Hippocampal circuit in brain linked to learning difficulties in Down syndrome

New brain research has mapped a key trouble spot likely to contribute to intellectual disability in Down syndrome. In a paper published in Nature Neuroscience, scientists from the University of Bristol and UCL suggest the findings could be used to inform future therapies which normalise the function of disrupted brain networks in the condition.

violinist-with-down-syndrome

3 August 2015 – Down syndrome is the most common genetic cause of intellectual disability, and is triggered by an extra copy of chromosome 21. These findings shed new light on precisely which part of the brain’s vast neural network contribute to problems in learning and memory in Down syndrome which until now, have remained unclear.

Karyotype for trisomy Down syndrome. Note there are three copies of chromosome 21. Courtesy of National Human Genome Research Institute

Karyotype for trisomy Down syndrome. Note there are three copies of chromosome 21. Courtesy of National Human Genome Research Institute.

Using genetically engineered mice that carry a copy of this additional human chromosome, the researchers showed that increased expression of chromosome 21 genes disrupts the function of key brain circuits involved in learning and memory.

Processing of information in the brain requires accurately coordinated communication between networks of nerve cells, which are wired together in electrical circuits by junctions called synapses. Using high-tech microscopy, nerve cell recordings and maze testing, the researchers showed abnormal structure and function of synapses in the networks of the hippocampus in the mouse model of Down syndrome.

The hippocampus acts as a central hub for learning and memory, allowing us to integrate our past experience with our current context. These functions are underpinned by ’place cells’ — cells that act like the brain’s GPS and form maps of our environment. Professor John O’Keefe, of UCL, was awarded the 2014 Nobel Prize for his discovery of these cells.

Continue reading at University of Bristol

Via Medical Xpress

Hippocampal circuit dysfunction in the Tc1 mouse model of Down syndrome, by J Witton et al in Nature Neuroscience.

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