Gordon C. Baylis - US grants

This project is an investigation into the role of the medial lobe of the primate brain in memory. Three experimental paradigms will be used in a multidisciplinary approach to this subject. There are: behavioral testing of monkeys with selective brain lesions, electrophysiological recording of single unit activity, and anatomical investigation of the medial temporal lobe. The project centers around five main aims. 1) A computerized version of the Wisconsin General Test Apparatus will be developed to assess the effect of lesions to the hippocampus and overlying cortex on performance of a number of memory tasks. The new apparatus will allow precise measurement of hand and eye position to be made, leading to an understanding of the difficulties faced by lesioned animals at a much more precise level than has been in previous studies. 2) New techniques of analysis of neuronal responses will be developed in order to understand the computations performed at the neuronal level. These include methods of looking at temporal patterning in individual spiketrains, and methods of understanding neuronal responses at the level of the whole population of neurons. 3) The activity of single neurons in the hippocampus will be recorded in awake, behaving monkeys sets of tasks which test memory, discriminative etc., including those shown to be performed poorly after lesions of this region. 4) Neuronal activity will be related to visuospatial and motor-spatial aspects of tasks, in order to understand the relation of the hippocampus to the representation of space, and to understand the relation of spatial deficits and deficits in other tasks. 5) Anatomical investigations will proceed to outline the relation of different types of neurons, defined in terms of responsiveness, to different anatomical subareas. Tracer substances such as horseradish peroxidase, nuclear yellow and true blue will be injected into subregions which have been identified physiologically in that particular animal, in order to trace the interconnections of subregions related to certain aspects of task performance. By bringing together a number of different techniques, this study will attempt to explicate anatomical ("hardware") and neuronal ("software") constraints on the actual processing of information performed by the brain.

This project is an investigation into the role of the medial lobe of the primate brain in memory. Three experimental paradigms will be used in a multidisciplinary approach to this subject. There are: behavioral testing of monkeys with selective brain lesions, electrophysiological recording of single unit activity, and anatomical investigation of the medial temporal lobe. The project centers around five main aims. 1) A computerized version of the Wisconsin General Test Apparatus will be developed to assess the effect of lesions to the hippocampus and overlying cortex on performance of a number of memory tasks. The new apparatus will allow precise measurement of hand and eye position to be made, leading to an understanding of the difficulties faced by lesioned animals at a much more precise level than has been in previous studies. 2) New techniques of analysis of neuronal responses will be developed in order to understand the computations performed at the neuronal level. These include methods of looking at temporal patterning in individual spiketrains, and methods of understanding neuronal responses at the level of the whole population of neurons. 3) The activity of single neurons in the hippocampus will be recorded in awake, behaving monkeys sets of tasks which test memory, discriminative etc., including those shown to be performed poorly after lesions of this region. 4) Neuronal activity will be related to visuospatial and motor-spatial aspects of tasks, in order to understand the relation of the hippocampus to the representation of space, and to understand the relation of spatial deficits and deficits in other tasks. 5) Anatomical investigations will proceed to outline the relation of different types of neurons, defined in terms of responsiveness, to different anatomical subareas. Tracer substances such as horseradish peroxidase, nuclear yellow and true blue will be injected into subregions which have been identified physiologically in that particular animal, in order to trace the interconnections of subregions related to certain aspects of task performance. By bringing together a number of different techniques, this study will attempt to explicate anatomical ("hardware") and neuronal ("software") constraints on the actual processing of information performed by the brain.

With National Science Foundation support Dr. John Richards and his collaborators at the University of South Carolina will purchase instrumentation necessary to establish a high-density EEG/ERP recording laboratory in the Department of Psychology. High-density EEG/ERP recording is a recently developed technique in which 128 electrodes are used to record scalp electrical potentials. These changes are hypothesized to be related to specific events in the cortex that in turn are closely related to psychological processes. The instrumentation allows the testing of cortical source generators and will be used for research and research training in cognitive psychology and cognitive neuroscience. The System has three components: 1. A NetAmps recording system and ancillary equipment made by Electrical Geodesics Inc. for high-density acquisition of EEG and ERP; 2. Software for source modeling of the cortical potentials; 3 related equipment including a computer for experimental testing, network switches to provide a virtual laboratory to allow access to the EEG/ERP equipment. Support is also provided to personnel to aid in the installation and maintenance of the equipment and laboratory.

The scientists with primary access to the instrumentation are involved in research and research training in the study of the neural basis of behavior and cognition and engage in hypothesis driven basic scientific research. Topics include reading, attention and perception, the development of the brain and brain control of attention and object cognition. It will be possible for example to study the psychophysiology of attention in infants aged 2 to 6 months and gain insight into the cortical processing involved in reading. The University of South Carolina Department of Psychology currently runs an NSF Summer Research Institute for Undergraduates and students will be permitted to participate in experiments which utilize this instrumentation. It will also be available for teaching and research purposes to both graduates and undergraduates.

The University of South Carolina Summer Research Institute in Experimental Psychology has provided and will continue to provide a mechanism for educating undergraduate students about the field of experimental psychology. Many students, including students from underrepresented minorities, are drawn to applied psychology programs. The intent of the Institute, in contrast, is to focus student interest and enthusiasm on the basic science areas of psychology. The eight-week USC Summer Research Institute will permit well-qualified minority and non-minority undergraduate students majoring in a behavioral science an experience in graduate-level research, including an opportunity to formulate and conduct an experiment with individual guidance from an energetic and supportive research faculty mentor. The student will participate in major phases of experimental research, including literature review, hypothesis generation, data collection, data organization, statistical analysis and report writing in the style of American Psychological Association journals. Student experiences will be enriched by weekly research seminars, in which assigned readings will be discussed, and by weekly sessions on problems of research design and statistics in experimental psychology. Students will receive gratis course credit for their work. This program emphasis is much needed, as the U.S. is perceived to be the leader in the field of experimental psychology, and our universities must be able to motivate and train the best students for future careers in vital areas of behavioral science. This Summer Institute will continue to provide one vehicle to enhance these goals.

DESCRIPTION (provided by applicant): This project seeks to understand the common deficits of attention that result from unilateral brain damage caused by strokes or other injuries. Deficits of attention can lead to grave consequences during rehabilitation, and predispose patients to falls, with attendant complications and mortality. Despite the seriousness of deficits such as extinction and neglect, and the fact that they have been described for more than a century, they are poorly understood. Extinction refers to an inability to attend to, or perceive, stimuli on the side of space opposite to the site of a lesion (i.e., contralesional stimuli) when a stimulus is present in the unaffected side of space, ipsilateral to the lesion. Extinction can occur in vision, audition, tactile sense, and even gustation, but it is not known whether similar causes underlie it in different modalities. A major problem in understanding extinction is that subtle changes in the method of testing may lead to major differences in the clinical impression of a given patient. Specifically, this project will test a new theory of how brain damage may lead to the phenomenon of extinction, although the results of this study will generalize to other deficits of attention. The present theory proposes that extinction in vision, audition and taction following cortical lesions, arises when the identity and location of stimuli cannot be bound together. This proposal will be tested using behavioral tasks that require patients to bind both these aspects of stimuli together, and tasks that do not. It is predicted that tasks that require binding will lead to much higher error rates than tasks that do not. It is suggested that a major source of inconsistency in clinical testing is that some tests make lower demands on binding than others, leading to great differences in the detected levels of inattention. A novel aspect of the present study is that visual, auditory and tactile extinction will all be tested using analogous tasks so that the general principles of our theory can be tested? Inherent in this view of extinction is the proposal that attentional failure arises independently within each perceptual modality, that, for example, visual extinction occurs as a binding failure of visual information. This contrasts with a view that overall unilateral inattention will lead to extinction in all modalities, and predicts that most patients will have extinction in only one or two modalities. The occasional co-existence of, say, visual and auditory extinction will be expected simply because areas crucial for auditory binding may be physically close to those crucial for visual binding, thus be affected by a single large lesion.

The University of South Carolina Summer Research Institute in Experimental Psychology has provided and will continue to provide a mechanism for educating undergraduate students about the field of experimental psychology. Many students, including students from underrepresented minorities, are drawn to applied psychology programs. The intent of the Institute, in contrast, is to focus student interest and enthusiasm on the basic science areas of psychology. The eight-week USC Summer Research Institute will permit well-qualified minority and non-minority undergraduate students majoring in a behavioral science an experience in graduate-level research, including an opportunity to formulate and conduct an experiment with individual guidance from an energetic and supportive research faculty mentor. The student will participate in major phases of experimental research, including literature review, hypothesis generation, data collection, data organization, statistical analysis and report writing in the style of American Psychological Association journals. Student experiences will be enriched by weekly research seminars, in which assigned readings will be discussed, and by weekly sessions on problems of research design and statistics in experimental psychology. Students will receive gratis course credit for their work. This program emphasis is much needed, as the U.S. is perceived to be the leader in the field of experimental psychology, and our universities must be able to motivate and train the best students for future careers in vital areas of behavioral science. This Summer Institute will continue to provide one vehicle to enhance these goals.

This award contributes to the Foundation's continuing efforts to attract talented students into careers in science through active undergraduate research experiences.