Mike Ludwig

Mike Ludwig is Professor of Neurophysiology at the University of Edinburgh’s Centre for Integrative Physiology.

Neurons use many different chemical signals to communicate information, including more than 100 different peptides. Neuropeptides are small proteinlike molecules and when released in the brain they have a powerful influence on specific behaviours. Our work focuses on two key neuropeptides — vasopressin and oxytocin — and their role in bonding, social interaction and autism spectrum disorder.

NEUROPEPTIDES, THE OLFACTORY SYSTEM AND BEHAVIOUR
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This confocal image shows a subpopulation of tufted cells in the rat main olfactory bulb expressing the neuropeptide vasopressin (shown in green). Each vasopressin neuron sends a primary dendrite into a glomerulus. The glomerulus is a spherical structure where synapses form between the terminals of the olfactory nerve and the dendrites of mitral, periglomerular and tufted cells. Each glomerulus is surrounded by a heterogeneous population of other cells – their nuclei shown in blue – including periglomerular calretinin expressing cells, which are labelled in red. We have shown that vasopressin cells in the main olfactory bulb influence the formation of olfactory memories.

Vasopressin and oxytocin were once thought of as circulating hormones whose actions were simply confined to peripheral organs. Now we know that they are also released in the brain — specifically in the olfactory bulb, which is the part of the vertebrate forebrain. When they are released in the brain, vasopressin and oxytocin play fundamentally important roles in changing social behaviours. For example, oxytocin is involved in social behaviours, including bonding and maternal behaviour, and vasopressin acts in the brain to affect social recognition and aggression.

Both neuropeptides have been linked to human neurological disorders such as autism spectrum disorder, social anxiety disorder, depression and schizophrenia.

Increasingly, we are recognising that peptide signals play a role in information processing that is quite unlike that of conventional neurotransmitters. One of the aims of my work is to understand how oxytocin and vasopressin affects behaviour and memory within the olfactory bulb at the level of odour perception.

The olfactory bulb is a large and complex structure involved in smell. Olfactory signals from the nose are processed, and the results of this information processing are conveyed via the olfactory tract to brain areas involved with behaviour and memory. That is why when we smell something it often brings back memories associated with the object. Understanding how neuropeptides act is important because drugs that mimic them may be valuable therapeutically for behavioural disorders like autism spectrum disorders and intellectual disabilities.

Email:Mike.Ludwig@ed.ac.uk

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