Scott H. Frey - US grants

DESCRIPTION (provided by applicant): Scott H. Johnson, Ph.D. was trained as a cognitive psychologist and has established an active research program in object perception and prehension. The purpose of this award is to allow Scott to develop additional knowledge, skills and experience necessary to pursue both the behavioral and neural bases of these processes. This goal will be undertaken with the support and supervision of sponsor Scott G. Grafton and co-sponsors Nancy G. Kanwisher, Andrew Barto. Functional MRI, and psychophysical studies will take place at the the Center for Cognitive Neuroscience at Dartmouth College where Scott is currently a Research Assistant Professor. Additional training will be pursued through Dr. Barto?s computational motor lab at the University of Massachusetts and Dr. Kanwisher?s lab at M.I.T. The proposed research plan describes a series of studies designed to increase our understanding the contributions of the human ventral and dorsal visual streams to the planning of visually-guided actions; i.e., tool prehension and manipulation. These experiments employ a variety of strategies (event-related fMRI, psychophysics, and computational modeling) to evaluate hypotheses motivated both by computational considerations and what is currently known about the functional architecture of the visual and motor systems. It is well-established that extrastriate visual areas of primates are organized into two primary streams of processing: an occipital-temporal (i.e., ventral) stream, and an occipital-parietal (i.e., dorsal) stream. Reciprocal connections exist between areas within these streams, and both pathways provide visual input to regions of prefrontal cortex that are involved in working memory and planning. At present, the functional significance of this organization for human behavior is not well-understood, and remains a source of active debate. Recent evidence from electrophysiology and neuroimaging point to the inadequacies of current theories, and suggest that areas within both streams may be considerably more interactive than previously supposed. Based on preliminary results, the present studies will evaluate an alternative model in which areas within the human dorsal and ventral streams are said to interact directly--via reciprocal interconnections, and/or indirectly-- through feedback from the prefrontal structures, during action planning.

[unreadable] DESCRIPTION (provided by applicant): As modern humans, a vast number of our daily activities (e.g., cooking and eating, writing, brushing teeth, etc.) involve the skillful use of manual tools and utensils. Thus, the consequences of brain injuries or diseases that compromise these behaviors are often devastating. Yet, strikingly little is known about the neural mechanisms responsible for these abilities. The overarching goal of this project is to advance our understanding of these neural mechanisms and the roles they play in activities of daily living (ADLs). Rapid, event-related, functional magnetic resonance imaging (fMRI) is used to achieve three specific aims that arise from a neurally-plausible model of tool use in human and non-human primates: 1) determine the relationship between neural representations involved in manual prehension versus grasping with a mechanical "hand," and specify how these change with experience. 2) Determine the neural substrates involved in grasping objects on the basis of their 3-D structural properties versus knowledge of their functions and uses. 3) Determine the cerebral organization of everyday uni- and bi-manual tool use skills and their relationship to well-established skills that do not involve tools. These studies address a fundamental aspect of everyday human behavior, tool use, that has been all but overlooked in the mainstream psychological and neuroscience literatures. Our techniques distinguish effectively between processes involved in action organization (planning) versus execution. Emphasis is placed on identifying reliable individual differences in neural representations as well as common features in group data. Left-handed as well as right-handed participants are included. Left-handers are often neglected in behavioral and functional imaging research, yet the way that they acquire and represent manual skills may differ from right-handers in ways that are of both theoretical and clinical importance. Results of this work will have relevance to understanding and improving the rehabilitation of injuries/diseases that compromise (ADLs) involving tools and other manipulable objects, including: Cerebral Vascular Accidents (CVAs), spinal cord injuries, Multiple Sclerosis (MS), and Parkinson's Disease (PD). Results are also relevant to the development of cognitive neuroprostheses and other assistive technologies. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): In modern neuroscience, the notion that the functional organization of sensory and motor cortex is dynamic-- changing in response either to increases or decreases in stimulation, is axiomatic. This has become a guiding principle of neurorehabilitation. Some of the earliest and most influential evidence for this plasticity comes from demonstrations of dramatic reorganization within the sensory and motor cortices of non-human primates following amputations (or other injuries to the peripheral nerves or spinal cord) that disrupt communications between the hand and brain. These findings are complimented by non-invasive neuroimaging demonstrations of extensive reorganization in human amputees. Together these observations are foundational to the prevailing view that cortical representations are activity-dependent, with their organization maintained through competitive interactions. Data indicating that increased stimulation (practice) induces functionally relevant changes in cortical organization are plentiful. By contrast, it remains unclear whether the reorganizational changes that follow injury-related decreases in activity in the intact brain are adaptive, maladaptive, or functionally irrelevant. Our overarching goal is to address this fundamental scientific, and broadly clinically relevant, issue in current and former hand amputees who have received hand replants. Our approach combines functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to determine changes occurring within the former hand territory, and behavioral testing to establish their functional relevance. Aim 1: Evaluate the functional relevance of cortical map reorganization within amputees' former hand territories. Issue A) What is the relationship between the expansion of the face map into the former hand territory and neuropathic (phantom) pain? Issue B) What is the relationship between the expansion of maps of the face, residual limb and intact hand into the former hand territory and sensibility? Issue C) Does cortical reorganization underlie non-painful tactile sensations referred from touch on other body regions to the missing limb? Aim 2: Establish the functional relevance of reorganizational changes in the cortical representation of amputees' intact hands following chronic forced use. Issue A) How does chronic forced use of the non-dominant hand affect performance? Issue B) What is the relationship between recruitment of the former hand territory during use of the intact hand and performance? Issue C) Is increased activity within the former hand territory causally involved in performances of the intact non-dominant hand? Aim 3: Determine the extent to which amputation-related cortical reorganization is reversed following hand replantation and elucidate the relevance of these changes to recovery of function. Issue A): Is recovery of function associated with re-establishing the hand map within the former hand territory? Issue B) Is the reversal of reorganizational changes within the former hand territory related to recovery?

DESCRIPTION (provided by applicant): In modern neuroscience, the notion that the functional organization of sensory and motor cortex is dynamic-- changing in response either to increases or decreases in stimulation, is axiomatic. This has become a guiding principle of neurorehabilitation. Some of the earliest and most influential evidence for this plasticity comes from demonstrations of dramatic reorganization within the sensory and motor cortices of non-human primates following amputations (or other injuries to the peripheral nerves or spinal cord) that disrupt communications between the hand and brain. These findings are complimented by non-invasive neuroimaging demonstrations of extensive reorganization in human amputees. Together these observations are foundational to the prevailing view that cortical representations are activity-dependent, with their organization maintained through competitive interactions. Data indicating that increased stimulation (practice) induces functionally relevant changes in cortical organization are plentiful. By contrast, it remains unclear whether the reorganizational changes that follow injury-related decreases in activity in the intact brain are adaptive, maladaptive, or functionally irrelevant. Our overarching goal is to address this fundamental scientific, and broadly clinically relevant, issue in current and former hand amputees who have received hand replants. Our approach combines functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to determine changes occurring within the former hand territory, and behavioral testing to establish their functional relevance. Aim 1: Evaluate the functional relevance of cortical map reorganization within amputees' former hand territories. Issue A) What is the relationship between the expansion of the face map into the former hand territory and neuropathic (phantom) pain? Issue B) What is the relationship between the expansion of maps of the face, residual limb and intact hand into the former hand territory and sensibility? Issue C) Does cortical reorganization underlie non-painful tactile sensations referred from touch on other body regions to the missing limb? Aim 2: Establish the functional relevance of reorganizational changes in the cortical representation of amputees' intact hands following chronic forced use. Issue A) How does chronic forced use of the non-dominant hand affect performance? Issue B) What is the relationship between recruitment of the former hand territory during use of the intact hand and performance? Issue C) Is increased activity within the former hand territory causally involved in performances of the intact non-dominant hand? Aim 3: Determine the extent to which amputation-related cortical reorganization is reversed following hand replantation and elucidate the relevance of these changes to recovery of function. Issue A): Is recovery of function associated with re-establishing the hand map within the former hand territory? Issue B) Is the reversal of reorganizational changes within the former hand territory related to recovery?