CEREBBRAL Center Seminar

Tuesday, September 20, 2016
LYLE 1028
12:30 pm

Speaker:  Sebastien Helie, Ph.D.

“A dopamine-based account of cognitive deficits in Parkinson’s disease”

ABSTRACT:

Parkinson’s disease (PD) is caused by the accelerated death of dopamine(DA) producing neurons.  Numerous  studies  documenting  cognitive deficits  of  PD  patients  have  revealed impairments  in  a  variety of  tasks  related  to  memory,  learning,  visuospatial  skills,  and attention.  While  there  have  been  several  studies  documenting cognitive  deficits  of  PD patients,  very  few  computational models have  been  proposed.  In  this  article,  we  use  the COVIS  model of category  learning  to  simulate  DA  depletion  and  show  that the model suffers  from cognitive symptoms similar to those of human participants  affected by PD. Specifically, DA depletion in COVIS produced deficits in rule-based categorization, non-linear information integration categorization, probabilistic classification, rule maintenance,  and  rule  switching.  These  were  observed  by simulating  results  from younger controls, older controls, PD patients, and severe PD patients in five well-known tasks. Differential performance  among  the  different age  groups  and clinical populations was modeled simply by changing the amount of DA available in the model. This suggests that  COVIS  may  not  only  be an  adequate model  of  the simulated  tasks  and  phenomena but also more generally of the role of DA in these tasks and phenomena.

Wednesday, October 5th, 2016
LYLE 1024
9:00 a.m.

Speaker:  Ulrike Dydak, Ph.D.

Brain GABA levels change with Welding Fume Exposure : A Longitudinal Neuroimaging Study

ABSTRACT:

Chronic high exposure to welding fumes containing the metal manganese (Mn) is a risk factor to develop a Parkinsonian disorder. But how high is “high”? Having been intrigued by significantly altered GABA levels in the brains of Chinese smelters exposed to Mn, we embarked to establish a local cohort of welders, working under typical U.S. exposure conditions, and follow them longitudinally – The “Wabash Study”. This talk will give an overview of the results four years into this study, in which we follow the welders with personal air sampling, exposure modeling, measures of biomarkers (toenails), cognitive and motor testing, and novel neuroimaging techniques to assess brain Mn and brain iron levels, changes in brain volume, as well as metabolic and neurotransmitter changes in the brain – in particular basal ganglia GABA levels and dopamine function. We have found strong relations between imaging markers such as brain Mn and GABA levels to exposure, but also to effects such as motor and cognitive impairment. Further, we could show that GABA levels only rise above a certain threshold of exposure, and are reversible with decreasing exposure levels. A population of idiopathic Parkinson Disease (IPD) patients, undergoing all the same study procedures, has been compared to the welders as positive control group to learn more about the similarities and differences of Mn toxicity to IPD.

Speech, Language, & Hearing Sciences, Lyles-Porter Hall, 715 Clinic Drive, West Lafayette, IN 47907-2122, PH: (765) 494-3789

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