Browsing by Author "Zauber, S. Elizabeth"
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Item The association of bone, fingernail and blood manganese with cognitive and olfactory function in Chinese workers(Elsevier, 2019-05-20) Rolle-McFarland, Danelle; Liu, Yingzi; Mostafaei, Farshad; Zauber, S. Elizabeth; Zhou, Yuanzhong; Li, Yan; Fan, Quiyan; Zheng, Wei; Nie, Linda H.; Wells, Ellen M.; Neurology, School of MedicineOccupational manganese (Mn) exposure has been associated with cognitive and olfactory dysfunction; however, few studies have incorporated cumulative biomarkers of Mn exposure such as bone Mn (BnMn). Our goal was to assess the cross-sectional association between BnMn, blood Mn (BMn), and fingernail Mn (FMn) with cognitive and olfactory function among Mn-exposed workers. A transportable in vivo neutron activation analysis (IVNAA) system was designed and utilized to assess BnMn among 60 Chinese workers. BMn and FMn were measured using inductively coupled plasma mass spectrometry. Cognitive and olfactory function was assessed using Animal and Fruit Naming tests, World Health Organization/University of California-Los Angeles Auditory Verbal Learning Test (AVLT) and the University of Pennsylvania Smell Identification Test (UPSIT). Additional data were obtained via questionnaire. Regression models adjusted for age, education, factory of employment, and smoking status (UPSIT only), were used to assess the relationship between Mn biomarkers and test scores. In adjusted models, increasing BnMn was significantly associated with decreased performance on average AVLT scores [β (95% confidence interval (CI)) = -0.65 (-1.21, -0.09)] and Animal Naming scores [β (95% CI) = -1.54 (-3.00, -0.07)]. Increasing FMn was significantly associated with reduced performance measured by the average AVLT [β (95% CI) = -0.35 (-0.70, -0.006)] and the difference in AVLT scores [β (95% CI) = -0.40 (-0.77, -0.03)]. BMn was not significantly associated with any test scores; no significant associations were observed with Fruit Naming or UPSIT tests. BnMn and FMn, but not BMn, are associated with cognitive function in Mn-exposed workers. None of theItem Cortex – basal ganglia synchronization in Parkinson’s disease(Office of the Vice Chancellor for Research, 2014-04-11) Zauber, S. Elizabeth; Ahn, Sungwoo; Worth, Robert M.; Witt, Thomas C.; Rubchinsky, Leonid L.Increased synchrony in the beta band in cortico-basal ganglia circuits is well described in patients with PD. Less is known, however, about how these abnormal firing patterns are correlated across these brain regions. In this study we investigated how this intra-operative data recorded from STN correlates with scalp recorded EEG. Intraoperative single unit recordings and LFPs were obtained from STN and scalp EEG recordings were collected from four electrodes positioned over prefrontal and motor areas. We computed the STN spike-LFP (Local Filed Potential) phase synchrony over short temporal windows as it fluctuates in time. We also computed the EEG phase synchrony index time series for all 6 pairs of EEG electrodes. Next we explored cross-correlation between the two synchrony level time-series of the spike-LFP vs. EEG pairs. EEG synchrony was found to be correlated with spike-LFP synchrony. Correlation between surface EEG and STN was strongest for ipsilateral EEG and STN recordings. Spike-LFP synchronization is believed to characterize the input-output characteristics of STN dynamics and to be strongly relevant to the expression of motor symptoms. Our results indicate that non-invasive and relatively simple EEG recordings retain some information about synchronous dynamics in the subcortical regions, which can be access only in an invasive manner during functional neurosurgical procedures.Item Interaction of synchronized dynamics in cortical and subcortical circuits in Parkinson’s disease(Office of the Vice Chancellor for Research, 2015-04-17) Ahn, Sungwoo; Zauber, S. Elizabeth; Worth, Robert M.; Witt, Thomas; Rubchinsky, Leonid L.Parkinson’s disease pathophysiology is marked by increased oscillatory and synchronous activity in the beta frequency band in cortical and basal ganglia circuits. This study explores the functional connections between synchronized dynamics of cortical areas and dynamics of subcortical areas in Parkinson’s disease. We simultaneously recorded neuronal units (spikes) and local field potentials (LFP) from subthalamic nucleus (STN), and electroencephalograms (EEGs) from the scalp in parkinsonian patients and analyzed the correlation between the time-courses of the spike-LFP synchronization and inter-electrode EEG synchronization. We found the (noninvasively obtained) time-course of the synchrony strength between EEG electrodes and the (invasively obtained) time-course of the synchrony between spiking unit and LFP in STN to be weakly, but significantly correlated with each other. This correlation is largest for the bilateral motor EEG synchronization followed by bilateral frontal EEG synchronization. Our observations suggest that there may be multiple functional modes by which the cortical and basal ganglia circuits interact with each other in Parkinson’s disease: not only synchronization may be observed between some areas in cortex and the basal ganglia, but also synchronization within cortex and within basal ganglia may be related, suggesting potentially more global way of functional interaction. More coherent dynamics in one brain region may modulate or activate the dynamics of another brain region in a more powerful way causing correlations between changes in synchrony strength in both regions.Item Neural synchronization: Average strength vs. temporal patterning(Elsevier, 2018-04) Ahn, Sungwoo; Zauber, S. Elizabeth; Worth, Robert M.; Witt, Thomas; Rubchinsky, Leonid L.; Mathematical Sciences, School of ScienceItem Social Comparisons, Social Support, and Self-Perceptions in Group Exercise for People With Parkinson's Disease(Taylor & Francis, 2017) Sheehy, Tammy L.; McDonough, Meghan H.; Zauber, S. Elizabeth; Department of Neurology, School of MedicinePeople with Parkinson's disease (PD) may experience declining function and limited interaction with others with PD. Group exercise provides opportunities for physical accomplishment and social support, as well as potential social challenges. We used interpretative phenomenological analysis to examine experiences of social comparison, social support, and self-perceptions of 20 people with PD in group exercise. Participants experienced (a) reticence evolving to inspiration, (b) anxiety relief through camaraderie and breaking taboos, and (c) maintaining athletic identity through participating and helping others. Practical implications include facilitating a safe space and support to alleviate anxiety and sustain participation.Item Striatal and thalamic GABA level concentrations play differential roles for the modulation of response selection processes by proprioceptive information.(Elsevier, 2015-10-15) Dharmadhikari, Shalmali; Ma, Ruoyun; Yeh, Chien-Lin; Stock, Ann-Kathrin; Snyder, Sandy; Zauber, S. Elizabeth; Dydak, Ulrike; Beste, Christian; Department of Radiology and Imaging Sciences, IU School of MedicineThe selection of appropriate responses is a complex endeavor requiring the integration of many different sources of information in fronto-striatal-thalamic circuits. An often neglected but relevant piece of information is provided by proprioceptive inputs about the current position of our limbs. This study examines the importance of striatal and thalamic GABA levels in these processes using GABA-edited magnetic resonance spectroscopy (GABAMRS) and a Simon task featuring proprioception-induced interference in healthy subjects. As a possible model of deficits in the processing of proprioceptive information, we also included Parkinson's disease (PD) patients in this study.The results show that proprioceptive information about unusual postures complicates response selection processes in controls, but not in PD patients. The well-known deficits of PD patients in processing proprioceptive information can turn into a benefit when altered proprioceptive information would normally complicate response selection processes. Striatal and thalamic GABA levels play dissociable roles in the modulation of response selection processes by proprioceptive information: Striatal GABA levels seem to be important for the general speed of responding, most likely because striatal GABA promotes response selection. In contrast, the modulation of response conflict by proprioceptive information is closely related to thalamic GABA concentrations with higher concentration being related to a smaller response conflict effect. The most likely explanation for this finding is that the thalamus is involved in the integration of sensorimotor, attentional, and cognitive information for the purpose of response formation. Yet, this effect in the thalamus vanishes when controls and PD patients were analyzed separately.Item Susceptibility-Weighted MRI Approximates Intraoperative Microelectrode Recording During Deep Brain Stimulation of the Subthalamic Nucleus for Parkinson's Disease(Elsevier, 2024-01) Budnick, Hailey C.; Schneider, Dylan; Zauber, S. Elizabeth; Witt, Thomas C.; Gupta, Kunal; Neurological Surgery, School of MedicineBackground Deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson's disease can be performed with intraoperative neurophysiological and radiographic guidance. Conventional T2-weighted magnetic resonance imaging sequences, however, often fail to provide definitive borders of the STN. Novel magnetic resonance imaging sequences, such as susceptibility-weighted imaging (SWI), might better localize the STN borders and facilitate radiographic targeting. We compared the radiographic location of the dorsal and ventral borders of the STN using SWI with intraoperative microelectrode recording (MER) during awake STN-DBS for Parkinson's disease. Methods Thirteen consecutive patients who underwent placement of 24 STN-DBS leads for Parkinson's disease were analyzed retrospectively. Preoperative targeting was performed with SWI, and MER data were obtained from intraoperative electrophysiology records. The boundaries of the STN on SWI were identified by a blinded investigator. Results The final electrode position differed significantly from the planned coordinates in depth but not in length or width, indicating that MER guided the final electrode depth. When we compared the boundaries of the STN by MER and SWI, SWI accurately predicted the entry into the STN but underestimated the length and ventral boundary of the STN by 1.2 mm. This extent of error approximates the span of a DBS contact and could affect the placement of directional contacts within the STN. Conclusions MER might continue to have a role in STN-DBS. This could potentially be mitigated by further refinement of imaging protocols to better image the ventral boundary of the STN.Item Synchronized Beta-Band Oscillations in a Model of the Globus Pallidus-Subthalamic Nucleus Network under External Input(Frontiers, 2016-12-20) Ahn, Sungwoo; Zauber, S. Elizabeth; Worth, Robert M.; Rubchinsky, Lenold L.; Department of Mathematical Sciences, School of ScienceHypokinetic symptoms of Parkinson's disease are usually associated with excessively strong oscillations and synchrony in the beta frequency band. The origin of this synchronized oscillatory dynamics is being debated. Cortical circuits may be a critical source of excessive beta in Parkinson's disease. However, subthalamo-pallidal circuits were also suggested to be a substantial component in generation and/or maintenance of Parkinsonian beta activity. Here we study how the subthalamo-pallidal circuits interact with input signals in the beta frequency band, representing cortical input. We use conductance-based models of the subthalamo-pallidal network and two types of input signals: artificially-generated inputs and input signals obtained from recordings in Parkinsonian patients. The resulting model network dynamics is compared with the dynamics of the experimental recordings from patient's basal ganglia. Our results indicate that the subthalamo-pallidal model network exhibits multiple resonances in response to inputs in the beta band. For a relatively broad range of network parameters, there is always a certain input strength, which will induce patterns of synchrony similar to the experimentally observed ones. This ability of the subthalamo-pallidal network to exhibit realistic patterns of synchronous oscillatory activity under broad conditions may indicate that these basal ganglia circuits are directly involved in the expression of Parkinsonian synchronized beta oscillations. Thus, Parkinsonian synchronized beta oscillations may be promoted by the simultaneous action of both cortical (or some other) and subthalamo-pallidal network mechanisms. Hence, these mechanisms are not necessarily mutually exclusive.Item Temporal patterning of neural synchrony in the basal ganglia in Parkinson’s disease(Elsevier, 2015-02) Ratnadurai-Giridharan, Shivakeshavan; Zauber, S. Elizabeth; Worth, Robert M.; Witt, Thomas; Ahn, Sungwoo; Rubchinsky, Leonid L.; Department of Mathematical Sciences, School of ScienceItem Thalamic GABA levels and Occupational Manganese Neurotoxicity: Association with Exposure Levels and Brain MRI(Elsevier, 2017) Ma, Ruoyun E.; Ward, Eric J.; Yeh, Chien-Lin; Snyder, Sandy; Long, Zaiyang; Yavuz, Fulya Gokalp; Zauber, S. Elizabeth; Dydak, Ulrike; Department of Neurology, School of MedicineExcessive occupational exposure to Manganese (Mn) has been associated with clinical symptoms resembling idiopathic Parkinson’s disease (IPD), impairing cognitive and motor functions. Several studies point towards an involvement of the brain neurotransmitter system in Mn intoxication, which is hypothesized to be disturbed prior to onset of symptoms. Edited Magnetic Resonance Spectroscopy (MRS) offers the unique possibility to measure γ-amminobutyric acid (GABA) and other neurometabolites in vivo non-invasively in workers exposed to Mn. In addition, the property of Mn as Magnetic Resonance Imaging (MRI) contrast agent may be used to study Mn deposition in the human brain. In this study, using MRI, MRS, personal air sampling at the working place, work history questionnaires, and neurological assessment (UPDRS-III), the effects of chronic Mn exposure on the thalamic GABAergic system was studied in a group of welders (N = 39) with exposure to Mn fumes in a typical occupational setting. Two subgroups of welders with different exposure levels (Low: N = 26; mean air Mn = 0.13 ± 0.1 mg/m3; High: N = 13; mean air Mn = 0.23 ± 0.18 mg/m3), as well as unexposed control workers (N = 22, mean air Mn = 0.002 ± 0.001 mg/m3) were recruited. The group of welders with higher exposure showed a significant increase of thalamic GABA levels by 45% (p < 0.01, F(1,33) = 9.55), as well as significantly worse performance in general motor function (p < 0.01, F(1,33) = 11.35). However, welders with lower exposure did not differ from the controls in GABA levels or motor performance. Further, in welders the thalamic GABA levels were best predicted by past-12-months exposure levels and were influenced by the Mn deposition in the substantia nigra and globus pallidus. Importantly, both thalamic GABA levels and motor function displayed a non-linear pattern of response to Mn exposure, suggesting a threshold effect.