Objective: Using an image analysis system to determine whether there is loss of axons in the olfactory tract (OT) in Alzheimer's disease (AD).
Design: A retrospective neuropathological study.
Patients: Nine control patients and eight clinically and pathologically verified AD cases.
Measurements And Results: There was a reduction in axon density in AD compared with control subjects in the central and peripheral regions of the tract. Axonal loss was mainly of axons with smaller (<2.99 microm(2)) myelinated cross-sectional areas.
Conclusions: The data suggest significant degeneration of axons within the OT involving the smaller sized axons. Loss of axons in the OT is likely to be secondary to pathological changes originating within the parahippocampal gyrus rather than to a pathogen spreading into the brain via the olfactory pathways.
Despite recent progress, the complex roles played by the extracellular matrix in development and disease are still far from being fully understood. Here, we took advantage of the zebrafish mutation which affects Laminin γ1, a major component of basement membranes, to explore its role in the development of the olfactory system. Following a detailed characterisation of Laminin distribution in the developing olfactory circuit, we analysed basement membrane integrity, olfactory placode and brain morphogenesis, and olfactory axon development in mutants, using a combination of immunochemistry, electron microscopy and quantitative live imaging of cell movements and axon behaviours.
The assembly and maintenance of neural circuits is crucial for proper brain function. Although the assembly of brain circuits has been extensively studied, much less is understood about the mechanisms controlling their maintenance as animals mature. In the olfactory system, the axons of olfactory sensory neurons (OSNs) expressing the same odor receptor converge into discrete synaptic structures of the olfactory bulb (OB) called glomeruli, forming a stereotypic odor map.
Air pollution is a significant environmental health risk for urban areas and developing countries. Air pollution may contribute to the incidence of cardiopulmonary and metabolic diseases. Evidence also points to the role of air pollution in worsening or developing neurological and neuropsychiatric conditions.
Chronic stress induces neural dysfunctions and risks mental illnesses. Clinical and preclinical studies have established the roles of brain regions underlying emotional and cognitive functions in stress and depression. However, neural pathways to perceive sensory stimuli as stress to cause behavioral disturbance remain unknown.
Inhalation of prions into the nasal cavity is an efficient route of infection. Following inhalation of infectious prions, animals develop disease with a similar incubation period compared with per os exposure, but with greater efficiency. To identify the reason for this increased efficiency, we identified neural structures that uniquely innervate the nasal cavity and neural structures known to mediate neuroinvasion following oral infection and used immunohistochemistry to determine the temporal and spatial accumulation of prions from hamster tissue sections containing cell bodies and axons at 2-week intervals following prion exposure.
