Tracy Henderson - Experimental Neuropsychology Research Unit

My research involves investigating the role of the basal ganglia (BG) in attention, and the effects of compromised BG functioning on generating and controlling smooth pursuit (SP) eye movements. Appropriate eye movements are vital for the accurate perception of, and interaction with the environment. These include, saccades, which are fast eye movements that acquire a target, and smooth pursuit (SP) eye movements that maintain foveation of a moving target. Traditionally saccades and SP have been viewed as distinct movements, subserved by independent networks. However, recent research has demonstrated significant overlap of their anatomical substrate. Further, both types of eye movement are influenced by the interaction of top-down cognitive, and bottom-up stimulus driven processes, which are strongly linked to visual attention. Most research to-date has investigated the close relationship between eye movements and attention using saccade paradigms, with relatively few expressly focusing on SP. Given the anatomical overlap between the saccade and SP networks, we hypothesise that similar attentional processes underlie these eye movements.  We aim to test this hypothesis by examining clinical evidence from Parkinson's (PD) and Huntington's diseases (HD). PD and HD are neurodegenerative disorders of the basal ganglia (BG), a group of sub-cortical nuclei that are arguably the most critical component of the saccade, SP and attentional networks. At least in the early stages, PD and HD compromise distinct regions of the BG, manifesting as essentially opposing ocular motor and attentional impairments. We aim to use these opposing disease profiles demonstrate the pivotal role of the BG in regulating attentional processes in SP eye movements.

Biography

I completed a BA (Hons) at the University of Melbourne. I am now a Doctor of Psychology (Clinical Neuropsychology) Candidate at Monash University.

My previous research has investigated the role of the right inferior frontal gyrus (IFG) in inhibitory processes, using transcranial magnetic stimulation (TMS).

My current research looks at the role of attention in smooth pursuit eye movements.

I'm currently working as a research assistant at the Van Cleef Roet Centre for Nervous Diseases at the Alfred Hospital working on 2 projects entitled:
1) Cognitive functions in congestive heart failure - a cross-sectional study
2) Does coeliac disease cause ataxia or cognitive impairment?

Publications

Henderson, T., Georgiou-Karistianis, N., White, O., & Fielding, J. (submitted). Shared attentional processes in saccades and smooth pursuit: Evidence from the basal ganglia.

Chambers, C.D., Bellgrove, M.A., Stokes, M.G., Henderson, T.R., Garavan, H., Robertson, I.H., Morris, A.P. & Mattingley, J.B. (in press). Executive 'brake failure' following deactivation of the human frontal lobe. Journal of Cognitive Neuroscience. (Multi authorship, Impact factor 5.3, Published in English)

Stokes, M.G., Chambers, C.D., Gould, I.C., Henderson, T.R., Janko, N.E., Allen, N. & Mattingley, J.B. (2005). A simple metric for scaling motor threshold based on scalp-cortex distance: Application to studies using transcranial magnetic stimulation. Journal of Neurophysiology. (Multi authorship, 8 pages, Published in English)

Henderson, T.R., Chambers, C.D., Bellgrove, M.A., Stokes, M.G., Garavan, H., Robertson, I.H., Morris, A.P. & Mattingley, J.B. (2005, Feb 5). Cortical control of response inhibition revealed through transcranial magnetic stimulation. Paper presented at the 7th annual Motor Control and Human Skill Conference.