Energy efficient sparse connectivity from imbalanced synaptic plasticity rules
It is believed that energy efficiency is an important constraint in brain evolution. As synaptic transmission dominates energy consumption, energy can be saved by ensuring that only a few synapses are active. It is therefore likely that the formation of sparse codes and sparse connectivity are funda...
| Main Authors: | , , |
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| Format: | Article |
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Public Library of Science
2015
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| Online Access: | https://eprints.nottingham.ac.uk/49632/ |
| _version_ | 1848798042119995392 |
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| author | Sacramento, João Wichert, Andreas van Rossum, Mark C.W. |
| author_facet | Sacramento, João Wichert, Andreas van Rossum, Mark C.W. |
| author_sort | Sacramento, João |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | It is believed that energy efficiency is an important constraint in brain evolution. As synaptic transmission dominates energy consumption, energy can be saved by ensuring that only a few synapses are active. It is therefore likely that the formation of sparse codes and sparse connectivity are fundamental objectives of synaptic plasticity. In this work we study how sparse connectivity can result from a synaptic learning rule of excitatory synapses. Information is maximised when potentiation and depression are balanced according to the mean presynaptic activity level and the resulting fraction of zero-weight synapses is around 50%. However, an imbalance towards depression increases the fraction of zero-weight synapses without significantly affecting performance. We show that imbalanced plasticity corresponds to imposing a regularising constraint on the L1-norm of the synaptic weight vector, a procedure that is well-known to induce sparseness. Imbalanced plasticity is biophysically plausible and leads to more efficient synaptic configurations than a previously suggested approach that prunes synapses after learning. Our framework gives a novel interpretation to the high fraction of silent synapses found in brain regions like the cerebellum. |
| first_indexed | 2025-11-14T20:13:28Z |
| format | Article |
| id | nottingham-49632 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T20:13:28Z |
| publishDate | 2015 |
| publisher | Public Library of Science |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-496322020-05-04T17:11:22Z https://eprints.nottingham.ac.uk/49632/ Energy efficient sparse connectivity from imbalanced synaptic plasticity rules Sacramento, João Wichert, Andreas van Rossum, Mark C.W. It is believed that energy efficiency is an important constraint in brain evolution. As synaptic transmission dominates energy consumption, energy can be saved by ensuring that only a few synapses are active. It is therefore likely that the formation of sparse codes and sparse connectivity are fundamental objectives of synaptic plasticity. In this work we study how sparse connectivity can result from a synaptic learning rule of excitatory synapses. Information is maximised when potentiation and depression are balanced according to the mean presynaptic activity level and the resulting fraction of zero-weight synapses is around 50%. However, an imbalance towards depression increases the fraction of zero-weight synapses without significantly affecting performance. We show that imbalanced plasticity corresponds to imposing a regularising constraint on the L1-norm of the synaptic weight vector, a procedure that is well-known to induce sparseness. Imbalanced plasticity is biophysically plausible and leads to more efficient synaptic configurations than a previously suggested approach that prunes synapses after learning. Our framework gives a novel interpretation to the high fraction of silent synapses found in brain regions like the cerebellum. Public Library of Science 2015-06-05 Article PeerReviewed Sacramento, João, Wichert, Andreas and van Rossum, Mark C.W. (2015) Energy efficient sparse connectivity from imbalanced synaptic plasticity rules. PLoS Computational Biology, 11 (6). e1004265. ISSN 1553-7358 http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1004265 doi:10.1371/journal.pcbi.1004265 doi:10.1371/journal.pcbi.1004265 |
| spellingShingle | Sacramento, João Wichert, Andreas van Rossum, Mark C.W. Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title | Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title_full | Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title_fullStr | Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title_full_unstemmed | Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title_short | Energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| title_sort | energy efficient sparse connectivity from imbalanced synaptic plasticity rules |
| url | https://eprints.nottingham.ac.uk/49632/ https://eprints.nottingham.ac.uk/49632/ https://eprints.nottingham.ac.uk/49632/ |