in the Action and Cognition @ Trent (ACT) Lab:
of our everyday activities – reaching for a cup of coffee, tossing
a ball to a child, talking to a friend – require that we interact
skillfully with the people and objects in our surroundings.
The goal of research in the ACT Lab is to understand how the brain
uses sensory information (vision, touch, and proprioception) to
learn and control limb and hand movements. We are also interested
in how our action capabilities influence how we attend to and perceive
our immediate surroundings.
To address these questions, we use specialized equipment to track
precisely how participants’ eyes, head, and limbs move as they perform
our experiments. We carefully manipulate what people see and feel
as they reach for targets, learn new motor skills, or use tools.
We also use brain stimulation techniques
(transcranial magnetic stimulation) to help us understand how the brain coordinates sensory and motor
information during movement.
Ultimately, our goal is to reveal strategies that can be used by
people with brain injuries to help them regain and maintain their
questions we are investigating:
Can we use
our hands to augment vision?
findings suggest that we can see targets more quickly and accurately
when the target appears in the space near our hands. For example,
MB - a young man who is blind in his upper-left visual field - could
report object size in his blind field if his hand was placed near
the target object (1). In studies of healthy participants, we've shown
that pointing movements are performed more precisely if the target
is shown on the participant's own real hand than on a similarly-positioned
fake hand (2), and that pointing precision varies with the distance
between target and the nearby hand (3). Can these effects be explained
by attention or is there a role for special neurons that code space
near the hands (visual-tactile bimodal neurons)? Are there other
situations in which people can see better near their hands and can
this effect be exploited to help patients overcome visual exploration
deficits? Our current studies address these questions.
1. Brown, L. E., Kroliczak, G., Demonet, J.-F., & Goodale, M. A.
(2008). A hand in blindsight: Hand placement near target improves
size perception in the blind visual field. Neuropsychologia, 46,
2. Brown, L. E., Morrissey, B. F., & Goodale, M. A. (2009). Vision
in the palm of your hand. Neuropsychologia, 47, 1621-6.
L. E., Reynolds, A., & Gozli, D. (2009). Hand-target proximity improves
target representation for reaching. Poster presented at Society for Neuroscience, Chicago, IL.
motor learning change the way we deal with sensory information?
The motor system helps us adapt to forces applied by the environment
(strong wind and current) and by objects (gravity and object inertia).
Is force information useful to other sensory systems? We recently
showed that visual motion processing changes in response to motor
adaptation to an environmental force field (4), and that the visual
system may also use learned force information to make predictions
about how far a hand-held tool can reach (5). Special regions of space
near the hand grow to encompass the entire tool, but only after
active tool use. What role does motor learning play in this adaptation?
4. Brown, L. E., Wilson, E. T., Goodale, M. A., & Gribble, P. L.
(2007). Motor force field learning influences visual processing
of target motion. Journal of Neuroscience, 27, 9975-9983.
5. Brown, L. E., Doole, R., & Malfait, N. (in press). The role of motor learning in spatial adaptation near a tool. PLoS One.
6. Gozli, D. G., & Brown, L. E. (in press). Agency and control for the integration of a virtual tool into peripersonal space. Perception.
motor learning occur by observing perfection or errors?
Common wisdom says that I will improve my own movement performance
if I watch an expert perform, but most motor learning by observing research emphasizes the importance of observing
errors. When do observers need to see a model of
perfect performance and when do they need to see errors? Do they
benefit from observing their own errors more than others' errors?
What role do the visual and motor systems play in learning by observing?
7. Brown, L. E., Wilson, E. T., Obhi, S. S., & Gribble, P. L. (2010). The effect of trial order and error magnitude on motor learning by observing. Journal of Neurophysiology, 104, 1409-16.
8. Brown, L. E., Wilson, E. T., & Gribble, P. L. (2009). Repetitive
transcranial magnetic stimulation to primary motor cortex interferes
with motor learning by observing. Journal of Cognitive Neuroscience,