Abstract
SummaryPersistent synapses are thought to underpin the storage of sensory experience, yet little is known about their structural plasticity in vivo. We investigated how persistent presynaptic structures respond to the loss of primary sensory input. Using in vivo two-photon (2P) imaging, we measured fluctuations in the size of excitatory axonal boutons in L2/3 of adult mouse visual cortex after monocular enucleation. The average size of boutons did not change after deprivation, but the range of bouton sizes was reduced. Large boutons decreased, and small boutons increased. Reduced bouton variance was accompanied by a reduced range of correlated calcium-mediated neural activity in L2/3 of awake animals. Network simulations predicted that size-dependent plasticity may promote conditions of greater bidirectional plasticity. These predictions were supported by electrophysiological measures of short- and long-term plasticity. We propose size-dependent dynamics facilitate cortical reorganization by maximizing the potential for bidirectional plasticity.
Highlights
Sensory experience modifies synaptic strength and connectivity between cortical neurons (Cheetham et al, 2007; Albieri et al, 2015)
If sensory experience is stored in the synaptic strength distribution, what happens to this distribution when primary sensory input is removed?
To test between these scenarios, we removed the contralateral visual drive to mouse monocular primary visual cortex (V1m), and we studied the dynamics of persistent presynaptic structures
Summary
Sensory experience modifies synaptic strength and connectivity between cortical neurons (Cheetham et al, 2007; Albieri et al, 2015). Prolonged loss of sensory activity may shape the distribution of surviving synaptic strengths. In this scenario, theoretical studies predict the loss of patterned sensory input would narrow the range of synaptic strengths/weights (Barbour et al, 2007). Theoretical studies predict the loss of patterned sensory input would narrow the range of synaptic strengths/weights (Barbour et al, 2007) To test between these scenarios, we removed the contralateral visual drive to mouse monocular primary visual cortex (V1m), and we studied the dynamics of persistent presynaptic structures
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