What is meditation and how to meditate?
This is always a good question worth exploring.
Meditation is often associated with religion. In different religions, there are many different definitions of meditation, which are usually narrower concepts tied to specific myths and rituals. In some religions, such as Late Buddhism and Hasidic Judaism, there are broad forms of meditation.
Can we find common ground in the concepts of meditation in different religions, remove the ritual and superficial differences, and accurately define meditation? I will try to give the answer from the basic perspective of neuroscience:
First, let us consider the difference between meditation and general activities or imagination. Meditation has something in common in many aspects of exercise, memory and imagination. They must share the same brain networks, but meditation is obviously different from general exercise, memory and imagination.
For example, a patient with anxiety disorder constantly imagines that bad things will happen and becomes anxious and nervous. This is obviously not a kind of meditation.
Meditation is usually not to make a specific plan, nor to create a new thing, but to achieve a state. This state is usually to get rid of pain, difficulty, evil, etc., but not by taking specific actions against specific events that cause pain, difficulty or evil, but to achieve a state of "enlightenment." In other words, it is to suppress the influence of negative emotions on actions in a certain way, and on the premise that the events leading to negative emotions cannot be ruled out, keeping oneself can still complete the actions that need to be done without being affected by negative emotions.
Before specifically analyzing what meditation is, let us first review some basic knowledge of neuroscience.
In the article I wrote before, I introduced the related mechanisms of recall, imagination, and attention regulation. Here, briefly summarize these mechanisms:
The information that the eye feels, first enters the thalamus and then passes into the primary visual cortex. Starting from the primary visual cortex (V1), visual information enters the Medial temporal lobe (ventral stream) and posterior parietal cortex (dorsal stream) through two streams.
Before arriving at the posterior parietal cortex, the information in the dorsal stream is processed step by step through V2, V4, V5, etc.
Various information from the dorsal stream is sent to the prefrontal lobe, which activates the hippocampus based on those information and then activates the whole ventral stream.
Neurons in Medial temporal lobe accepts information from V1 and V2 via Inferior longitudinal fasciculus and identifies selectively to images of faces, animals, objects or scenes.
When absence of external stimuli such as closed eye memories or imagination, the mechanism by which the ventral stream actively recognizes the object is equivalent to inputting additional information to the primary visual cortex through the Inferior longitudinal fasciculus, so the continuous circulation of the process can make the image gradually clear in our primary visual cortex.
It is getting closer and closer to the images stored in the form of spatial positions between neurons in the Hippocampus and Parahippocampal gyrus.
These two processes can also be mixed, allowing us to turn our attention to something imaginary when we are awake.
In addition, auditory information can also participate in the construction of images by activating the hippocampus and the prefrontal lobes.
It is more complicated to imagine a moving image, which involves the connection between the premotor cortex, the associative cortex and the visual cortex.
In fact, visual motor imagination can be divided into two categories:
Object-based spatial transformation and Egocentric perspective transformation
More activation of the prefrontal cortex, the premotor cortex, and the lateral temporal lobe were found in the Egocentric perspective transformation rather then Object-based spatial transformation.
Combined with the previous discussion, this shows that the Object-based spatial transformation is more the change of the position of the image in the visual cortex space, which is more based on re-mobilizing the hippocampus to encode the position, while the role of the posterior parietal cortex and the prefrontal cortex is mainly regulates activation of different locations in the hippocampus through cyclic feedback.
And the Egocentric perspective transformation involves another mechanism: Efference copy
When the brain makes a motion command, the prefrontal cortex and posterior parietal cortex will further issue commands to the motor cortex. These commands enter the Premotor cortex(PMA) through the Motor thalamus, and circulate between the Motor thalamus and Premotor cortex again and again, during which they are regulated by the nucleus in Basal ganglia and the cerebellum.
In this process, the associative cortex or Premotor cortex, while issuing commands to the motor cortex, also sends a Efference copy of the movement of self-body to the visual-related cortex to correct visual perception and keep it unaffected by body movements.
It may be through the posterior parietal cortex to the V2 or V4, or it may be directly to the V2 or V4, which need more research to reveal.
Sometimes the Supplementary motor area is also activated by the associative cortex and it inhibits the motor cortex, therefore, the action is not made, but the Efference copy of the movement of self-body is still sent to the visual cortex, and the phenomenon of Egocentric perspective transformation is appeared.
Combining all of the above mechanisms, now we could preliminarily explain how the imaginary images appear and move around in our minds.
In addition, in the previous article, I also specifically mentioned the facial recognition function of the inferior temporal gyrus and fusiform gyrus.
However, recent studies have found that the representation of visual objects by the inferior temporal gyrus and hippocampus is actually based on more basic patterns, such as coarse, thin, animate, and inanimate, similar to the mechanism of the Classifier in machine learning. Its function is to make classification based on the most basic features of the visual object, there is no such ability as the "face area" to recognize a complex whole [1]. This system is further connected with the amygdala and hippocampus, through the memory activation mediated by dorsal stream, to screen out objects that need to be recognized [2] [3]. This process is usually based on the harmfulness of the object and is associated with negative emotions.
As the key structure of ventral stream, the function of the inferior temporal gyrus is so basic, then who will recognize the complex object as a whole? As mentioned in the previous article, it is realized by a part of the dorsal stream.
In some early studies, the areas responsible for different functions were collectively referred to as the "associative cortex", but later studies specifically distinguished their functions. Specifically, the area for recognizing the whole object is mainly located superior temporal sulcus. This area has a wide range of connections with the inferior temporal gyrus. Based on the feature recognition of the inferior temporal lobe, it can complete object recognition together with the ventral stream [4] [5] [6], representing spatial and logical relationships [6] [7], and provide a basis for decision-making in various areas of the parietal lobe, especially identifying the physical activities of other individuals in society to imitate [8] [9] [10], and identifying dangerous objects to avoid dangers [11]. In humans, this area on the left is specialized as an area to processing languages [7] [12] [13].
In the posterior parietal lobe, it is actually independent of most of the dorsal stream structure, and there is a third set of independent visual representations that specifically characterize the visual characteristics of the action object [14] [15]. The posterior parietal lobe characterizes these visual features related to movement and transmits information to the premotor cortex. They work together to complete the decision-making of body movement, and constantly cooperate with the dorsolateral prefrontal cortex to regulate attention during tasks [10] [16] [17].
To sum up, there are actually three independent sets of visual representations in the brain. In traditional classification, the lower temporal lobe is involved in the ventral stream and is mainly responsible for the representation of memory-related features, and the upper two sets jointly complete the decision-making of the activity. Later research found that the lower two sets are jointly responsible for identifying emotions and dangers, while the parietal lobe focuses on completing ongoing tasks [18]. This functional distinction between emotions and tasks even extends from superior temporal sulcus to the frontal lobe, dividing the function of the prefrontal cortex into attention and emotion [19].
There are short-range interconnections between both sides of the superior temporal sulcus and they are also connection with the thalamus [16] [20] [21] [22]. Through these connections, the superior temporal sulcus provide a basis for motion decisions in various areas of the parietal lobe, especially identifying the activities of other individuals in society for imitation, and identifying dangerous objects to avoid these dangers. However, when external negative events cannot be rid, or when suffering from depression, anxiety disorder, and obsessive-compulsive disorder, the above-mentioned mechanisms may become negative, participating in the mechanism by which negative emotions affect movement and attention and interfering with the parietal lobe's focus on completing tasks.
Some studies have shown that through training the posterior parietal lobe and through transcranial magnetic stimulation to promote the function of the posterior parietal neurons, especially the right posterior parietal lobe, can inhibit the influence of negative emotions and negative events on the current task execution [11]. This leads to the first form of meditation, which corresponds to mindfulness meditation in meditation, which mainly appears in Late Buddhism and Hasidic Judaism, which trains us to focus on what is happening now, experience what is happening in the moment without evaluating it.
Enhancing the mobility of the posterior parietal lobe can inhibit information related to negative events and negative emotions from being input into the posterior parietal lobe from the superior temporal sulcus. Then, conversely, training the function of the superior temporal sulcus itself and enhancing its ability to screen and judge can also reduce the untimely input of negative events and negative emotion-related information into the posterior parietal lobe, reducing their impact on the task being performed. If we routinely practice moral and other judgments, we can train this function. Most religions require people to abide by certain commandments, and the entries of these commandments are often related to specific interpersonal ethics or bioethics of compassion for other creatures. In fact, this kind of meditation could be carried out on a daily basis. One form is to train the ability of moral judgment by keeping the commandments.
However, the exercise of this kind of judgment and commandment can relieve anxiety, and it may also be related to obsessive-compulsive neurosis, becoming a mechanism for showing obsessive thinking and compulsive behavior on the basis of anxiety. So it is not a panacea, it needs to be done according to the situation.
In the posterior temporal parietal sulcus and inferior parietal lobe, there are several areas that are closely related to the experience of "selflessness" and "out of body". From experience, this area can also reduce the input of negative information to the posterior parietal lobe. Although the specific mechanism has not been clearly studied, the mechanism can generally be supported by network connection research [16] [20] [21] [22] [23] [24]. The existence of these regions is also related to the behavior of imitating peers in the evolutionary history, but later it has the function of abstractly representing the relationship between itself and the outside world. This also explains why monism and philosophical monotheism appear and prevail in different cultures and religions (even if it is mixed with specific mythology in many religions, and does not stand out as a pure philosophical form), because it is equivalent to one of the simplest and most accessible forms of meditation, without the need to consume a lot of time like the practice of mindfulness and commandments.
To sum up again, based on the explanation of neuroscience, we can divide meditation into three categories, mindfulness meditation, commandment-keeping, and selfless meditation, which coincides with the highly theoretical meditation theories in Late Buddhism and Hasidic Judaism. It proves that these theories have a certain neuroscience basis.
Mindfulness meditation trains us to focus on what is happening now, experience what is happening now, and practice to accept what happened and our emotions without making any evaluation. The most common training includes observing breathing, sitting still, and focusing on walking in Buddhism, and focusing on experiencing inner light and observing the scenery while walking in Hasidic Judaism.
Observing a set of commandments, the specific items of this set of commandments are related to the specific moral ethics of interpersonal communication or the bioethics of compassion for other living beings. More broadly speaking, it is the daily training of moral judgments. And when we really encounter problems, we can quickly make judgments.
Selfless meditation, "coming into one with the Holy One", is the simplest and easiest kind of meditation to observe and judge from the perspective of transcending the individual's own self. At present, its mechanism is supported by certain neuroscientific evidence, but more specific mechanisms still need to be studied.
Finally, I want to emphasize that meditation is currently only recommended for patients with mild depression, anxiety, and obsessive-compulsiveness. For severe depression, anxiety, and obsessive-compulsions, there have been secondary obvious changes in the structure of the temporal lobe and hippocampus, and meditation may not work well. For the effect, medications and transcranial magnetic stimulation should be carried out in accordance with the doctor's advice to avoid delaying the disease.
Schizophrenia and other severe mental illnesses are neurodegenerative diseases that mainly affect the temporal brain network caused by the interaction of genetics and the environment [25]. They cannot be improved by meditation and require timely medical treatment.
In addition, I have another idea here:
The structures involved in meditation are mainly related to the visual function area, and the language function area on the left side of the brain is also specialized by the area responsible for the overall recognition and representation of the object. Therefore, the proposal of painting through the brain-computer interface that I have previously proposed will also have a certain significance in improving negative emotions and compensating language dysfunction in addition to helping people with movement disorders realize painting:
תשובה של יעקב מיכאל לו (Yaakov Mikhael Liu) על השאלה מהו לדעתך עתיד הקומיקס והמאנגה?
Hebrew version:
Spanish version:
Respuesta de Yaakov Mikhael Liu (יעקב מיכאל לו) a ¿Qué es y cómo se practica la meditación?
Japanese version:
瞑想のやり方は何ですか？に対するYaakov Mikhael Liuさんの回答
References
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