Brain and Computation – Shared Principles?web.cecs.pdx.edu/~mm/SharedPrinciplesWorkshopMay... ·...
Transcript of Brain and Computation – Shared Principles?web.cecs.pdx.edu/~mm/SharedPrinciplesWorkshopMay... ·...
Shared Principles in Computing and Biology 2010
Brain and Computation – Shared Principles?
Olaf SpornsDepartment of Psychological and Brain Sciences
Indiana University, Bloomington, IN 47405
http://www.indiana.edu/~cortex , [email protected]
Brain Networks
Multiple Scales – Cells, Circuits, Systems
Tamily A. Weissman (Harvard University) Patric Hagmann (EPFL/CHUV Lausanne)
Anatomical (Structural) Connectivity: Pattern of structural connections
between neurons, neuronal populations, or brain regions.
Functional Connectivity: Pattern of statistical dependencies (e.g. temporal
correlations) between distinct (often remote) neuronal elements.
Brain Networks
Multiple Modes – Structural, Functional, Effective
Effective Connectivity: Network of
causal effects, combination of
functional connectivity and structural
model.
Patric Hagmann (EPFL/CHUV Lausanne) Achard et al. (2006) J. Neurosci. 26, 63 McIntosh et al. (1994) J. Neurosci. 14, 655
Networks of mammalian cerebral cortex form a small world (high clustering, short path length), and contain modules linked by hubs.
Brain Networks
Modules and Hubs Brain Networks
regions of macaque visual and sensorimotor cortex
Sporns et al. (2000) Cereb Cortex 10, 127. Sporns & Zwi (2004) Neuroinformatics 2, 145.Sporns et al. (2007) PLoS ONE 2, e1049.
Each functionally specialized cortical region has a unique connectional fingerprint – a unique set of inputs and outputs.
Brain Networks
Structure Shapes Function
Structural modules consist of nodes that have similar connections with other nodes.
Passingham et al. (2002) Nature Rev Neurosci 3, 606. Hilgetag et al. (2000) Phil. Trans. Royal Soc. B 355, 91
Structural modules reflect functional relationships.
regions and interconnections of
cat cerebral cortex
A BBrain Connectivity
Mapping Human Brain: Connectome and Brain Architecture
Hagmann et al. (2008) PLoS Biol. 6, e159
A significant proportion of brain activity is “intrinsic” or “spontaneous”, occurring even in the absence of explicit task or stimulus.
This intrinsic computational mode stands in contrast to standard computational models that emphasize reflexive, momentary responses.
Intrinsic Dynamics
Endogenous Neural Activity in the Human Brain
Raichle et al. (2001) PNAS 98, 676. Greicius et al. (2003) PNAS 100, 253.Fox et al. (2005) PNAS 102, 9673. Movie: Vincent, Raichle et al. (Washington University)
The Human BrainComplexity
Network Dynamics
Small-world networks promote the coexistence of functional specialization and functional integration, enabling neural dynamics of high complexity.
∑ −−=i ii
xxHHC ).()()( XXX
entropy-based measure of complexity
Kitzbichler et al. (2009) PLoS Comput Biol 5, e1000314. Petermann et al. (2009) PNAS 106, 15921.
complex neural activitysmall-world structural network
MEGPower laws in neural dynamics (human MEG, monkey MEA) suggestthat the brain exists in a critical state.
Questions:
Q1+2: Shared principles between computing and biological (neuro)sciences
Research focus on methods and approaches from complex networks
Key features of brain architecture and network topology
Importance of information integration – role of hubs?
Intrinsic versus reflexive mode of processing
The brain is a multiscale complex systems
Computation and the critical state
Serial computation – parallel networks?Serial computation – parallel networks?
Q3: Future directions
Structure-function relationships in networks
Connectomics and brain architecture – mapping of circuits and connections
Theoretical principles
Q4: Training and Resources
Interdisciplinary training programs in computational biology
Further Reading:
Graham & Rockmore (2010, in press) The packet-switching brain. J Cogn. Neurosci.
Laughlin & Sejnowski (2003) Communication in neuronal networks. Science.
Raichle (2010) Two views of brain function. Trends Cogn. Sci.
Bullmore & Sporns (2009) Complex brain networks. Nature. Rev. Neurosci.
Sporns (2010, forthcoming) Networks of the Brain. Cambridge: MIT Press.
Funded by the James S. McDonnell Foundation