Abstract
Research studies that focus on understanding the onset of neurodegenerative pathology and therapeutic interventions to inhibit its causative factors, have shown a crucial role of olfactory bulb neurons as they transmit and propagate nerve impulses to higher cortical and limbic structures. In rodent models, removal of the olfactory bulb results in pathology of the frontal cortex that shows striking similarity with frontal cortex features of patients diagnosed with neurodegenerative disorders. Widely different approaches involving behavioral symptom analysis, histopathological and molecular alterations, genetic and environmental influences, along with age-related alterations in cellular pathways, indicate a strong correlation of olfactory dysfunction and neurodegeneration. Indeed, declining olfactory acuity and olfactory deficits emerge either as the very first symptoms or as prodromal symptoms of progressing neurodegeneration of classical conditions. Olfactory dysfunction has been associated with most neurodegenerative, neuropsychiatric, and communication disorders. Evidence revealing the dual molecular function of the olfactory receptor neurons at dendritic and axonal ends indicates the significance of olfactory processing pathways that come under environmental pressure right from the onset. Here, we review findings that olfactory bulb neuronal processing serves as a marker of neuropsychiatric and neurodegenerative disorders.
Highlights
The mammalian olfactory system, the prime sensory modality for odor detection, is widely involved in detecting and processing olfactory signals
As olfactory signals reach and traverse through the olfactory bulb cell layers, the central olfactory neurons serve as the first contact point in the brain for external stimuli/stressors
Recent experimental evidence from mice indicates that together with odor detection, receptor molecules define the target in the olfactory bulb, thereby modulating odor map and its specificity through the dual function: response to odor at the dendritic end and as olfactory bulb guidance molecules at the axonal end of the same neuron [20]
Summary
The mammalian olfactory system, the prime sensory modality for odor detection, is widely involved in detecting and processing olfactory signals Processing of these sensory signals obtained from diverse chemical stimuli plays a pivotal role in physiological homeostasis. The olfactory bulb is a large structure occupying a quarter of the cranial cavity [4], whereas, in humans, it presents itself as a small extension of the brain This cortical brain structure is a master sensory processor in mammals as it possesses all the features of the mammalian brain in a small space [5] with the exclusive allocation of its cell layers for processing odorant information [1,2,3]. Together with a decline in olfactory acuity, has been suggested as a preliminary indicator of classical neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). We review and analyze the literature revealing insights into the fine-tuning of sensory processing in the olfactory system that points to the existence of novel yet unidentified pathways for neuromodulation in olfactory and limbic structures with a potential contribution to the onset of neurodegenerative pathology
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International journal of environmental research and public health
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
