In the visual system, retinal axons convey visual information from the outside world to dozens of distinct retinorecipient brain regions. In rodents, two major areas that are densely innervated by this retinal input are the dorsal lateral geniculate nucleus (dLGN) and ventral lateral geniculate nucleus (vLGN), both of which reside in the thalamus. The dLGN is well-studied and known to be important for classical image‐forming vision. The vLGN, on the other hand, is associated with non‐image‐forming vision and its neurochemistry, cytoarchitecture, and retinothalamic connectivity all remain unresolved, raising fundamental questions of its role within the visual system. Here, we sought to shed light on these important questions by studying the cellular and extracellular landscape of the vLGN and map its connectivity with the retina. Using bulk RNA sequencing and proteomics, we identified extracellular matrix proteins that form two molecularly distinct types of perineuronal nets in two major laminae of vLGN: the retinorecipient external vLGN (vLGNe) and the non‐retinorecipient internal vLGN. Using in situ hybridization, immunohistochemistry, electrophysiology, and genetic reporter lines, we found that vLGNe and vLGNi are also composed of diverse subtypes of neurons. In vLGNe, we discovered at least six transcriptionally distinct subtypes of inhibitory neurons that are distributed into distinct adjacent sublaminae. Using trans‐synaptic viral tracing and ex vivo electrophysiology, we found that cells in each these sublaminae receive direct inputs from retina. Lastly, by genetically removing visual input, we found that the organization of these sublaminae is dramatically disrupted, suggesting a crucial role for sensory input in the cytoarchitectural maintenance of the vLGN. Taken together, these results not only identify novel subtypes of vLGN cells, but they also point to new means of organizing visual information into parallel pathways – by anatomically creating distinct sensory channels. This subtype-specific organization may be key to understanding how the vLGN receives, processes, and transmits light‐derived signals in the subcortical visual system. / Doctor of Philosophy / As you look around, even as you read this abstract, your retinas are constantly taking in light, converting it into neural signals, and parsing it into different types of visual features. Those light-derived signals are then transmitted from the eye to dozens of brain areas through the optic nerve. Each of these brain areas is important for specialized visual functions. One of the most major visual areas is a region in the thalamus known as the ventral lateral geniculate nucleus (vLGN). Unlike the type of vision we typically think of which involves "seeing" an image, the vLGN primarily receives non-image-forming visual information from the eye which is important for a whole host of light-derived behaviors that do not involve image forming vision. These non-image-forming functions can impact things ranging from jet lag to eye movement to mood disorders and depression. Yet, despite the dense amount of visual information it receives, and the connections it has with many other brain regions, the vLGN has been largely understudied over the years, leaving many fundamental questions unanswered. Here, we unmasked the molecular and cellular landscape of the vLGN and discovered a rich and diverse set of neuronal cell types in this region. Further, by simultaneously labeling these neuronal types, we found that they stratify into their own layers, revealing a striking level of organization which suggests that the vLGN organizes visual information into parallel channels. These discoveries are important because understanding the composition and structure of the vLGN paves the way to understanding how it receives, processes, and transmits sensory signals in the visual system.

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Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 181 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 161-179).

Acute brain cell swelling (cytotoxic edema) can occur in the first minutes of stroke, presumably as a result of brain cells taking up water. In extreme hypo-osmotic situations such as excessive water-loading by patients, uptake by brain cells can expand the brain, causing seizures. But is ischemic brain cell swelling the same as hypo-osmotic swelling? Water can passively diffuse across the plasma membrane. However the presence of water channels termed aquaporins (AQP) facilitates passive water diffusion by 10-100 times. Unlike astrocytes, there is no evidence of water channels on neuronal plasma membrane. However, there is still much debate about which cells (neurons or astrocytes) swell during over-hydration or during stroke and if neurons and astrocytes can volume-regulate during osmotic stress. The purpose of this study was to examine and compare the volume responses of PyNs and magnocellular neuroendocrine cells (MNCs) to acute osmotic challenge and to OGD. We examined MNCs because they are intrinsically osmosensitive to small changes (2-3 mOsm) of plasma osmolality. We also examined if the same neurons behave similarly in brain slices or when dissociated and if they respond differently to acute osmotic stress and stroke-like stress. Our results indicate that during acute osmotic stress (±40 mOsm) half of dissociated PyNs and MNCs tended to show appropriate responses. MNCs in brain slices showed similar responses to when they were dissociated, while brain slice PyNs were less responsive than when dissociated. Exposure to OGD resulted in obvious differences between the two types of in vitro preparations. Dissociated PyNs and MNCs showed no consistency in their volume responses to 10 minutes of OGD. Dissociated neurons swelled, shrunk or were unchanged in about equal numbers. In contrast, brain slice PyNs underwent profound swelling whereas, brain slice MNCs showed minor volume decreases. We conclude that about half of our dissociated neurons were too variable and unpredictable in their osmotic volume responses to be useful for osmotic studies. They also were too resistant to stroke-like stress to be good models for ischemia. Brain slice neurons were similar in their osmotic responses to dissociated neurons but proved to have consistent and predictable responses to stroke-like stress. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2011-02-07 17:55:08.333

When an organism is dehydrated, neurons in the Organum vasculosum lamina terminalis (OVL T) sense this variation in plasma osmolality (OSM) and excite magnocellular neurosecretory cells (MNCs) in the supraoptic nucleus (SON) via glutamatergic synapses. The resulting action potential firing of MNCs will result in the secretion of vasopressin (VP) into the blood, which will promote water reabsorption from the kidney. The relationship between plasma VP and OSM (know as the VP-OSM ratio) is known to change in sensitivity during the course of a day. / Lorsqu'un organisme est déshydraté, les neurones dans l'Organum vasculosum lamina terminalis (OVL T) détectent le changement dans l'osmolalité du plasma (OSM) et excitent les cellules magnocellulaires neurosécrétoires (MNCs) dans le noyau supraoptique (SON) avec des synapses glutamatergique. La décharge des potentiels d'action qui survient dans les MNCs génère la sécrétion de vasopressine (VP) dans le sang, qui permettra la réabsorption d'eau au niveau du rein. Le rapport entre la VP et OSM (connu comme étant le rapport VP/OSM) subit des changements de sensibilité durant une journée.

Background: The neuropeptide S receptor (NPSR1) and its ligand neuropeptide S (NPS) have received increased attention in the last few years, as both establish a previously unknown system of neuromodulation. Animal research studies have suggested that NPS may be involved in arousal/wakefulness and may also have a crucial role in sleep regulation. The single nucleotide polymorphism (SNP) rs324981 in NPSR1 has begun to shed light on a function of the NPS-system in human sleep regulation. Due to an amino acid exchange, the T-allele leads to an increased sensitivity of the NPSR1. In the only genomewide association study to date on circadian sleep parameters in humans, an association was found between rs324981 and regular bedtime. However, the sleep parameters in this study were only measured by self-rating. Therefore, our study aimed to replicate these findings using an objective measure of sleep. Methods: The study included n = 393 white subjects (62–79 years) who participated in an actigraphic assessment for determining sleep duration, rest duration, sleep onset, rest onset and sleep onset latency. Genotyping of the SNP rs324981 was performed using the TaqMan OpenArray System. Results: The genotype at rs324981 was not significantly associated with rest onset (bedtime) or sleep onset (p = .146 and p = .199, respectively). However, the SNP showed a significant effect on sleep- and rest duration (p = .007 and p = .003, respectively). Subjects that were homozygous for the minor T-allele had a significantly decreased sleep- and rest duration compared to A-allele carriers. Conclusion: The results of this study indicate that the sleep pattern in humans is influenced by the NPS-system. However, the previously reported association between bedtime and rs324981 could not be confirmed. The current finding of decreased sleep duration in T/T allele carriers is in accordance with studies in rodents reporting similar results after NPS application.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 126-139).

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 166-187). Also available on the Internet.