ADVERTISEMENT
See Inside June/July 2006

See It, Grab It

When you open your eyes and reach out to shut off the alarm clock, two distinct brain systems are activated: one recognizes the clock, and the other guides your hand. Neuroscientists have long been aware of this “dissociation” between the recognition and guidance systems, but they had not been able to observe both in action. Now Lior Shmuelof and Ehud Zohary of Hebrew University in Jerusalem have used functional magnetic resonance imaging to see the duality in action in human volunteers.

The subjects watched videos of hands entering the screen from one side and grasping objects on the opposite side. Most previous studies of the two visual systems, Shmuelof explains, “were of people who had had brain damage. Those suffering from agnosia could not recognize objects, whereas those with ataxia could identify objects but could not guide their hands to grab them.” He says his work with Zohary is the first to test individuals for whom both systems operate normally.

This is only a preview. Get the rest of this article now!

Select an option below:

Customer Sign In

*You must have purchased this issue or have a qualifying subscription to access this content


It has been identified that the institution you are trying to access this article from has institutional site license access to Scientific American on nature.com.
Click here to access this article in its entirety through site license access.

Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American Back To School

Back to School Sale!

12 Digital Issues + 4 Years of Archive Access just $19.99

Order Now >

X

Email this Article

X