Biology subjects

Beckman, D.

Publications and source records attributed to Beckman, D..

4 recordsLinked to original sources

bioRxiv2026

Loss of neuronal population organization links pathology to behavior in a model of Alzheimer's disease

Alzheimers disease (AD) and related dementias (ADRD) are defined by molecular and cellular pathology and cognitive decline, but linking these levels requires understanding how pathology alters large-scale neuronal activity. We longitudinally tracked behavior, multi-area neuronal population activity, and fluid and histological biomarkers in a macaque model of early-stage ADRD. As pathology progressed, visually guided behavior became increasingly disorganized, reflected in less structured exploration despite preserved task performance. Guided by systems neuroscience principles linking neuronal population activity with organized goal-directed behavior, we found progressive reductions in coordinated neuronal population activity within and between visual and parietal cortices, even as single-neuron tuning and basic feature encoding remained stable. These changes emerged when tau pathology was largely confined to regions providing feedback to visual cortex. This disorganized state appears modifiable: proof-of-concept methylphenidate administration was associated with transient improvement in behavioral organization. Together, these findings identify disruption of neuronal population organization as a defining feature of early-stage ADRD and frame early dysfunction as a disorder of coordinated population activity.

neuroscience↗

bioRxiv2023

CCR7+ CD4 T Cell Immunosurveillance Disrupted in Chronic SIV-Induced Neuroinflammation in Rhesus Brain.

CD4 T cells survey and maintain immune homeostasis in the brain, yet their differentiation states and functional capabilities remain unclear. Our approach, combining single-cell transcriptomic analysis, ATAC-seq, spatial transcriptomics, and flow cytometry, revealed a distinct subset of CCR7+ CD4 T cells resembling lymph node central memory (TCM) cells. We observed chromatin accessibility at the CCR7, CD28, and BCL-6 loci, defining molecular features of TCM. Brain CCR7+ CD4 T cells exhibited recall proliferation and interleukin-2 production ex vivo, showcasing their functional competence. We identified the skull bone marrow as a local niche for these cells alongside other CNS border tissues. Sequestering TCM cells in lymph nodes using FTY720 led to reduced CCR7+ CD4 T cell frequencies in the cerebrospinal fluid, accompanied by increased monocyte levels and soluble markers indicating immune activation. In macaques chronically infected with SIVCL57 and experiencing viral rebound due to cessation of antiretroviral therapy, a decrease in brain CCR7+ CD4 T cells was observed, along with increased microglial activation and initiation of neurodegenerative pathways. Our findings highlight a role for CCR7+ CD4 T cells in CNS immune surveillance and their decline during chronic SIV-induced neuroinflammation highlights their responsiveness to neuroinflammatory processes. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/555037v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@191f9caorg.highwire.dtl.DTLVardef@a67d2dorg.highwire.dtl.DTLVardef@645443org.highwire.dtl.DTLVardef@d81fd6_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefUtilizing single-cell and spatial transcriptomics on adult rhesus brain, we uncover a unique CCR7+ CD4 T cell subset resembling central memory T cells (TCM) within brain and border tissues, including skull bone marrow. Our findings show decreased frequencies of this subset during SIV- induced chronic neuroinflammation, emphasizing responsiveness of CCR7+ CD4 T cells to CNS disruptions. HighlightsO_LICCR7+ CD4 T cells survey border and parenchymal CNS compartments during homeostasis; reduced presence of CCR7+ CD4 T cells in cerebrospinal fluid leads to immune activation, implying a role in neuroimmune homeostasis. C_LIO_LICNS CCR7+ CD4 T cells exhibit phenotypic and functional features of central memory T cells (TCM) including production of interleukin 2 and the capacity for rapid recall proliferation. Furthermore, CCR7+ CD4 T cells reside in the skull bone marrow. C_LIO_LICCR7+ CD4 T cells are markedly decreased within the brain parenchyma during chronic viral neuroinflammation. C_LI

neuroscience↗

bioRxiv2020

Neuroanatomical abnormalities in a nonhuman primate model of congenital Zika virus infection

Zika virus (ZIKV) infection of pregnant women can cause major congenital neuronal abnormalities. In the present study, we evaluated neuropathological consequences of fetal ZIKV exposure in rhesus macaques, a highly translatable animal model for human neural development. Quantitative neuroanatomical analyses of the nearly full-term brains of fetuses infected with ZIKV at gestational days 50, 64, and 90, and three procedure-matched sham-inoculated controls were carried out. Whole tissue sections across a complete cerebral hemisphere were evaluated using immunohistochemical and neuroanatomical staining techniques to detect virus localization, identify affected cell types and evaluate gross neuroanatomical abnormalities. None of the subjects were microcephalic. Immunohistochemical staining revealed the presence of ZIKV in the frontal lobe, which contained activated microglia and showed increased apoptosis of immature neurons. ZIKV-infected animals exhibited macrostructural changes within the occipital lobe, including a reduction in gyrification as well as a higher proportion of white matter. Finally, the ZIKV-infected subjects had abnormalities throughout the visual pathway, including disorganization within the lateral geniculate nucleus (LGN) and primary visual cortex (V1). Regional differences tracked with the temporal patterns of the developing brain and likely reflect the neural progenitor cell tropism ZIKV exhibits - painting a picture of inflammatory processes related to viral infiltration sweeping through the cortex, followed by a wave of cell death resulting in morphological changes. These findings may help explain why some infants born with normal sized heads during the ZIKV epidemic manifest developmental challenges as they age, and ultimately may contribute to developing effective treatments and interventions. One sentence summaryMacaque fetuses infected with Zika virus show both macro- and micro-scale neuropathological abnormalities, including decreased gyrencephality, relative increases in cortical white matter, activation of glia, and increased apoptosis.

neuroscience↗

bioRxiv2018

Quantitative analysis of synaptic pathology and neuroinflammation: an initial study in a female rhesus monkey model of the “synaptic” phase of Alzheimer’s disease

BackgroundSoluble oligomers of the A{beta} peptide (A{beta}Os) are toxins that target and disrupt synapses. Generation of A{beta}Os has been recently recognized as a probable initiating event in Alzheimers disease (AD), leading to cognitive impairment. There is a translational gap in AD studies, with promising drugs developed based on work in rodent models failing in AD patients in clinical trials. Additionally, although women have a two-fold greater lifetime risk of developing AD compared to men, females have not been a focus of preclinical studies. Thus, we sought to develop a model of A{beta}O toxicity in female rhesus monkeys, to take advantage of the more highly differentiated cortical structure in this species as well as the similarities in the endocrine system between rhesus monkeys and humans.\n\nMethodsRepeated intracerebroventricular (i.c.v) injections of A{beta}Os were performed in adult female rhesus monkeys. Controls were unoperated aged matched monkeys. High-resolution confocal microscopy and morphometric analysis of Alexa 568 (A568) filled neurons were used to evaluate synaptic, neuronal, and glial markers in the dorsolateral prefrontal cortex (dlPFC) and hippocampus after A{beta}O injections. Cerebrospinal fluid (CSF) and brain tissue were also collected and analyzed for biomarkers of AD pathology, including: phosphorylated Tau protein (pTau), total Tau, A{beta}1-42, A{beta}1-40 and TNF- levels.\n\nResultsHere, we report that A{beta}O injection into the lateral ventricle of the brain induces loss of 37% of thin spines in targeted dlPFC neurons, an area highly vulnerable in AD and aging. Further, A{beta}Os associate with the synaptic marker PSD95, inducing loss of more than 60% of local excitatory synapses. A{beta}Os induce a robust neuroinflammatory response in the hippocampus, far from the injection site, with numerous activated ameboid microglia and TNF- release. Finally, A{beta}Os increased CSF levels of A{beta}1-42, pTau Ser396 and pTau Ser199, but not A{beta}1-40 or total Tau.\n\nConclusionsThese initial findings from detailed quantitative analysis of effects of A{beta}O administration on synapses in a female nonhuman primate model are a very promising step toward understanding the mechanism of early AD pathogenesis in the primate brain, and may help develop an effective disease-modifying therapy of high relevance to womens health.

neuroscience↗