UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    A Voxel Based Approach to Identifying Lesion Sites in Aphasia: Comprehension and Production Deficits in Syntax, Semantics and Phonology
    (2007-08-20) Kling, Therese Danielle; Shah, Yasmeen; Braun, Allen; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The cortical regions of the brain traditionally associated with deficits of production and comprehension in language are Broca's and Wernicke's areas. Recent evidence suggests that other brain regions are involved and may be specific to linguistic areas of syntax, semantics and phonology. This paper describes the MRI results and language scores of 31 left hemisphere stroke patients with aphasia. Patients' lesions obtained from these MRI scans were reconstructed onto templates and entered into a voxel-based analysis program called Analysis of Brain lesion (ABLe) (Solomon, Raymont, Braun, Butman & Grafman, 2007) along with language scores. The results provided evidence for five key neuroanatomical regions of interest. These include the insula, the planum temporale, the operculum, the temporoparietal occipital (TPO) junction and the putamen. The results revealed common as well as unique areas of brain lesion for each of the behaviors.
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    CHOLINERGIC CONTRIBUTIONS TO EMOTION REGULATION
    (2004-12-17) Benson, Brenda Ellen; Cohen, Avis H; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Theories based on clinical and neuroanatomical studies implicate the muscarinic cholinergic system in normal and pathological emotion regulation. Emotional and sensory experiences can be induced with intravenous administration of the local anesthetic procaine hydrochloride, which selectively activates limbic regions in humans and animals. Procaine has a high affinity for muscarinic cholinergic receptors in vitro. This research tests three hypotheses: (1) procaine binds to muscarinic receptors in vivo; (2) procaine alters functional connectivity among cholinergic brain regions and their targets; and (3) procaine-induced emotions are related to core cholinergic regions. In Experiment I, anesthetized rhesus monkeys underwent positron emission tomography (PET) studies before and after administration of six doses of procaine on separate days using a radioligand with preferential binding to muscarinic M2 receptors ([18F]FP-TZTP). Procaine blocked [18F]FP-TZTP in a dose-response fashion uniformly across the brain, while significantly increasing tracer flow in limbic compared with non-limbic regions. In Experiment II, behavioral and physiological measures were assessed at baseline and following procaine in 32 healthy controls and 15 patients with bipolar disorder undergoing [15O] PET yielding regional cerebral blood flow (rCBF). Procaine selectively increased rCBF in anterior paralimbic regions in healthy controls, but to a lesser degree in patients. Regions connected via cholinergic pathways showed significantly different functional connectivity in both groups with procaine, however, prefrontal regions showed differential functional connectivity with cholinergic brain regions in patients compared with controls. Changes in activity of cholinergic regions explained the variance in anxiety ratings in an opposite manner in each group, and in euphoria ratings only in patients. In conclusion, procaine binds directly with muscarinic receptors in vivo while selectively increasing limbic activity in anesthetized monkeys. Two key findings herein procaine-induced alterations in functional connectivity of core cholinergic regions in humans, and the association of core cholinergic regional activity with emotional experience support theories implicating cholinergic contributions to emotion regulation. Decreased anterior paralimbic activity and altered functional connectivity of cholinergic regions in patients with bipolar illness compared with controls revealed by procaine offers additional insight into the regional neurobiology of the disease, and may ultimately be targeted in therapeutic approaches to bipolar disorder.