Background: One in two older adults report sleep problems, which not only cause fatigue, but also negatively affect general functioning, activities of daily living, and physical and mental health. Although it is known that physical activity is positively associated with sleep in older adults, the effects of physical activity programs on sleep in older adults has not been reviewed. The aim of this systematic review was to systematically review the effects of physical activity programs on sleep in generally healthy older adults aged 60+ years. Methods: Searches were performed in PubMed, Embase, Web of Science, SPORTDiscus, PEDro and CINAHL. The methodological quality of the included studies was rated using the 'Quality Assessment Tool for Quantitative Studies'. Only studies of moderate and strong quality were included. This review was registered in PROSPERO (CRD42018094007). Results: Fourteen studies met the inclusion criteria (six randomised controlled trials and eight pretest-posttest studies). Of these studies, five were moderate and nine were strong quality studies. Mean age of study samples ranged from 64 to 76 years. Exercise programs included various activities aimed at improving mobility, endurance and strength. Intervention duration ranged from 2 weeks to 12 months. Eleven studies used subjective measures of sleep, two used objective measures and one used both. Sixteen different sleep outcomes were reported. All but one study, found at least one significant improvement on sleep outcomes. No significantly detrimental effects were reported. Effect sizes, calculated in ten studies, ranged from 0,34-1,55 and were substantial (≥0,8) in four studies. Conclusions: This systematic review suggests that exercise programs positively affect various aspects of sleep in generally healthy older adults. More specifically, moderate intensity exercise programs, with a frequency of three times per week and a duration of 12 weeks up to 6 months, showed the highest number of significant improvements in different sleep outcomes in older adults. Furthermore, programs that offered single exercise types, such as Baduanjin, Tai chi and the silver yoga program, or a combination of exercises showed the highest proportion of significant versus reported effects on sleep outcomes.

Pyramidal neurons express rich repertoires of leucine-rich repeat (LRR)-containing adhesion molecules with similar synaptogenic activity in culture. The in vivo relevance of this molecular diversity is unclear. We show that hippocampal CA1 pyramidal neurons express multiple synaptogenic LRR proteins that differentially distribute to the major excitatory inputs on their apical dendrites. At Schaffer collateral (SC) inputs, FLRT2, LRRTM1, and Slitrk1 are postsynaptically localized and differentially regulate synaptic structure and function. FLRT2 controls spine density, whereas LRRTM1 and Slitrk1 exert opposing effects on synaptic vesicle distribution at the active zone. All LRR proteins differentially affect synaptic transmission, and their combinatorial loss results in a cumulative phenotype. At temporoammonic (TA) inputs, LRRTM1 is absent; FLRT2 similarly controls functional synapse number, whereas Slitrk1 function diverges to regulate postsynaptic AMPA receptor density. Thus, LRR proteins differentially control synaptic architecture and function and act in input-specific combinations and a context-dependent manner to specify synaptic properties.

Excitatory and inhibitory neurons are connected into microcircuits that generate circuit output. Central in the hippocampal CA3 microcircuit is the mossy fiber (MF) synapse, which provides powerful direct excitatory input and indirect feedforward inhibition to CA3 pyramidal neurons. Here, we dissect its cell-surface protein (CSP) composition to discover novel regulators of MF synaptic connectivity. Proteomic profiling of isolated MF synaptosomes uncovers a rich CSP composition, including many CSPs without synaptic function and several that are uncharacterized. Cell-surface interactome screening identifies IgSF8 as a neuronal receptor enriched in the MF pathway. Presynaptic Igsf8 deletion impairs MF synaptic architecture and robustly decreases the density of bouton filopodia that provide feedforward inhibition. Consequently, IgSF8 loss impairs excitation/inhibition balance and increases excitability of CA3 pyramidal neurons. Our results provide insight into the CSP landscape and interactome of a specific excitatory synapse and reveal IgSF8 as a critical regulator of CA3 microcircuit connectivity and function.

Synaptic diversity is a key feature of neural circuits. Its underlying molecular basis is largely unknown, due to the challenge of analyzing the protein composition of specific synapse types.Here, we isolate the hippocampal mossy fiber (MF) synapse, taking advantage of its unique size and architecture, and dissect its proteome. We identify a rich cell-surface repertoire that includes 5 adhesion proteins, guidance cue receptors, extracellular matrix (ECM) proteins, and proteins of unknown function. Among the latter, we find IgSF8, a previously uncharacterized neuronal receptor, and uncover its role in regulating MF synapse architecture and feedforward inhibition on CA3 pyramidal neurons. Our findings reveal a diverse MF synapse surface proteome and highlight the role of neuronal surface-ECM interactions in the specification of synapse identity and circuit 10 formation. One Sentence Summary:Proteomic dissection of a specific synapse 15 3 Main Text:Neural circuits are composed of distinct neuronal cell types connected in highly specific patterns.Establishing these patterns of connectivity critically relies on cell-surface proteins (CSPs) expressed in cell type-specific combinations. CSPs, including transmembrane, membraneanchored, and secreted proteins, engage in networks of interactions that control neurite guidance, 5 target selection, and synapse development required for the formation of functional circuits (1).Single-cell RNA sequencing has enabled the characterization of cell type-specific CSP repertoires (2-6), but determining how these dictate complex patterns of connectivity (7, 8) poses a major challenge.This challenge is exemplified by pyramidal neurons, which receive different types of 10 synapses on their dendritic arbor, each with a distinct architecture, subcellular location, and functional properties. This synaptic diversity is essential for information processing in pyramidal neurons (9). Recent studies reveal a synapse type-specific localization and function of postsynaptic adhesion molecules in hippocampal pyramidal neuron dendrites (10-12), suggesting that compartmentalized distributions of CSPs contribute to the specification of synaptic structure and 15 function. Analogous to single-cell sequencing, probing the mechanisms underlying synaptic diversity requires dissecting the molecular composition of specific synapse types. This has remained challenging, as microdissection or chemical labeling strategies combined with mass spectrometry (MS) (13-15) average different synapse types, and affinity purification of synapse type-specific protein complexes (16) requires genetically engineered mice. Here, we isolate the 20 hippocampal mossy fiber (MF) synapse, a large and morphologically complex excitatory synapse (17) connecting dentate granule cell axons (mossy fibers) and CA3 pyramidal neuron dendrites in stratum lucidum (SL) (Fig. 1A, B), from wild-type (WT) tissue and map its CSP landscape. 4To isolate a specific synapse type from the hippocampus, we started with a previously published approach (18) ...