Wiesel, Torsten Nils, 1924–, Swedish neurobiologist, b. Uppsala, Sweden. After earning a degree in medicine from Karolinska Univ., Stockholm (1954), he took a research position at Johns Hopkins, where he began his work with David Hunter Hubel. The two relocated their research operations to Harvard in 1959. Wiesel and Hubel noted that various forms of visual stimuli are handled by different sections of the brain. Their collaborative work spanned over several decades, leading to the Nobel Prize in Physiology or Medicine in 1981 for their important studies of the visual cortex.