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What happens to the brain during meditation?
With the summer days fast approaching, finding inner peace through meditation is a great way to enjoy the longer days. But what happens in the brain during meditation?
By Dr Samantha J. Brooks Ph.D.
Look around this summer in Cape Town and you’ll find, in various locations and poses, people going crazy for meditation. After the cold, dark winter months it seems that long, warm, sunny days bring out our sense of inner peace! You’ll find people inside wooden-floored sanctuaries on cushions, and outside on the beach by the ocean, even half-way up Table Mountain on a ledge overlooking the city! People in Cape Town are friendly and will happily meditate in a group, but if you prefer, solitary meditation is also popular. Various methods of meditation exist, such as Metta Bhavana (“loving kindness”), Mindfulness of Breathing, and the Body Scan. With all the variations in meditation practices, they all still have something in common – lowering of arousal and strengthening of inward-looking attention, so that the outside world becomes less distracting. We all know that meditation is good for our well-being, but what happens in our brain to make us more mindful?
The amygdala – an almond-shaped structure deep in the mid-brain houses a collection of brain cells (neurons) that get activated whenever we feel stressed, afraid, or just generally over-stimulated. Most of us in this day and age feel overwhelmed by sensory input, with increasing numbers of people living in Cape Town, traffic jams, noise, multi-tasking and the 24/7 consumer culture. When the amygdala is activated by too much unfiltered sensory input, the fight, flight or freeze stress response might be turned on. In a hectic environment, the amygdala response becomes predictable, and repetitive activation makes a person feel stressed. It is also this middle part of the brain, along with other regions that allows us to feel emotions (positive or negative). It is certainly not good for our health to be unbalanced, over-stimulated and regularly emotional.
Meditation helps to slow down and reduce environmental over-stimulation, and focusing regularly on breathing, thoughts of loving kindness towards others, or paying attention to the feeling of one’s body during a body scan, relies on another part of our brain – the prefrontal cortex. In particular, the medial prefrontal cortex maintains a sense of self, so that one can hold loving thoughts about others in mind, and the orbitofrontal cortex allows us to evaluate the feeling of our bodies and our breath. The anterior cingulate cortex – the gateway between the prefrontal cortex and the emotional mid-brain helps to maintain good self-regulation. But these prefrontal cortex systems essentially go to sleep when we have too much stress. And this is where meditation comes in. Regular practice of a method of meditation – or mindfulness – can strengthen the neural circuits that can be used to lower the stress response. Strengthening the brain circuits in this way allows meta-cognition – or thinking about one’s thoughts – for an objective view of the self. Meditating over approximately 8 weeks has been linked to increasing the size of the prefrontal cortex and hippocampus, which also helps to improve memory, and reducing the size and activation of the amygdala. Neuroplasticity (e.g. new connections between brain cells) underlies the changes in brain size, and helps with better self-regulation, decision-making, and a reduction in the activity of our wandering, day-dreaming mind - also known as the Default Mode Network.
Meditation alters neuronal oscillations – or brain waves - measured by electroencephalogram (EEG), which may strengthen and synchronise networks over the longer term. At the beginning of a mediation session beta waves (13-30 Hz) govern the settling down process and conscious thought. Next, as we go deeper during meditation, brain function is reflected in alpha waves (8-13 Hz), often felt in the day-dreaming and the default-mode state. After this comes theta waves (4-8 Hz) where a person experiences deep relaxation and high levels of creative thinking. Finally, the deepest level occurs during delta waves (1/2 – 4 Hz) and is related to unconscious processing and intuition.
Meditation is perhaps one of the oldest practices known to man with very few negative consequences. Some of the earliest records of meditation (depicted on cave paintings in India) come from the Hindu tradition as early as 5000 BCE, whereas other versions of meditation also emerged from Taoist China and Buddhist India. And in other religions too, meditative practices such as regular prayer ritual often evoke a sense of well-being and mental health. And with the modern advent of neuroimaging techniques, we are now able to correlate the subjective feeling of meditation with objective measures of the brain. However, modern neuroscience does not fully explain the profound spiritual experience that most report when they meditate. Nevertheless, I think many would agree, if you can get in to the habit of regular meditation, whichever method you choose, it is a healthy habit to cultivate!
Dr Samantha Brooks is a neuroscientist at the UCT Department of Psychiatry and Mental Health, specialising in the neural correlates of impulse control from eating disorders to addiction. For more information on neuroscience at UCT and to contact Samantha, see www.drsamanthabrooks.com.