Identifying the Neurocognitive Determinants of HIV-Risk Behaviors
Landenberger Foundation (Marvel, PI)
National Institute on Drug Abuse (Marvel, PI)
Investigating the Motor System's Contribution to Cognitive Function
Funded in part by the Macklin Foundation
Motor System's Support of Working Memory
Our research has shown that, in healthy adults, areas of the brain used for motor function (motor planning and preparation) are highly active when holding information in mind over seconds. This suggests that the brain is rapidly creating a motor representation of this information, perhaps to form a redundant copy that strengthens the memory trace.
We found that one's ability to hold information in mind is challenged when the brain's motor pathway is disrupted (using brain stimulation methods).
Cognition in Addiction (Hyperactive Motor-Cognitive Interplay)
The extent to which brain structure, and cognition, is restored following drug abstinence is not well known in those with a history of heroin dependence. Our research has shown that even when heroin users abstain for several months, their pattern of brain activity is unusually active during working memory, especially in the cerebellum and amygdala. This suggests the brain has to work harder than usual to keep up with everyday working memory demands. This struggle to keep up also means it is exhausted sooner, relative to that of a healthy brain -- leading to working memory problems in those with a history of heroin dependence.
Cerebellar Ataxia: Exploring Cognitive and Motor Deficits
Cerebellar ataxia is a degenerative and progressive disorder that can be genetic. Neurons in the cerebellum begin to die off, leading to severe motor impairments: unsteady gait (requiring a walker or wheelchair), uncoordinated fine motor control (e.g., inability to write), dysarthric speech (can be incomprehensible), and abnormal eye movements (e.g., nystagmus). In addition to motor impairments, patients also complain of poor working memory, an inability to multi-task, and word finding difficulties. This line of research explores cognitive deficits in ataxia. Specifically, we are interested in understanding how the cerebellum contributes to cognitive processes, and how these processes are affected by cerebellar dysfunction.
Addiction & HIV: How a learned reward can influence risky behavior.
Rewarding stimuli command one's attention. The ability to ignore a learned reward is critical to behavioral control over impulsive, risky decisions. This line of research uses brain imaging to examine what parts of the brain are affected by attentional bias for learned reward in two populations that tend to engage in risky behaviors: HIV positive individuals, and those with opioid dependence.