Fruit flies offer insight into memory formation

An independent pathway for olfactory memory formation in Drosophila has been discovered by scientists at Scripps Research institute.

The scientists – led by Ron Davis – were puzzled by an unexplained residual memory performance of flies carrying a mutation in the rutabaga gene, a learning pathway that is essential to memory formation. They used a novel screen for new memory mutants looking for lines that showed abnormal learning when only one of two copies of the gene was mutant.

They discovered different alleles of gilagimesh (gish) are required for short-term memory formation, and that they work independently of the known signalling pathway.

“We used a dominant screen because we realised that behaviour such as learning and memory are very sensitive to gene dosage” Davis said, “That is, the mutation of just one copy of a gene involved in behaviour is often sufficient to produce an abnormality.”

“This is the first time we have a new memory and learning gene that lies outside what has been considered the most fundamental signalling pathway that underlies learning in the fruit fly,” Davis added.

The study also discovered that the gish gene encodes a kind of casein kinase called Iy – which helps to regulate signalling pathways in cells – and this is the first time that this specific kinase has been found to have a role in memory formation.

The work may have important implications for human memory as many of the genes in the fruit fly have been conserved in higher organisms. The findings may provide insight into diseases like Alzheimer’s and schizophrenia.

“Since many of the learning and memory genes originally identified in the fruit fly are clearly involved in human neurological and psychiatric disease, this discovery may offer significant new insights into multiple neurological disorders. We’re definitely in the right ballpark.”