Format

Send to

Choose Destination
Curr Biol. 2018 Nov 5;28(21):3508-3515.e5. doi: 10.1016/j.cub.2018.09.012. Epub 2018 Oct 25.

Silent Learning.

Author information

1
Centre for Cognitive and Neural Systems, Edinburgh Neuroscience, University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK.
2
Centre for Cognitive and Neural Systems, Edinburgh Neuroscience, University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK; Instituto de Neurociencias, CSIC-UMH, San Juan de Alicante, Spain.
3
Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, 060-8638, Japan.
4
Instituto de Neurociencias, CSIC-UMH, San Juan de Alicante, Spain.
5
Centre for Cognitive and Neural Systems, Edinburgh Neuroscience, University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK; Instituto de Neurociencias, CSIC-UMH, San Juan de Alicante, Spain. Electronic address: r.g.m.morris@ed.ac.uk.

Abstract

We introduce the concept of "silent learning"-the capacity to learn despite neuronal cell-firing being largely absent. This idea emerged from thinking about dendritic computation [1, 2] and examining whether the encoding, expression, and retrieval of hippocampal-dependent memory could be dissociated using the intrahippocampal infusion of pharmacological compounds. We observed that very modest enhancement of GABAergic inhibition with low-dose muscimol blocked both cell-firing and the retrieval of an already-formed memory but left induction of long-term potentiation (LTP) and new spatial memory encoding intact (silent learning). In contrast, blockade of hippocampal NMDA receptors by intrahippocampal D-AP5 impaired both the induction of LTP and encoding but had no effect on memory retrieval. Blockade of AMPA receptors by CNQX impaired excitatory synaptic transmission and cell-firing and both memory encoding and retrieval. Thus, in keeping with the synaptic plasticity and memory hypothesis [3], the hippocampal network can mediate new memory encoding when LTP induction is intact even under conditions in which somatic cell-firing is blocked.

KEYWORDS:

AMPA receptors; GABA receptors; NMDA receptors; learning; long-term potentiation; memory encoding; memory retrieval; synaptic plasticity; watermaze

PMID:
30415706
DOI:
10.1016/j.cub.2018.09.012

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center