We study evolution of the neural substrate of behaviour by highlighting similarities and differences in the brain pathways that organize behaviour in different vertebrates. Investigations relate to the structure and function of brain regions that that integrate sensory input and control behaviour in amphibians and fish. The approach is threefold: 1) behavioural experiments; 2) anatomical methods to describe the architecture of brain pathways; 3) measure of brain activity by direct recording of electrical activity or labelling of indirect markers of neuronal activation.
Neurobiology of learning in amphibians
Important similarities have been noted between the organization of the amphibian telencephalon and the mammalian limbic pathways involved in the regulation of motivated behaviour. We study the brain substrate of behavioural flexibility and habit learning in amphibians with the objective of comparing to the situation in mammals. For that purpose, protocols of appetitive and aversive conditioning are established using amphibians in the laboratory. These conditioning protocols are then adapted for methods of functional neuroanatomy, which measure brain activity indirectly.
Olfactory neurobiology in plethodontid salamanders
Most amphibians possess both a vomeronasal (accessory olfactory) and a main olfactory system. The vomeronasal pathway in salamander displays uniquely direct connections to brain regions involved in behavioural control and mediates the detection of a variety of biologically relevant chemical cues. Thus, it appears a good model pathway to study how the nervous system processes sensory information from molecules to behaviour. We study behaviour and brain responses following the delivery of olfactory stimuli to the vomeronasal organ of salamanders. Electrophysiology can be used to establish how bioelectrical signals are processed from the vomeronasal sensory neurons to the behavioural control centres of the brain.
Anatomy of the behavioural brain in amphibians
In mammals, it is thought that brain regions organized as paired longitudinal columns in the preoptic area, hypothalamus and ventral brainstem exert control over the motor aspects of motivated behaviour, with distinct regions dedicated to ingestive/reproductive/defensive and exploratory/foraging behaviours. These regions receive diverse inputs, notably from many parts of the telencephalon. However, the complexity of connections is such that a synthesis is difficult. Amphibians possess simpler brains, but little is known about the functional organization of behavioural pathways in these animals. Comparison of amphibian brains with the better known but highly complex mammalian brain could help elucidate the basic pathways and mechanisms organizing behaviour. We attempt to establish the anatomical and functional brain subdivisions involved in behavioural control in selected amphibian species.
Neuroecology of teleost fishes
Along with the lab of Dr. Kevin McCann, we have recently begun a collaborative research effort focused on the relationship between brain and sense organ morphology and ecology in teleost fishes. We hope to expand this project with additional collaborators to include investigations of physiological parameters and behaviour to get a better picture of what a fish needs to occupy its position in a food web. This research is part of an effort to explain the source of stability in food webs.