Christof Koch, Ph.D
Chief Scientific Officer at the Allen Institute for Brain Science, Seattle.
Lois and Victor Troendle Professor of Cognitive and Behavioral Biology at California Institute of Technology, Pasadena, CA.
Photo: Courtesy of California Institute of Technology
Studying the Murine Mind
Christof Koch. Ph.D.
Mice are a very promising model system for studying the neuronal correlates of consciousness. Their brain structure is similar to that of the human, they display complex behavior, and their underlying neuronal responses can be measured using optics and silicon probes at cellular level of resolution. In contrast to the blunt and edentate tools available to probe the human brain, the recent emergence of optogenetics allows scientists to delicately, transiently, and reversibly control defined events in defined cell types at defined times in mice. This allows us to move from correlation to causation, from observing that this circuit is activated whenever the subject is perceiving something to inferring that this circuit is necessary for conscious perception. I shall report on the large-scale and high throughput efforts to build brain observatories to understand the mouse visual system that are ongoing at the Allen Institute.
The Properties of Neurons at the Root of Consciousness
Donald Pfaff, Ph.D.
The origins of consciousness in the human brain are not at the thalamus and cortex, where most explorers concentrate their efforts. Instead, the most powerful and essential neurons for facilitating and maintaining the conscious state are deep in the lower brainstem, in the reticular formation just above the spinal cord. Following a description of the generalized arousal concept fundamental to consciousness, I will describe the neural pathways and neurochemical mechanisms involved. The properties of the gigantocellularneurons deep in the brainstem reticular formation will be highlighted. Exactly how are their properties well suited to their essential task? My talk will give a 2012 answer to that question.
Neural Correlates of Unconsciousness in Drosophila
Bruno van Swinderen, Ph.D.
Our understanding of consciousness often follows from studies of selective attention, sleep, and general anaesthesia in humans. However, these behavioural states can also be studied in the simpler animals, such as the fruit fly Drosophila melanogaster, where responsiveness to stimuli can be indicative of the level arousal in the animal. Multichannel brain recordings from flies can then be used to identify processes, such as local field potential coherence, associated with different arousal states in the tiny insect brain. In my talk, I will argue that distinct arousal states, such as sleep and selective attention, may involve similar stimulus suppression mechanisms, and that perceptual suppression may have been the evolutionary innovation leading to conscious and unconscious states in higher animals. I will then proceed to show how one can use the genetic model Drosophila to manipulate and dissect perceptual suppression mechanisms in a small brain.
The Claustrum and the Orchestra of Cognitive Control
Ryan Remedios, Ph.D.
Francis Crick and Christoph Koch were interested in the claustrum as a site of multisensory integration due to its extensive topographic connections with the sensory cortices (1). We showed that the claustrum did not integrate sensory information as neurons here were highly modality specific and did not exhibit the response characteristics typically associated with multisensory processing (2). Our recent observations do however support Crick and Koch's conjecture of the claustrum as a conductor in the orchestra of cortical regions (1). To identify claustrum function, we targetedly ablated claustral neurons and observed free-exploratory behaviors, as well as behaviors within paradigms designed to distinguish between cognitive and motor abilities. We uncovered a severe impairment in cost-benefit decision making by lesioned animals contingent to emotional modulation, paralleling the emotive role of the prefrontal cortex. We correspondingly identified a direct, interhemispheric, bidirectional network between the claustrum and prefrontal areas, and determined changes in global and regional brain network activity on claustral ablation using functional magnetic resonance imaging. Overall we suggest that the claustrum regulates cognitive control.
(1) Crick & Koch, 2005. (2) Remedios, Logothetis, Kayser, 2010.
David B. Edelman, Ph.D.
Associate Fellow, Experimental Neurobiology, The Neurosciences Institute
Assistant Professor of Neurobiology, The Scripps Research Institute
Photo: Courtesy of 'Cephalove'
Through the Eyes of an Octopus: An Invertebrate Model for Consciousness Studies
David B. Edelman, Ph.D.
Endowed with a nervous system containing as many as 500 million neurons, as well as eyes that are structurally convergent with those of vertebrates, the octopus may be an excellent model for investigating consciousness in an invertebrate. Here, I will make such a case on neuroanatomical, neurophysiological, and behavioral grounds. I will: 1) lay out a working definition for consciousness that may be extended beyond the vertebrate case; 2) describe structural and functional properties which may be the sine qua non of consciousness; 3) suggest evolutionary trends (e.g., the emergence of complex vision) that may have set the stage for the advent of conscious states in a variety of species; and 4) discuss the latest results from ongoing studies of cephalopod vision and offer a 'roadmap' for additional experiments that may lead to a robust methodology for the explicit investigation of sensory consciousness in these, and perhaps certain other, invertebrates (e.g., jumping spiders).
Human-like Consciousness in Non-Humans: Evidence from Grey Parrots
Irene Pepperberg, Ph.D.
To obtain data on nonhuman consciousness, researchers often examine "perceptual consciousness" (1) &ldash; how sensory information is acknowledged, processed, and integrated.(2) An organism may be aware it is processing information, possibly of how it is processing information, but not necessarily be aware it is aware of how information is processed. This awareness is required for complex tasks which require integrating perception, centralized monitoring, and behavioral control(3) and is a form of higher-order cognition, sensu Delacour (1997); it may involve the capacity to choose, from various possible sets of acquired rules, the set that appropriately governs the processing of certain data.(4) Sometimes, however, even this information-processing account cannot explain observed data. Three studies on Grey parrots — predominantly on Alex, who used English speech intentionally to label objects, colors, shapes, and categories, who understood concepts of same-different, relative size, absence, conjunction, exact numbers, conjunctivity, equivalence, and segmentation(5) provide evidence for some level of consciousness approaching that of humans.
(1) Griffin, 1998, 2000; Griffin & Speck, 2004. (2) Natsoulas, 1978. (3) Pepperberg & Lynn, 2000. (4) Pepperberg, 1999. (5) Pepperberg, 1999, 2006a,b, 2007
Are Commonalities in Brain Microarchitecture and Behavior in Humans and Birds a Coincidence?
Harvey Karten, MD
A "Turing Test" for cognitive and sensory-motor capabilities presuming to distinguish Monkeys and Parrots would likely prove difficult for an external observor/predictor. Which animal is hiding behind each "Turing Curtain"? Rigid conformity to semantics and outdated definitions of homology remains an obstacle to understanding brain evolution. Are there common features in brain organization of birds and mammals that mediate such striking similarities? Comparative studies of brain evolution over the past 50 years have resulted in a drastically modified view of brain organization amongst these closely related vertebrates. With very few exceptions, virtually identical neuronal connections and microcircuits have been found to mediate similar behaviors.
Diana Reiss, Ph.D.
Professor of Psychology, Hunter College and City University of New York Biopsychology Graduate Program
Photo: Courtesy Elizabeth Nolan
Mirror Self-recognition: A Case of Cognitive Convergence in Humans and other Animals
Diana Reiss, Ph.D.
The ability to recognize oneself in a mirror, once considered a uniquely human attribute, is shared by great apes, dolphins, elephants and magpies. In comparative studies of mirror self-recognition (MSR) dolphins and elephants, show striking similarities to humans and the great apes in the stages of behavior and the specific types of behaviors they show when exposed to a mirror. MSR emerges in children between 18-24 months and in chimpanzees between 2.5-4.5 years of age. In a developmental study conducted to determine the age of onset of self-directed behaviors and MSR in dolphins, we found dolphins at 14-18 months of age exhibiting self-directed behavior - evidence of MSR. Dolphins are precocious at birth and exceed human and non-human primates in motor skills and coordination. Our findings suggest, that young dolphins may show advanced cognition at an earlier age with respect to mirror self-directed behavior as compared to humans and chimpanzees.
Franz X. Vollenweider, MD.
Professor of Psychiatry, University of Z�rich School of Medicine,
Vice-Director of Research and Teaching and Director of the Neuropsychopharmacology and Brain Imaging Research Unit of the University Hospital of Psychiatry Z�rich East,
Director of Heffter Research Centre Z�rich for Consciousness Studies
Photo: Courtesy Heffter Research Institute
Neuronal Correlates of Psychedelic Drug-Induced Imagery in Humans
Franz X. Vollenweider, MD.
Classic psychedelics such as psilocybin produce an altered state of consciousness (ASC) characterized by vivid imagery and profound changes in mood, thought, intuition, and self that is otherwise rarely experienced except in dreams. Recent findings suggest that the serotonin system and particularly agonistic activity at 5-HT2A/1A receptors is implicated in the formation of psilocybin-induced and also naturally occurring visual hallucinations. To elucidate the relationship between regional brain activity and imagery and the mechanism of action of psychedelics, the effect of psilocybin in combination w/o serotonin 2A and 1A receptor antagonists on visual processing and subjective experience was investigated using high-density electrical mapping with source analysis and H2O-PET imaging. The results show reduced activation in the right extrastriate and posterior parietal areas, and disrupted modal object completion. Furthermore, they suggest that psilocybin-induced imagery is primarily mediated by 5-HT2A receptor activation based on a disruption in cortical feedforward and feedback processing.
Naotsugu Tsuchiya, Ph.D.
PRESTO (Sakigake) fellow, Japan Science and Technology Agency (JST), Japan
Visiting scholar in Laboratory for Adaptive Intelligence, RIKEN, Japan
Visiting scholar in ATR, Japan
Visitor, Division of Biology, Caltech, USA
Associate Professor, School of Psychology and Psychiatry, Faculty of Medicine, Nursing and Health Sciences, Monash University
Visual Consciousness Tracked with Direct Intracranial Recording from Early Visual Cortices in Humans
Naotsugu Tsuchiya, Ph.D.
A fundamental question in cognitive neuroscience is how neuronal representations are related to conscious experience. Two key questions are: where in the brain such representations are located, and at what point in time they correlate with conscious experience. In line with this issue, a hotly debated question is whether primary visual cortex (V1) contributes to visual consciousness, or whether this depends only on higher-order cortices. Here we investigated this issue by recording directly from early visual cortex in two neurosurgical patients undergoing epilepsy monitoring with intracranial electrocorticogram (ECoG) electrodes that covered early visual cortices, including the dorsal and ventral banks of the calcarine sulcus. We used Continuous Flash Suppression (CFS) to investigate the time course of when 'invisible' stimuli broke interocular suppression. Participants were asked to watch faces presented under CFS, to push a button when they started to see any part of the face, and then to indicate its spatial location. This occured over several seconds. During the task performance we recorded intracranial ECoG at high spatiotemporal resolution from all contacts in parallel. We used multivariate decoding techniques and found that the location of the invisible face stimulus became decodable from neuronal activity 1.8 sec before the subject's button press. We will discuss the neuronal dynamics associated with the break of inter-ocular suppression.
Melanie Boly, MD, Ph.D.
Research Fellow, Coma Science Group, University of Liege, Liege, Belgium.
Center for Sleep and Consciousness, University of Wisconsin, Madison, USA.
Hospital, University of Li�ge.
Photo: Courtesy of Center of Consciousness Studies
Cerebral Connectivity in Disorders of Consciousness
Melanie Boly, MD, Ph.D.
During the last decade, functional neuroimaging of disorders of consciousness (i.e., coma, vegetative state and minimally conscious state) has evolved from measuring resting cerebral blood flow or electrical activity to studying functional response to sensory stimuli and to active paradigm asking patients to concentrate on doing a task like playing tennis. While these methods have improved the care of the patients, they also show how difficult it is to distinguish different states of consciousness. Brain connectivity studies aim at evaluating global cerebral function in patients with disorders of consciousness. In this talk, I will cover results obtained using a range of functional and effective connectivity approaches based on PET, fMRI, high density EEG, and TMS-EEG recordings. Experimental work performed in other unconscious states (i.e., anesthesia and deep sleep) will also be compared and reviewed. Practical and conceptual implications of these studies will be discussed in light of recent theories of consciousness.
Steven Laureys, MD, Ph.D.
Research Associate at the Belgian National Fund for Scientific Research (FNRS)
Head of the Coma Science Group, Cyclotron Research Center
Head of Clinics, Neurology Dept., University Hospital, University of Li�ge.
Photo: Courtesy International Brain Injury Association
Identifying the Brain's Awareness System: Lessons from Coma and Related States
Steven Laureys, MD, Ph.D.
Following severe brain damage some patients loose all brain and brainstem functions and evolve to brain death while others can open their eyes, but only show reflex behavior. Some patients will remain unresponsive for decades; others may evolve to a minimally responsive/conscious state with more than simple reflex behaviors but lacking communication. Finally, coma patients may awaken, being fully aware but paralyzed and mute. We here review neuroimaging and electrophysiology studies that illuminate the relationships between awareness and brain function in these challenging conditions. Such studies show that awareness is an emergent property of the collective behavior of frontoparietal top-down connectivity where external (sensory) awareness depends on lateral prefrontal/parietal cortices, while internal (self) awareness correlates with precuneal/mesiofrontal midline activity. This knowledge improves diagnosis of patients with disorders of consciousness. Technology can also now show command-specific changes in EEG or fMRI signals providing motor-independent evidence of conscious thoughts and in some cases communication.
Edward Boyden, Ph.D.
Assistant Professor, MIT Media Lab
Benesse Career Development Professor of Research in Education, MIT
Leader, Synthetic Neurobiology Group, MIT
Optogenetics, Robotic Physiology, and Other Neural Circuit Tools
Edward Boyden, Ph.D.
Understanding how neural circuits implement brain functions, and how these computations go awry in brain disorders, is a top priority for neuroscience. Over the last several years we have developed a rapidly-expanding suite of genetically-encoded reagents that, when expressed in specific neuron types in the nervous system, enable their electrical activities to be powerfully and precisely activated and silenced in response to pulses of light. These tools are in widespread use for analyzing the causal role of defined cell types in normal and pathological brain functions. In this talk I will briefly give an overview of the field, and then I will discuss a number of new tools for neural activation and silencing that we are developing, including new molecules with augmented amplitudes, improved safety profiles, novel color and light-sensitivity capabilities, and unique new capabilities. We have begun to develop hardware to enable complex and distributed neural circuits to be precisely controlled, and for the network-wide impact of a neural control event to be measured using distributed electrodes, fMRI, and robotic intracellular neural recording. We explore how these tools can be used to enable systematic analysis of neural circuit functions in the fields of emotion, sensation, and movement, and in neurological and psychiatric disorders. Finally, we discuss our pre-clinical work on translation of such tools to support novel ultraprecise neuromodulation therapies for human patients.
Philip Low, Ph.D.
Founder, Chairman, and CEO of NeuroVigil, Inc.
Adjunct Professor, Stanford School of Medicine
Research Affiliate, MIT Media Lab
Stephen W. Hawking, D.Phil.
Director of Research, Centre for Theoretical Cosmology, University of Cambridge
Towards Establishing Neural Correlates of Intended Movements and Speech
Philip Low, Ph.D. & Stephen W. Hawking, D.Phil.
Single-Channel iBrain EEG recordings were conducted in a high-functioning 70 year old ALS patient attempting to move one of four limbs after a verbal cue: the left and right hand and foot. Raw EEG signals were analyzed with the SPEARS algorithm in order to make high-frequency/low spectral power signals detectable. Concurrent video recordings were obtained. During the attempted movements, the subject's brain activity demonstrated distinct broad-spectrum pulses extending to the Gamma and ultra-high Gamma ranges. Such pulses were present in the absence of actual movement and absent when the subject was not attempting motion. Activity in the Alpha range was detected when the subject closed his eyes, as expected. The emergence of such high bandwidth biomarkers opens the possibility to link intended movements to a library of words and convert them into speech, thus providing ALS sufferers with communication tools more dependent on the brain than on the body.