Category Archives: Nevroanatomi

Review article on Consciousness in The Journal of Neuroscience

A Review article on Consciousness was recently published in The Journal of Neuroscience (8 Nov. 2017).

“Consciousness Regained: Disentangling Mechanisms, Brain Systems, and Behavioral Responses”
Johan F. Storm, Mélanie Boly, Adenauer G. Casali, Marcello Massimini, Umberto Olcese, Cyriel M.A. Pennartz and Melanie Wilke
The Journal of Neuroscience, 8 November 2017, 37(45):10882-10893;doi:10.1523/JNEUROSCI.1838-17.2017

Review

(http://www.jneurosci.org/content/37/45/10882?etoc=)

 

Abstract:

How consciousness (experience) arises from and relates to material brain processes (the “mind-body problem”) has been pondered by thinkers for centuries, and is regarded as among the deepest unsolved problems in science, with wide-ranging theoretical, clinical, and ethical implications. Until the last few decades, this was largely seen as a philosophical topic, but not widely accepted in mainstream neuroscience. Since the 1980s, however, novel methods and theoretical advances have yielded remarkable results, opening up the field for scientific and clinical progress. Since a seminal paper by Crick and Koch (1998) claimed that a science of consciousness should first search for its neural correlates (NCC), a variety of correlates have been suggested, including both content-specific NCCs, determining particular phenomenal components within an experience, and the full NCC, the neural substrates supporting entire conscious experiences. In this review, we present recent progress on theoretical, experimental, and clinical issues. Specifically, we (1) review methodological advances that are important for dissociating conscious experience from related enabling and executive functions, (2) suggest how critically reconsidering the role of the frontal cortex may further delineate NCCs, (3) advocate the need for general, objective, brain-based measures of the capacity for consciousness that are independent of sensory processing and executive functions, and (4) show how animal studies can reveal population and network phenomena of relevance for understanding mechanisms of consciousness.

 

Figures:

Figure 1. Examples of bistable stimuli. A, In binocular rivalry, two stimuli are shown to different eyes and perception wavers between left and right eye stimuli (Blake and Logothetis, 2002). B, Ambiguous structure-from-motion (SfM) stimulus. Dots moving back and forth on a flat screen, without perspective cues to differentiate between front and rear surfaces, induce the perception of a 3D rotating object that periodically switches direction. (Sterzer et al., 2009) C, Generalized flash suppression. A target stimulus (red dot) is shown parafoveally followed by the onset of a moving surround, causing the red target to disappear in ∼50% of trials (Wilke et al., 2003).
Figure 1.
Examples of bistable stimuli. A, In binocular rivalry, two stimuli are shown to different eyes and perception wavers between left and right eye stimuli (Blake and Logothetis, 2002). B, Ambiguous structure-from-motion (SfM) stimulus. Dots moving back and forth on a flat screen, without perspective cues to differentiate between front and rear surfaces, induce the perception of a 3D rotating object that periodically switches direction. (Sterzer et al., 2009) C, Generalized flash suppression. A target stimulus (red dot) is shown parafoveally followed by the onset of a moving surround, causing the red target to disappear in ∼50% of trials (Wilke et al., 2003).
Experimental outline for the no-report paradigm for NCC studies. A, Depiction of the problem. We aim for the correlation between a conscious content and a given brain state. What is measured experimentally is the correlation between a behavioral report and a measure of brain activity, which might be appropriate or not. Report-related neural activity poses a confound for the NCC. B, Involuntary physiological measures taken to infer the perceptual state of a subject to circumvent the behavioral report (Tononi et al., 1998; Leopold et al., 2003; Laeng and Endestad, 2012; Tsuchiya et al., 2015).
Experimental outline for the no-report paradigm for NCC studies. A, Depiction of the problem. We aim for the correlation between a conscious content and a given brain state. What is measured experimentally is the correlation between a behavioral report and a measure of brain activity, which might be appropriate or not. Report-related neural activity poses a confound for the NCC. B, Involuntary physiological measures taken to infer the perceptual state of a subject to circumvent the behavioral report (Tononi et al., 1998; Leopold et al., 2003; Laeng and Endestad, 2012; Tsuchiya et al., 2015).
Figure 3. A, Major cortical and subcortical brain regions where lesions lead to spatial neglect in humans (left), and corresponding recent experimental results in monkeys (right) (lateral view). In humans, lesions in frontal (Brodmann area 44), inferior parietal cortex (Brodmann area 40), superior temporal gyrus (STG), basal ganglia, and pulvinar have been reported to lead to spatially biased behavior that might appear as a visual consciousness deficit (Karnath, 2001). B, Recent pharmacological inactivation studies in monkeys have shown primarily effector-specific spatial deficits after lesions in parietal subregions such as the lateral intraparietal area (LIP, red shading) and the parietal reach region (PRR, which includes the medial intraparietal area MIP and area V6A, green shading). Dorsal pulvinar (dPULV, orange shading) inactivation leads to spatial orienting bias for both eye and hand movements which can be compensated by visual reward cues, suggesting that visual perception might be preserved. Ventral pulvinar (vPULV, purple shading) inactivation leads to change detection deficits resembling visual neglect. Summarized from local inactivation studies in monkeys (Wardak et al., 2002; Wilke et al., 2010; Hwang et al., 2012; Wilke et al., 2012; Wilke et al., 2013; Hwang et al., 2014; Christopoulos et al., 2015; Katz et al., 2016; Zhou et al., 2016).
Figure 3.
A, Major cortical and subcortical brain regions where lesions lead to spatial neglect in humans (left), and corresponding recent experimental results in monkeys (right) (lateral view). In humans, lesions in frontal (Brodmann area 44), inferior parietal cortex (Brodmann area 40), superior temporal gyrus (STG), basal ganglia, and pulvinar have been reported to lead to spatially biased behavior that might appear as a visual consciousness deficit (Karnath, 2001). B, Recent pharmacological inactivation studies in monkeys have shown primarily effector-specific spatial deficits after lesions in parietal subregions such as the lateral intraparietal area (LIP, red shading) and the parietal reach region (PRR, which includes the medial intraparietal area MIP and area V6A, green shading). Dorsal pulvinar (dPULV, orange shading) inactivation leads to spatial orienting bias for both eye and hand movements which can be compensated by visual reward cues, suggesting that visual perception might be preserved. Ventral pulvinar (vPULV, purple shading) inactivation leads to change detection deficits resembling visual neglect. Summarized from local inactivation studies in monkeys (Wardak et al., 2002; Wilke et al., 2010; Hwang et al., 2012; Wilke et al., 2012; Wilke et al., 2013; Hwang et al., 2014; Christopoulos et al., 2015; Katz et al., 2016; Zhou et al., 2016).
Figure 4. A, Summary of main findings on spike-based functional connectivity in rats (Olcese et al., 2016). Coupling was measured as pairwise cMI between single neurons. During wakefulness, cMI between neurons located in the same or different areas is largely balanced (left) for both excitatory and inhibitory neurons (black and red lines, respectively). In NREM sleep, interareal (but not intra-area) coupling between excitatory neurons is significantly reduced. This did not apply to intra-area cMI and interareal cMI (between interneurons). Line thickness indicates the proportion of neuronal pairs for which cMI was significantly >0. Asterisks indicate which connections showed a significant change between wakefulness and NREM sleep (the only significant differences found pertained to interareal coupling between excitatory neurons). Thus, during NREM sleep, neural computations may continue in local “islands of activity,” whereas global integration capabilities are reduced. B, Calculation of heterogeneity across a neuronal population (compare Montijn et al., 2015). A measure of a neuronal activity change (A, e.g., the relative fluorescence response of a neuron in 2-photon imaging, dF/F0) is computed across all neurons. Next, the responses are z-scored per neuron across all trials and all trial types (e.g., in a given session, visual stimuli are presented at 6 different contrasts; each contrast is presented 20 times; 120 trials in total). Per trial, the absolute difference in z-scored activity is then calculated across all pairs of neurons (e.g., ΔA1,2 is the difference between the responses of neurons 1 and 2). The population heterogeneity in a given trial is the mean of activity differences across all pairs. C, Examples of high (left) versus low heterogeneity (right) in a neuronal population, where response strength is indicated by color saturation. D, In a visual stimulus detection task performed by mice that were subjected to 2-photon imaging of V1 neuronal populations, heterogeneity was better capable of separating hit (detection) and miss (nondetection) trials than the mean fluorescence response (area under the curve resulting from receiver-operating characteristic analysis). Both measures predicted response behavior above chance: mean response, *p < 0.05; heterogeneity, ***p < 0.001; area under the curve = 0.5, chance level. Behavior was predicted better by heterogeneity than mean response (**p < 0.01). Values are mean ± SEM across animals. Data from Montijn et al. (2015).
Figure 4.
A, Summary of main findings on spike-based functional connectivity in rats (Olcese et al., 2016). Coupling was measured as pairwise cMI between single neurons. During wakefulness, cMI between neurons located in the same or different areas is largely balanced (left) for both excitatory and inhibitory neurons (black and red lines, respectively). In NREM sleep, interareal (but not intra-area) coupling between excitatory neurons is significantly reduced. This did not apply to intra-area cMI and interareal cMI (between interneurons). Line thickness indicates the proportion of neuronal pairs for which cMI was significantly >0. Asterisks indicate which connections showed a significant change between wakefulness and NREM sleep (the only significant differences found pertained to interareal coupling between excitatory neurons). Thus, during NREM sleep, neural computations may continue in local “islands of activity,” whereas global integration capabilities are reduced. B, Calculation of heterogeneity across a neuronal population (compare Montijn et al., 2015). A measure of a neuronal activity change (A, e.g., the relative fluorescence response of a neuron in 2-photon imaging, dF/F0) is computed across all neurons. Next, the responses are z-scored per neuron across all trials and all trial types (e.g., in a given session, visual stimuli are presented at 6 different contrasts; each contrast is presented 20 times; 120 trials in total). Per trial, the absolute difference in z-scored activity is then calculated across all pairs of neurons (e.g., ΔA1,2 is the difference between the responses of neurons 1 and 2). The population heterogeneity in a given trial is the mean of activity differences across all pairs. C, Examples of high (left) versus low heterogeneity (right) in a neuronal population, where response strength is indicated by color saturation. D, In a visual stimulus detection task performed by mice that were subjected to 2-photon imaging of V1 neuronal populations, heterogeneity was better capable of separating hit (detection) and miss (nondetection) trials than the mean fluorescence response (area under the curve resulting from receiver-operating characteristic analysis). Both measures predicted response behavior above chance: mean response, *p < 0.05; heterogeneity, ***p < 0.001; area under the curve = 0.5, chance level. Behavior was predicted better by heterogeneity than mean response (**p < 0.01). Values are mean ± SEM across animals. Data from Montijn et al. (2015).

Excellent lecture by Adrian Owen in The Norwegian Academy of Science And Letters, October 7, 2014

The lecture hall of the Norwegian Academy of Science And Letters in Oslo was filled with scientists, philosophers, clinicians (MDs, psychologists) and others when Dr. Adrian Owen presented his outstanding research on consciousness in an excellent lecture: «Using Functional Neuroimaging to Detect Awareness After Serious Brain Injury».

Owen lecturing
Professor Adrian Owen lecturing in Oslo: «Using Functional Neuroimaging to Detect Awareness After Serious Brain Injury»

The lecture was followed by questions and discussion, including a panel discussion with Adrian Owen, Olav Gjelsvik (philosophy, University of Oslo), Johan Storm (neurophysiology, University of Oslo), and Marianne Løvstad (clinical neurophysiology, Sunnaas Rehabilitation Hospital/Oslo University Hospital, Oslo).

 

Owen - panel discussion
Panel discussion with (from left) Adrian Owen, Olav Gjelsvik (philosophy, University of Oslo), Johan Storm (neurophysiology, University of Oslo), and Marianne Løvstad (clinical neurophysiology, Sunnaas Rehabilitation Hospital /OUS, Oslo).
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Panel discussion

 

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Professor Nils Christian Stenseth (Biology, University of Oslo, leader of the Norwegian Academy of Science and Letters), opened the Meeting.

As before, this open meeting was hosted jointly by the Forum for Consciousness Research and the Norwegian Academy of Science and Letters.

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Arian Owen in conversation with Johan F. Storm.
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Adrian Owen in conversation with Marianne Løvstad.

 

Lecture on sleep by G. Tononi and C Cirelli, 4 April 2014

Guest Lecture by:

Giulio Tononi and Chiara Cirelli, University of Wisconsin:

Sleep and the price of plasticity

Time:   Friday, 4 April, 14.30-15.30 Place:    Auditorium 13, Domus Medica, Gaustad,

Inst. of Basal Medical Sciences (IMB), University of Oslo

 

Giulio Tononi is a psychiatrist and neuroscientist (MD, PhD). He is currently Professor of Psychiatry at the University of Wisconsin, David P. White Chair in Sleep Medicine and is a Distinguished Chair in Consciousness Science. He has previously held faculty positions in Pisa, New York, San Diego.

Dr. Tononi and collaborators have pioneered several complementary approaches to study sleep.

Chiara Cirelli (MD, PhD, Pisa, Italy) is currently Professor of Psychiatry at the University of Wisconsin, Madison, where she moved in 2001. In 1994-2000 she was Fellow of The Neurosciences Institute in San Diego, California.

The research in Dr. Cirelli’s laboratory aims at understanding the function of sleep and clarifying the functional consequences of sleep loss. Her team uses a combination of different approaches, from genetics in fruit flies to whole-genome expression profiling in invertebrates and mammals, to behavioral and EEG analysis in mice and rats.

The research of Tononi and Cirelli include genomics, proteomics, fruit fly models, rodent models employing multiunit / local field potential recordings in behaving animals, in vivo voltammetry and microscopy, high-density EEG recordings and transcranial magnetic stimulation in humans, and large-scale computer models of sleep and wakefulness. This research has led to a comprehensive hypothesis on the function of sleep, the synaptic homeostasis hypothesis. According to the hypothesis, wakefulness leads to a net increase in synaptic strength, and sleep is necessary to reestablish synaptic homeostasis. The hypothesis has implications for understanding the effects of sleep deprivation and for developing novel diagnostic and therapeutic approaches to sleep disorders and neuropsychiatric disorders.

Another focus of Dr. Tononi’s work is the integrated information theory of consciousness: a scientific theory of what consciousness is, how it can be measured, how it is realized in the brain and, of course, why it fades when we fall into dreamless sleep and returns when we dream. The theory is being tested with neuroimaging, transcranial magnetic stimulation, and computer models. In 2005, Dr. Tononi received the NIH Director’s Pioneer Award for his work on sleep mechanism and function, and in 2008 he was made the David P. White Chair in Sleep Medicine and is a Distinguished Chair in Consciousness Science.           (Sources: http://tononi.psychiatry.wisc.edu/people/cirelli.html; Wikipeia, PubMed etc.)

Some selected papers on sleep by Tononi and Cirelli

  • Tononi G, and Cirelli C. Sleep and the price of plasticity: from synaptic and cellular homeostasis to memory consolidation and integration. Neuron, 81(1):12-34, 2014.
  • Bushey D, Tononi G, Cirelli C. Sleep and synaptic homeostasis: structural evidence in Drosophila. Science, 332(6037):1576-1581, 2011
  • Maret S, Faraguna U, Nelson AB, Cirelli C, Tononi G. Sleep and wake modulate spine turnover in the adolescent mouse cortex. Nat Neurosci., 14(11):1418-20, 2011.
  • Gilestro GF, Tononi G, Cirelli C. Widespread changes in synaptic markers as a function of sleep and wakefulness in Drosophila. Science, 324:109-12, 2009.
  • Vyazovskiy VV, Cirelli C, Pfister-Genskow M, Faraguna U, Tononi G. Molecular and electrophysiological evidence for net synaptic potentiation in wake and depression in sleep. Nature Neuroscience, 11:200-8, 2008
  • Cirelli C, Gutierrez CM, Tononi G. Extensive and divergent effects of sleep and wakefulness on brain gene expression. Neuron 41: 35-43, 2004

 Welcome!

Johan F. Storm,

On behalf of Forum for Consciousness Rearearch

 

Large turnout and brilliant lecture by Stanislas Dehaene in Oslo / Godt oppmøte på foredrag av Dehaene

Av: Olve Moldestad, Johan F. Storm

Large turnout and brilliant lecture by Stanislas Dehaene in Oslo

There was a large turnout when Dr. Stanislas Dehaene  gave a brilliant lecture about his research on consciousness at Litteraturhuset in Oslo, in an open meeting hosted by the Forum for Consciousness Research and the Norwegian Academy of Science and Letters. The lecture hall was over-filled.

Sammen med Det Norske Videnskaps-Akademi, arrangerte forum for bevissthetsforskning et åpent møte med professor i kognitiv psykologi Stanislas Dehaene den 6. november. Mer en 150 deltakere møtte opp for å høre ham snakke om sin forskning på bevissthet. 

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Mer en 150 hadde møtt opp for å høre Stanislas Dehaene (foto: Olve Moldestad).

Dehaene holdt et foredrag om en serie eksperimenter han har gjort med sine samarbeidspartnere som forsøker å beskrive de endringene som skjer i hjernen når forsøkspersonene blir oppmerksom på ny informasjon. Forsøkene benytter små endringer i de eksperimentelle betingelsene som kan avgjøre om de samme stimuli blir registrert eller ikke. Det er, for eksempel, små endringer i hvor lenge et stimulus blir presentert for forsøkspersonene. Forskningen benytter EEG, fMRI og MEG for å studere endringer i hjernes aktivitet under disse eksperimentene.

Møtet ble holdt på Litteraturhuset 6. november 2013 (foto: Olve Moldestad).
Møtet ble holdt på Litteraturhuset 6. november 2013 (foto: Olve Moldestad).

Resultatene fra Dehaenes forskning indikerer at bevissthet er forbundet med global økning i sen synkronisert aktivitet (en cortical “antenning”) som er spredt over mange corticale områder. Sammen med sine medarbeidere har han utviklet en teori om et globalt nevronalt arbeidsminne eller -område i hjernen. I denne teorien er opplevelsen av bevissthet knyttet til tilgjengeligheten av informasjon i store nettverk i hjernen av pyramide-nevroner med langedistanse aksoner.

Foredraget ble etterfulgt av en debatt ledet av Visepreses Nils Chr. Stenseth, og i panelet satt professor i nevrofysiologi Johan F. Storm, førsteamanuensis i psykologi Thomas Espeseth, post. doc. i filosofi Sebastian Watzl sammen med professor i kognitiv psykologi Stanislas Dehaene.

Visepreses Nils Chr. Stenseth (ytterst til høyre) ledet debatten under møtet (foto: Olve Moldestad).
Visepreses Nils Chr. Stenseth (ytterst til høyre) ledet debatten under møtet (foto: Olve Moldestad).
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I panelet satt (fra venstre) professor i nevrofysiolog Johan F. Storm, førsteamanuensis i psykologi Thomas Espeseth, post. doc. i filosofi Sebastian Watzl og professor i kognitiv psykologi Stanislas Dehaene (foto: Olve Moldestad).