Much of this work is in collaboration with Dr. Andrew Iwaniuk, Lethbridge University. We have been fortunate to obtain a wealth of brains from over 100 different species of birds from numerous museums and private collectors. With these data were are analysing the size of various nuclei in the brain and attempting to correlate this with behavioural differences amongst various bird species. We have been looking at the size of various nuclei in the avian brain, including the visual areas in the brainstem and cerebellum. Thus, this comparative work nicely complements my neurophysiological and neuroanatomical work. Much of the work examines sensory systems, but also brain evolution in relation to complex behaviors such as tool use.
A Specific example: The pretectal nucleis Lentiformis Mesencephali is Hypertrophied in Hummingbirds: I have been studying in the neuroanatomy and neurophysiology of the nucleus lentiformis mesencephali, or LM, for quite some time. We know that the LM is involved in the analysis of optic flow and the generation of the optomotor response to facilitate gaze stabilization . Recently, Andy and I examined variation within the LM in birds. Of all of the feeding methods known to occur in birds, hovering flight is perhaps the most demanding in terms of gaze stabilization. Hummingbirds and other hovering species (e.g., sunbirds, kingfishers, raptors) need to keep their vision stable in order to successfully feed. After examining the brains of several hummingbird species, we found that LM was significantly enlarged in hummingbirds compared to other birds. Other species that hover, such as the Eastern Spinebill (Acanthorhynchus tenuirostris), American Kestrel (Falco sparverius) and Belted Kingfisher (Ceryle alcyon) also had an enlarged LM, but not to the same extent as the hummingbirds. In contrast,other visual structure including the nucleus of the nasal optic root (nBOR), the ventral leaflet of the lateral geniculate nucleus (GLv) and the optic tectum (TeO) were all not significantly larger in hummingbirds. Thus, the hypertrophy is specific to LM and is present in all hovering species, but greatest in the hummingbirds.
This study led directly to work examining motion processing in the hummingbird brain with Doug Altshuler’s lab at UBC.