The prefrontal cortex (PFC) mediates higher order processes and behaviors including working memory, rule application, sustained attention, decision-making, and flexible and appropriate adaptation of behavior. These cognitive functions can be significantly affected by the administration of psychostimulants such as Methylphenidate (MPH), low doses of which are used to treat attention deficit hyperactivity disorder (ADHD). MPH increases catecholamine levels in the brain, including PFC. I am currently working on a manuscript describing work I have done in the lab showing that MPH affects PFC-mediated behaviors dose-dependently and affects behaviors differentially at different doses. With varying doses of MPH we can both improve and impair performance on working memory and task-switching. My thesis project will focus on understanding how MPH changes brain circuitry, including PFC and basal ganglia, to produce these behavioral changes and how the norepinephrine (NE) and dopamine (DA) systems contribute to these behaviors. This work has importance for extending our understanding of the basic science of higher control of behavior and its circuitry as well as clinical importance as this research will shed light on the mechanism of action of MPH and what dysfunction of circuitry is causing diseases such as ADHD and, therefore, have the potential to improve their treatment.
Abstracts and Publications:
- Populin LC and Rajala AZ. 2011. Target modality determines eye-head coordination in non-human primates: implications for gaze control. In press – J Neurophys.
- Rajala AZ and Populin LC. 2011. Methylphenidate-induced changes in PFC activity are correlated with altered task-switching performance. Soc. Neurosci. Abstr.
- Rajala AZ and Populin LC. 2011. Oculomotor task-switching and prefrontal cortex activity are affected by methylphenidate. Gordon Conference Abstr.
- Rajala AZ and Populin LC. 2011. Methylphenidate affects oculomotor task-switching and prefrontal cortex activity. Neural Control of Movement Abstr.
- Populin LC and Rajala AZ. 2010. Neural mechanisms underlying the allocation of spatial attention in the auditory modality within the superior colliculus. Soc. Neurosci. Abstr.
- Rajala AZ, Reininger KR, and Populin LC. 2010. Effects of methylphenidate of PFC-mediated task-switching behavior in monkeys. Soc. Neurosci. Abstr.
- Rajala, AZ, Reininger, KR, Lancaster, KM, and Populin, LC. 2010. Rhesus monkeys (Macaca mulatta) do recognize themselves in the mirror: implications for the evolution of self-recognition. PLoS one. 5(9). pii: e12865. PMCID: PMC2947497.
- Populin, LC and Rajala, AZ. 2010. Timecourse of allocation of spatial attention by acoustic cues in non-human primates. Eur. J. Neurosc. 32(6): 1040-1048. PMCID: PMC2943018
- Rajala AZ and Populin LC. 2010. Allocation of spatial attention in the auditory modality: behavioral effects and neural correlate. Neural Control of Movement Abstr.
- Zdrale A, Meier TB, Berridge CW, and Populin LC. 2008. Effect of methylphenidate on monkey prefrontal cortex-mediated behavior. Soc. Neurosci. Abstr.