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Default mode speaker Stuart Hameroff MD Professor, Anesthesiology and Psychology Director, Center for Consciousness Studies The University of Arizona,

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Presentation on theme: "Default mode speaker Stuart Hameroff MD Professor, Anesthesiology and Psychology Director, Center for Consciousness Studies The University of Arizona,"— Presentation transcript:

1 Default mode speaker Stuart Hameroff MD Professor, Anesthesiology and Psychology Director, Center for Consciousness Studies The University of Arizona, Tucson Arizona

2 Whilst part of what we perceive comes though our senses from the object before us, another part (and it may be the larger part) always comes out of own head. William James, 1890

3 For Des For Descartes, content of consciousness li like a like a play on stage The Cartesian Theater

4 Simon and Newell developed similar brain/mind computer architectures CPU

5 Baars, Edelman/Tononi, Changeux/ Dehaene, Crick/Koch cast thalamo-cortical oscillations, recurrence, global workspace broadcasting…… Based on hierarchical sensory stimuli, arousal, response - bottom-up, top-down, feed-forward, feedback..

6 PET, fMRI show reduced metabolism, blood flow in thalamo-cortical hierarchical arousal pathways with anesthesia and loss of consciousness – a thalamo-cortical switch (Alkire)

7 In neuroscience, consciousness has been viewed in the context of sensory processing and response, i.e. attention-based tasks But what about mental states without sensory inputs? What about task-free, stimulus-independent thought, internally-generated states, mind wandering, episodic memory, meditation, daydreaming?

8 The Brain's Dark Energy/Default mode networks Raichle (2006) Science 314: 1249 – 1250, 2006)

9 Copyright restrictions may apply. Carhart-Harris, R. L. et al. Brain : ; doi: /brain/awq010 DMN regions in orange MTL: Medial temporal lobe mPFC: Medial prefrontal cortex PCC: Posterior cingulate cortex pIPL: Posterior inferior parietal

10 Raichle M E et al. PNAS 2001;98: ©2001 by The National Academy of Sciences Brain regions regularly observed to decrease activity during attention demanding cognitive tasks

11 Axial (A) and coronal (B) images showing default-mode network for healthy young subjects. Green arrows highlight coactivation in hippocampus and entorhinal cortex.

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13 Default-mode networks: healthy elderly Default mode networks: Alzheimers

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16 Default mode network activity is one type of intrinsic neuronal activity which was considered noise, until brain-wide correlations in the noise were discovered (? Israel) DMN activities require 95% of the energy required for thalamo-cortical sensory processes what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

17 The brain operates in two distinct modes – 1) Attention-based sensory processing, task performance (Thalamo-cortical) 2) Mindwandering, episodic memory, internally-generated states daydreaming, thinking…? (Default mode networks)

18 Default mode networks: Episodic memory Thinking about consciousness Introspection Meditation Self-referential thought Creativity Daydreaming Jamesian fringe Mind wandering Freudian Id Envisioning the future Anesthesia Gauging others perspective Sleep Context/filling in

19 Default mode networks: Diminished in Alzheimers, autism? Overactive in schizophrenia, anxiety, OCD?

20 The brain operates in two distinct modes – 1) Attention-based sensory processing, task performance (Thalamo-cortical) 2) Mindwandering, episodic memory, internally-generated states daydreaming, thinking…? (Default mode networks)

21 The brain operates in two distinct modes – 1) Attention-based sensory processing, task performance (Thalamo-cortical) 2) Mindwandering, episodic memory, internally-generated states daydreaming, thinking…? (Default mode networks) and flips back and forth between the two on the order of roughly 10 seconds Anticorrelated networks (Raichle)

22 J Neurophysiol 101: , First published April 1, 2009; doi: /The Global Signal and Observed Anticorrelated Resting State Brain Networks Michael D. Fox1,*, Dongyang Zhang1,*, Abraham Z. Snyder1,2 and Marcus E. Raichle1,2,3,4 The Global Signal and Observed Anticorrelated Resting State Brain Networks MD Fox, D Zhang, AZ Snyder and ME RaichleJ Neurophysiol 101: , 2009

23 Questions: 1) How does switching between sensory/attention/task and mindwandering/default modes occur? Locus coeruleus ? (UCSB group) based on saliency of sensory input? what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

24 Questions: 2) What is/are the function(s) of default mode network activity? Raichle: Synchrony and orchestration what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

25 Default mode networks synchronize all parts of the brain, so like racers in a track competition, they are all in a proper set mode when the starting gun goes off. Raichle 2010

26 Orchestrator of The Self : The DMN is thought to behave something like an orchestra conductor, issuing timing signals, much as a conductor waves a baton, to coordinate activity among different brain regions. This cuingamong the visual and auditory parts of the cortex, for instanceprobably ensures that all regions of the brain are ready to react in concert to stimuli. Raichle, 2010

27 Steve Lehar

28 Questions: 3) What about consciousness? What does default mode network activity tell us about consciousness? Thalamo-cortical sensory processing and behavior can be either conscious, or non-conscious Default mode network activity can either be conscious, or non-conscious what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

29 Thalamo-cortical processing (driving to work) can be either conscious or non-conscious (auto-pilot, zombie mode) with daydreaming, mindwandering what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

30 Default mode network activity can either be conscious (daydreaming about vacation on the beach)…. what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

31 Default mode network activity can either be conscious (daydreaming about vacation on the beach) or non-conscious (tough day ahead at work, send impulses to small bowel, tighten sphincters…..) what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

32 Activity supporting consciousness switches between 1) Thalamo-cortical input-driven processing and 2) Default mode network activity what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

33 Consciousness switches between 1) Thalamo-cortical input-driven processing and 2) Default mode network activity Thalamo-cortical activity is hierarchical, but how is default mode network activity mediated? Self-organized? what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

34 Consciousness switches between 1) Thalamo-cortical input-driven processing and 2) Default mode network activity Could consciousness involve some self- organizing neuronal process moving between the two modes? what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

35 Consciousness switches between 1) Thalamo-cortical input-driven processing and 2) Default mode network activity Could consciousness involve some self- organizing neuronal process moving between the two modes? What distinguishes conscious from non- conscious brain activity? what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

36 The best neurophysiological correlate of consciousness (NCC) comes from EEG, voltage fluctuations recorded from scalp or brain surface. EEG is divided into frequency bands: Delta (< 4 Hz) Theta (4 to 8 Hz) Alpha (8 to 12 Hz) Beta (13 to 30 Hz) Gamma (> 30 Hz) Coherence in gamma synchrony among different brain regions is the best correlate of consciousness

37 Gap junction-mediated gamma synchrony in olfactory bulb cortex correlates with conscious smell. J Neuroscience. 26(8): , 2006 Neuron46(5):761-72, 2005 BING!!

38 Neuroscience. 159(4): , 2009 Brain Research. 1156:46-58, 2007 Conscious feelings of pleasure, sex and reward correlate with gap junction-mediated gamma synchrony in dopaminergic nucleus accumbens BING!!

39 EEG measures post- synaptic dendritic activity (not axonal firings)

40 Biological brain neuron McCulloch-Pitts artificial neuron, Perceptron Toy neuron

41 Integrate

42 Fire

43 Integrate

44 Fire

45

46

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48 B I N G !

49 BING!!

50 B I N G !

51 The conscious pilotdendritic synchrony moves through the brain to mediate consciousness. Journal of Biological Physics, 36:1 January, 2010 DOI: /s x

52 Conclusions - Raichle work implies The brain switches between sensory-driven and (self-organizing) internally-driven modes what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

53 Conclusions - Raichle work implies Consciousness switches between sensory- driven and (self-organizing) internally-driven modes what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?

54 Conclusions - Raichle work implies Consciousness switches between sensory- driven and (self-organizing) internally-driven modes Anesthesia cannot depend solely on a thalamo-cortical switch what about internally-generated mental states without sensory inputs? Stimulus-independent thought, e.g. meditation, daydreaming, mind wandering?


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