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Acetylcholine is a neuromodulator that plays a variety of roles in the central nervous system and is highly implicated in visual perception and visual cortical plasticity. Visual sequence learning, defined here as the ability to encode and predict the spatiotemporal content of visual information, has been shown to depend on muscarinic signaling in the mouse primary visual cortex (V1). Muscarinic signaling is a complex process involving the combined activities of five different G-protein coupled receptors, M1-M5, all of which are expressed in the murine brain but differ from each other functionally and in anatomical localization. While previous work has isolated the required signaling to V1, it is unknown which muscarinic receptors are required for spatiotemporal sequence learning. We hypothesized that M1 or M2 receptors are required for sequence learning since they are known to be abundantly expressed in rodent V1. Our aim was to identify the muscarinic receptor required for sequence learning using electrophysiology, followed by immunofluorescence to determine the anatomical distribution of the identified receptor in V1 in a layer-wise and cell-type fashion. Another aim was to better tease out the timing of muscarinic activity required for encoding the visual sequence. Here we present electrophysiological evidence that M2, but not M1, receptors are required for spatiotemporal sequence learning in mouse V1. We show that M2 is highly expressed in the neuropil in V1, especially in thalamorecipient layer 4, and co-localizes to the soma of a subset of somatostatin expressing neurons in deep layers. We also show that expression of M2 receptors is higher in the monocular region of V1 than it is in the binocular region, but that the amount of experience-dependent sequence potentiation is similar in both regions. Finally, we show that interrupting mAChR activity after visual stimulation does not prevent sequence potentiation. This work establishes a new functional role for M2-type receptors in processing temporal information and demonstrates that monocular circuits are modified by experience in a manner like binocular circuits.

An important initial event in the life cycle of a virus is its attachment to a specific receptor at the surface of a cell. The presence of specific virus receptors on cells and in tissues contribute to the tropism of the virus as well as to tissue specific pathology associated with virus infection. Despite the importance of this initial event in virus infection very few virus receptors have been identified. Data presented in this dissertation strongly imply that major histocompatibility encoded class I proteins are receptors for the simian papovavirus, SV40. Adsorption of SV40 to rhesus monkey kidney cells inhibits the binding of anti-class I antibody to cells by 62%. This same pretreatment inhibits the binding of antibodies directed at two other cell surface proteins, anti-LFA-3 and anti-vitronectin receptor, by 22%. Pretreatment of rhesus monkey kidney cells with anti-class I antibody inhibits SV40 infection by 85%. The amount of inhibition decreases with increasing dilutions of antibody. Anti-LFA-3 and anti-vitronectin receptor antibodies do not inhibit infection by SV40. SV40 infection of class I negative Daudi cells were compared with infection of class I positive Raji cells. Raji cells were three fold more infectable than Daudi cells at multiplicities of infection (MOI) of both 10 and 100 plaque forming units per milliliter (PFU/ml). To demonstrate a direct interaction between SV40 and class I proteins, cell surface extracts were prepared from rhesus monkey kidney cells. When SV40 is incubated with these extracts and immunoprecipitated with anti-SV40 antibody class I proteins are specifically coimmunoprecipitated. Finally, purified class I proteins were found to inhibit SV40 infection by 68%.

The studies described in this dissertation were designed to examine certain aspects of the neuronal networks controlling sexual receptivity facilitated by estradiol and progesterone in female guinea pigs. In particular, the first part of this thesis was designed to localize discrete sites within the mediobasal hypothalamus (MBH) where local activation by estradiol is sufficient to induce responsiveness to progesterone-facilitated sexual receptivity. Implants localized within the rostroventral ventrolateral hypothalamus (rostro-ventral VLH) were sufficient to induce responsiveness to progesterone. Using immunocytochemistry for progestin receptors, the same implants were found to induce progestin receptors within the same area. The second part of this thesis was focussed on the description of afferent connections to the rostro-ventral VLH, and the identification of some of these afferents as originating from estradiol-sensitive neurons. Using retrograde tracing techniques, afferents to the rostro-ventral VLH were observed throughout the forebrain and the midbrain, particularly within the medial preoptic nucleus, bed nucleus of the stria terminalis, anterior hypothalamus, amygdala, and lateral parabrachial nucleus. Using immunoreactivity to label neurons containing estrogen receptors, retrogradely labelled neurons were found is most areas highlighted by immunolabelling. Furthermore, within some areas, particularly within the medial preoptic nucleus, medial amygdala, and bed nucleus of the stria terminalis, retrogradely labelled neurons were also immunoreactive to estrogen receptors. The third part of this thesis was designed to study connections between estrogen receptor-rich hypothalamic areas. Interestingly, the results show that neurons within the estrogen receptor-poor ventromedial nucleus were connected to estrogen receptor-immunoreactive neurons in estrogen receptor-rich areas such as the rostro-ventral VLH, suggesting that this nucleus integrates estrogen-dependent hypothalamic functions. In conclusion, the present results point to a discrete part of the hypothalamus as a site of action for estradiol and progesterone in the facilitation of sexual receptivity. Furthermore, this area is connected to a network of estrogen-sensitive neurons integrating several sensory functions involved in the behavior. Finally, this estrogen-dependent function might be integrated with other estrogen-dependent functions at the level of the hypothalamus.

The interactions between the cortex, thalamus and inhibitory thalamic reticular nucleus compose the thalamocortical system that is responsible for sensory processing and attention, during wakeful states, and sleep spindle generation, during sleep states. The TC system is divided into two sub-circuits, the core and matrix, the former involved with sensory processing, while the latter focused on limbic processing and memory consolidation. The core and matrix TC circuit is present in all species, both in open and closed loop fashions, but the composition of the circuit is not the same across rodents and primates. While the role of the corticothalamic system in sleep spindle generation is well established, the individual role of the core and matrix is not well understood in rodents and primates. Therefore, we created both a rodent and primate biophysical neural model of the core and matrix thalamocortical circuit. We found that the primate model was able to synchronize the network activity faster than the rodent model; primate TC relay neurons were less likely to sustain their activity, and primate matrix and mixed spindles had a higher amplitude than their rodent counterparts. The primate open-loop circuitry also produced higher spindle density. Therefore, the core and matrix thalamocortical circuit model of the rodent and primate was able to shed light into how these two species spindling patterns differ. / 2025-05-30T00:00:00Z

NIBP (NIK-and-IKK2-binding protein; also known as TRAPPC9), is an important mediator of NFκB signaling and protein transport/trafficking, both of which play key roles in many physiological processes and pathological conditions. Recently, human NIBP deficiency has been linked to a novel autosomal recessive intellectual disability syndrome, NIBP Syndrome. Patients with NIBP Syndrome exhibit various symptoms including intellectual disability, developmental delays, facial dysmorphia, microcephaly, brain abnormalities, and obesity. However, the pathogenic mechanisms underlying NIBP syndrome is still unclear. In order to elucidate the mechanistic pathways impacted by NIBP deficiency, we focused on two major aspects of this disorder: neuropathological dysfunctions and spontaneous obesity. Our major hypothesis is that NIBP deficiency causes defective neural induction and impaired neuronal differentiation and causes impaired energy homeostasis in the hypothalamus.In the first part of this study, we focused on the role of NIBP in neural induction and neurogenesis, and generated microglia-containing cerebral organoids (MCOs) and neural stem/progenitor cells (NS/PCs) from NIBP Syndrome patient-derived induced pluripotent stem cells (iPSCs). Our results show that NIBP patient-derived MCOs and NS/PCs have a distinct phenotype from healthy subjects, with MCOs displaying abnormal morphology after neural induction and NS/PCs having impaired neuronal lineage differentiation. Patient MCOs have reduced numbers of NS/PCs during early stages of development, and form fewer neural rosettes during maturation. Additionally, the laminar structures present in patient MCOs are thinner and less intricate. Bulk RNAseq analysis highlights several dysregulated pathways in patient MCOs, including many genes related to protein transport/trafficking, neuritogenesis, and synaptogenesis. The second half of this study characterized novel mouse models of Nibp deficiency, with a focus on elucidating mechanisms related to obesity and energy homeostasis. Global knockout mice (Nibp-/-) recapitulated most phenotypical characteristics with NIBP Syndrome patients, including neurogenic deficits, neurocognitive impairments, and spontaneous obesity. As mice do not develop obesity without the introduction of a high fat diet in general, this spontaneous obesity under normal chow diet is an exceptionally interesting phenotype, highlighting an important anti-obesity role of NIBP under physiological conditions. Further DEXA (dual-energy X-ray absorptiometry) and metabolic characterization of global Nibp-/- mice demonstrated that they have increased fat mass, impaired glucose and insulin tolerance, and increased food intake in addition to increased body weight. Indirect calorimetry using Comprehensive Lab Animal Monitoring System (CLAMS) metabolic cages showed Nibp-/- mice had increased respiratory exchange ratio (RER) as well as reduced locomotor activity. Finally, whole body histopathological analysis showed no apparent histopathologic abnormalities in fat, liver, pancreas, intestine, kidney, heart, and spleen tissues in Nibp-/- mice, indicating that these tissues/organs may not be directly impaired, at least at a gross level, and therefore the obesity is occurring because of other factors. Given the hypothalamus is the master regulator of feeding behavior and energy expenditure, we addressed whether hypothalamic NIBP knockout contributes to the obese phenotype. Most interestingly, targeted knockout of Nibp in the arcuate nucleus of floxed Nibp mice via AAV-DJ8-Cre stereotactic injection resulted in spontaneous obesity similar to the global Nibp-/- mice, indicating a key role for hypothalamic NIBP signaling in food intake and energy homeostasis. To elucidate the cellular mechanisms that may be involved, we generated AgRP and POMC-specific neuronal knockout mice. However, these mice showed no significant differences in food intake and body weight from wildtype littermates during longitudinal tracking studies. Indirect calorimetry showed increased RER in both AgRP and POMC knockout mice, as well as increased food intake, locomotor activity, and energy expenditure in POMC knockout mice. Therefore, this data suggests that while hypothalamic NIBP plays an important role in energy homeostasis, it likely involves additional or separate cell types than AGRP and/or POMC neurons. In summary, the studies conducted provide evidence that NIBP plays a significant role in neurodevelopment related to neural induction and neuronal differentiation and hypothalamic NIBP is important for maintaining energy homeostasis. / Biomedical Sciences

Extracellular vesicles (EVs) are released by nearly every cell type and are an important structure in inter-cellular communication. Abnormal EV signaling is found in many conditions including ischemia, Alzheimer’s Disease (AD) and Down Syndrome (DS). However, EVs from stem cells from healthy animals have recently emerged as a possible therapeutic intervention to address a variety of neurological conditions. Mesenchymal stromal cell-derived (MSCs) extracellular vesicles from the bone marrow of young healthy monkeys contain microRNAs and proteins and previous studies have shown that MSC-EV treatment mitigates inflammation and oxidative stress, promotes myelination, and improves functional recovery in a rhesus monkey model of cortical injury. EVs have also been shown to reduce AD pathology in mouse models by promoting anti-inflammatory processes and slowing the progression of AD. While AD currently effects over 6 million people in the United States, individuals with DS are disproportionately affected by early onset AD. Therefore, investigating the efficacy of MSC-EVs as a potential therapeutic to mitigate AD like pathology in DS is critical. Accordingly, the current study aims to explore the application of EVs on 3D human brain models of DS, ischemia, and oxygen glucose deprivation (OGD). We generated human oligocortical spheroids (OLS) containing neurons, astrocytes and oligodendrocytes allowing investigation of the effects of the EVs in human, physiologically relevant conditions. First, with OLS in ischemic conditions results were insufficient in demonstrating the recapitulation of cell death and oxidative damage associated with ischemia in vivo. Consequently, the inconsistency of the model prevented us from comprehensive evaluation of the therapeutic potential of EVs in OGD model in OLS. However, we next used DS-derived OLS generated from isogenic induced pluripotent stem cell (iPSCs) lines to evaluate the efficacy of EV treatment in DS. Trisomic OLS display significantly higher levels of amyloid beta (Aβ40 and Aβ42) depositions in both the soluble and insoluble fractions. Additionally, trisomic OLS are consistently smaller than their euploid counterparts, and have elevated levels of cleaved-caspase 3 (CC3) detection indicating more cell death. When treated with EVs, trisomic OLS demonstrated greater preserved cortical volume, significantly decreased levels of Aβ40 and Aβ42 in both fractions, and significant reduction in cell death compared to the untreated trisomic OLS. These results suggest that EVs alleviated the AD-related pathology in DS-derived OLS. Evaluation of the markers of cortical layer neurons demonstrated significantly higher counts of neurons expressing deep and superficial layer markers, suggesting that EVs contributed to greater preserved cortical volume of trisomic OLS by promoting neurogenesis and alleviating trisomy-induced deficits. Our studies show for the first time the efficacy of MSC-EVs in mitigating DS and AD-related cellular phenotypes and pathological depositions in human OLS. Furthermore, oligocortical spheroids present a unique tool for a target validation of potential therapeutics.

Parkinson’s disease (PD) has devastating effects that include both motor and non-motor impairments. Advanced medicine including pharmacotherapy and surgical options have made it possible for individuals that hold this diagnosis to live somewhat normal lives. As treatment options for this disease have been further investigated, exercise has been found to have benefit by preserving function and quality of life for Parkinson’s patients. Although the positive effects of exercise on Parkinson’s patients have been explored, the exact type and how much has not been narrowed down. Not one form of exercise can be said to be more efficacious than another for patients with Parkinson’s disease. In addition, exercise has not been thoroughly analyzed in the long term for patients with Parkinson’s disease. An exercise modality that recently has gained popularity due to its benefits is high intensity interval training (HIIT). This modality of exercise allows modifiable and accessible training sessions that improve cardiorespiratory fitness. Its benefit has extended to individuals with chronic disease but not robustly in the Parkinson’s population. The proposed study below will consist of a randomized control trial in people with Parkinson’s disease comparing a 24-month HIIT program to a control group. Symptoms will be scored on the movement disorder society’s unified Parkinson’s disease rating scale (MDS-UPDRS) at baseline, throughout and after treatment and further analyzed to see if there is clinical significance in using this type of exercise in this population. If HIIT proves its efficacy in this study, it allows clinicians more insight on the most appropriate treatment for Parkinson’s patients.

Communication between the cortex and thalamus is imperative for performing cognitive processes. This communication can be modulated at the level of the thalamus through a strategically positioned inhibitory nucleus called the thalamic reticular nucleus (TRN). The TRN’s ability to modify thalamocortical communication through a distinctly inhibitory action has implicated it in the sleep-wake cycle and in selective attention, where its effects are so profound that is has commonly been coined the attentional searchlight of the brain. While the TRN projects to the thalamus only, it receives input from both cortical and thalamic projections which organize topographically into sectors within the TRN. These projections can either be categorized as core or matrix, which refer to first-order sensory or high-order association, respectively. The topographic organization of these two projection types into sectors within the TRN creates functional diversity, as well as complexity. Neuroscientists have begun to consider the importance of core-matrix fibers as their integration is central to the brain’s ability to perform complex and dynamic functions. However, little is known about the organizational aspects underlying their divergent sensory and association functions which is central to further classifying the broad functions of thalamocortical communication. Additionally, disruptions in circuitry at the level of the TRN can act as a precursor to numerous neurological deficits and disease, which further stresses a need for a morphological understanding of these functionally distinct regions. To address this gap in knowledge, we examined functionally distinct regions on the basis of their core-matrix distributions and compared their morphological features through the use of electron microscopy (EM) and brightfield microscopy (BF). We hypothesize that there will be cellular and dendritic architectural differences in regions with core and matrix distinctions, confirming that TRN sectors are heterogenous not just on a functional basis but also on an anatomic basis. In regions predominated with matrix projections, synaptic density was shown to be preserved across dendritic order while bouton diameters decreased across all orders of dendrites. Meanwhile, for regions populated with core fibers, synaptic density decreased between some orders of dendrites, and bouton diameter was mostly preserved across all orders of dendrites. Furthermore, across the TRN as a whole, the vast majority of boutons were deemed to be excitatory. The relative proportions of boutons arising from other brain afferents such as the amygdala, superior colliculus, and basal ganglia were different among the sectors predominated with core and matrix fibers, suggesting a specific balance of excitation and inhibition is required for TRN function. As such, heterogeneity was confirmed in the TRN on a morphological basis. / 2025-07-05T00:00:00Z

Attention is the psychological process by which the external world is actively perceived, interpreted, and navigated, allowing for organisms to selectively focus on relevant stimuli at the exclusion of irrelevant noise and distraction. Schizophrenia is a neuropsychiatric condition that arises from excitatory imbalances throughout the brain and is associated with not only hallucinations and delusions, but treatment-resistant attentional impairments, providing a clinical impetus to explore alternate antipsychotic targets. Receptors of the hypothalamic orexin system represent promising targets, as they are expressed on numerous attention- and schizophrenia-relevant nuclei. The experiments included in this dissertation tested the capacity for orexin receptor antagonists to treat attentional and electrophysiological deficits associated with a commonly-employed rodent model of psychosis. It was found that the dual orexin receptor antagonist filorexant and the selective orexin-1 receptor inhibitor SB-334867 both improved performance in a sustained visual attention task for rats co-administered a low dose of the psychotogenic N-methyl-D-aspartate receptor antagonist dizocilpine. However, for mice given a higher concentration of dizocilpine, filorexant was unable to improve deficient synchronization of neuronal firing at frequencies in the gamma band that coincide with attentional processing. Taken together, these findings are the first to reveal a potential dissociation of the efficacy of anti-orexinergic compounds for the treatment of attentional impairments in animal models of schizophrenia; namely, the behavioral abnormalities which arise from low degrees of psychotomimesis may be more easily reversed than the anomalous neuronal oscillatory activity present in a more potently psychosis-like state.