Download Top-Down Processing in Neurocognitive Networks

Steven L. Bressler
Cognitive Neurodynamics Laboratory
Center for Complex Systems & Brain Sciences
Department of Psychology
Florida Atlantic University
http://www.ccs.fau.edu/~bressler/
• Top-down processing is a tractable problem in
cognition
• Neurocognitive networks provide a workable
theoretical framework for understanding topdown processing in the brain
• Novel approaches are being developed to
investigate top-down processing by
neurocognitive networks
• Cognitive Science: Effect of knowledge
on sensory processing
• Brain Science: Effect of “higher-level”
neurons on “lower-level” neurons
• Attention: selecting items in perception
• Expectation: priming items for perception
• Inference: identifying items in perception
• The Dorsal Attention
Network (DAN) is a
system of frontal and
parietal regions
consistently activated by
cues indicating where a
visual object will appear.
• The DAN is postulated to
exert attentional topdown control of visual
cortical.
Prestimulus Processing in
Visual Expectation
Poststimulus Processing
in Visual Inference
Synchronized beta
rhythms between V1
& extrastriate cortex
(V4, TEO) form a
large-scale network
in visual cortex
before stimulus
presentation.
1,2,3 – V1
5 – V4
6 –TEO
A. Prestimulus extrastriate & V1 beta rhythms are
synchronized.
B. Synchronized beta rhythms support top-down extrastriateto-V1, but not bottom-up V1-to-extrastriate, influences.
“The concept of localization of functions …
has come to mean a network of complex
dynamic structures or combination centers,
consisting of mosaics of distant points of the
nervous system, united in a common task.”
Higher Cortical Functions in Man, 1962
NeuroCognitive Networks are large-scale
systems of distributed and interconnected
neuronal populations in the brain organized
to perform cognitive functions.
Bressler, Scholarpedia, 2008
Bressler & Menon, TICS, 2010
Fuster & Bressler, TICS, 2012
Meehan & Bressler, NBR, 2012
•
Top-down processing in the brain involves the
effect that neurons in a “higher” area have on
neurons in a “lower” area.
• It can be observed in the brain wherever a
hierarchical order exists
• It may involve effects within or between
NeuroCognitive Networks (NCNs):

Between NCNs: FEF  V4

Within NCN: V4  V1
•
A variety of analytic techniques are used to
investigate top-down processing in the brain
▶
Stimulation: TMS, TACS, CMS
▶
Ablation: clinical analysis of stroke
▶
Electrophysiological Time Series
Recording
▶
BOLD Time Series Recording
▶
Causal Time Series Modeling: AR
models, DCM
▶
Biophysical Modeling: Neural mass
models, integrate-and-fire models
•
Multi-Site Recording Modalities
•
Improved Causal Modeling Techniques
•
Improved Large-Scale Biophysical Modeling
•
Graph Theoretic Methods Tailored to Brain
Networks
•
•
Top-down processing is essential in cognition
Top-down processing underlies attention,
expectation, and inference – all used in perception
• Top-down processing in cognitive science has a
parallel interpretation in neuroscience
• Top-down processing in the brain is readily
accommodated by the concept of neurocognitive
networks
• Numerous analytic techniques are available, or are
being developed, to study top-down processing by
neurocognitive networks.