Emily L. Morrow - US grants

PROJECT SUMMARY Word learning relies heavily on memory systems and processes that are routinely impaired in traumatic brain injury (TBI) (e.g., the declarative memory system). The ability to learn new words and concepts is critical to a person?s potential to benefit from therapy or engage in academic, vocational, and interpersonal spheres. However, the nature and severity of word learning deficits in TBI are unknown. Examining word learning over time following TBI is particularly critical given advances in the cognitive neuroscience literature linking sleep to memory and learning in healthy individuals. Although approximately half of individuals with TBI report sleep disturbance, the role of sleep in learning following TBI has not been tested. The proposed study will be the first investigation of word learning over time after TBI and will break new ground in examining how sleep affects learning after injury. Our approach is novel to the field and bridges theories of psycholinguistics, cognitive neuroscience of memory, and rehabilitation in TBI. We combine well-established word learning protocols with the novel use of actigraphy as an objective measure of sleep. Individuals in the chronic phase of moderate- severe TBI and demographically-matched non-injured healthy comparison (NC) peers will train on a group of novel words, then be assessed immediately on their encoding of those words. Next, they will participate in ongoing assessment of their consolidation of the novel words over regular time intervals that do or do not involve sleep. In Aim 1, we will test the hypothesis that word learning is impaired following TBI by contrasting group word learning performance at an immediate post-test. In Aim 2, we will determine if individuals with TBI get a similar sleep-learning benefit to NC peers by comparing performance at post-tests with and without an interim period of sleep. In exploratory Aim 3, we will examine the relationship between sleep, as measured over time via actigraphy, and word learning in the short (24 hour post-test) and long (1 week post-test) term. Exploring sleep?s role as a mediator of learning after TBI will improve basic knowledge of the causal relationships between TBI, sleep, and word learning. These findings will advance theoretical and clinical knowledge about sleep, memory, and learning in TBI and will directly contribute to our long-term goal of refining clinical management of learning deficits for improved functional outcomes after injury. Because memory and learning are critical to an individual?s ability to benefit from intervention, understanding sleep?s role in supporting learning could underlie future trials of both direct sleep interventions and targeted therapy schedules for improved learning across domains. This project represents a novel direction in TBI research, presents a unique training opportunity for the PI, and is the first step in a programmatic line of research focused on improving basic and clinical knowledge of memory and learning after TBI, with direct implications for improved therapy outcomes, community reintegration, and independence.