Research Fellows Directory
Dr Mark Ungless
Imperial College London
I study a small group of neurons, buried deep in the brain, that produce the neurochemical dopamine. It is well-established that dopamine neurons are clinically important. For example, the degeneration of one group of dopamine neurons underlies Parkinson’s disease. In addition, dopamine neurons play a key role in both drug addiction and schizophrenia.
Despite only numbering several hundred thousand, these neurons have a crucial influence on the normal functioning of the brain through their dense axonal projections to many other brain regions involved in memory, movement and attention. Many fundamental questions about dopamine neurons remain unanswered. This is in part because of the enormous complexity of the brain which makes examining cellular issues in the whole brain extremely challenging. The overall aim of our research is to provide a more detailed understanding of the anatomy and physiology of midbrain dopamine neurons and their associated neural networks. To do this, we use a combination of high-resolution electrophysiological and neuroanatomical techniques in animal models.
Under normal circumstances, dopamine neurons are activated by ‘better-than-expected’ events, such as the surprising presentation of food, juice, or even money. This activation leads to a rapid and brief wave of dopamine release at projection sites, which in turn modulates attention, memory formation and controls behaviour. What is less well understood is how dopamine neurons respond to ‘worse-than-expected’ events and this is something my colleagues and I work on. We have shown that this problem has been difficult to solve for two reasons. First, some neurons, assumed to be dopamine neurons, are in fact not dopaminergic. And second, we have found that sub-groups of dopamine neurons respond in different ways. In addition to our studies in the healthy brain, we examine the effects of drugs of abuse on dopamine neurons, in an attempt to gain insight into the molecular basis of addiction.
Interests and expertise (Subject groups)