Workshop

Tuesday April 3, 2018

9:00 am - 12:30 pm

Room: TBA

 

Network Science and Consciousness

 

Workshop outline: Tuesday Morning, April 3 (Session 3) (9am-12:30 pm)

  • George A Mashour (9 - 9:15 am): Introduction
  • Anthony G Hudetz (9:15-10 am, 30 min lecture, 15 min discussion): Network dynamics and consciousness
  • UnCheol Lee (10:00-10:45 am, 30 min lecture, 15 min discussion): Network science and anesthetic state transition
  • Break (10:45-11am)
  • Dinesh Pal (11:00-11:45 am, 30 min lecture, 15 min discussion): Neurochemical modulation of consciousness and brain connectivity
  • Zirui Zhang (11:45 -12:30 pm, 30 min lecture, 15 min discussion): Temporo-spatial organization and large-scale brain networks supporting consciousness

 

 

George Mashour, MD PhD

Bert N. La Du Professor of Anesthesiology Research 

University of Michigan, Anesthesiology

Founding Director of the Center for Consciousness Science

 

Anthony G Hudetz, PhD

Professor, Anesthesiology

Professor, Biomedical Engineering, University of Michigan

Research Areas: Neural Engineering

Network dynamics and consciousness

Network science is about analyzing the properties of interacting systems. It applies to many systems in physics, biology, social interactions, and the brain.  All brain operations are supported by communication along neuronal pathways that form a network.  We hypothesize that network communication is necessary for consciousness with respect to both content and state. The fundamental question is if there is anything special about the organization of the brains networks that allow phenomenal experience to arise.  Networks constitute the basis for processing and integrating information in the brain. It is assumed that complex networks can generate information over and above that contained by their parts. This can be measured by the reduction of system entropy due to the interaction of its elements.

The diversity and intrinsic complexity of functional network configurations, within the constraints of anatomical structure of the brain, are two principal properties that may determine the state of consciousness.  What is the organizational level at which these properties are expressed?  Complex signal interactions occur within the dendritic tree, within local circuits of neurons, within and among cortical columns and larger brain regions. Practical assessment of network properties is based on the statistical correlation of measurable quantities such as, EEG, fMRI, LFP, neuronal firing, etc., either during rest or some form of stimulation, which may allow the inference of causal interactions. An important outstanding question is whether stimulation enhances or constrains the diversity of states the brain can access.

Representation of correlations within networks by mathematical graphs reveals preferred topological pathways of information transmission.  However, graphs ignore topographical relationships.  Investigation of the dynamics of network topography is an important new direction in searching for the neural correlates of conscious state.  In the workshop, this will be illustrated in model systems allowed to gradually regain consciousness from general anesthesia. 

 

UnCheol Lee, PhD

Research Assistant Professor, University of Michigan, Anesthesiology

Associate Director, Center for Consciousness Science

Network science and anesthetic state transitions

No single brain region or mechanism has been identified as the neural correlate of consciousness, suggesting that consciousness might emerge through complex interactions of spatially and temporally distributed brain functions. Thus, the integrative perspective of both brain function and structure would be especially pivotal in order to understand multi-scale mechanisms of anesthetic actions for inducing state transition between consciousness and unconsciousness. We suggest that network science is not just a useful tool, but a necessary theoretical framework and method to uncover common principles of diverse molecular anesthetic actions. In this talk, we will introduce the basic concepts of network science and explain why the application of network science could be a pathway to discover a fundamental mechanism of anesthetic-induced state transition between consciousness and unconsciousness.

 

Dinesh Pal, PhD

Research Assistant Professor, University of Michigan, Anesthesiology

Neurochemical modulation of consciousness and brain connectivity

Chemical signaling through neurotransmitters is the primary mode of communication between the neuronal populations and underlies the changes in brain connectivity and behavior. We will discuss the brain neurochemistry across physiological (sleep-wake) and pharmacologically-induced (general anesthesia) states of consciousness and the associated changes in brain connectivity.

Dr. Pal is a NIH-funded neurobiologist studying the mechanistic underpinnings of interactions between sleep homeostasis and sedation, and the correlates and mechanism of anesthetic-induced unconsciousness. He employs electroencephalographic recordings and in vivo measurement of brain neurotransmitter levels using high performance liquid chromatography in his studies.

 

 

Zirui Zhang, PhD

Research Fellow, Center for Consciousness Science

Department of Anesthesiology

University of Michigan Medical School      

Temporo-spatial organization and large-scale brain networks supporting consciousness

The marriage of network science and neuroimaging techniques offers a new avenue in the scientific study of consciousness. Brain activity has been shown to organize into large-scale networks with characteristic spatial architectures such as functional connectivity, modularity, scale-free and small-world properties. These spatial features are crucial for supporting information integration necessary for consciousness. However, little is known about the temporal characteristics (e.g. functional timescales) of large-scale brain networks, and how they are related to consciousness. In this workshop, we will elaborate this idea by presenting empirical data on temporal and spatial alterations of large-scale brain activity during graded sedation with propofol. We will discuss the interplay between intrinsic functional timescales and local/regional/distant functional connectivity during diminished consciousness. Finally, there will be an introduction to a recent neuroscientific theory of the brain and consciousness (temporo-spatial theory of consciousness; Northoff and Huang, 2017) to complement and extend the above discussions.