[Abstract Title]. - Society for Neuroscience

Title: Neuronal activity of SI cortex of untrained monkeys in haptic-haptic unimodal and visuohaptic
crossmodal working memory tasks
Authors: X. LI 1 , L. WANG 1 , S. HSIAO 2 , M. BODNER 1,3 , F. LENZ 1 , Y. KU 1 , J. FUSTER 4 , *Y.
ZHOU 1 ;
1 Dept Neurosurg., 2 Dept Neurosci., Johns Hopkins Univ. Sch. Med., Baltimore, MD; 3 MIND
Res. Inst., Santa Ana, CA; 4 Semel Inst. for Neurosci. and Human Behavior, UCLA, Los Aneles,
CA
Abstract: Previous studies have shown that somatosensory cortical neurons in well-trained
monkeys participate in both haptic-haptic (HH) unimodal and visuo-haptic (VH) cross-modal
delayed matching-to-sample tasks. In the present study, we recorded from single units in SI
cortex from monkeys “naïve” to those tasks. During unit recording, the naïve animals performed
tasks identical to those for trained monkeys but without the requirements (untrained) to
discriminate and memorize sensory cues. In the HH trials, the naïve animal had to touch
("sample") an object and after a delay, grasp and pull another object that was the same or
different from the first (the animal was given the same reward in either case). In the VH trials,
the animal was first given a visual stimulus (presented at the animal‟s eye level), and after a
delay, the animal was required to grasp and pull an object as it did in the second part of the HH
task to get a reward. In HH, the majority of cells showed significant firing rate change when the
monkey touched the first tactile object in the sample period; some of those touch-responsive cells
showed differential activity depending on which object was touched. These results were similar
to those from well-trained monkeys in the first-stimulus sample period, suggesting a similar
neuronal process of perception in the trained and the naïve monkeys. However, the percentage of
delay-active cells, including differential delay cells, was significantly lower in naïve monkeys
than that in well-trained monkeys. In the VH task, significantly lower percentages of active cells-
-in both sample and delay periods--were found in naïve than in trained monkeys. Present data, in
conclusion, indicate that a population of SI neurons in naïve monkeys responds to tactile or
visual stimuli even though their retention is not necessary for task performance. Our data also
indicate that, through training, unimodal and cross-modal networks in SI cortex increase their
involvement in working memory and cross-modal association.
Disclosures: X. Li, None; L. Wang, None; S. Hsiao, None; M. Bodner, None; F. Lenz,
None; Y. Ku, None; J. Fuster, None; Y. Zhou, None.
Poster
296. Learning and Memory: Physiology and Imaging III
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 296.8/TT14