Mindfulness meditation is an Eastern practice with a history of more than two millennia that has attracted the attention of Western neuroscientists in the past few years. Under "awareness" in this case is understood as the awareness of their psychological and physiological state at a given time. This review summarizes various hypotheses regarding the effects of mindfulness meditation and related changes in the brain; the following highlights some of the more relevant theories dealing with various aspects of consciousness. Finally, a perspective on the relationship between mindfulness meditation and consciousness is proposed, supported by the identification of the brain regions involved in both processes: the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), Reil islet, and the thalamus.
1. Introduction
Meditation is a practice that has been around for centuries. It includes a variety of techniques and can be found in a variety of cultures, from India and China to Arab and Western countries. Nevertheless, meditation has traditionally been associated with oriental culture and spirituality, especially in the Indian religion - Hinduism, in the ancient writings (Vedas) of which the earliest mentions of this practice are contained; meditation is also a key element of the philosophy of Buddhism. (Siegel et al., 2008)
In recent years, the idea of meditation has become more common in Western communities, in particular due to the interest in Buddhism provided by the charisma of the current Dalai Lama, Tenzin Gyatso. Moreover, meditation practices have been studied in various scientific studies, the results of which have drawn increased attention to these practices in the context of psychotherapeutic treatment and health care. (Samuel, 2014; Tang et al., 2015).
While there is no single overarching definition of meditation, it is possible to intuitively understand what it is by identifying what it is not. Meditation is neither a method of purifying consciousness, nor a method of achieving emotional equanimity. It is not a way to pursue a state of bliss, or a way to avoid sadness and pain (Siegel et al, 2008). It also does not imply an isolated lifestyle.
Often, the meditative state is inappropriately associated with esotericism and mysticism. But the Theravada monk Nyanaponika Thera (1998) clearly emphasizes that “mindfulness […] is not at all a“mystical”state outside the horizon and reach of the average person. On the contrary, it is something quite simple and widespread, and very familiar to us. This is an elementary manifestation of the property known as "attention", one of the main functions of consciousness, without which there can be no perception of any objects. " (Thera, 1962). As will be shown later, this position allows us to consider the phenomenon of meditation from a neurobiological point of view.
While there are many different techniques of meditation, they are all united by the fundamental idea of "sati", which translated from Pali means "mindfulness", "mindfulness". This word was first translated into English in 1921 (Awasthi, 2012; Siegel et al., 2008). Sati is also central to the philosophy of Buddhism. Jon Kabat-Zinn, a pioneer of the mindfulness approach in the context of therapy, defines this state of consciousness as “awareness that arises by deliberately drawing attention at a given moment in time, and without evaluating the experience at that moment” (Kabat-Zinn, 2003).
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The purpose of this review is to synthesize the results of studies of morphological and functional changes found in meditating people using functional magnetic resonance imaging (fMRI) with data obtained by neurobiologists describing the nervous processes that ensure the emergence and maintenance of consciousness.
2. Different styles of meditation
According to Siegel (2008), three meditation techniques can be distinguished within mindfulness meditation (MOO).
Concentration meditation. This technique is based on focusing attention on a single object, such as the breath or a mantra. The main attitude is to direct the attention back to the focal object every time the practitioner notices that it goes to the side. The Pali term for this technique is "samata bhavana", which can be translated into Russian as "to promote concentration."
Mindfulness meditation. This technique does not use a focal object, it aims to study the changing experience that occurs over time. The main setting is to direct attention to everything that happens in consciousness from one moment to the next. The Pali term for this technique is vipassana bhavana, which translates to "foster inner awareness."
Meditation of "goodness and love". In this technique, the mind is directed to focus on meek statements such as "May I and all other beings be safe, happy, healthy, and may we live in simplicity." The goal is to soften emotions and observe experiences without judgment, free from overwhelming emotionality. The Pali term for this technique is metta bhavana, which translates to "foster confidence."
While these three techniques are independent, they can be used together; in fact they all contribute to "sati" and, at the same time, require constant support in some sort of cyclical thought process.
3. Meditation and the brain
Since its early stages of development, meditation has been seen as a primary method of increasing awareness and maintaining physical and mental health (Siegal et al., 2008). It is therefore not surprising that over the past few years, “mindfulness-based interventions” (MBIs), which are MOO-based therapeutic approaches, have attracted more and more interest in a variety of fields, from physiology and neurobiology to health and education (Chiesa and Serretti, 2010; Hölzel et al., 2011). Mindfulness-Based Stress Reduction (Mindfulness-Based Stress Reduction), Mindfulness-Based Cognitive Therapy (Mindfulness-Based Therapy), and Integrative Mind-Body Training (ITTR) are the most well-known BMI techniques. In particular, the SSAS, which was developed in 1979 at the University of Massachusetts Medical Center (Kabat-Zinn,2003), is currently being used as an alternative or integrative clinical approach to the treatment of psychological disorders in people with chronic conditions (Chiesa and Serretti, 2011; Merkes, 2010). However, the understanding of the neuroanatomical and functional correlations on which the benefits of HEI are based is not yet fully developed. (Tang et al., 2015).
Despite the existence of different styles of meditation and techniques of SBI, “sati” or “mindfulness” is the aspect that unites them all. As we have seen, the state of mindfulness is characterized by consciously paying attention to the experience that is happening at the moment (Kabat-Zinn, 2003). Thus, since mindfulness directly includes both consciousness and attention, the neural correlates of these brain processes and these meditative states should appear very similarly.
Interoceptive Attention (IO) is highlighted as a key process in mindfulness meditation. Interoception is a series of body sensations associated with digestion, circulation, respiration, and proprioception (Farb et al., 2013).
Neuroanatomical studies have provided evidence for the projection of the spinothalamic-cotrical pathways onto the granular middle region of the islet, which is thought to function as the primary interoceptive cortex (Flynn, 1999). Moreover, descending projections to the sensory and motor regions of the brainstem originate from the insula and the anterior cingulate cortex (ACC) (Craig, 2009a).
In a recent experiment, Farb et al. (2013) found that after 8 weeks of CVS, participants showed increased functional plasticity in the middle (same) and anterior insular regions associated with present awareness (Craig, 2009a; Farb et al., 2007). Moreover, the practice of mindfulness meditation can promote functional connectivity between the posterior insular area and the anterior insular gyrus, thereby enhancing the overall activation of the anterior insular area and, at the same time, weakening the involvement of the dorsomedial prefrontal cortex (DMPFC) (Farb et al., 2013) … Disconnection of DMPPC can also be detected in connection with exogenous stimulation of interoceptive signaling pathways, for example, during gastric distension (Van Oudenhove et al., 2009). In contrast, DMPFC activation is associated with executive control of behavior,associated with a sudden shift in attention during problem solving (Mullette-Gillman and Huettel, 2009) and possibly either stimulus-independent or stimulus-oriented thought in a state of mind-wandering., translator's note) (Christoff et al., 2009).
Thus, the disabling of DMPPC after SSAS may be one of the signs that will help distinguish between states of "awareness" and "wandering of the mind", as well as states of "awareness" and intellectual load (Farb et al., 2010; Farb et al., 2007) …
A recent study to assess the effects of mindfulness meditation practice compared CVS and aerobic exercise for stress reduction. The results showed that SSAS alone significantly contributes to the control of negative emotions in people with social anxiety. The authors report that this effect may be associated with the functional integration of various different neural networks in the brain during somatic, attenuation, and cognitive control (Goldin et al., 2013).
Other studies have sought to find out if meditation practice can cause structural changes in the brain in the long term; it has been suggested that meditation in the long term may be associated with thickening of the cortex, especially the prefrontal and right anterior insula involved in the processes of attention, interoception and processing of sensory information (Lazar et al. 2005; Sato et al. 2012). It should be noted that one study identified both meditators and non-meditators based on several different patterns in different regions of the brain (Sato et al., 2012). This study investigated whether a single subject could be identified as a regular meditator using a multivariate pattern recognition method.such as support vector machine (SVM). The accuracy of the MOU was 94.87%, allowing 37 of 39 participants to be accurately identified. The right precentral gyrus, the left entorhinal cortex, the right tectal cortex of the inferior frontal gyrus, the basal part of the shell on the right, and the thalamus on both sides were the most informative brain regions used for classification. The involvement of these areas suggests the potential of mindfulness meditation to increase attention and sensory awareness, as well as the potential to improve interoceptive observation skills (Kozasa et al. 2012; Lazar et al. 2005).the basal part of the shell on the right and the thalamus on both sides were the most informative areas of the brain used for classification. The involvement of these areas suggests the potential of mindfulness meditation to increase attention and sensory awareness, as well as the potential to improve interoceptive observation skills (Kozasa et al. 2012; Lazar et al. 2005).the basal part of the shell on the right and the thalamus on both sides were the most informative areas of the brain used for classification. The involvement of these areas suggests the potential of mindfulness meditation to increase attention and sensory awareness, as well as the potential to improve interoceptive observation skills (Kozasa et al. 2012; Lazar et al. 2005).
4. Neurobiology of consciousness
As we have seen, the concepts of awareness and consciousness are inseparable. Both neurophysiological and neuroimaging studies have provided evidence that neural correlates of consciousness can be described in a two-dimensional model based on the parameter of arousal level on the one hand, and on the other on the parameter of intensity of different content of experience (Cavanna et al., 2011; Laureys, 2005; Laureys et al., 2004; Nani et al., 2013). Within this framework, arousal determines the quantitative characteristics of consciousness, while content determines the qualitative characteristics of subjective awareness (Blumenfeld, 2009; Plum and Posner, 1980; Zeman, 2001). In other words, the level of arousal sets the degree of wakefulness, the highest degree of which is complete alertness, intermediate - drowsiness and sleep,the lowest is coma (Baars et al., 2003; Laureys and Boly, 2008). To maintain consciousness, it is necessary to connect the thalamo-cortical networks and the reticular formation of the pons and midbrain through the ascending pathways. (Steriade, 1996a, b).
The concept of the content of experience includes everything that can arise in consciousness, for example, feelings, emotions, thoughts, memories, aspirations, etc. They are probably caused by influences between exogenous factors (for example, environmental stimuli) and endogenous factors (for example, stimuli that arise in the body itself). Thus, the concept of content can be divided into external awareness (what is perceived through the senses) and internal awareness (thoughts independent of specific environmental stimuli) (Demertzi et al., 2013) [Fig. 1].
Figure 1. Two-dimensional model of consciousness. According to the two-dimensional model, the neural correlates of consciousness can be described on the basis of both the level of arousal (from complete alertness to coma) and different content of the experience, which can also be divided into external and internal awareness
This distinction is important because different neural correlates seem to be involved in internal and external awareness. Demertzi et al. (2013) described an “internal awareness network” that includes the posterior cingulate cortex (PCC), ACC, precuneus, and medial prefrontal cortex (MPFC), and an “external awareness network” that includes the dorsolateral prefrontal cortex (DPPC) and posterior parietal cortex (ZPark).
The interaction between these two networks creates a so-called “global neural workspace,” which is believed to play a fundamental role in maintaining consciousness (Baars et al., 2003; Dehaene and Changeux, 2011). Moreover, it has been shown that the structures of internal and external awareness networks overlap some of the areas involved in the Default Mode Network (SDN), such as ZPK, Pre-Wedge and MPFC, as well as some areas involved in the Salienza Network. (CC), such as the PPK and thalamus, and the Central Executive Network (CIC), such as DLPFC and ZPK.
4.1. Consciousness and self-awareness
Within the neurobiological research of consciousness, other important and debated issues are put forward, such as the origin of personality, the formation of self-awareness, and the relationship between consciousness and self-awareness. The concept of personality is difficult to define as the concept of consciousness. Many studies (Metzinger and Gallese, 2003; Pacherie, 2008; Roessler and Eilan, 2003), focusing on the central representation of different parts of the body, have linked the sense of personality to other concepts, such as the Anokhin outcome acceptor (orig. translator's note) - that is, “the feeling that the individual's actions are the consequences of his intentions” (Seth et al., 2012) - and personification - that is, “the feeling of being in the physical body” (Arzy et al., 2006). The result acceptor and personification can be associated with the so-called “minimal phenomenal self” (MFS), which means “the experience of being a separate, integral object capable of global self-control and attention, with a body and location in space and time” (Blanke and Metzinger, 2009). MFS can be impaired in people with brain injuries who are more likely to have autoscopic experiences (Blanke et al. 2004; Blanke and Mohr 2005; Brugger 2006; Devinsky et al. 1989).who are more likely to have an autoscopic experience (Blanke et al. 2004; Blanke and Mohr 2005; Brugger 2006; Devinsky et al. 1989).who are more likely to have an autoscopic experience (Blanke et al. 2004; Blanke and Mohr 2005; Brugger 2006; Devinsky et al. 1989).
A belief system based on the notion of an outcome acceptor in relation to interoceptive predictive coding has been put forward to address the sense of conscious presence, which has been defined as “the subjective sense of the reality of the world and personality within the world” (Seth et al., 2012). This model is characterized by predictive signals of the result acceptor and relies on the mechanism of interoceptive predictive error in the perception of the state of the body through autonomous physiological responses, which are often involved in the generation of emotions (Craig, 2009b; Critchley et al., 2004). The mechanism of interoception has traditionally been thought to be associated only with visceral sensations, but modern neuroanatomical and neurophysiological studies suggest that it may also include information from muscles, joints,skin and organs. And all this various information seems to be processed jointly.
According to this model, a sense of conscious presence occurs when interoceptive predictive signals and true input signals are matched, while erroneous signals are suppressed (Seth et al., 2012) [Fig. 2].
Figure 2. Schematic model of the sense of presence. When interoceptive predictive cues and input cues match, erroneous cues are suppressed and a sense of presence arises (adaptation from Seth et al., 2012)
Cortical regions that are thought to play a key role in this process include the orbitofrontal cortex, AUC, and Reil's islet (Critchley et al., 2004); in particular, it has been suggested that the islet is responsible for the integration between interoceptive and exteroceptive signals, thus contributing to the generation of subjective emotional states (Cauda et al., 2011; Seth et al., 2012).
Interestingly, the anterior insula and ACC are among the few areas of the human brain that contain von Economo neurons (NPEs) (Craig, 2004; Sturm et al., 2006; von Economo, 1926, 1927, von Economo and Koskinas, 1925.). These large fusiform neurons have been hypothesized to be involved in the perception of bodily states (Allman et al. 2005; Cauda et al. 2014). Moreover, they have recently been linked to neural correlates of consciousness based on two principal morphological and cytochemical findings (Cauda et al., 2014; Cauda et al., 2013; Critchley and Seth, 2012; Medford and Critchley, 2010; Menon and Uddin, 2010). First, consciousness is probably supported by long links (Cauda et al., 2014; Dehaene and Changeux, 2011; Dehaene et al., 1998), and NPEs are projected over long distances. Secondly,NPEs selectively express high levels of the bombesin-dependent protein neuromedin B (LMW) and gastrin-releasing peptide (GRP), which are “involved in peripheral control of digestion and are also involved in providing conscious awareness of body conditions” (Allman et al., 2010, 2011; Cauda et al., 2014; Stimpson et al., 2011).
In the Seth model, NPE can be projected onto autonomous visceral nuclei (for example, the periaqueductal gray matter and parabrachial nuclei), which are largely involved in interoception (Allman et al., 2005; Butti et al., 2009; Cauda et al., 2009 et al., 2014; Craig, 2002; Seeley, 2008). The anterior insula and ACC, which are functionally (Taylor et al., 2009; Torta and Cauda, 2011) and structurally (van den Heuvel et al., 2009) inseparable, are part of the CC (Medford and Critchley, 2010; Palaniyappan and Liddle, 2012; Seeley et al. 2007b). This network responds to behaviorally significant events and things by recognizing the relevant aspects and the qualities in which they differ from the environment. Thus, it seems plausible that ST could play a critical role in the model proposed by Seth,processing extraceptive signals with defined salience (Seth et al., 2012). Moreover, recent evidence suggests that a specific portion of the SS (eg, the anterior insular region) may induce a switch between CIS and PSA, thus directing attention to the external or internal environment (Bressler and Menon, 2010).
4.2. Consciousness and predictive functions of the brain
Another hypothesis, according to which awareness of the present moment is highly dependent on the neurofunctional mechanisms designed to form predictions, was put forward by Moshe Bar (2007). His theory of the "proactive brain" states that the brain continually makes predictions based on sensory and cognitive information. The Bar hypothesis is supported by observations in which it was found that most of the PSAs active during the resting state (Tang et al., 2012) coincide with brain regions (MPPC, medial parietal cortex, medial temporal lobe) that are active during task execution. requiring associative development (Bar et al., 2007).
A similar view of brain architecture can be traced to the Bayesian Brain hypothesis, according to which "we [always] try to draw conclusions about the causes of our feelings based on the generative model of the world." (Dayan et al. 1995; Friston 2012; Gregory 1980; Kersten et al. 2004; Knill and Pouget 2004; Lee and Mumford 2003). As a consequence, we often try to predict the future by taking into account the statistical history of previous events and incentives (Bar, 2007).
All of these predictive theories (the Seth model, the “proactive brain” and the “Bayesian brain” hypotheses) can be reassessed within the broader context of the “free energy principle” (Friston et al., 2006), according to which “any self-organizing system being in equilibrium with its environment should minimize its free energy”(Friston, 2010). Free energy can be viewed as the difference between the distribution of the energy of the environment, which acts on biological systems, and the distribution of energy contained in the organization of these biological systems. In other words, free energy arises from the exchange of energy between biological systems and their environment (Friston et al., 2006). Thus, if we consider individuals as the summation of their models of the world, they need to find a state of equilibrium,at which their free energy is minimized. And the emergence of consciousness seems to be the most appropriate way to achieve and maintain this balance.
4.3 The theory of the global brain workspace
As described in the previous paragraphs, huge spindle-shaped NFEs are likely to play an important role not only in predictive models of brain function, but also in theories that address the emergence of consciousness. In particular, NPEs are likely to be central to the Global Workspace Model of consciousness development (Baars, 1988; Dehaene and Changeux, 2011). This model assumes that there are two different computational spaces within the brain (Dehance et al. 1998). One of them is a network of various functionally specialized modular subsystems (Baars, 1988; Shallice, 1988). Each subsystem is located in a specific cortical region and has medium-range connections with other regions (Mesulam, 1998). The other is a distributed global workspace (GDW),consisting of neurons, cross-connected by horizontal two-sided long-range projections. The concentration of these neurons is variably associated with different parts of the brain. These long-range projections can easily explain the property of reportability (Weiskrantz, 1997), which is a characteristic feature of the phenomenon of consciousness. Essentially, within the fracture, the areas responsible for both speech and motor skills can be connected to the associative areas that deal with the content of the experience.translator) (Weiskrantz, 1997), which is a characteristic feature of the phenomenon of consciousness. Essentially, within the fracture, the areas responsible for both speech and motor skills can be connected to the associative areas that deal with the content of the experience.translator) (Weiskrantz, 1997), which is a characteristic feature of the phenomenon of consciousness. Essentially, within the fracture, the areas responsible for both speech and motor skills can be connected to the associative areas that deal with the content of the experience.
According to this model, “what we perceive subjectively as a conscious state” is due to distributed access to information within a common global space, the existence of which is ensured by the presence of long-range projections (Dehaene and Neccache, 2001). As a consequence, conscious stimuli appear to be less pronounced in specific processes and more pronounced in unconscious ones (Dehaene and Changeux, 2001). Moreover, there is evidence that hydraulic fracturing is activated during non-routine tasks, gradually shuts down during training, and suddenly becomes active again if an error is detected (Dehaene et al., 1998). From a neuroanatomical point of view, areas of the brain that may be associated with fracturing are the dorsolateral prefrontal cara and the ACC (Dehaene et al., 1998), which thus,are believed to be involved in the process of awareness of subjective states (Grafton et al. 1995; Sahraie et al. 1997).
5. Discussion
The practice of mindfulness meditation can be effective in increasing focus, control, and orientation, as well as improving cognitive flexibility. Many practitioners describe their experiences during meditation as “focused awareness” and “effortless action” (Garrison et al., 2013). Accordingly, Tang et al. (2012) observed that the effort required to maintain attention tends to gradually decrease during a meditation session.
If the hypothesis that mindfulness meditation can have an effect on consciousness is correct, we assume that there is some degree of overlap between the regions of the brain involved in each of these processes and, as a consequence, a change in the activity of these areas, at least in people who practice meditation regularly for a long period of time. Along with this hypothesis, modern research has indicated that some major areas of the brain are strongly associated with both meditation and consciousness [Fig. 3] [Fig. 4].
Figure 3. Areas of the brain involved in both mindfulness meditation and consciousness. Above: insular cortex and prefrontal lateral regions (left), medial regions (right). Bottom: thalamus
Figure 4. Awareness and interaction of brain regions. The figure shows the most cited cases of mutual use of the terms "meditation" and "mindfulness" in the scientific literature. Areas of the brain that are simultaneously involved in the processes of both meditation and awareness have a higher Jaccard coefficient, as shown in the figure by a thicker radial line.
The involvement of these four of these areas (islet, ACC, PPC, and prefrontal cortex (PFC)), whose activity is believed to be highly relevant in supporting both meditative and conscious states, is discussed in the following paragraphs.
5.1. Role of Reil Isle and PPK
There is evidence that in deep meditation the striatum, left lobe of the islet, and the ACC are functionally active, while the lateral PFC and the parietal cortex show reduced activity (Craigmyle, 2013; Hasenkamp et al., 2012; Hözel et al., 2011; Posner et al. 2010; Tang et al. 2009; Tang and Posner 2009). As we saw earlier, the ACC appears to be part of an “internal awareness network” (Demertzi et al., 2013) and, together with the islet, is an important component of Seth's interoceptive predictive model (Seth et al., 2012).
These two areas of the brain that show structural changes in regular meditators (Craigmyle, 2013; Lazar et al., 2005) are also rich in NFE (Cauda et al., 2014), the wear of which has been associated with loss of emotional awareness and self-awareness in patients with frontotemporal dementia (Seeley et al. 2007a; Seeley et al. 2006; Sturm et al. 2006). Within the predictive model, ACC activity appears to correlate with the likelihood of predicting errors (Brown and Braver, 2005) as well as with the control of exploratory behaviors (Aston-Jones and Cohen, 2005). Together with the MPPC, the ACC plays a significant role in assessing possible future scenarios (Redderinkhof et al., 2004), which is consistent with the “proactive brain” hypothesis. Moreover, the FAC is an important part of the hydraulic fracturing model.
5.2. Role of ZPK and PFC
During meditation using a focal object such as breathing, there is a decrease in activity in the lateral PFC and parietal cortex (Hözel et al. 2011; Posner et al. 2010; Tang et al. 2009; Tang and Posner 2009). which is consistent with the hypothesis that these areas of the brain are involved in the “external awareness network” (Dementzi et al., 2013). Based on real-time analysis of neural feedback graphs, Garrison et al. showed that the states of mind described by meditators as "focused awareness" and "effortless action" correspond to deactivation of CPA, while states of mind described as "distracted awareness" and "control" correspond to activation of CPA. CPA, which is part of Demertzi's "network of inner awareness", is metabolically active in normal states of consciousness,but often its activity is weakened in coma and vegetative state (Cauda et al., 2010; Cauda et al., 2009; Demertzi et al., 2013). Thus, it has been suggested that co-activation of PPC patterns may be a reliable marker of consciousness modulation (Amico et al., 2014).
Thus, empirical evidence suggests that the practice of meditation can induce both functional and structural changes within the neural networks that contribute to the emergence of consciousness and maintain it in a functional state. This phenomenon occurs more frequently in meditators regularly and over time (Goleman, 1988; Shapiro, 2008) and can lead to a kind of "altered perception of space and time" (Berkhovich-Ohana et al., 2013). This feeling may be related to decreased activity in the PCA (Brewer et al., 2013). This view probably relates to a state of mind that regular meditators who have mastered the techniques of meditation describe it as “the mind observing itself” (for example, observing thoughts in a detached, non-judgmental manner). The Dalai Lama is watchingthat something similar happens when a person thinks about past experiences, although even then there is no temporal synchronicity between who thinks and what he thinks about (Dalai Lama et al., 1991).
5.3. Unresolved Issues and Future Directions
An important issue still in need of research is figuring out how long the practice of meditation must be continued in order to induce any significant neurophysiological changes, and whether these changes persist after the practice is interrupted. Related to this is the question of introducing a criterion on the basis of which it is possible to accurately distinguish between subjects into two groups: "meditators" and "non-meditators".
So far, scientific research has focused mainly on how meditation can affect neurophysiology in long-term Buddhist practitioners, but it is still necessary to investigate whether such changes can be found in people who are just starting to meditate. Therefore, long studies need to be planned to measure the impact of meditation over time.
Research should also be directed towards elucidating how meditation can affect the activity of the resting network (Froeliger et al., 2012), as well as other brain networks such as CC, CEN, dorsal and ventral attenuation systems. The relationship between the ability to control and maintain attention and the practice of meditation is of particular interest given the fact that long-term meditators seem to use the resource of mindfulness more efficiently than non-meditators. Moreover, this ability can slow down cognitive and emotional processes (such as thinking), which in turn can cause or exacerbate stress, anxiety, and depression (Brefczynsky-Lewis et al., 2007). As a result, long-term meditators are likely toare characterized by psycho-emotional stability and better attenuation skills (Aftanas and Golosheykin, 2005). Such thinking can lead to changes in their lifestyle, which can also positively affect health and personality, as well as changes in the quality of conscious experience, in particular through increased awareness of the internal state of the body (Rubia, 2009). In this case, it can be expected that it will be possible to observe changes in both the dorsal and ventral attenuation systems of meditators. Subsequent studies should therefore pay attention to this, and in their course it should be found out whether both systems are under the same influence, or the influence over one of them prevails over the influence over the other. Such thinking can lead to changes in their lifestyle, which can also positively affect health and personality, as well as changes in the quality of conscious experience, in particular through increased awareness of the internal state of the body (Rubia, 2009). In this case, it can be expected that it will be possible to observe changes in both the dorsal and ventral attenuation systems of meditators. Subsequent studies should therefore pay attention to this, and in their course it should be clarified whether both systems are under the same influence, or the influence over one of them prevails over the influence over the other. Such thinking can lead to changes in their lifestyle, which can also positively influence health and personality, as well as changes in the quality of conscious experience, in particular through increased awareness of the internal state of the body (Rubia, 2009). In this case, it can be expected that it will be possible to observe changes in both the dorsal and ventral attenuation systems of meditators. Subsequent studies should therefore pay attention to this, and in their course it should be found out whether both systems are under the same influence, or the influence over one of them prevails over the influence over the other.in particular through increased awareness of the internal state of the body (Rubia, 2009). In this case, it can be expected that it will be possible to observe changes in both the dorsal and ventral attenuation systems of meditators. Subsequent studies should therefore pay attention to this, and in their course it should be found out whether both systems are under the same influence, or the influence over one of them prevails over the influence over the other.in particular through increased awareness of the internal state of the body (Rubia, 2009). In this case, it can be expected that it will be possible to observe changes in both the dorsal and ventral attenuation systems of meditators. Subsequent studies should therefore pay attention to this, and in their course it should be found out whether both systems are under the same influence, or the influence over one of them prevails over the influence over the other.whether both systems are under the same influence, or influence over one of them prevails over influence over the other.whether both systems are under the same influence, or influence over one of them prevails over influence over the other.
Research into this issue can lead to interesting results. In fact, since consciousness and attention are closely related, it seems plausible that the effect of mindfulness meditation on consciousness can greatly influence changes in the manner of orienting and controlling attention. It has been shown that interoceptive influence is necessarily involved in a mechanism that, according to the predictive brain model, underlies the experience of conscious presence (Seth et al., 2012). Moreover, attenuation processes play a fundamental role in the functional organization described in the theory of hydraulic fracturing.
Finally, there is an intriguing, but at the same time highly speculative, suggestion that the brain areas involved in meditation practice may form a separate wide network in long-term meditators. In fact, there is evidence to suggest that mindfulness meditation practice is associated with neuroplastic changes in the anterior cingulate cortex, Reil's islet, temporoparietal junction, and frontolimbic areas (Hözel et al., 2011). These neuroplastic mechanisms can thus enhance some pathways and facilitate the generation of a self-sustaining process. This "mindfulness meditation network" may be composed of other smaller network structures (such as those associated with the resting state, as well as the dorsal and ventral attenuation systems) capable of creating a higher brain organization.
6. Conclusion
Mindfulness meditation is a mind training technique that has been practiced in Eastern countries for over two thousand years and has only recently attracted the attention of neuroscientists. In particular, neurobiological research on mindfulness meditation has generated a lot of interest in psychotherapeutic contexts and inspired some cognitive approaches to reducing stress and mood disorders (Tang et al., 2015). In fact, there is strong evidence that the practice of meditation can significantly affect cognitive and emotional processes with various beneficial effects on physical and mental health (Lutz et al. 2007; Soler et al. 2014; Tang et al. 2015.).
A promising hypothesis from this review suggests that some areas of the brain involved in meditation and consciousness may overlap, albeit in part. This overlap covers the ACC, Reil islet, ZPC, some areas of the prefrontal cortex, and the thalamus. As a result, the practice of meditation can somehow influence some of the properties of consciousness. In other words, the patterns of activity in areas of the brain thought to promote and maintain conscious states may have typical differences. When this is taken into account, neuroscientific research on meditation seems highly warranted to better understand both the potential effects of meditation techniques on the brain and the neural basis of subjective experience.
Moreover, these studies are very important if meditation-based mind training can be developed into a standard procedure for therapeutic use (Tang et al., 2015). Thus, the time has come for an integrative approach characterized by a broader theoretical framework in which meditation can be taken into account from neurophysiological, psychological and behavioral perspectives.
Acknowledgments
The authors wish to thank the Department of Psychology at the University of Turin and the GCS-fMRI Research Group at the Koelliker Clinic for their support and assistance with the research. Special thanks to Prof. Guiliano Geminiani et al. Sergio Duca, whose advice and guidance are always invaluable.
Translation: Stanislav Kirsanov