What can pond snails teach us about dementia?
How the humble members of the Lymnaeidae family are helping scientists to make and keep memories.
Drug manufacturers are looking at ways to alleviate memory loss, one of the most distressing symptoms of diseases such as Alzheimer's. Professor George Kemenes intends to show how such drugs could work.
‘The goal is to identify brain molecules that are crucial for the building up and maintenance of long-term memory,’ he says. ‘We aim to find ways to manipulate these molecules to enable us to control functions and improve the speed at which animals learn, or help them remember for longer periods of time. This would then link into drug development for humans.’
Pond snails are ideal for this kind of study because they share important characteristics with humans. These include the basic molecular mechanisms that control long-term memory and learning. These mechanisms involve the activation or suppression of a protein, CREB, which is key to the formation of long-term memory. CREB is present in species ranging from molluscs and flies to rats and humans.
Memory responses can be tested with classic Pavlovian experiments. Snails exposed to the smell of pear drops followed by food still respond weeks later to the smell by moving their mouth parts in anticipation of food. This ‘flashbulb’ memory is created by just one exposure to the two stimuli. The snails have a memory associating the smell of pear drops with the arrival of food – a learned and remembered response.
In a similar test, a snail is exposed to a mildly unpleasant stimulus by touching its head with a paintbrush (snails don’t like being tickled) before food is introduced. It takes much longer for the snail to associate an unpleasant stimulus with the arrival of food. Recently, George has succeeded in inhibiting the quickly learned memory and improving the weaker, more slowly-acquired memory at molecular level.
Working in collaboration with colleagues at the University, key findings include the discovery that amyloid peptides, substances that are thought to underlie Alzheimer’s disease in humans, also cause memory loss in snails. Another finding is that age-related memory loss in snails can be prevented by treatment with a small peptide known as PACAP.
George Kemenes is a Professor of Neuroscience and the Director of the Doctoral School at the University of Sussex. His research focus is on cellular and molecular mechanisms of memory function and dysfunction.
The knowledge obtained from this work will help us to understand, and ultimately prevent and treat, memory disorders or even enhance normal memory.” Professor George Kemenes
Professor of Neuroscience and the Director of the Doctoral School at the University of Sussex