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Millán AP, Torres JJ, Johnson S, Marro J. Growth strategy determines the memory and structural properties of brain networks. Neural Netw 2021; 142:44-56. [PMID: 33984735 DOI: 10.1016/j.neunet.2021.04.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/04/2021] [Accepted: 04/20/2021] [Indexed: 11/18/2022]
Abstract
The interplay between structure and function affects the emerging properties of many natural systems. Here we use an adaptive neural network model that couples activity and topological dynamics and reproduces the experimental temporal profiles of synaptic density observed in the brain. We prove that the existence of a transient period of relatively high synaptic connectivity is critical for the development of the system under noise circumstances, such that the resulting network can recover stored memories. Moreover, we show that intermediate synaptic densities provide optimal developmental paths with minimum energy consumption, and that ultimately it is the transient heterogeneity in the network that determines its evolution. These results could explain why the pruning curves observed in actual brain areas present their characteristic temporal profiles and they also suggest new design strategies to build biologically inspired neural networks with particular information processing capabilities.
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Affiliation(s)
- Ana P Millán
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Clinical Neurophysiology and MEG Center, Amsterdam Neuroscience, De Boelelaan 1117, Amsterdam, The Netherlands.
| | - Joaquín J Torres
- Institute 'Carlos I' for Theoretical and Computational Physics, University of Granada, Spain
| | - Samuel Johnson
- School of Mathematics, University of Birmingham, Edgbaston B15 2TT, UK; Alan Turing Institute, London NW1 2DB, UK
| | - J Marro
- Institute 'Carlos I' for Theoretical and Computational Physics, University of Granada, Spain
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Saccone M, Hofhuis K, Bracher D, Kleibert A, van Dijken S, Farhan A. Elevated effective dimension in tree-like nanomagnetic Cayley structures. NANOSCALE 2020; 12:189-194. [PMID: 31803884 DOI: 10.1039/c9nr07510k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using state-of-the-art electron-beam lithography, Ising-type nanomagnets may be defined onto nearly any two-dimensional pattern imaginable. The ability to directly observe magnetic configurations achieved in such artificial spin systems makes them a perfect playground for the realization of artificial spin glasses. However, no experimental realization of a finite-temperature artificial spin glass has been achieved so far. Here, we aim to get a significant step closer in achieving that goal by introducing an artificial spin system with random interactions and increased effective dimension: dipolar Cayley tree. Through synchrotron-based photoemission electron microscopy, we show that an improved balance of ferro- and antiferromagnetic ordering can be achieved in this type of system. This combined with an effective dimension as high as d = 2.72 suggests that future systems generated out of these building blocks can host finite temperature spin glass phases, allowing for real-time observation of glassy dynamics.
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Affiliation(s)
- Michael Saccone
- Physics Department, University of California, 1156 High Street, Santa Cruz, CA 95064, USA. and NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
| | - Kevin Hofhuis
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland and Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - David Bracher
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Armin Kleibert
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
| | - Alan Farhan
- NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland. and Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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