Effect of the number of response alternatives on brain activity in response selection

• Published in: Human brain mapping Vol. 28; no. 10; pp. 950 - 958
• Main Authors: Woo, Sung-Ho, Lee, Kyoung-Min
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.10.2007; Wiley-Liss
• Subjects: Adult; Biological and medical sciences; Brain Mapping; Cardiovascular system; Central nervous system; Cerebral Cortex - anatomy & histology; Cerebral Cortex - physiology; Cognition - physiology; Cues; Decision Making - physiology; Electrophysiology; Evoked Potentials - physiology; Female; fMRI; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Gyrus Cinguli - anatomy & histology; Gyrus Cinguli - physiology; Hick's law; Humans; Information Theory; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging; Male; Medical sciences; Nervous system; Neuropsychological Tests; Parietal Lobe - anatomy & histology; Parietal Lobe - physiology; Photic Stimulation; Prefrontal Cortex - anatomy & histology; Prefrontal Cortex - physiology; Psychomotor Performance - physiology; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Reaction Time - physiology; response selection; Temporal Lobe - anatomy & histology; Temporal Lobe - physiology; Time Factors; Vertebrates: nervous system and sense organs; Visual Cortex - anatomy & histology; Visual Cortex - physiology; fMRI; Nervous system diseases; Radiodiagnosis; Selection; Central nervous system; response selection; Nuclear magnetic resonance imaging; Hick's law; Encephalon; Information theory
• ISSN: 1065-9471; 1097-0193
• DOI: 10.1002/hbm.20317

It is well‐known in motor control literature that a response time (RT) increases as a logarithmic function of the number of response alternatives (NA) (Hick's law). In this study, we identified neural correlates for this relationship using event‐related functional MRI and a choice finger‐movement task. Behaviorally, average RTs of all subjects increased as a logarithmic function of the NA in accordance with the law. From a voxel‐wise search for brain areas where the activity was correlated with NA and thence the RT, a positive correlation was found at the posterior cingulate and left superior frontal gyri, whereas a negative correlation was observed at areas in bilateral inferior parietal lobules. This differential modulation by the task context, namely, the NA available for a choice response with identical stimulus and response, indicates that these regions are involved in various aspects of response selection, intentional retrieval of motor program, or spatial expectancy. Hum Brain Mapp 2006. © 2006 Wiley‐Liss, Inc.