A Shifting Island Landscape: Changes in Land Use and Daily Life in the 19th and 20th Century Village of Inishark, Co. Galway, Ireland

This thesis investigates changes to village spatial arrangement and land use patterns in the nineteenth and twentieth century village of Inishark, Co. Galway, Ireland. To understand how spatial changes within the historic village were shaped by interactions between villagers and outside groups, including landlords and government agencies, a landscape approach was utilized. An examination of historic maps, valuation documents, and Irish Census documents, combined with ground-penetrating radar (GPR) survey and archaeological excavation, were used to understand how historical pressures impacted island life. Inishark\u27s geographic isolation creates a unique case study to understand the impact of historical pressures on rural Irish communities during this period. Historical pressures examined were landlord and tenant relationships, the imposition of British ideals, and the shifts in economic activity and movement of people. Villagers\u27 responses to these outside forces impacted the movement of people and their economic activities, shaping the cultural landscape of the island

Functional Modulation of the Mouse Prefrontal Cortex by Nicotinic Acetylcholine Receptors

Mansvelder, H.D. [Promotor]Brussaard, A.B. [Copromotor]Smit, A.B. [Copromotor]Spijker, S. [Copromotor

Simulation Model for Analysis of Alternative Financial Policies at the State Level

Higher Educatio

Distributed Network Actions by Nicotine Increase the Threshold for Spike-Timing-Dependent Plasticity in Prefrontal Cortex

SummaryNicotine enhances attention and working memory by activating nicotinic acetylcholine receptors (nAChRs). The prefrontal cortex (PFC) is critical for these cognitive functions and is also rich in nAChR expression. Specific cellular and synaptic mechanisms underlying nicotine's effects on cognition remain elusive. Here we show that nicotine exposure increases the threshold for synaptic spike-timing-dependent potentiation (STDP) in layer V pyramidal neurons of the mouse PFC. During coincident presynaptic and postsynaptic activity, nicotine reduces dendritic calcium signals associated with action potential propagation by enhancing GABAergic transmission. This results from a series of presynaptic actions involving different PFC interneurons and multiple nAChR subtypes. Pharmacological block of nAChRs or GABAA receptors prevented nicotine's actions and restored STDP, as did increasing dendritic calcium signals with stronger postsynaptic activity. Thus, by activating nAChRs distributed throughout the PFC neuronal network, nicotine affects PFC information processing and storage by increasing the amount of postsynaptic activity necessary to induce STDP

Fast-spiking Parvalbumin Interneurons are Frequently Myelinated in the Cerebral Cortex of Mice and Humans

Myelination, the insulating ensheathment of axons by oligodendrocytes, is thought to both optimize signal propagation and provide metabolic support. Despite the well-established physiological importance of myelination to neuronal function, relatively little is known about the myelination of GABAergic interneurons in the cerebral cortex. Here, we report that a large fraction of myelin in mouse cerebral cortex ensheaths GABAergic interneurons, reaching up to 80% in hippocampal subregions. Moreover, we find that a very high proportion of neocortical and hippocampal parvalbumin (PV) interneurons exhibit axonal myelination. Using a combination of intracellular recordings and biocytin labeling of ex vivo human neocortex, we also confirm that axons of fast-spiking PV interneurons are extensively myelinated in the human brain. PV interneuron myelination in both mice and humans exhibits a stereotyped topography with a bias towards proximal axonal segments and relatively short internodes (∼27 μm) interspersed with branch points. Interestingly, myelin-deficient Shiverer mice exhibit an increased density and more proximal location of en passant boutons, suggesting that myelination might function in part to regu

Fast-spiking Parvalbumin Interneurons are Frequently Myelinated in the Cerebral Cortex of Mice and Humans

Myelination, the insulating ensheathment of axons by oligodendrocytes, is thought to both optimize signal propagation and provide metabolic support. Despite the well-established physiological importance of myelination to neuronal function, relatively little is known about the myelination of GABAergic interneurons in the cerebral cortex. Here, we report that a large fraction of myelin in mouse cerebral cortex ensheaths GABAergic interneurons, reaching up to 80% in hippocampal subregions. Moreover, we find that a very high proportion of neocortical and hippocampal parvalbumin (PV) interneurons exhibit axonal myelination. Using a combination of intracellular recordings and biocytin labeling of ex vivo human neocortex, we also confirm that axons of fast-spiking PV interneurons are extensively myelinated in the human brain. PV interneuron myelination in both mice and humans exhibits a stereotyped topography with a bias towards proximal axonal segments and relatively short internodes (~27 μm) interspersed with branch points. Interestingly, myelin-deficient Shiverer mice exhibit an increased density and more proximal location of en passant boutons, suggesting that myelination might function in part to regulate synapse formation along PV interneuron axons. Taken together, fast-spiking interneuron myelination is likely to have broad implications for cerebral cortex function in health and disease