Dartmouth College, Hanover, NH

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Stop Animal Exploitation NOW!
S. A. E. N.
"Exposing the truth to wipe out animal experimentation"

Government Grants Promoting Cruelty to Animals

Dartmouth College, Hanover, NH

YALE E. COHEN - Primate Testing - 2005

Grant Number: 1R01DC007172-01A1
Project Title: Auditory response properties of the prefrontal cortex
PI Information: PROFESSOR YALE E. COHEN, yec@dartmouth.edu 

Abstract: DESCRIPTION (provided by applicant): Communication is one of the fundamental components of human and non-human animal behavior. The ventrolateral prefrontal cortex (vPFC) in rhesus monkeys has recently been identified as a cortical area that plays an important role in auditory-object and vocalization processing. This grant proposal tests the response properties of vPFC neurons in order to determine its role in auditory-object processing. In Aim #1, we construct the spectrotemporal receptive field (STRF) of vPFC neurons to determine how the vPFC codes the features of ensembles of vocalizations and ripple noise (an artificial stimulus with properties similar to vocalizations). We test two alternative hypotheses. First, if the vPFC is involved in low-level feature extraction, as measured by our STRF model, we hypothesize that (1) a significant proportion of vPFC neurons have significant STRFs and that (2) the STRFs are accurate predictors of a neuron's response to an auditory stimulus. The second, alternative hypothesis is that if the vPFC is involved in computations related to higher-order mechanisms beyond feature extraction, such as auditory-object processing, we hypothesize that a significant proportion of vPFC neurons do not have significant or predictive STRFs. In Aim #2, we test the selectivity of vPFC neurons for the spatial and non-spatial attributes of an auditory stimulus. Since the vPFC is thought to be part of a pathway involved in auditory-object processing, we hypothesize that vPFC neurons should be modulated preferentially by the non-spatial attributes of an auditory stimulus. We hypothesize that the ventrolateral prefrontal cortex are more selective for the non-spatial attributes of an auditory stimulus but only when monkeys attend selectively to these attributes. To test this hypothesis, we compare the selectivity of vPFC neurons to auditory stimuli when monkeys attend to changes in the spatial or non-spatial attributes of an auditory stimulus and (2) do not attend overtly to either of these attributes. In Aim #3, we test whether vPFC neurons respond to auditory and visual communication signals that convey similar information. We hypothesize that vPFC neurons will respond preferentially to stimuli that transmit complementary information. To test this hypothesis, vPFC activity is obtained while species-specific vocalizations and the visual images of the facial expressions that typically accompany or do not accompany the production of these vocalizations are presented.

Thesaurus Terms:
auditory feedback, auditory stimulus, neural information processing, neuron, prefrontal lobe /cortex, visual stimulus
neurophysiology, visual feedback, vocalization
Macaca mulatta, behavior test, computational biology, electrode

Office of Sponsored Projects
Fiscal Year: 2005
Project Start: 01-JUL-2005
Project End: 30-JUN-2010

Selectivity for the Spatial and Nonspatial Attributes of Auditory Stimuli in the Ventrolateral Prefrontal Cortex

Yale E. Cohen,1,2 Brian E. Russ,1 Gordon W. Gifford, III,1 Ruwan Kiringoda,1 and Katherine A. MacLean1

1Department of Psychological and Brain Sciences and 2Center for Cognitive Neuroscience, Dartmouth College, Hanover, New Hampshire 03755

Two female rhesus monkeys (Macaca mulatta) were used in these experiments. Both monkeys (weighing between 8.0 and 9.0 kg) were trained on both of the tasks described in this study. All surgical, recording, and training sessions were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and were approved by the Dartmouth Institutional Animal Care and Use Committee.

Surgical procedures
Surgical procedures were conducted under aseptic, sterile conditions using general anesthesia (isoflurane). These procedures were performed in a dedicated surgical suite operated by the Animal Resource Center at Dartmouth College.
In the first procedure, titanium bone screws were implanted in the skull, and a methyl methacrylate implant was constructed. A Teflon-insulated, 50 gauge, stainless-steel wire coil was also implanted between the conjunctiva and the sclera; the wire coil allowed us to monitor the monkey's eye position (Judge et al., 1980 ). Finally, a head-positioning cylinder (FHC-S2; Crist Instruments, Hagerstown, MD) was embedded in the implant. This cylinder connected to a primate chair and stabilized the monkey's head during behavioral training and recording sessions.
After the monkeys learned the behavioral tasks (see below), a craniotomy was performed, and a recording cylinder (ICO-J20; Crist Instruments) was implanted. This surgical procedure provided chronic access to the vPFC for neurophysiological recordings.

Experimental setup
Behavioral training and recording sessions were conducted in a darkened room with sound-attenuating walls. The walls and floor of the room were covered with anechoic foam insulation (Sonomatt; Auralex, Indianapolis, IN). When inside the room, the monkeys were seated in the primate chair and placed in front of a stimulus array; because the room was darkened, the speakers producing the auditory stimuli were not visible to the monkeys. The primate chair was placed in the center of a 1.2 m diameter, two-dimensional, magnetic coil (CNC Engineering, Seattle, WA) that was part of the eye position-monitoring system (Judge et al., 1980 ). Eye position was sampled with an analog-to-digital converter (PXI-6052E; National Instruments, Austin, TX) at a rate of 1.0 kHz. The monkeys were monitored during all sessions with an infrared camera

Please email:  YALE E. COHEN, yec@dartmouth.edu  to protest the inhumane use of animals in this experiment. We would also love to know about your efforts with this cause: saen@saenonline.org

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Rats, mice, birds, amphibians and other animals have been excluded from coverage by the Animal Welfare Act. Therefore research facility reports do not include these animals. As a result of this situation, a blank report, or one with few animals listed, does not mean that a facility has not performed experiments on non-reportable animals. A blank form does mean that the facility in question has not used covered animals (primates, dogs, cats, rabbits, guinea pigs, hamsters, pigs, sheep, goats, etc.). Rats and mice alone are believed to comprise over 90% of the animals used in experimentation. Therefore the majority of animals used at research facilities are not even counted.

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