RT Journal Article
SR Electronic
T1 Reaching in Depth: Hand Position Dominates over Binocular Eye Position in the Rostral Superior Parietal Lobule
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 11461
OP 11470
DO 10.1523/JNEUROSCI.1305-09.2009
VO 29
IS 37
A1 Stefano Ferraina
A1 Emiliano Brunamonti
A1 Maria Assunta Giusti
A1 Stefania Costa
A1 Aldo Genovesio
A1 Roberto Caminiti
YR 2009
UL http://www.jneurosci.org/content/29/37/11461.abstract
AB 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.