Jeffrey J. Padberg - US grants

The goal of this study is to examine the organization of area 5 of in the posterior parietal cortex of New World titi monkeys. Historically, area 5 has been largely regarded as a somatosensory area, but recent data confirms that it is a bimodal visual and somatosensory area, with specialized functions for visually guided reaching with the forelimb. Nearby posterior parietal visual areas such as 7a, LtP and VIP have been explored with single and multiunit recording techniques, but the total extent and internal organization of area 5 has not been developed, and little is known about its connections pertaining to the reaching behavior described above. The titi monkey cortical fields are organized similarly to the macaque, but are more easily accessible due to the relatively fewer number of sulci in the posterior parietal region. In this study, multiunit electrophysiological recordings will be used to guide the placement of neuroanatomical tracers into area 5 of the titi monkey to examine the anatomical connections of area 5 with other visual and motor areas of the brain. Multiunit electrophysiology will also be used to examine the visual and somatosensory responses within area 5. Histochemical methods will also be used to determine the internal anatomical organization of area 5, and will be compared with the connectional and physiological data. This combination of multiunit electrophysiology with connectional and histochemical methods in the same animals is a novel and powerful approach.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Regions of posterior parietal cortex are important in all mammals, including humans, for navigating through, and manipulating objects in, their environment. We propose to characterize and compare the posterior parietal cortex of rats for later comparison with other mammalian species (e.g., opossum, squirrel, ferret, and raccoon), each of which has distinct forelimb morphology related to specific use. The aims of this study are 1) to determine the functional organization of posterior parietal cortex located between somatosensory and visual regions in rats using electrophysiological techniques, and 2) to determine the full extent of corticocortical and thalamocortical connections of these areas using neuroanatomical tracers combined with architectonic techniques. Our results in rats will be relevant to understanding the organization of other species because the organization of all mammalian brains is tightly governed by developmental constraints. A detailed understanding of how these brains areas are organized across mammalian species will allow us to better understand how these important brains regions that govern interactions with objects in the surroundings may be organized in humans. These studies will lay the groundwork for further behavioral studies involving experimental lesions, which will provide useful data for direct comparison to victims of stroke or traumatic brain injury. The proposed research will allow students to study in neurobiology laboratories at both the University of Central Arkansas and the National Center for Toxicological Research;and will establish collaborations between my primarily undergraduate institution and a federal laboratory, within the umbrella of INBRE, thus contributing to the crucial objective of promoting exceptional biomedical research in underrepresented institutions.

Understanding how brains become organized into specialized regions (touch, motor, vision, etc.) is essential to understanding how brains develop, as well as how they might be impacted and potentially repaired following developmental disorders or injuries. An effective strategy for acquiring a better understanding of brain organization involves examining mammals that possess unique body structures and behaviors. The goal of these studies is to characterize the organization and function of brain regions in the nine-banded armadillo (Dasypus novemcinctus), utilizing anatomical and electrophysiological recording methods. This project will reveal how mammalian nervous systems process specialized sensory inputs. Armadillos are covered in bony plates and are highly dependent upon their sense of hearing. These traits are expected to impact the brain regions responsible for touch, movement and hearing; understanding this relationship will shed light on analogous systems in other mammals such as humans. In addition to possessing sensory specializations, armadillos also uniquely give birth to identical quadruplets (basically clones), setting the stage for related neurodevelopmental studies with identical littermates for comparison, an ideal experimental situation unattainable with any other mammalian developmental model.

These studies will take place at the University of Central Arkansas and involve training undergraduate and master's students, many of whom are first generation college students, in cutting edge neurobiology research methods. Participating students will engage in the scientific process in a comprehensive hands-on manner, and gain research experience that will prepare them to pursue careers in neurobiology or other related STEM fields. The intense interest this work has generated in the pilot stages indicates that the incorporated educational outreach programs will help address a serious need for science education, particularly among Arkansas grade school students, where approximately 40% of those assessed perform below basic achievement levels (2011 Nation's Report Card, National Assessment of Educational Programs, U.S. Department of Education).