Neural Activity in the Frontal Eye Fields Modulated by the Number of Alternatives in Target Choice

@article{citeulike:2822703, abstract = {Selection of identical responses may not use the same neural mechanisms when the number of alternatives (NA) for the selection changes, as suggested by Hick's law. For elucidating the choice mechanisms, frontal eye field (FEF) neurons were monitored during a color-to-location choice saccade task as the number of potential targets was varied. Visual responses to alternative targets decreased as NA increased, whereas perisaccade activities increased with NA. These modulations of FEF activities seem closely related to the choice process because the activity enhancements coincided with the timing of target selection, and the neural modulation was greater as NA increased, features expected of neural correlates for a choice process from the perspective of Hick's law. Our current observations suggest two novel notions of FEF neuronal behavior that have not been reported previously: (1) cells called "phasic visual" that do not discharge in the perisaccade interval in a delayed-saccade paradigm show such activity in a choice response task at the time of the saccade; and (2) the activity in FEF visuomotor cells display an inverse relationship between perisaccadic activity and the time of saccade triggering with higher levels of activity leading to longer saccade reaction times. These findings support the area's involvement in sensory-motor translation for target selection through coactivation and competitive interaction of neural populations that code for alternative action sets. 10.1523/JNEUROSCI.3596-07.2008}, author = {Lee, Kyoung-Min and Keller, Edward L. }, citeulike-article-id = {2822703}, comment = {* Examination of FEF neurons during a free choice task showing that FEF activity is modulated by the number of alternative targets * Background includes a discussion of the finding that RTs increase as the number of alterntative targets increases (according to Hick's Law RT is a function of the log of the number of alternatives, see 'Hick 1952':http://www.citeulike.org/user/klouie/article/2919822... ), which was shown by the authors previously to hold for saccadic eye movements ( 'Lee et al 2005':http://www.citeulike.org/user/klouie/article/2919837 ) * Such RT data is used to motivate the notion that the number of alternatives influences the choice process (not mentioned, but related is choice set size effects as in 'Iyengar and Lepper 2000':http://www.citeulike.org/user/klouie/article/1431264... and 'Schwarz 2004':http://www.citeulike.org/user/klouie/article/1431265 ) * Task is a color-cued choice saccade task, with either 1, 2, or 4 colored alternatives which turn uniformly gray; color change of the central fixation target indicated appropriate later response (required memory of color-location association) * Authors designed task in an attempt to separate visual, cognitive (target selection), and motor processes * Neurons were classified as visual, visuomotor, or motor based on activity in a delayed-saccade task, consistenet with previous FEF studies * Behavioral results showed a monotonic increase in RT with increasing number of alternatives (NA): 251, 272, 284 ms; there were no significant difference in accuracy or peak velocities * 165 FEF neurons classified as 33 visual, 71 visuomotor, 36 motor and 25 not responsive}, doi = {http://dx.doi.org/10.1523/JNEUROSCI.3596-07.2008}, journal = {J. Neurosci.}, keywords = {fef, monkey, neurophysiology, normalization}, month = {February}, number = {9}, pages = {2242--2251}, posted-at = {2008-05-22 11:01:10}, priority = {2}, title = {Neural Activity in the Frontal Eye Fields Modulated by the Number of Alternatives in Target Choice}, url = {http://dx.doi.org/10.1523/JNEUROSCI.3596-07.2008}, volume = {28}, year = {2008} }

TY - JOUR ID - citeulike:2822703 L3 - citeulike-article-id:2822703 TI - Neural Activity in the Frontal Eye Fields Modulated by the Number of Alternatives in Target Choice JF - J. Neurosci. VL - 28 IS - 9 SP - 2242 EP - 2251 N2 - Selection of identical responses may not use the same neural mechanisms when the number of alternatives (NA) for the selection changes, as suggested by Hick's law. For elucidating the choice mechanisms, frontal eye field (FEF) neurons were monitored during a color-to-location choice saccade task as the number of potential targets was varied. Visual responses to alternative targets decreased as NA increased, whereas perisaccade activities increased with NA. These modulations of FEF activities seem closely related to the choice process because the activity enhancements coincided with the timing of target selection, and the neural modulation was greater as NA increased, features expected of neural correlates for a choice process from the perspective of Hick's law. Our current observations suggest two novel notions of FEF neuronal behavior that have not been reported previously: (1) cells called "phasic visual" that do not discharge in the perisaccade interval in a delayed-saccade paradigm show such activity in a choice response task at the time of the saccade; and (2) the activity in FEF visuomotor cells display an inverse relationship between perisaccadic activity and the time of saccade triggering with higher levels of activity leading to longer saccade reaction times. These findings support the area's involvement in sensory-motor translation for target selection through coactivation and competitive interaction of neural populations that code for alternative action sets. 10.1523/JNEUROSCI.3596-07.2008 KW - fef KW - monkey KW - neurophysiology KW - normalization N1 - * Examination of FEF neurons during a free choice task showing that FEF activity is modulated by the number of alternative targets * Background includes a discussion of the finding that RTs increase as the number of alterntative targets increases (according to Hick's Law RT is a function of the log of the number of alternatives, see 'Hick 1952':http://www.citeulike.org/user/klouie/article/2919822... ), which was shown by the authors previously to hold for saccadic eye movements ( 'Lee et al 2005':http://www.citeulike.org/user/klouie/article/2919837 ) * Such RT data is used to motivate the notion that the number of alternatives influences the choice process (not mentioned, but related is choice set size effects as in 'Iyengar and Lepper 2000':http://www.citeulike.org/user/klouie/article/1431264... and 'Schwarz 2004':http://www.citeulike.org/user/klouie/article/1431265 ) * Task is a color-cued choice saccade task, with either 1, 2, or 4 colored alternatives which turn uniformly gray; color change of the central fixation target indicated appropriate later response (required memory of color-location association) * Authors designed task in an attempt to separate visual, cognitive (target selection), and motor processes * Neurons were classified as visual, visuomotor, or motor based on activity in a delayed-saccade task, consistenet with previous FEF studies * Behavioral results showed a monotonic increase in RT with increasing number of alternatives (NA): 251, 272, 284 ms; there were no significant difference in accuracy or peak velocities * 165 FEF neurons classified as 33 visual, 71 visuomotor, 36 motor and 25 not responsive AU - Lee, Kyoung-Min AU - Keller, Edward PY - 2008/02/27/ UR - http://dx.doi.org/10.1523/JNEUROSCI.3596-07.2008 ER -