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Arvanitogiannis is a Great Montrealer
by Janice Hamilton
Why do we do what we do? Why, at a particular time, do we decide to find food or water, for example, or pursue any other goal? And what part of our brain is involved in generating goal-directed behaviour? Andreas Arvanitogiannis studied these questions as he worked on his PhD in Psychology at Concordia’s Centre for Studies in Behavioural Neurobiology (CSBN).
Tonight, at a gala banquet, Arvanitogiannis is receiving a prix d’excellence for his work. The award is presented by l’Académie des Grands Montréalais, an initiative of the Montreal Board of Trade, to recognize the best doctoral thesis defended in 1998 by a student from one of Montreal’s four universities in the field of natural sciences and engineering.
Greek-born Arvanitogiannis is a long-time member of the Concordia community. He got his BSc from Concordia in Biology in 1990, and continued in post-graduate psychology, supervised by Centre director Professor Peter Shizgal. He is currently doing post-doctoral work at the CSBN with Professor Shimon Amir. The CSBN promotes interdisciplinary research on brain mechanisms of motivated behaviour, including pharmacological, neuroanatomical, neurochemical and electrophysiological aspects of brain research.
For 50 years, psychologists have observed that if you attach an electrode to the brain of a rat, and connect the electrode to a lever, the rat will press the lever over and over to stimulate its brain, Arvanitogiannis said. It will even forgo eating and drinking, and endure painful shocks to reach that lever. Similar behaviour has been observed in other animals, from goldfish to humans.
"The premise is that the electrode sends a meaningful signal into some component of the circuitry of the brain to tell the animal to do that again," Arvanitogiannis said, "but no one as yet knows the identity of the nerve cells that are directly activated in this phenomenon of intracranial self-stimulation." He set out to identify those neurons.
Arvanitogiannis applied a method used in other fields of biology to find an area of the brain where the neurons seem to be activated during this phenomenon. By locating the presence of a certain protein that is produced by activated cells, he identified a region in the basal forebrain (at the bottom front of the brain). The next step was to perform a lesion to see what would happen if those neurons were missing. He observed that, after lateral lesions were performed, the stimulation had to be increased before it would elicit the same behaviour.
A further suggestion that key neurons are located here comes from a recent study by researchers in Boston. Magnetic resonance studies of the brains of cocaine addicts indicated the same area was activated after the subjects were administered cocaine.
Arvanitogiannis took his research another step by testing a mathematical model that involves an original combination of behavioural economics and conditioning theory. This model allows researchers to sketch a portrait of the brain circuitry involved in goal-directed behaviour.
"For example, drugs of abuse affect dopamine neurons – sometimes referred to as pleasure cells – but what is the relationship between the dopamine neurons and the directly activated neurons I’m trying to find? Are they in a series, so one activates the other, or is there some other arrangement?"
His work has many applications. Some CSBN researchers are applying methods described in Arvanitogiannis’s thesis to determine how a particular abuse drug, such as cocaine, affects the brain’s reward circuitry. This research may eventually make it possible to treat problems like drug dependence, compulsive gambling and depression (which involves a complete lack of goal-directed behaviour) with medication that acts on this circuitry.
