- What is it about New Caledonian crows’ brains that allow them to manufacture tools when their relatives can’t?
- What is special about the lyrebird’s brain that lets it incorporate new elements to their song while zebra finches can’t?
- And how does each species, starting off from a single cell, end up with those differences?
These questions form the core of the research in the lab.
To try to get to some answers the lab takes 3 different approaches. We study comparative anatomy, comparative physiology and embryology.
Vertebrate brains may appear to be quite different but they are all organised along similar patterns. The lab tries to understand how evolution acts to modify these basic circuits to generate different behaviours. Our approach is to study the brains of closely related vertebrates exhibiting different behaviours, or brains of unrelated species expressing similar behaviours. We work primarily on birds because they express many behaviours otherwise thought to be exclusive to humans (like episodic memory, mirror recognition, language development, etc).
Most of our work focuses on the auditory system. The auditory system processes sounds that are important in vertebrates, for example, for recognising individuals of their own species, mating, defending their territories, finding food or avoiding predators.
- Comparative Anatomy and Physiology:
We study how brain size (and sizes of individual brain regions) vary in different species, how different parts of the brain are connected differently and how neurons may respond differently to various sets of stimuli. The lab uses traditional histological techniques and immunocytochemistry to aid in this analysis. We also use extracellular and intracellular physiology to explore the responses of individual cells (or groups of cells) to stimuli having different biological significance.
This experimental approach helps us identify general principles that apply to brain circuits and uncover differences that may be related to the individual characteristics of a given species.
- Comparative Embryology:
The diversity of animal forms is fascinating – whether it is the differences in plumage of birds, the terrifying jaws of crocodiles, or the trunk of an elephant, each vertebrate has a distinct body shape and size. A core question in biology is how do you get such diversity in body plans when all vertebrates start as a single cell. We know that as this original cell divides each daughter cell will follow a different developmental path. The choices made by each daughter cell ultimately leads to all the body plans present in biological systems.
Brain cells not only need to decide ‘who’ they will become but also what place they will occupy within the overall circuit.
The lab studies the basic rules that govern this decision making process in the embryonic hindbrain. Early during development, the hindbrain has well-defined morphological segments each expressing a specific set of genes. We have considerable knowledge about how gene expression patterns guide the differentiation of the hindbrain in different vertebrates, but we know much less about how sensory axons – originating outside the brain – come to connect with the right hindbrain neurons.
We use tract-tracing techniques, normal histology and immunocytochemstry to study the normal development of the sensory axons and how they connect to hindbrain neurons. We also do surgical manipulations to study how interfering with the normal environment affects the decisions made by sensory axons.