Researchers from the MRC Centre for Developmental Neurobiology
(MRC CDN) at the Institute of Psychiatry, Psychology &
Neuroscience (IoPPN), King's College London, have discovered a new
molecular 'switch' that controls the properties of neurons in
response to changes in the activity of their neural network.
The findings suggest that the 'hardware' in our brain is
tuneable and could have implications that go far beyond basic
neuroscience - from informing education policy to developing new
therapies for neurological disorders such as epilepsy.
Computers are often used as a metaphor for the brain, with logic
boards and microprocessors representing neural circuits and
neurons, respectively. While this analogy has served neuroscience
well in the past, it is far from correct, according to the
researchers. They suggest that the brain is a highly dynamic,
self-organising system, in which internal and external influences
continuously shape information processing 'hardware' by mechanisms
not yet understood, and in a way not achieved by computers.
Researchers from the MRC CDN, led by Professor Oscar Marín, have
shed light on this problem by discovering that some neurons in the
cerebral cortex can adapt their properties in response to changes
in network activity - such as those observed during learning of a
motor task. The authors studied two apparently different classes of
fast-spiking interneurons, only to discover that they were actually
looking at the same piece of 'hardware' which had the ability to
oscillate between two different ground states. The authors also
identified the molecular factor responsible for tuning the
properties of these cells, a transcription factor - a protein able
to influence gene expression - known as Er81.
Fast-spiking interneurons are part of a general class of neurons
whose primary role is regulating the activity of the principal
cells of the cerebral cortex, known as pyramidal cells. The
cerebral cortex is outer layer of the brain and is associated with
cognition, language and memory.
"Our findings explain the underlying mechanisms behind the
dynamic regulation of the identity of interneurons", said Nathalie
Dehorter of the MRC CDN. "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."
Understanding the dynamic mechanisms that lead to the emergence
of brain functions through the development and continuous
remodelling of neural circuits, and the constraints that disease
and ageing impose to this multi-modal plasticity has important
implications that go beyond fundamental neuroscience, from
education policies to brain repair.
Professor Oscar Marín, also of the MRC CDN, 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 beyond
fundamental neuroscience, from informing education policies to
developing new therapies for neurological disorders such as
epilepsy."
The paper, Tuning
of Fast-Spiking Interneuron Properties by an Activity-Dependent
Transcriptional Switch, is published inScience.