PUBLICATION

Geometry and dynamics of representations in a precisely balanced memory network related to olfactory cortex

Authors
Meissner-Bernard, C., Zenke, F., Friedrich, R.W.
ID
ZDB-PUB-250114-4
Date
2025
Source
eLIFE   13: (Journal)
Registered Authors
Friedrich, Rainer
Keywords
assembly, autoassociative memory, computational model, neural manifold, neuroscience, none, olfactory cortex, zebrafish
MeSH Terms
  • Animals
  • Neurons/physiology
  • Models, Neurological*
  • Zebrafish*/physiology
  • Olfactory Cortex*/physiology
  • Nerve Net/physiology
  • Action Potentials/physiology
  • Memory*/physiology
PubMed
39804831 Full text @ Elife
Abstract
Biological memory networks are thought to store information by experience-dependent changes in the synaptic connectivity between assemblies of neurons. Recent models suggest that these assemblies contain both excitatory and inhibitory neurons (E/I assemblies), resulting in co-tuning and precise balance of excitation and inhibition. To understand computational consequences of E/I assemblies under biologically realistic constraints we built a spiking network model based on experimental data from telencephalic area Dp of adult zebrafish, a precisely balanced recurrent network homologous to piriform cortex. We found that E/I assemblies stabilized firing rate distributions compared to networks with excitatory assemblies and global inhibition. Unlike classical memory models, networks with E/I assemblies did not show discrete attractor dynamics. Rather, responses to learned inputs were locally constrained onto manifolds that 'focused' activity into neuronal subspaces. The covariance structure of these manifolds supported pattern classification when information was retrieved from selected neuronal subsets. Networks with E/I assemblies therefore transformed the geometry of neuronal coding space, resulting in continuous representations that reflected both relatedness of inputs and an individual's experience. Such continuous representations enable fast pattern classification, can support continual learning, and may provide a basis for higher-order learning and cognitive computations.
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