Can hyper-synchrony in meditation lead to seizures? Similarities in meditative and epileptic brain states

Meditation is used worldwide by millions of people for relaxation and stress relief. Given sufficient practice, meditators may also experience a variety of altered states of consciousness. These states can lead to a variety of unusual experiences, including physical, emotional and psychic disturbances. This paper highlights the correspondences between brain states associated with these experiences and the symptoms and neurophysiology of epileptic simple partial seizures. Seizures, like meditation practice, can result in both positive and negative experiences. The neurophysiology and chemistry underlying simple partial seizures are characterised by a high degree of excitability and high levels of neuronal synchrony in gamma-band brain activity. Following a survey of the literature that shows that meditation practice is also linked to high power gamma activity, an account of how meditation could cause such activity is provided. This paper discusses the diagnostic challenges for the claim that meditation practices lead to brain states similar to those found in epileptic seizures, and seeks to develop our understanding of the range of pathological and non-pathological states that result from a hyper-excited and hyper-synchronous brain

EMPIRICAL STUDIES OF MEDITATION: DOES A SLEEP RHYTHM HYPOTHESIS EXPLAIN THE DATA?

This article reviews the findings of important empirical studies of meditators and shows that these findings can be explained by the hypothesis that meditation is generated by induction of slow wave sleep rhythms. This hypothesis explains why radionucleide imaging (PET, SPECT, and fMRI) studies report increases in neuronal activity in the thalamus (where sleep rhythms are generated) and in the hippocampus (which receives a barrage of vision-related signals caused by manipulations of attention and sleep rhythm activity). It also explains the diverse findings of EEG/QEEG studies, for example, the observed short-term increases in alpha band frequencies and coherence, the subsequent shifts to slower theta/delta frequencies, and the reports of a sudden frequency-splitting and amplitude-doubling concurrent with ecstatic raptures. The author suggests that existing studies of meditation do not account for the likelihood that the theta/delta frequency distribution associated with meditation can be generated by two very different mechanisms: (1) by induction of a drowsy, hypnagogic state ("stage 1" NREMS), an experience familiar to many people and thus easily achievable by novice meditators, and alternatively, (2) by inducing the full progression of thalamic sleep rhythms, an option available only to advanced meditators who are able to move beyond "stage 1" NREMS ro induce thalamic spindle-burst typical of "stage 2" NREMS, then beyond that to induce delta waves typical of "stage 3" NREMS. These thalamic delta waves, after augmentation by intracortical circuits, register in the cortical EEG as low-theta/high-delta band activity, making it easy to mistake the underlying mechanism as stage 1 NREMS

EMPIRICAL STUDIES OF MEDITATION: DOES A SLEEP RHYTHM HYPOTHESIS EXPLAIN THE DATA?

This article reviews the findings of important empirical studies of meditators and shows that these findings can be explained by the hypothesis that meditation is generated by induction of slow wave sleep rhythms. This hypothesis explains why radionucleide imaging (PET, SPECT, and fMRI) studies report increases in neuronal activity in the thalamus (where sleep rhythms are generated) and in the hippocampus (which receives a barrage of vision-related signals caused by manipulations of attention and sleep rhythm activity). It also explains the diverse findings of EEG/QEEG studies, for example, the observed short-term increases in alpha band frequencies and coherence, the subsequent shifts to slower theta/delta frequencies, and the reports of a sudden frequency-splitting and amplitude-doubling concurrent with ecstatic raptures. The author suggests that existing studies of meditation do not account for the likelihood that the theta/delta frequency distribution associated with meditation can be generated by two very different mechanisms: (1) by induction of a drowsy, hypnagogic state ("stage 1" NREMS), an experience familiar to many people and thus easily achievable by novice meditators, and alternatively, (2) by inducing the full progression of thalamic sleep rhythms, an option available only to advanced meditators who are able to move beyond "stage 1" NREMS ro induce thalamic spindle-burst typical of "stage 2" NREMS, then beyond that to induce delta waves typical of "stage 3" NREMS. These thalamic delta waves, after augmentation by intracortical circuits, register in the cortical EEG as low-theta/high-delta band activity, making it easy to mistake the underlying mechanism as stage 1 NREMS

Neural Correlates of Induced Light Experience during Meditation: A Pilot Hyperscanning Study

Certain individuals during deep meditative states can transmitt and give out an aura or ‘light, which is perceived by others through some unknown connections, visual, telepathic or other. Despite various anecdotal, historical accounts of such induced light experience (ILE), its underlying neural mechanism is not known. In this pilot study, we investigated the neural correlates of ILE by simultaneously recording the EEGs of an expert Teacher, who is claimed to elicit ILE, and his Pupil (N=2) during joint sessions under various instructions, given separately to the Teacher (transmit/ do not transmit) and to the Pupil (receive/ do not receive). In a further condition both teacher and pupil wear opaque goggles during transmit/receive instruction, limiting the visual/outputinput. We observed a robust increase in the high frequency beta (12-30 Hz) and gamma oscillations (30-70 Hz) in the Teacher’s brain whenever he was instructed to transmit. Electric field tomography analysis localized these effects over several brain regions including the fusiform gyrus, angular gyrus and the cerebellum. Finally, we found that the Teacher’s and Pupil’s brain responses were synchronized, especially in the alpha band (8-12 Hz) during transmit/receive condition, and the information flow was directional, i.e. from the Teacher to the Pupil; interestingly, this enhanced interbrain synchrony disappeared with opaque goggles. These results were interpreted in terms of heightened internally selective attention as manifested by high frequency beta-gamma oscillations and of joint attention as manifested by interbrain alpha synchrony. Altogether, our results provide the first neuroscientific evidence underlying the phenomenological experience of induced light

Neural Correlates of Transmitted Light Experience during Meditation: A Pilot Hyperscanning Study

Certain individuals during deep meditative states can transmitt and give out an aura or ‘light, which is perceived by others through some unknown connections, visual, telepathic or other. Despite various anecdotal, historical accounts of such induced light experience (ILE), its underlying neural mechanism is not known. In this pilot study, we investigated the neural correlates of ILE by simultaneously recording the EEGs of an expert Teacher, who is claimed to elicit ILE, and his Pupil (N=2) during joint sessions under various instructions, given separately to the Teacher (transmit/ do not transmit) and to the Pupil (receive/ do not receive). In a further condition both teacher and pupil wear opaque goggles during transmit/receive instruction, limiting the visual/outputinput. We observed a robust increase in the high frequency beta (12-30 Hz) and gamma oscillations (30-70 Hz) in the Teacher’s brain whenever he was instructed to transmit. Electric field tomography analysis localized these effects over several brain regions including the fusiform gyrus, angular gyrus and the cerebellum. Finally, we found that the Teacher’s and Pupil’s brain responses were synchronized, especially in the alpha band (8-12 Hz) during transmit/receive condition, and the information flow was directional, i.e. from the Teacher to the Pupil; interestingly, this enhanced interbrain synchrony disappeared with opaque goggles. These results were interpreted in terms of heightened internally selective attention as manifested by high frequency beta-gamma oscillations and of joint attention as manifested by interbrain alpha synchrony. Altogether, our results provide the first neuroscientific evidence underlying the phenomenological experience of induced light

Shamanism in Cross-Cultural Perspective

This article reviews the origins of the concept of the shaman and the principal sources of controversy regarding the existence and nature of shamanism. Confusion regarding the nature of shamanism is clarified with a review of research providing empirical support for a cross-cultural concept of shamans that distinguishes them from related shamanistic healers. The common shamanistic universals involving altered states of consciousness are examined from psychobiological perspectives to illustrate shamanism’s relationships to human nature. Common biological aspects of altered states of consciousness help explain the origins of shamanism while social influences on this aspect of human nature help to explain the diverse manifestations of shamanistic phenomena involving an elicitation of endogenous healing responses

Oscillatory architecture of memory circuits

The coordinated activity between remote brain regions underlies cognition and memory function. Although neuronal oscillations have been proposed as a mechanistic substrate for the coordination of information transfer and memory consolidation during sleep, little is known about the mechanisms that support the widespread synchronization of brain regions and the relationship of neuronal dynamics with other bodily rhythms, such as breathing. During exploratory behavior, the hippocampus and the prefrontal cortex are organized by theta oscillations, known to support memory encoding and retrieval, while during sleep the same structures are dominated by slow oscillations that are believed to underlie the consolidation of recent experiences. The expression of conditioned fear and extinction memories relies on the coordinated activity between the mPFC and the basolateral amygdala (BLA), a neuronal structure encoding associative fear memories. However, to date, the mechanisms allowing this long-range network synchronization of neuronal activity between the mPFC and BLA during fear behavior remain virtually unknown. Using a combination of extracellular recordings and open- and closed-loop optogenetic manipulations, we investigated the oscillatory and coding mechanisms mediating the organization and coupling of the limbic circuit in the awake and asleep brain, as well as during memory encoding and retrieval. We found that freezing, a behavioral expression of fear, is tightly associated with an internally generated brain state that manifests in sustained 4Hz oscillatory dynamics in prefrontal-amygdala circuits. 4Hz oscillations accurately predict the onset and termination of the freezing state. These oscillations synchronize prefrontal-amygdala circuits and entrain neuronal activity to dynamically regulate the development of neuronal ensembles. This enables the precise timing of information transfer between the two structures and the expression of fear responses. Optogenetic induction of prefrontal 4Hz oscillations promotes freezing behavior and the formation of long-lasting fear memory, while closed-loop phase specific manipulations bidirectionally modulate fear expression. Our results unravel a physiological signature of fear memory and identify a novel internally generated brain state, characterized by 4Hz oscillations. This oscillation enables the temporal coordination and information transfer in the prefrontal-amygdala circuit via a phase-specific coding mechanism, facilitating the encoding and expression of fear memory. In the search for the origin of this oscillation, we focused our attention on breathing, the most fundamental and ubiquitous rhythmic activity in life. Using large-scale extracellular recordings from a number of structures, including the medial prefrontal cortex, hippocampus, thalamus, amygdala and nucleus accumbens in mice we identified and characterized the entrainment by breathing of a host of network dynamics across the limbic circuit. We established that fear-related 4Hz oscillations are a state-specific manifestation of this cortical entrainment by the respiratory rhythm. We characterized the translaminar and transregional profile of this entrainment and demonstrated a causal role of breathing in synchronizing neuronal activity and network dynamics between these structures in a variety of behavioral scenarios in the awake and sleep state. We further revealed a dual mechanism of respiratory entrainment, in the form of an intracerebral corollary discharge that acts jointly with an olfactory reafference to coordinate limbic network dynamics, such as hippocampal ripples and cortical UP and DOWN states, involved in memory consolidation. Respiration provides a perennial stream of rhythmic input to the brain. In addition to its role as the condicio sine qua non for life, here we provide evidence that breathing rhythm acts as a global pacemaker for the brain, providing a reference signal that enables the integration of exteroceptive and interoceptive inputs with the internally generated dynamics of the hippocampus and the neocortex. Our results highlight breathing, a perennial rhythmic input to the brain, as an oscillatory scaffold for the functional coordination of the limbic circuit, enabling the segregation and integration of information flow across neuronal networks

Kognitivní dezorganizace a náhled u schizofrenie.

Tereza Petrásková Toušková - Cognitive Disorganisation and Insight in Schizophrenia 1 Souhrn domí p edstavuje projev aktivit mozku, které zahrnují jednotný, integra ní a m nlivý proces, odrážející vazbu mezi rozdílnými modali- tami základních informa ních a subjektivních komponent. Podle sou asného výzkumu hrají zm ny v domí a sebeuv dom ní význam- nou roli v patofyziologii schizofrenie a asto zahrnují zvýšenou aktivaci hypothalamo-hypofyzární osy. Studie poukazují na to, že proces po- ruchy uv dom ní a dezintegrace v domí u schizofrenie spolu pravd podobn mohou souviset a být zp sobeny obdobnými zm nami na úrovni mozku, které pak mohou být vysv tleny r znými stupni narušení konektivity a zpracování informací, což negativn ovliv uje žný vzorec synchronní aktivity tvo ící adaptivní integra ní funkce domí. S ohledem na tento kontext je ú elem teoretické ásti diserta ní práce popsat základní neurobiologické mechanismy provázející integra ní procesy v mozku spolu s komplementární duševní aktivitou zahrnující sebeuv dom ní a náhled, které odrážejí návzájem propojené procesy psychiky a mozkové aktivity, což implikuje p ímý efekt psy- choterapie a dalších metakognitivních aktivit na funkci mozku. První ást empirického výzkumu zkoumá konceptuální dezorganiza- ci a její d ležitou roli v patofyziologii schizofrenie....Tereza Petrásková Toušková - Cognitive Disorganisation and Insight in Schizophrenia 1 SUMMARY Conscious awareness is related to brain activities represented as unita- ry, integrated and changeable processes reflecting binding of diverse modalities of basic neural informational processes and their subjective components. According to recent research disturbances of self- awareness and conscious experience have a critical role in pathophysi- ology of schizophrenia, which in early stages of the disease mainly in- clude overactivation of the HPA axis. Together these studies suggest that the processes of disrupted awareness and conscious disintegration in schizophrenia likely might be related and represented by similar dis- ruptions on the brain level, which in principle could be explained by various levels of disturbed connectivity and information disintegration that may negatively affect usual patterns of synchronous activity consti- tuting adaptive integrative functions of consciousness. In this context, a purpose of the theoretical part of the disertation is to describe basic neu- robiological mechanisms underlying integrative processes in the brain with its complementarily related mental activities including self- awareness and insight reflecting interrelated processes between mind and brain that implicate...Department of Psychiatry First Faculty of Medicine and General University Hospital in PraguePsychiatrická klinika 1. LF a VFN v PrazeFirst Faculty of Medicine1. lékařská fakult

Doctor of Philosophy

dissertationThe concept of compassion is complex, where religious and philosophical writings are abundant but scientific publications remain sparse. The surge in neuroscientific publications related to prosocial behaviors, spirituality, and Buddhist-based meditation practices has sparked a growing interest in issues once considered foreign to the scientific arena. There is currently a strong need to develop neuroscientific methods that incorporate subjective trait and state measures. In addition, the use of powerful new technologies such as high density whole head magnetoencephalography (MEG) provides novel methods for mapping brain states over time in a way never before thought possible. The current proposal will attempt to use MEG in combination with both state and trait scales to better understand how mind and brain are related to the production of induced compassion. The sample for investigation will include high level Zen Buddhist practitioners with many years of intensive religious practice within a Buddhist framework that requires the cultivation of compassion. The hope is that these findings may one day shed light on an array of psychiatric disorders where certain forms of social impairments could benefit from practices traditionally sequestered within only religious context;s