Using a novel technology to map and study billions of individual brain cell connections, scientists found that mice exposed to an enriched environment showed changes in different populations of synapses – the connections through which nerve cells communicate – across many brain regions.
Distinct synapse types responded differently to environmental influences, with some increasing or reducing in number, whilst others remained unchanged.
Understanding these patterns could help to pinpoint why some events can support the brain to adapt, whilst others may contribute to impaired function, experts say.
Diverse synapses
Synapse changes have previously been linked to sleep deprivation, brain injury and genetic variants associated with autism, schizophrenia and other disorders.
Alterations to the brain’s diverse synapse populations could be a common mechanism through which it adapts to both inherited and environmental influences, the research team suggest.
Understanding how experiences influence brain activity could point to potential interventions to modify synapse populations that may have been disrupted by environmental and genetic factors or injury, they add.
Whole brain
Scientists have long known that experience changes the brain. Learning and sensory input can alter the strength of communication between nerve cells, and synapses can form, disappear or change their structure.
Previous studies have concentrated on relatively small numbers of synapses in localised areas, providing a limited view of how experience changes synapse populations across the brain.
The University of Edinburgh-led research team used synaptome mapping – a technology combining high-resolution microscopy with automated image analysis – to look at brain cell connections across the whole mouse brain.
Connection type
The team studied mice exposed to enriched environments – containing running wheels, changing mazes and greater opportunities for social interaction – both during development and in adulthood.
They found the overall density of synapses in the brain did not increase, indicating the quality and type of synaptic connections are more important than the quantity when it comes to brain changes, researchers say.
Widespread changes
To explore the impact of sensory changes across the brain, scientists studied mice who had one eye closed for one week. Altering vision in one eye led to synapse changes beyond the parts of the brain linked to sight, including areas involved in other senses and memory.
The findings suggest that changes affecting one sensory experience can lead to widespread molecular adaptations in the brain, underlining the complex interconnectivity of brain functions, experts say.