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New research published in Nature, led by Department of Physiology, Anatomy & Genetics researchers Dr Zeynep Okray, Dr Pedro Jacob and Professor Scott Waddell, has discovered a detailed neural circuit mechanism that explains how multisensory learning improves memory performance.

3-Dimensional reconstructions of neurons in one hemisphere of the fly’s mushroom bodies © Images based on FlyEM / Hemibrain project data from the Janelia Research Campus
3-Dimensional reconstructions of neurons in one hemisphere of the fly’s mushroom bodies: Kenyon cells receiving visual input (left), Kenyon cells receiving olfactory input (middle), and a large serotonergic neuron that spans the mushroom body and connects the two sensory streams (right).

It is widely appreciated, from observational studies of children in the classroom and controlled experiments in animals, that using multiple senses aids learning and improves later memory. While it was known that cross-talk between the brain’s various sensory cortices likely supports this phenomenon, there was no mechanistic explanation for how such an interaction could occur and how memory could be enhanced by such a process.

To identify these neural mechanisms, Dr Zeynep Okray and Dr Pedro Jacob (Centre for Neural Circuits and Behaviour, Department of Physiology, Anatomy & Genetics) developed a novel multisensory learning paradigm where fruit flies learn to associate an odour, a colour, or a combination of the two, with a reward or punishment. They found that learning and later memory retrieval were improved when multiple senses were engaged.

The researchers studied the fly’s neuronal responses using cutting-edge optical recording techniques and found that training with odours and colours together altered subsequent responses to these sensory cues in learning-relevant neurons. Surprisingly, visual-selective cells became activatable by the learned odour, whereas odour-selective cells became responsive to the learned colours. These changes in neural responsiveness in effect permit the flies to conjure a mental representation of the whole memory from only partial information.

Read the full story on the Department of Physiology, Anatomy and Genetics website