24 Jul 2014

Memory and Brain Plasticity

From Our Changing World, 9:20 pm on 24 July 2014

The hippocampus is a seahorse-shaped structure located deep in the brain which plays a major role in the formation of memories.

It’s a structure that Professor Cliff Abraham, is particularly interested in, partially because the neurons in the hippocampus appear to be especially vulnerable in people with Alzheimer’s disease.

“Our brains are constantly learning new information and updating old information,” says Cliff, Director of the Brain Health Research Centre. “How it actually does that, and what happens when things go wrong such as in Alzheimer’s disease are of particular interest in my work.”

At the University of Otago, he’s working with fellow researcher Bruce Mockett to look at the hippocampus in a mouse model of Alzheimer’s disease, and specifically to look at what happens during learning, right down to the level of the synapses -- the connections between the nerve cells. This process is called synaptic plasticity.

“When cells are active during an experience, the synaptic connections between those cells strengthen. We call this process long-term potentiation (LTP).” says Cliff. “If you disturb this long-term potentiation you can disturb memory and it is now understood that this happens in Alzheimer’s disease, for example.”

By electrically stimulating a particular pathway in slices of the hippocampus, and recording the responses of the receiving cells, this process of LTP can be studied.

Bruce Mockett explains to Ruth Beran that many experiments can be compared over time to determine whether or not plasticity has increased or decreased.

The Health Research Council funded research is trying to find molecules to rescue LTP, and is looking at a protein called secreted amyloid precursor protein-alpha (sAPPa).

“We have found that at the right concentrations it can bring the long-term potentiation effect back to normal levels. So we’re quite excited by this, although this is all of course somewhat artificial environments,” says Cliff.

The next step is to find ways of delivering the protein when the animals are actually learning.

While the work is currently in animal models, Cliff believes it may inspire others to find the effective components of sAPPa protein, and discover safe delivery methods, to help people recover from memory deficits in the future.

From left to right: Cliff Abraham, Owen Jones, Shane Ohline and Bruce Mockett

Other research being undertaken in Cliff’s laboratory includes work by Owen Jones who is funded by the Neurological Foundation to look at brain cells, called astrocytes, and their role in regulating synaptic plasticity.

Another area of research is being conducted by Shane Ohline, who is looking at an unusual feature of the hippocampus. Contrary to popular belief, the brain can produce new cells, although only a few areas can do this, and the hippocampus is one of them. Why this neurogenesis occurs is very poorly understood, and Shane’s Marsden funded research revolves around dating cells in the brain and asking what the new neurons are good for.

Listen to more about the research Owen Jones and Shane Ohline are undertaking.

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