Abstract: Although decline in cognitive functions is often observed with aging, language functions show a pattern of both impaired and spared performance. Semantic processes, such as vocabulary, are well maintained throughout adulthood. In contrast, older adults show impairments in phonological aspects of language production such as in increased slips of the tongue and increased pauses during speech. This asymmetric pattern suggests a fundamental difference in the cognitive and neural organization of these two language abilities. In this talk, I will discuss our work which has looked at semantic and phonological decisions, as well as more recent work that has examined inherent aspects of words, such as phonological and semantic neighborhood densities. Our work examines how cognition, behavior, and neural factors relate to each other and how they contribute to language function in healthy younger and older adults.

Bio: Professor Michele Diaz, PhD is currently Associate Professor of Psychology and Linguistics as well as Director of Human Imaging, at the Social, Life, & Engineering Sciences Imaging Center (SLEIC) at Pennsylvania State University. Previously, she has used electrophysiology to examine how semantic and phonological processes interact during spoken language comprehension. Using functional Magnetic Resonance Imaging (fMRI), she has investigated the neural substrates of orthographic, lexical, and semantic aspects of visual word processing, and the influence of conscious perception on the engagement of brain regions that support these processes. Finally, her involvement with the Biomedical Informatics Research Network (BIRN) project has allowed her to explore technical issues related to multi-site imaging, such as quality assurance measures and reliability. This experience facilitates her current role as the Director of Human Imaging at the Social, Life, and Engineering Sciences Imaging Center. 

Visitors from UCHC are encouraged to use the UCHC-Storrs shuttle service. Talks can also be joined remotely. Please contact us if you are interested in meeting with the speaker.

Abstract: Performing sequential tasks such as making your breakfast are an integral part of daily life. The majority of previous studies have focused on motor sequences or non-sequential abstract control, rather than these kinds of more abstract sequential tasks. Our work using high-density multi-electrode chronic recordings in nonhuman primates has shown that an integrated cost-benefit signal in the striatum predicts the acquisition of habitual motor sequences. To move beyond motor sequences and address this gap in our knowledge of more abstract sequential tasks, we asked human participants to repeatedly perform simple four-item sequences of shape and color judgments during fMRI scanning. We found a novel dynamic in the rostrolateral prefrontal cortex (RLPFC), where activation ramped up across the four items in each sequence and reset at the beginning of each new sequence. Transcranial magnetic stimulation (TMS) to RLPFC during the same task selectively produced an increasing pattern of errors as each sequence progressed, mirroring the fMRI activation. Effects in the RLPFC during fMRI and two independent TMS experiments dissociated from two other prefrontal control regions. These results show that RLPFC is necessary for sequential control and resolution of uncertainty during sequence performance. Current work focuses on dissociating some of the processes that underlie sequential task control: task execution, sequential monitoring, and sequence memory. Recent results show that ramping in the RLPFC is robust to changes in sequential stimuli and monitoring conditions, suggesting that these dynamics in the frontal cortex may be a common mechanism for tracking sequential information. New studies are focusing on investigating frontal cortical dynamics during sequential control in parallel nonhuman primate fMRI and multi-electrode recordings.

Bio: Dr. Theresa Desrochers is currently Assistant Professor in the Departments of Neuroscience and Psychiatry & Human Behavior at Brown University. She earned her PhD in Neuroscience from the Massachusetts Institute of Technology in 2011. There she trained with Dr. Ann M. Graybiel and co-developed a new method of performing high-density, reconfigurable recordings on awake-behaving nonhuman primates. For her postdoctoral fellowship, Dr. Desrochers worked with Dr. David Badre at Brown University where she discovered a novel brain dynamic that was necessary for the sequential executive functions. Dr. Desrochers joined the faculty of the Department of Neuroscience at Brown University in the fall of 2016. The Desrochers lab uses human and nonhuman primate models to investigate the neural underpinnings of sequential control. Work in the lab focuses on explicitly addressing these questions using a cross-species approach, which is rare in both human and nonhuman primate research. Current experiments are focused on using nonhuman primate fMRI, a technique that only a few labs are able to use, to explicitly bridge between human fMRI and nonhuman primate neural recordings and directly examine functional homology between the species.

Visitors from UCHC are encouraged to use the UCHC-Storrs shuttle service. Talks can also be joined remotely. Please contact us if you are interested in meeting with the speaker.