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What can Electrophysiology (and Brain Rythms) tell us about ‘Meditation’ ? Jean-Philippe LACHAUX

What can Electrophysiology (and Brain Rythms) tell us about ‘Meditation’ ? Jean-Philippe LACHAUX CNRS - LENA - PARIS INSERM – U280 – LYON Stirling Workshop June 11-12, 2004 Buddhist inspired Models of the Mind. GENERAL FRAMEWORK ‘Meditation(s)’ … ?. Varieties of attention

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What can Electrophysiology (and Brain Rythms) tell us about ‘Meditation’ ? Jean-Philippe LACHAUX

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  1. What can Electrophysiology (and Brain Rythms) tell us about ‘Meditation’ ? Jean-Philippe LACHAUX CNRS - LENA - PARIS INSERM – U280 – LYON Stirling Workshop June 11-12, 2004 Buddhist inspired Models of the Mind

  2. GENERAL FRAMEWORK ‘Meditation(s)’ … ? • Varieties of attention • Focal (‘external’ or ‘internal’ targets) • - Open attention (whatever happens, happens) If we can talk about the dynamic of the mind Then meditation has to do with the fine tuning of parameters that determine this dynamic

  3. Mind’s Dynamic Plasticity of Attention Grasping, Frozen Mind, Overexcitment, …

  4. Mind’s Dynamic Deeply Rooted into a Large-Scale Non-linear Dynamical System under constant external perturbations (reactivity vs. inertia)

  5. If the dynamic of the Mind has to do with the dynamic of the Brain, Then it should be possible to understand, or at least witness, the effects of meditation on this dynamic via brain imaging Optimally, it would be nice to describe the neural dynamic at a time-scale that is compatible with the time-scale of subjective experience And at a spatial scale compatible with the spatial scale of the brain’s functional architecture

  6. cms meg -eeg fmri pet spatial resolution seeg neurons minutes ms temporal resolution

  7. EEG/MEG in Humans Evoked Potentials EEG Oscillations ‘spontaneous EEG’

  8. Synchronization of large neural populations EEG Oscillations Several characteristic frequency bands with different functional specificities (more or less) d (<4Hz) q (4-7 Hz) : working memory, mental load ? a , m (7-14 Hz) : relax ? ‘idle rythm?’ b (15 – 30 Hz) : sustained attention ? Relax ? g (> 30 Hz) : attention ? Visual processing ? Motor ? …

  9. G M K response Gating of the THETA band

  10. How is the spontaneous EEG modified during meditative states ?

  11. EEG Oscillations : it’s more complicated than that …. … But more interesting for our main topic

  12. My main point The function of EEG Oscillations depends on where they originate from Therefore, they must be studied and understood at the level of functionally homogeneous neural populations (at first….) Then, we should be able to understand what they tell us about meditation

  13. Some proposals on how to use electrophysiology to study meditation Select a set of cognitive tasks …. In which expert meditators perform much better than ‘normal’ subjects With well-known electrophysiological characteristics (functional anatomy + dynamics) Compare those characteristics between the two groups

  14. Background Study of EEG at the intracerebral level In humans, in a variety of cognitive tasks Visual perception Memory Attention Language Movement …

  15. A simple face perception paradigm …. And how it related to visual attention the notion of ‘brain availibility’ and visual imagery

  16. Readily recognized when presented in upright orientation Usually seen as meaningless black and white spots when presented upside-down. Brain Oscillations during the perception of visual objects Stimuli: 'Mooney' faces

  17. F5-F4 : Fusiform Gyrus 121 trials mean std Very little freedom ….

  18. Pat1, fusiform gyrus III IV II I

  19. Pat1, fusiform gyrus Mean Deviation [50 – 200 Hz] P NP

  20. Pat2, Inferior temporal gyrus BA37 (Bipole e’7e’8) Mean Deviation [50 – 200 Hz] P NP Evoked Potential P NP

  21. O’ E’ PRIMARY VISUAL CORTEX FUSIFORM GYRUS

  22. PRIMARY VISUAL CORTEX Fusiform gyrus Sorry, my brain is busy, I can’t get your call right now …

  23. Sorry, my brain is busy, I can’t get your call right now … The Attentional blink : how to hide things to the brain Do seasoned meditators Blink attentionally ?

  24. OK, you have my full attention, now

  25. And now, MENTAL IMAGERY and the BETA range

  26. from ( Tallon-Baudry et al., 01 )

  27. Yes

  28. Yes

  29. A simple occulo-motor paradigm …. And how it related to self (executive) control

  30. time Look Away ! Saccade Anti-Saccade

  31. « This ability to control behaviour flexibly, responding automatically to stimuli in one situation and suppressing this automatic response in favour of an alternative response in a different situation, is the hallmark of executive control. In this review, we describe how the antisaccade task can be used to investigate the volitional control of action » Munoz et al. Nature Reviews Neuroscience 2004

  32. Two simple language paradigms …. And how they related to ‘the little voice in the head’

  33. le il etait petit une chat fois time 1s adapted from Nobre et al. 1998

  34. : GREEN TARGET AMPLITUDE MODULATION BETWEEN 30 AND 150 Hz (z-score / ligne de base [-500ms : -100ms]) : RED TARGET : GREEN IGNORED : RED IGNORED Left Motor Operculum

  35. + + + + cheval SEMAN : living entity or not ? nefoul PHONO : final sound : vowel or cons. ? xwsxkz ORTHO : twice the same letter ? VISUAL : twice the same item ? adapted from Bentin et al. 1999

  36. Broca Area Amplitude Modulation between 30 and 150 Hz (z-score / base line[-500ms : -100 ms]) Associative Auditory Cortex Motor Operculum Inferior Frontal Gyrus

  37. Some proposals on how to use electrophysiology to study meditation Select a set of cognitive tasks …. In which expert meditators perform much better than ‘normal’ subjects With well-known electrophysiological characteristics (functional anatomy + dynamics) Compare those characteristics between the two groups

  38. Non-invasive dynamic mapping using EEG/MEG and source modelling THE FUTURE Real-time Feedback

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