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Principal Investigator: ERIC F MOOSHAGIAN
Organization: UNIVERSITY OF CALIFORNIA, SAN DIEGO
Fiscal Year: 2024
Award: $415,766
Funding agency: National Institute of Neurological Disorders and Stroke
Abstract The central goal of this proposal is to understand the neural systems subserving the decision to
use the left or right hand1 – a simple choice that is central to our daily functions. Here we focus on parietal
mechanisms of limb selection. Despite it being one of the most common decisions faced in everyday behavior,
a largely neglected aspect of decision making is deciding which hand to use to achieve a goal. For instance,
when deciding which hand to use to flip a light switch upon entering a room, the choice is influenced by many
factors. These factors include what each hand is already doing (e.g, holding a phone), proximity of each hand
to the switch, and future goals (e.g., desire to subsequently pick up an object with a particular hand). Our long-
term goals are to elucidate the fundamental mechanisms of limb selection and movement coordination.
Because limb selection is present in most behaviors, this work will provide insights broadly applicable to motor
control. The posterior parietal cortex (PPC) is known to be involved in the planning and control of actions in an
effector-specific manner. An emerging concept is that the same PPC regions that are involved in movement
preparation and control also participate in action selection. We recently demonstrated that a parietal region
known to contribute to the planning of arm movements and dubbed “the parietal reach region” (PRR), codes
the spatial targets for reaches with the contralateral arm but receives information about the ipsilateral arm from
the opposite hemisphere. PRR has also been implicated in the decision to reach versus saccade to a spatial
target. In our first aim, we characterize limb selection behavior and determine the factors that drive limb
selection. In our second aim we test the hypothesis that PRR is involved in limb selection during unimanual
reaching. Next, we examine interhemispheric communication as a function of limb choice. Finally, we use
reversible inactivation of the callosal fibers connecting PRR in each hemisphere to determine the role of
interhemispheric competition in determining which limb to use. Collectively, these studies will have a broad
impact on the field by illuminating the roles of PPC and callosal connections in a fundamental choice motor
behavior. The results will lay the foundation for future studies that probe the larger bilateral frontoparietal
network involved in movement control. The work may inform rehabilitation approaches for patients with
neurological disorders including stroke and traumatic brain injuries in whom limb use is affected.
1 We will use the terms limb, arm, and hand interchangeably.
Terms: <Affect><Animals><Apoplexy><Attention><Behavior><Bilateral><Biomechanics><Brain><Brain Nervous System><Brain Trauma><Brain Vascular Accident><Cell Communication and Signaling><Cell Signaling><Cerebral Stroke><Cerebrovascular Apoplexy><Cerebrovascular Stroke><Code><Coding System><Communication><Contralateral><Corpus Callosum><Corpus Callosums><Decision Making><Dimensions><Encephalon><Experimental Designs><Extremities><Eye><Eyeball><Face><Fiber><Foundations><Future><Goals><Hand><Hand functions><Handedness><Intracellular Communication and Signaling><Ipsilateral><Laterality><Left><Lidocaine><Light><Lignocaine><Limb structure><Limbs><Macaca><Macaque><Maps><Measures><Mediating><Mediation><Medical Rehabilitation><Monkeys><Motion><Motor><Movement><Negotiating><Negotiation><Nerve Cells><Nerve Unit><Nervous System Diseases><Nervous System Disorder><Neural Cell><Neurocyte><Neurologic Disorders><Neurological Disorders><Neurons><Non-Trunk><Parietal><Parietal Lobe><Patients><Phone><Photoradiation><Physiologic><Physiological><Physiology><Position><Positioning Attribute><Preparation><Rehabilitation><Rehabilitation therapy><Research><Role><Saccades><Saccadic Eye Movements><Saccadic Pursuit><Signal Transduction><Signal Transduction Systems><Signaling><Stimulus><Stroke><System><Telephone><Testing><Time><Training><Traumatic Brain Injury><Using hands><Work><arm><arm movement><biological signal transduction><biomechanical><body movement><brain attack><cerebral vascular accident><cerebrovascular accident><daily functioning><faces><facial><hands><insight><motor behavior><motor control><neglect><neural><neurological disease><neuronal><non-human primate><nonhuman primate><parietal cortex><preference><preparations><rehab therapy><rehabilitative><rehabilitative therapy><response><social role><stroked><strokes><traumatic brain damage><visual motor><visuomotor>