Models of the cerebellar microcircuit often assume that input signals from the mossy-fibers are expanded and recoded to provide a foundation from which the Purkinje cells can synthesize output filters to implement specific input-signal transformations. Details of this process are however unclear. While previous work has shown that recurrent granule cell inhibition could in principle generate a wide variety of random outputs suitable for coding signal onsets, the more general application for temporally varying signals has yet to be demonstrated. Here we show for the first time that using a mechanism very similar to reservoir computing enables random neuronal networks in the granule cell layer to provide the necessary signal separation and extension from which Purkinje cells could construct basis filters of various time-constants. The main requirement for this is that the network operates in a state of criticality close to the edge of random chaotic behavior. We further show that the lack of recurrent excitation in the granular layer as commonly required in traditional reservoir networks can be circumvented by considering other inherent granular layer features such as inverted input signals or mGluR2 inhibition of Golgi cells. Other properties that facilitate filter construction are direct mossy fiber excitation of Golgi cells, variability of synaptic weights or input signals and output-feedback via the nucleocortical pathway. Our findings are well supported by previous experimental and theoretical work and will help to bridge the gap between system-level models and detailed models of the granular layer network.
At the Edge of Chaos: How Cerebellar Granular Layer Network Dynamics Can Provide the Basis for Temporal Filters
Christian A. Rössert,P. Dean,J. Porrill
Published 2015 in PLoS Comput. Biol.
ABSTRACT
PUBLICATION RECORD
- Publication year
2015
- Venue
PLoS Comput. Biol.
- Publication date
2015-10-01
- Fields of study
Biology, Medicine, Computer Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- basis filters
Output filter components with different time constants that can be combined to represent temporal transformations.
- direct mossy fiber excitation of golgi cells
Direct excitatory drive from mossy fibers onto Golgi cells in the cerebellar granular layer.
- edge of chaos
A dynamical regime near the boundary between stable and chaotic network activity.
- granule cell layer network
The cerebellar granule-cell circuit in which mossy-fiber-driven activity is processed by the local network.
- mglur2 inhibition of golgi cells
Inhibitory modulation of Golgi-cell activity mediated by metabotropic glutamate receptor 2.
- nucleocortical pathway
A feedback pathway from cerebellar nuclei back to the cortex that can influence granular-layer processing.
- recurrent excitation
Excitatory feedback connections within the granular-layer circuit.
- reservoir computing
A network-computation framework that uses rich recurrent dynamics to expand input signals into a useful basis for downstream readout.
- signal separation and extension
The transformation of input streams into a higher-dimensional activity pattern that separates input states over time.
REFERENCES
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