Stories about: synapses

Synapse ‘protection’ signal found; helps to refine brain circuits

a combination of 'eat me' and 'don't eat me' signals fine-tune synapse pruning
New evidence suggests that a ‘yin/yang’ system fine-tunes brain connections and synapse pruning (IMAGE: NANCY FLIESLER/ADOBE STOCK)

The developing brain is constantly forming new connections, or synapses, between nerve cells. Many connections are eventually lost, while others are strengthened. In 2012, Beth Stevens, PhD and her lab at Boston Children’s Hospital showed that microglia, immune cells that live in the brain, prune back unwanted synapses by engulfing or “eating” them. They also identified a set of “eat me” signals required to promote this process: complement proteins, best known for helping the immune system combat infection.

In new work published today in Neuron, Stevens and colleagues reveal the flip side: a “don’t eat me” signal that prevents microglia from pruning useful connections away.

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Targeting synapse loss in Alzheimer’s to preserve cognition — before plaques appear

Alzheimer's microglia complement
Microglia (in red) consume synapses (in green) after mice are injected with the oligomeric form of beta-amyloid, before plaques appear in the brain. (Soyon Hong, Boston Children’s Hospital)

Currently, there are five FDA-approved drugs for Alzheimer’s disease, but these only boost cognition temporarily and don’t address the root causes of Alzheimer’s dementia. Many newer drugs in the pipeline seek to eliminate amyloid plaque deposits or reduce inflammation in the brain, but by the time this pathology is detectable, it’s unlikely medications can do much to slow the disease.

New research published in Science today suggests several ways that Alzheimer’s could be targeted much earlier to preserve cognitive function — before plaques or inflammation are evident.

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