The brain is the most complex, and arguably the most important, part of the human body, and yet, it is something that most people know very little about. To get a better understanding of how meditation affects the brain, we’ll first want to understand the basics of the brain itself.
The brain is a three-pound organ that is the seat of the intellect, the interpreter of the senses, the initiator of body movement, and the controller of our behavior. The brain resides within the cavity of the skull, and is immersed in a protective fluid called Cerebrospinal Fluid (CSF).
The brain can be divided into three basic units, all of which work together synergistically: the forebrain, the midbrain, and the hindbrain.
The hindbrain includes the upper part of the spinal cord, the brain stem, and a wrinkled ball of tissue called the cerebellum. The hindbrain controls the body’s vital functions such as digestion, respiration and heart rate. The cerebellum coordinates movement and is involved in learned habitual movements.
The uppermost part of the brainstem is the midbrain, which controls some reflex actions and is part of the circuit involved in the control of eye movements and other voluntary movements.
The forebrain is the largest and most highly developed part of the human brain: it consists primarily of the cerebrum and the structures hidden beneath it. The cerebrum sits at the topmost part of the brain and is the source of intellectual activities. It holds your memories, allows you to plan, enables you to imagine and think and allows you to recognize familiar faces, read books, and solve puzzles.
The cerebrum is structurally composed of an outer layer of gray matter, called the cerebral cortex, and a centrally located white matter.
The cerebrum is split into two halves (hemispheres) by a deep fissure. Despite this split, the two hemispheres of the cerebrum communicate with each other through a thick tract of nerve fibers that lies at the base of this fissure, called the corpus callosum.
Although the two hemispheres appear to be mirror images of each other, they are actually quite different. For instance, the ability to form words seems to lie primarily in the left hemisphere, while the right hemisphere seems to control many abstract reasoning skills.
For reasons that are still not fully understood, nearly all of the signals from the brain to the body and vice-versa cross over on their way to and from the brain—meaning that the left cerebral hemisphere primarily controls the right side of the body and the right hemisphere primarily controls the left side. When one side of the brain is damaged, the opposite side of the body is affected. For example, a stroke in the left hemisphere of the brain can leave the right arm and right leg paralyzed.
Traditionally, each of the hemispheres of the brain have been divided into four lobes: frontal, parietal, temporal and occipital.
Most brain functions rely on many different regions across the entire brain working in conjunction, however, it is also true that each lobe carries out the bulk of certain functions in the brain.
The lobes of the brain are divided by a number of bumps and grooves, known as gyri (bumps) and sulci (groves or fissures). The folding of the brain, and the resulting gyri and sulci, increases its surface area and enables more cerebral cortex matter to fit inside the skull.
The frontal lobe is separated from the parietal lobe by a space called the central sulcus, and from the temporal lobe by the lateral sulcus. The frontal lobe is generally where higher executive functions including emotional regulation, planning, reasoning and problem solving occur.
The parietal lobe is behind the frontal lobe, separated by the central sulcus. Areas in the parietal lobe are responsible for integrating sensory information, including touch, temperature, pressure and pain.
Separated from the frontal lobe by the lateral fissure, the temporal lobe also contains regions dedicated to processing sensory information, particularly important for hearing, recognizing language, and forming memories.
The occipital lobe is the major visual processing center in the brain. The primary visual cortex, also known as V1, receives visual information from the eyes. This information is relayed to several secondary visual processing areas, which interpret depth, distance, location and the identity of seen objects.
Isn’t it fascinating that all of these different areas of the brain are working together, even now as you read these words?
Deep within the brain, hidden from view, lie structures that are the gatekeepers between the spinal cord and the cerebral hemispheres. These structures play key roles in our emotional state, modify our perceptions and responses depending on that state, and allow us to initiate movements that are made spontaneously without thinking about them. Just like the lobes in the cerebral hemispheres, the structures of the inner brain are each duplicated in the opposite half of the brain.
The hypothalamus, about the size of a pearl, directs a multitude of important functions. It wakes you up in the morning, gets adrenaline flowing when it is needed, and is an important emotional center that helps to control the molecules that make you feel energized, irritated, or unhappy.
Near the hypothalamus lies the thalamus, a major clearinghouse for information going to and from the spinal cord and the cerebrum.
An arching tract of nerve cells leads from the hypothalamus and the thalamus to the hippocampus. This tiny nub acts as a memory indexer—sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary.
The basal ganglia (not pictured) are clusters of nerve cells surrounding the thalamus. They are responsible for initiating and integrating movements. Parkinson’s disease, which results in tremors, rigidity, and a stiff, shuffling walk, is a disease of nerve cells that lead into the basal ganglia.
You may have heard of the default mode network before, but if you haven’t, this is an extremely relevant topic for meditation practice. The DMN is a network of interacting brain regions that are essentially what are responsible for what you sense as the voice in your mind (you know, the voice that says, “I look kind of fat in this shirt” “that was a stupid thing to say” “I’m bored” “what should I have for dinner tonight?”)
The DMN consists of the brain regions of the medial prefrontal cortex, posterior cingulate cortex, and the inferior parietal lobule, all of which are important for our survival. This network is most active when we are awake, when we are thinking about ourselves, remembering the past, imagining the future, or anything that involves not being relaxed and attentive to what’s happening right now.
The DMN is useful because it’s involved in our memory, particularly in the daily memories that play a role in helping us make a model of the world, and predict the future based on past events. The problem is, however, the models we create may not always be true, and sometimes we get stuck in these mental models and it makes it difficult to see anything other than the image our mind has created.
Another common issue, is that people unknowingly identify with the voice in the mind, as well as the models that the DMN has created for themselves, and don’t realize that this is actually a process of the brain, one that is now measurable by magnetic resonance imaging.
Essentially, the DMN is what many people refer to as the ego, or the monkey mind. It is the inner voice inside the mind, the one dialoguing all of our thoughts and creating our mental stories. The constant stream of thoughts that just won’t turn off sometimes.
The DMN is an essential part of the brain, but it is also a great source of psychological stress. The DMN easily leads to a wandering mind and distracts us from being present to life. Instead, we are consumed by thoughts of the past or future, planning, fantasizing, imagining, reflecting, memorizing, regretting and so on.
University of Berkley researcher Matt Killingsworth conducted a study, observing people’s levels of happiness throughout the day. What he found, and what many other research studies have concluded, is that people become less happy when they let their minds wander.
When we let our minds wander, and spend significant amounts of time lost in thought, it leaves at the mercy of whatever our thoughts are—and often many of us have rather fearful, negative, and limiting thoughts.
These thoughts are not actually reality, but are our DMN’s best attempt at interpreting or creating a model for reality. Unfortunately, many of us, mistake the model for the real thing, and become stressed out, anxious, or depressed because of the voice in our heads.
Thankfully, there are times when we are free of that voice. In particular, when we are doing something active, something we enjoy, or something that engages our attention enough to quiet the mind. In these moments, we feel most alive. This is when we are in a state of flow.
The flow-state is essentially a state of presence, or present-moment awareness, and this is what meditation helps us accomplish. Meditation helps us become more present to life, so we can actually be oriented to life from this flow state, rather than being dominated by the DMN and the voice inside our heads.
Several studies have been done on meditation and its effect on the default mode network. One such study was published in the National Academy of Sciences Journal and states “We investigated brain activity in experienced meditators and matched meditation-naive controls as they performed several different meditations (Concentration, Loving-Kindness, Choiceless Awareness). We found that the main nodes of the default-mode network (medial prefrontal and posterior cingulate cortices) were relatively deactivated in experienced meditators across all meditation types. Furthermore, functional connectivity analysis revealed stronger coupling in experienced meditators between the posterior cingulate, dorsal anterior cingulate, and dorsolateral prefrontal cortices (regions previously implicated in self-monitoring and cognitive control), both at baseline and during meditation. Our findings demonstrate differences in the default-mode network that are consistent with decreased mind-wandering. As such, these provide a unique understanding of possible neural mechanisms of meditation.”
In numerous studies, it has been shown that meditation, in as little as 20 minutes, can significantly reduce activity in the DMN and quiet the voice in the mind, allowing meditators to achieve a state of presence and flow.
For thousands of years meditators and spiritual traditions have talked about the importance of living in the present moment, and the misery that is caused by the mind and its untamed, restless thinking. Now, we have scientific research that can back up these claims, and shows that people do in fact experience less happiness when they are at the mercy of their restless mind, and that they can train the mind to quiet the inner voice, and open awareness to the reality of life in the present moment.
While the quieting down of the inner voice and the reduced activity in the DMN are significant brain changes that occur in meditation, they are not at all the only changes that occur in the brain.
One Harvard study found that when people went through 8 weeks of meditation, critical areas of the brain that associate with awareness, stress, and empathy changed. They grew new grey matter in their cerebral cortex, which connects to attention and emotional integration. The participants in the study all gained more control over their emotions and even impulse control became better.
Using modern technology like fMRI scans, scientists have developed a more thorough understanding of what’s taking place in our brains when we meditate. The overall difference is that our brains stop processing information as actively as they normally would. We start to show a decrease in beta waves, which indicate that our brains are processing information. This decrease can happen in as little as 20-minutes, even if we’ve never tried meditation before.
In the image here you can see an MRI scan of how the beta waves (shown in bright colors on the left) are dramatically reduced during meditation (as seen on the right).
Our brain develops and adapts throughout our entire lives. This phenomenon, called neuroplasticity, means that gray matter can thicken or shrink, connections between neurons can be improved, new connections can be created, and old connections can be degraded or even terminated.
It was long believed that once your “child brain” was fully developed, the only thing you could anticipate for the future was a gradual decline in intelligence. Now we know that our everyday behaviors literally change our brains, and it appears that the same mechanisms which allow our brains to learn new languages or sports can help us learn how to be happy and to experience more joy in our daily lives.
The brain is truly a fascinating organ, and the more we understand it, the better we can work with it to shape our lives in a positive way. Meditation is a powerful tool for improving your brain’s health and overall functioning.
If you’d like to learn more about how to start and maintain a regular meditation practice, our Introduction to Meditation course is a great place to start.
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