TABLE 1.

Evidence for ECM molecules in sleep and memory consolidation processes.

Reference	Summary of Findings
Taishi et al., 2001	Sleep deprivation results in decreased mRNA expression and enzymatic activity of MMP-9
Szklarczyk et al., 2002	Dendritic spine remodeling coincides with increased MMP-9 expression
Nagy et al., 2006	MMP-9 expression is crucial in late-stage LTP and hippocampal-dependent memory
Nagy et al., 2007	Disrupted MMP-3 and MMP-9 activity in the hippocampus causes avoidance learning impairments
Brown et al., 2009	Pharmacological disruption of MMP activity results in disruption of fear memory reconsolidation
Beurdeley et al., 2012	Inhibition of OTX2 and PNN binding enhances synaptic plasticity and reduces PNN and PVB expression
Hayashi et al., 2013a	Cathepsin-S KO mice lack diurnal rhythms in dendritic spine density
Niethard et al., 2016	Increased PVB neuron firing rates are accompanied by decreased pyramidal neuron activity during REM sleep
Harkness et al., 2019	PNN composition is increased in the prelimbic cortex of sleep-deprived rats, suggesting that PNN composition decreases during sleep
Shi et al., 2019	PNN degradation contributes to GABAergic inhibition on hippocampal pyramidal neurons, contributing to LTP and memory consolidation impairment
Delorme J. et al., 2020	Gene expression for CSPG synthesis and degradation pathways is altered in mice sleep deprived following fear conditioning
Harkness et al., 2020	Diurnal rhythms of PNN intensity and OTX2 expression occurs in the rat medial prefrontal cortex, with decreased PNN intensity and OTX2 expression during sleep.
Nguyen et al., 2020	IL-33 signaling stimulates ECM engulfment by microglia, promoting experience-dependent synaptic plasticity
Pantazopoulos et al., 2020a	PNN composition decreases during sleep and increases during wakefulness; sleep deprivation prevents decreases in PNN composition
Pantazopoulos et al., 2020a	The CSPG protease cathepsin-S is expressed in a diurnal manner by microglia in the mouse brain, antiphase to PNN composition rhythms.