Fig. 1
After a Stroke
Fig. 2
Fig. 3
IMAGE COURTESY OF CRAIG BROWN
Advanced brain imagery aids stroke recovery research. “In order to help people, you need to know what’s going on in the brain,” says Craig Brown, a neuroscientist in the Division of Medical Sciences, who studies the effects of stroke by using voltage-sensitive dye imaging, or VSD. Fifty-thousand Canadians die from strokes every year and 300,000 are living with effects that mostly result from clots that interrupt blood flow to the brain. At the centre of his research, Brown — a native Manitoban in ripped jeans and a short-sleeved cowboy shirt — uses VSD to see what’s happening in the brain of a mouse, before and after stroke. The adjacent image shows how a mouse brain responds to touch of the left forepaw. Warm colours represent more vigorous brain responses. (The right side of the brain responds to touch on the left side of body.) Panel one shows how the brain normally responds to touch of the left forepaw (measured in milliseconds of response time).
Panel two shows that the brain fails to respond to forepaw touch one week after a stroke in the somatosensory cortex (region that senses the body). The lack of responsiveness correlates with marked impairments in the use of the forepaw. And panel three shows how the brain regains responsiveness to forepaw touch eight weeks after stroke. Also, the areas that don’t normally respond very much to touch (red-circled in left panel) start responding more (red-circled in panel three). The strokeaffected area shows no sign of response. Nor will it. Other parts of the brain have taken over. This applies to humans as well. “How well people recover from a stroke varies considerably from person to person,” says Brown. “Ultimately, we hope to understand what type of brain changes are associated with optimal stroke recovery, and then use genetic or pharmacological tools to stimulate these positive brain changes.” – GRANT KERR
Voltage-sensitive dye images show brain responses before, one week, and eight weeks after a stroke.
Banding Together Volunteers take aim at declining hummingbird populations.
HEATHER REID
BY HEATHER REID, BSC ’02 With throat feathers scattering iridescent light in every direction, a male rufous hummingbird approaches a red plastic feeder. He lands and a gauzy net falls, trapping the bird inside. A gentle hand slips in and cups the feisty flier. The bird is wrapped in a soft cloth and brought to a table where volunteers record a series of measurements. A licenced bird-bander applies an aluminum cuff on the bird’s leg with an identifying number. The band is about the size of the letter C on a Canadian quarter. Information gathered at this and 12 other banding and monitoring >> sites run by the Hummingbird Project of British Columbia
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