Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [58]-64).

Many neurones in the thalamus, like neurones in other parts of the CNS are excited by iontophoretlcally applied acetylcholine (ACh), and it has been suggested that ACh may be involved in synaptic transmission in the thalamus. In these experiments, the iontophoretlc technique was employed to investigate the location, and the neurophysiological and pharmacological properties of neurones in the ventrolateral nucleus of the thalamus (VL), which responded to electrical stimulation of the ipsilateral nucleus of the posterior commisure (NPC). Stimulation of the contralateral brachium conjunetivum (BC) was used to confirm the presence of the recording micropipette in VL. Four drugs were applied in various sequences to most neurones encountered above, in and below VL. DL-homocysteate (DLH) was used for the activation and localisation of quiescent neurones; ACh was applied to test whether the neurones were cholinoceptivej eserine (physostigmine) was used as an anticholinesterase; and atropine was used as a muscarinic blocking agent. Choiinoceptive cells were found above (3.0-6.0 mm below the fornix), and In VL (0.0-10.0mm below the fornix), the highest proportion being located in VL. The majority of cholinoceptive cells in VL responded to NPC and to BC stimulation. Cholinoceptive neurones located above VL were not evoked either by NPC or BC stimulation, while those in the lowest part of VL were evoked by NPC stimulation only. Although atropine blocked the effect of iontophoretically applied ACh, It did not affect synaptic responses evoked by stimulation of NPC and/or BC fibers. Eserine excited some cells and potentiated the actions of ACh. These results indicate that a pathway arising from the NPC projects to the ipsilateral VL and that this fiber tract is non-cholinergic. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

Sparse thalamocortical cell population synchronicity during sleep spindle oscillations has been hypothesized to promote the integration of hippocampal memory information into associated neocortical representations 1. We asked the question of whether sparse or rhythmic activity in thalamocortical cells of the reuniens nucleus influence memory consolidation and cognitive flexibility during learning after sleep. For this study, I designed a novel attentional set-shifting task and incorporated optogenetics with closed-loop stimulation in sleeping rats to investigate the effects of sparse (nonrhythmic) or rhythmic spindle-like (~10Hz) activity in thalamic cells of the reuniens nucleus on learning and cognitive flexibility. We show that, as predicted, post-sleep setshifting performance improved after sleep with non-rhythmic optogenetic stimulation in the thalamic nucleus reuniens relative to rhythmic optogenetic stimulation. While both non-rhythmic and rhythmic optogenetic stimulation led to an increase in perseverative errors, only non-rhythmic optogenetic stimulation showed effects of learning from errors, which correlated with sleep, and which ultimately had a net benefit in set-shifting performance compared to rhythmic optogenetic stimulation and the control group. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Fast, automated segmentation of the thalamic nuclei in the brain has long been desired as it provides for direct visualization of the target for certain procedures like Deep Brain Stimulation (DBS) that target a specific nucleus. It is also beneficial in the study of other pathologies that pertain to different nuclei. In this thesis, a novel approach to fast automated segmentation of thalamic nuclei called Shortened Template and THalamus for Optimal Multi Atlas Segmentation (ST THOMAS) was developed using the multi-atlas segmentation approach. It was designed with a focus on robustness and speed by making use of an averaged template for registration and cropping the inputs and the template. The performance of ST THOMAS was first evaluated on 7T MRI data by comparing with manual delineation (ground truth) by an expert neuroradiologist. Dice coefficients and Volumetric Similarity Indices were used as metrics. To extend the applicability of this method, 3T MRI data were also evaluated. Finally, applications to real time ventralintermideiate (VIM) nucleus targeting for DBS and study of the effects of alcoholism are demonstrated.

Diencephalic amnesia is thought to be the result of damage to a single thalamic structure that is responsible for the memory impairment. However, an alternative view is that different thalamic structures contribute to the memory impairment in subtly different ways. Paired-associate learning is one important measure of learning and memory that is highly sensitive to disruption in people with amnesia or dementia. The current study will investigate the influence of lesions to two thalamic subregions, the anterior thalamic nuclei (AT) and the lateral thalamic nuclei (LT) in an object-odour paired associate learning task. Each of these subregions has been suggested by the literature as critical for amnesia after thalamus injury. The current study does not involve a place/ space component. Both AT and LT lesions caused impairments in the object-odour paired associate task, but not in the simple discrimination tasks. The results of this study provide new evidence to suggest that the anterior thalamic region may be responsible for more than spatial memory processing. This result is inconsistent with those of Aggleton & Brown (1999) that consider the AT to be part of an 'extended hippocampal system'. The deficits observed from LT lesions in this study provide new insight into the lateral thalamic region's role in pattern processing.

Diencephalic amnesia is thought to be the result of damage to a single thalamic structure that is responsible for the memory impairment. However, an alternative view is that different thalamic structures contribute to the memory impairment in subtly different ways. Paired-associate learning is one important measure of learning and memory that is highly sensitive to disruption in people with amnesia or dementia. The current study will investigate the influence of lesions to two thalamic subregions, the anterior thalamic nuclei (AT) and the lateral thalamic nuclei (LT) in an object-odour paired associate learning task. Each of these subregions has been suggested by the literature as critical for amnesia after thalamus injury. The current study does not involve a place/ space component. Both AT and LT lesions caused impairments in the object-odour paired associate task, but not in the simple discrimination tasks. The results of this study provide new evidence to suggest that the anterior thalamic region may be responsible for more than spatial memory processing. This result is inconsistent with those of Aggleton & Brown (1999) that consider the AT to be part of an 'extended hippocampal system'. The deficits observed from LT lesions in this study provide new insight into the lateral thalamic region's role in pattern processing.

Thesis (Ph.D.)--University of Florida, 2005. / Typescript. Title from title page of source document. Document formatted into pages; contains 119 pages. Includes Vita. Includes bibliographical references.

The brainstem localization of acetylcholinesterase (AChE)-containing neurons projecting to the anteroventral thalamic nucleus (AVN) was studied in rats. The AVN is one of several forebrain regions innervated by the AChE-containing dorsal tegmental pathway described by Shute and Lewis. In the present study, horseradish peroxidase (HRP) was injected into the region of the AVN to determine the brainstem origin of afferent projections. Alternate sections of tissue were stained for HRP or AChE. HRP-labeled neurons were found in the laterodorsal tegmental nucleus (LTN) and the locus coeruleus. Examination of adjacent sections revealed AChE-containing neurons in both of these nuclear regions. Combined HRP/AChE histochemistry demonstrated that transported HRP and AChE were in the same cells. In further experiments, unilateral lesions of the LTN were found to cause a decrease in AChE staining of the ipsilateral AVN. Destruction of the locus coeruleus had no effect. In combination with available evidence, the present findings suggest that cholinergic neurons in the LTN innervate the AVN. © 1980, All rights reserved.

Animals with one of septal, medial thalamic or tegmental reticular formation lesions were compared on three measures of spontaneous activity (a brief test in a novel maze and seven-day tests in running wheels or photocells cages) and on active avoidance learning. Wheel running was depressed by all the lesions (especially septal and tegmental lesions) while locomotion in the maze and photocell cages was unaffected. Avoidance learning was depressed by septal and thalamic lesions but not by tegmental lesions. These results are discussed in terms of the hypothesis that these brain structures form part of systems which facilitate or inhibit somatomotor activity. / Thesis / Master of Arts (MA)

Episodic memory is processed by the extended hippocampal system, and pathology or injury to individual components of this system can result in deficits in spatial learning and memory (Aggleton & Brown, 1999). Extensive research regarding spatial memory has been carried out on the anterior thalamic nuclei, a component of the extended hippocampal system, but the contribution of the laterodorsal thalamic nuclei, an adjacent structure with similar neural connections, is less clear. The purpose of the present study was to compare the effects of selective anterior thalamic nuclei lesions (AT) with selective laterodorsal thalamic nuclei lesions (LD) in a novel land-based spatial reference memory task. This assessed the use of proximal and distal visual cues on the propensity to use allocentric or egocentric navigation strategies to locate a specific place in space, as well as the temporal evolution of these navigation strategies. AT lesion impairments were observed in the acquisition trials in both proximal and distal cue conditions. LD lesion rats were unimpaired in the acquisition trials in both visual cue conditions. Across the probe trials, lesion effects were not observed when tested for general navigation, egocentric or allocentric strategies, and there was no clear improvement in performance over the four weeks of probe trials. However, performance was consistently poorer for all groups when proximal cues facilitated navigation compared to distal cues. Performance differences related to cue proximity may reflect the influence of motion parallax, the perceived displacement rate of visual cues. The absence of lesion effects across probes were thought to be due to the preferential use of cued navigation, which was reliant on a single salient beacon, and the lack of integration between cued and place navigation, which was reliant on the formation of a spatial representation.