Dr. Okihide Hikosaka, senior investigator at the National Eye Institute (NEI) Laboratory of Sensorimotor Research, is a recipient of the 2018 Gruber Prize in Neuroscience. The prestigious award, given by the Gruber Foundation at Yale University, recognizes scientists whose research fundamentally shifts the field of neuroscience.
Hikosaka first came to the NIH as a postdoctoral fellow in 1979, joining the laboratory of Dr. Robert Wurtz to pursue his interest in the brain’s control of eye movement. At the time, Wurtz’ lab focused on the visual cortex, the part of the brain that directly receives information from the eyes. Surprisingly, Dr. Wurtz encouraged Hikosaka to study the basal ganglia and the substantia nigra, regions of the brain that seemed unrelated to vision.
“Nowadays, people are interested in the basal ganglia, because lots of disorders – motor function disorders, motivational deficiency, Parkinson’s disease – are tied to those regions of the brain,” said Hikosaka. But in the late 1970s, few visual-oculomotor scientists considered the basal ganglia to be important. Nevertheless, over the next three years at NIH, and 20 following years in Japan, Hikosaka discovered complex neural pathways through the basal ganglia that play crucial roles in processing visual information, and in governing movements like saccades (eye movements).
Along the way, Hikosaka began to focus on the caudate nucleus, a tadpole-shaped region of the basal ganglia that loops with the cerebral cortex. Initially, his work on the head portion of the caudate nucleus showed that this region responded to visual information, quickly registering values (a fruit is good, vs. a wasp is bad, for example) – and adjusting to changing values – of visual objects.
Upon returning to the NIH in 2002, Hikosaka turned his attention to the caudate tail, whose function was largely unknown. Initially, he thought that similar types of neurons in different parts of the caudate nucleus would work the same way. But Hikosaka found instead that individual neurons in the caudate tail recognize and respond to unique objects, encoding stable values for those objects after a long period of time. In effect: while the caudate head reflects short-term learning, the caudate tail seems to reflect long-term learning. “It’s what we call an emotional life history,” said Hikosaka.
These regions – along with others that respond to different conditions in the environment – provide context to govern motivation and motion. The future of this research lies in connections: “It’s very important now to study interactions across brain areas,” Hikosaka said. He believes the interplay between the basal ganglia and other regions of the brain holds keys for understanding how we see, learn, and interact with the world.
Hikosaka shares this year's Gruber Prize with Dr. Ann M. Graybiel, Massachusetts Institute of Technology, and Dr. Wolfram Schultz, University of Cambridge, who have also made seminal discoveries about the structure, function, and organization of the basal ganglia. An award ceremony will take place November 4, 2018, at the annual meeting of the Society for Neuroscience in San Diego.
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NEI leads the federal government’s research on the visual system and eye diseases. NEI supports basic and clinical science programs to develop sight-saving treatments and address special needs of people with vision loss. For more information, visit https://www.nei.nih.gov.
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