title: Reaching in depth: hand position dominates over binocular eye position in the rostral superior parietal lobule.
abstract: Neural activity was recorded in area PE (dorsorostral part of Brodmann's area 5) of the posterior parietal cortex while monkeys performed arm reaching toward memorized targets located at different distances from the body. For any given distance, arm movements were performed while the animal kept binocular eye fixation constant. Under these conditions, the activity of a large proportion (36%) of neurons was modulated by reach distance during the memory period. By varying binocular eye position (vergence angle) and initial hand position, we found that the reaching-related activity of most neurons (61%) was influenced by changing the starting position of the hand, whereas that of a smaller, although substantial, population (13%) was influenced by changes of binocular eye position (i.e., by the angle of vergence). Furthermore, the modulation of the neural activity was better explained expressing the reach movement end-point, corresponding to the memorized target location, in terms of distance from the initial hand position, rather than from the body. These results suggest that the activity of neurons in area PE combines information about eye and hand position to encode target distance for reaching in depth predominantly in hand coordinates. This encoding mechanism is consistent with the position of PE in the functional gradient that characterizes the parieto-frontal network underlying reaching.
authors.affiliation: Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy. stefano.ferraina@uniroma1.it
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferraina
authors.forename: Emiliano
authors.initials: E
authors.lastname: Brunamonti
authors.forename: Maria Assunta
authors.initials: MA
authors.lastname: Giusti
authors.forename: Stefania
authors.initials: S
authors.lastname: Costa
authors.forename: Aldo
authors.initials: A
authors.lastname: Genovesio
authors.forename: Roberto
authors.initials: R
authors.lastname: Caminiti
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001288:Attention / Q000502:physiology; D001522:Behavior, Animal; D003867:Depth Perception / Q000502:physiology*; D023882:Dominance, Ocular / Q000502:physiology*; D006225:Hand; D016014:Linear Models; D008253:Macaca mulatta; D008568:Memory / Q000502:physiology; D009068:Movement / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010296:Parietal Lobe / Q000166:cytology / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D014794:Visual Fields / Q000502:physiology