Grant Number: 5F31NS046193-03
Project Title: Coordinate Frameworks in Macaque Posterior Cingulate
PI Information: HEATHER L. DEAN,  dean@cns.nyu.edu 

Abstract: DESCRIPTION (provided by applicant): Anatomical and physiological evidence suggest that posterior cingulate cortex (CGp) participates in sensorimotor transformations. CGp is strongly connected with visual and premotor cortical areas, and CGp neurons respond following saccades. Previous studies suggest that the activity of CGp neurons is modulated by the position of the eye in the orbit, as well as by saccade direction and amplitude. The -first goal of this project is to fully quantify the spatial and temporal properties of CGp neurons by studying single CGp neurons while monkeys (M. mulatta) perform saccadic trials with or without a delay intervening between target onset and movement onset. This intervening delay allows for a temporal separation of neuronal responses to the target and to the movement. The next goal is to determine whether CGp encodes spatial information in a coordinate frame anchored to the fovea, head, or world. Single CGp neurons are studied while monkeys perform delayed-saccade trials from different initial fixation positions to targets positioned along an axis passing through the previously-mapped neuronal response field (RF). If the movement vector accounts for the variance in firing rate a retinotopic coordinate framework may be used in CGp. If the final eye position is most important, CGp could be using framework anchored to the head or world. Differentiating between these possibilities requires comparing activity on this task before and after rotating the monkey with respect to the visual targets. Preliminary data suggest that CGp encodes information in a coordinate framework centered on the head or world rather than in one that is retinotopic.

Thesaurus Terms:
cingulate gyrus, neural information processing, saccade, visual perception
Macaca mulatta, predoctoral investigator

Institution: DUKE UNIVERSITY
2200 W. Main St.
DURHAM, NC 27705
Fiscal Year: 2006
Department: NEUROBIOLOGY
Project Start: 01-DEC-2003
Project End: 31-MAY-2006
ICD: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
IRG: ZRG1

Visual and Saccade-Related Activity in Macaque Posterior Cingulate Cortex

Heather L. Dean¹, Justin C. Crowley^4,5 and Michael L. Platt<sup>1,2,3

1</sup>Department of Neurobiology, ²Center for Cognitive Neuroscience, and ³Department of Biological Anthropology and Anatomy, Duke University Medical Center, Durham, North Carolina 27710; and ⁴Department of Biological Sciences and ⁵Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213

Submitted 17 July 2003; accepted in final form 9 June 2004
J Neurophysiol 92: 3056-3068, 2004

Surgical procedures
A head-restraint prosthesis and scleral search coil (*Fuchs and Robinson 1966 ; Judge et al. 1980 ) were implanted in an initial aseptic surgical procedure performed under isoflurane anesthesia. First, the dorsal rostrum of the skull was exposed and six 2.5-mm holes were drilled through the skull with standard orthopedic surgical instruments. These holes were then tapped for 3.5-mm fine-thread orthopedic cortical bone screws. Sterile orthopedic bone cement (Biomet; Palacos) was used to bond a stainless steel head post (Crist Instruments) lowered to just above the skull surface to 6 titanium screws (Zimmer) inserted into the tapped holes. The Teflon-insulated scleral search coil (Cooner Wire AS634) was implanted beneath the conjunctiva, passing just rostral to the insertions of the extraocular muscles (Judge et al. 1980 ). The wire exited the conjunctiva temporally, exited the orbit subdermally, was embedded in the bone cement that formed the restraint prosthesis, and terminated in a gold and plastic electrical connector (Winchester Electronics/Litton). After surgery, animals received analgesics for a minimum of 3 days. Antibiotic prophylaxis was initiated intraoperatively and continued for 7–10 days. Animals were given a 4- to 6-wk recovery period after surgery.
 
A second aseptic surgical procedure was performed once animals could reliably execute all the behavioral tasks used in the study. A stainless steel recording chamber (Crist Instruments) was positioned stereotaxically perpendicular to the horizontal plane over a 15-mm craniotomy and bonded to 4–6 additional orthopedic bone screws and the original implant with orthopedic bone cement. The recording chamber was centered stereotaxically at position 0,0, the intersection of the midsagittal and interaural planes (cf. Olson et al. 1996 ). Postoperatively, animals received analgesics for a minimum of 3 days and antibiotics for 7–10 days. The recording chamber was kept clean with daily antibiotic washes and sealed with replaceable sterile Cilux caps. Single-cell recording experiments began after a 1-wk postoperative period.

Behavioral techniques
Access to water was controlled during training and testing, and animals were habituated to head restraint and trained to perform oculomotor tasks for a fruit-juice reward using a custom-built software interface (Ryklin Software). Visual stimuli consisted of light-emitting diodes (LEDs; LEDtronics), which could be illuminated to appear red, green, or yellow to normal human observers. The LEDs were fixed on a tangent screen placed 144.78 cm (57 in.) from the eyes of the animal, forming a grid of points, separated by 1°, spanning 49° horizontally and 41° vertically. These LEDs could be illuminated within 1 ms and extinguished within 7 ms by the computer system controlling the experiments.

* Fuchs and Robinson 1966