Finely tuned: Dynamically tweaking interneurons on-the-go

Scientists have identified a new molecular ‘switch’ that controls the properties of neurons in response to changes in the activity of their neural network.

The research, published in Science, shows that neurons can be tuned dynamically, throughout their lifetime. A finding that could have implications for areas as far apart as education policy and new therapies for neurological conditions like epilepsy.

Professor Oscar Marín, last author for the paper, said: “Our study demonstrates the tremendous plasticity of the brain, and how this relates to fundamental processes such as learning. Understanding the mechanisms that regulate this plasticity, and why it tends to dissipate when we age, has enormous implications that go far beyond fundamental neuroscience.”

The researchers, from the MRC Centre for Developmental Neurobiology (MRC CDN), discovered that certain neurons within the cerebral cortex can adapt their properties when learning tasks such as a new motor skill.

They illustrated that two apparently distinct classes of fast-spiking interneuron, were in fact the same, but had the ability to switch between two different ground states. Their state is tuned by a transcription factor called Er81.

In the adult brain, Er81 expression levels define a spectrum of fast-spiking interneurons within the cortex, whose relative proportions are continuously adjusted in response to neuronal activity.

The work demonstrates that unlike a computer, made up of components with fixed properties, the brain is a highly dynamic, self-organising system, which is shaped in a way not yet fully understood.

Dr Nathalie Dehorter, first author of the paper, said: “Our findings explain the underlying mechanisms behind the dynamic regulation of the identity of interneurons. The results of this study support the notion that activity plays a prominent role in the specification of neuronal properties, which adapt in response to internal and external influences to encode information. In other words, that our ‘hardware’ is tuneable, at least to some extent.”

Electrophysiology recordings were carried out on a Scientifica SliceScope Pro 2000.

Paper reference

Dehorter N., Ciceri G., Bartolini G., Lim L., del Pino I., Marín O. Tuning of fast-spiking interneuron properties by an activity-dependent transcriptional switch Science (2015) doi: 10.1126/science.aab3415