed by other authors who explain mindfulness as being “characterized by dispassionate, non-evaluative, and sustained moment-to-moment awareness of perceptible mental states and processes. This includes continuous, immediate awareness of physical sensations, perceptions, affective states, thoughts, and imagery” (Front Neurosci.2013;7:8).
Mindfulness interventions do begin with concentrative attention practices, such as attending to parts of the body or one’s breath, initially seeking to strengthen attentional control. Practice however then transitions to more ‘open monitoring’ practices of widespread attention to all sensations, thoughts and emotions (Can J Psychiatry. 2012 Feb; 57(2): 70–77.)
When practicing mindfulness the activation of the amygdala confers emotional significance to the lack of sensory information. Through these actions on the hypothalamus, the amygdala modifies the activity of the autonomic nervous system. First a blissful, peaceful state arises from the maximal activation of the parasympathetic (relaxation) nervous system, and then, as the different neural, hormonal and other triggers swing in, there is a maximal activation of the sympathetic (arousal) nervous system, producing a mentally clear and alert state. Physiological effects, such as changes to breathing rate, heart rate or blood pressure are the result of the amygdala’s effect on midbrain structures that control these functions. Both of the left and right orientation and verbal-conceptual association areas are virtually switched off. A lack of activity in the right orientation association area gives rise to a sense of unity and wholeness, where as lack of activity in the left orientation association area results in the dissolving of the self/non-self boundary (http://www.mindfulnet.org/page25.htm). In emotion regulation, mindfulness provides prefrontal training that seems to promote the stable recruitment of a non-conceptual sensory pathway, an alternative to conventional cognitive reappraisal strategies. The attentional resources are directed towards a limbic pathway for present-moment sensory awareness, involving the thalamus, insula (Can J Psychiatry. 2012 Feb; 57(2): 70–77.)
What happens in the brain during meditation?
In experiments of Mindfulness Based Stress Reduction – MBSR subjects showed (1) increased functional connectivity within auditory and visual networks, (2) increased functional connectivity between auditory cortex and areas associated with attentional and self-referential processes, (3) stronger anticorrelation between auditory and visual cortex, and (4) stronger anticorrelation between visual cortex and areas associated with attentional and self-referential processes. These findings depicts that 8 weeks of mindfulness meditation training can alter intrinsic functional connectivity in ways that may reflect a more consistent attentional focus, enhanced sensory processing, and reflective awareness of sensory experience (Neuroimage. 2011 May 1;56(1):290-8)
Meditation includes a variety of practices aimed at focusing attention and awareness. Two general forms of meditation exist, namely “focused attention” and “open monitoring“. Initially a practitioner will often utilize focused attention practice to enhance attentional skills. The “open monitoring” practices focus widespread attention to all sensations, thoughts and emotions. Then, it will be possible to engage in open monitoring, which involves moment-by-moment awareness of whatever occurs in one’s awareness (Front Neurosci.2013;7:8).
Another experiments in expert Theravada Buddhist monks and lay novices with 10 days of meditation practice on the above modalities, suggests that expert meditators control cognitive engagement in conscious processing of sensory-related, thought and emotion contents, by massive self-regulation of fronto-parietal and insular areas in the left hemisphere, in a meditation state-dependent fashion. So then, a functional reorganization of brain activity patterns for meditation type takes place with mental practice, and that meditation-related neuroplasticity is crucially associated to a functional reorganization of activity patterns in prefrontal cortex and in the insula (Brain Res Bull. 2010 Apr 29;82(1-2):46-56.)
Cognition Improved By Mindfulness Meditation
In another experiments in the framework of meditation, it was explored the hippocampal features analyzing high-resolution structural magnetic resonance imaging data from 30 long-term meditators and 30 matched controls. It was found that left and right hippocampal volumes were larger in meditators than in controls, significantly so for the left hippocampus. The implications of larger hippocampal dimensions in long-term meditators may constitute part of the underlying neurological substrate for cognitive skills, mental capacities, and/or personal traits associated with the practice of meditation (Hum Brain Mapp. 2013 Dec;34(12):3369-75.)
To know more about interventions improving functioning and mental conditions will be of utility when dealing stressful conditions and maybe to avoid risk factors to develop neurodegenerative conditions. Mindfulness shows evidence when executed during eight weeks and the more the practice, the better the benefits.