Biology subjects

Papadimitriou, G.

Publications and source records attributed to Papadimitriou, G..

3 recordsLinked to original sources

bioRxiv2026

Neuroanatomy of substantia nigra and ventral tegmental area dopaminergic, and dorsal raphe serotonergic circuits in the human brain using T1-weighted and diffusion magnetic resonance imaging: A morphometric pilot study with estimate of reliability

IntroductionWe present here a methodology for morphometric analysis of the substantia nigra (SN), the ventral tegmental area (VTA), the dorsal raphe nucleus (DRN) and their respective structural brain circuits. MethodsOur analyses were based on multimodal T1-weighted MRI and diffusion MRI (dMRI) segmentation and tractography in 12 human subjects drawn from the Human Connectome Project (HCP) repository. ResultsWe were able to demonstrate strong connections of the SN, VTA and DRN with several brain regions, in particular the dorsolateral prefrontal cortex (DLPFC) and the cerebellum. More specifically, we created comprehensive visualizations of the SN and VTA dopaminergic as well as the DRN serotonergic structural circuits in the human brain, which, although preliminary, demonstrate the potential of multimodal neuroimaging to investigate these circuits quantitatively in clinical conditions. Finally, we created a pilot dataset for the most frequently observed structural connections, specifically those that were present more than 92% of the time among all subjects. Discussion This pilot morphometric report examines the structural circuits of the SN, VTA and DRN, which are critically involved in several biobehaviors and clinical conditions such as addiction, stress, Parkinsons disease (PD), schizophrenia, obsessive-compulsive disorder, post-traumatic stress disorder, attention deficit hyperactivity disorder, mood disorders, COVID-19 and long COVID. Importantly, the strong structural connectivity of the DLPFC and cerebellum with the SN, VTA and DRN is expected to be a potential target of noninvasive neuromodulation treatments in neuropsychiatry. Our findings demonstrate the potential of current clinical multimodal neuroimaging to delineate the dopaminergic (DA) and serotonergic (5-HT) circuits in the human brain in clinical conditions.

neuroscience↗

bioRxiv2025

Neuroanatomy of catecholaminergic circuits in the brainstem and hypothalamus using T1-weighted and diffusion magnetic resonance imaging in humans: implications for brain-immune interactions, cardiovascular disease, neuropsychiatric disorders, stress response, and COVID-19

Neuroimaging allows the study of brain structures that previously were undetectable due to their small size and location. Herein we focused on the core catecholaminergic circuitries in the human brain, involving the coerulean noradrenergic (or norepi-nephrine, NE) and dopaminergic (DA) systems. Using T1-weighted MRI morphometry and dMRI tractography, this study was carried out in one post-mortem human ultra-high-resolution dataset of the brainstem and diencephalon and in healthy human datasets from the Human Connectome Project repository. We investigated 26 connections of brainstem origin (13 in the left side and 13 in the right side) associated with the NE and DA circuitries. We delineated the coerulean NE and DA core central catechol-aminergic circuitries of the brainstem and hypothalamus in the post-mortem dataset, including all targeted fiber connections. Importantly, this was also achieved in the HCP datasets. These results emphasize the importance of multispectral neuroimaging in the study of chemical neuroanatomical circuitries and its application in clinical conditions such as cardiovascular disease, major depression, schizophrenia, and other disorders associated with chronic stress and brain-immune interactions such as COVID-19.

neuroscience↗

bioRxiv2019

3D Exploration of the Brainstem in 50-micron Resolution MRI

The brainstem, a structure of vital importance in the mammals, is currently becoming a principal focus in cognitive, affective and clinical neuroscience. Midbrain, pontine and medullar structures are the epicenter of conduit, cranial nerve and such integrative functions as consciousness, emotional processing, pain and motivation. In this study, we parcellated the nuclear masses and the principal fiber pathways that were visible in a high resolution T2-weighted MRI dataset of 50-micron isotropic voxels of a postmortem human brainstem. Based on this analysis, we generated a detailed map of the human brainstem. To assess the validity of our maps, we compared our observations with histological maps of traditional human brainstem atlases. Moreover, we reconstructed the motor, sensory and integrative neural systems of the brainstem and rendered them in 3D representations. We anticipate the utilization of these maps by the neuroimaging community at large for applications in basic neuroscience as well as in neurology, psychiatry and neurosurgery, due to their versatile computational nature in 2D and 3D representations in a publicly available capacity.

neuroscience↗