Distinguishing subregions of the human mt+ complex using visual fields and pursuit
eye movements.
Dukelow, Sean P., Joseph F. X. Desouza, Jody C. Culham, Albert V. Van Den Berg,
Ravi S. Menon, Tutis Vilis.
1Graduate Program in Neuroscience, Siebens-Drake Research Institute, Room 216,
University of Western Ontario, London, Ontario, Canada, N6G 2V4. 2Department of
Psychology, University of Western Ontario, London, Ontario, N6A 5C2. 3Department of
Physiology, Erasmus Universiteit Rotterdam, PO Box 1738, 3000 DR Rotterdam, The
Netherlands. 4Advanced Imaging Labs, The John P. Robarts Research Institute, 100
Perth Drive, London, Ontario, Canada N6A 5K8. 5Department of Physiology, University
of Western Ontario, London, Ontario, Canada, N6A 5C1.
APStracts 8:0228J, 2001.
In humans, functional imaging studies have demonstrated a homologue of the macaque
motion complex, MT+, (suggested to contain both MT and MST) in the ascending limb
of the inferior temporal sulcus. In the macaque monkey, motion sensitive areas MT
(middle temporal) and MST (medial superior temporal) are adjacent in the superior
temporal sulcus. Electrophysiological research has demonstrated that while MT
receptive fields primarily encode the contralateral visual field, MSTd(dorsal) receptive
fields extend well into the ipsilateral visual field. Additionally, macaque MST has been
shown to receive extraretinal smooth pursuit eye movement signals, whereas MT does
not. We used functional magnetic resonance imaging (fMRI) and the neural properties
that had been observed in monkeys to attempt to distinguish putative human areas MT
from MST. Optic flow stimuli placed in the full field, or contralateral field only,
produced a large cluster of functional activation in our subjects, consistent with previous
reports of human area MT+. Ipsilateral optic flow stimuli limited to the peripheral retina
produced activation only in an anterior subsection of the MT+ complex, likely
corresponding to putative MSTd. During visual pursuit of a single target, a large portion
of the MT+ complex was activated. However, during non-visual pursuit, only the
anterolateral portion of the MT+ complex was activated. This subsection of the MT+
cluster could correspond to putative MSTl(lateral). In summary, we observed three
distinct subregions of the human MT+ complex that were arranged in a manner similar to
that seen in the monkey.
Received 18 August 2000; accepted in final form 24 May 2001
APS Manuscript Number J604-0.
Article publication pending Am J Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 31 July 2001