99,296 research outputs found
Generative models of the human connectome
The human connectome represents a network map of the brain's wiring diagram
and the pattern into which its connections are organized is thought to play an
important role in cognitive function. The generative rules that shape the
topology of the human connectome remain incompletely understood. Earlier work
in model organisms has suggested that wiring rules based on geometric
relationships (distance) can account for many but likely not all topological
features. Here we systematically explore a family of generative models of the
human connectome that yield synthetic networks designed according to different
wiring rules combining geometric and a broad range of topological factors. We
find that a combination of geometric constraints with a homophilic attachment
mechanism can create synthetic networks that closely match many topological
characteristics of individual human connectomes, including features that were
not included in the optimization of the generative model itself. We use these
models to investigate a lifespan dataset and show that, with age, the model
parameters undergo progressive changes, suggesting a rebalancing of the
generative factors underlying the connectome across the lifespan.Comment: 38 pages, 5 figures + 19 supplemental figures, 1 tabl
On Reverse Engineering in the Cognitive and Brain Sciences
Various research initiatives try to utilize the operational principles of
organisms and brains to develop alternative, biologically inspired computing
paradigms and artificial cognitive systems. This paper reviews key features of
the standard method applied to complexity in the cognitive and brain sciences,
i.e. decompositional analysis or reverse engineering. The indisputable
complexity of brain and mind raise the issue of whether they can be understood
by applying the standard method. Actually, recent findings in the experimental
and theoretical fields, question central assumptions and hypotheses made for
reverse engineering. Using the modeling relation as analyzed by Robert Rosen,
the scientific analysis method itself is made a subject of discussion. It is
concluded that the fundamental assumption of cognitive science, i.e. complex
cognitive systems can be analyzed, understood and duplicated by reverse
engineering, must be abandoned. Implications for investigations of organisms
and behavior as well as for engineering artificial cognitive systems are
discussed.Comment: 19 pages, 5 figure
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