Biology subjects

Schneider, K. A.

Publications and source records attributed to Schneider, K. A..

3 recordsLinked to original sources

bioRxiv2022

The magnocellular division of the human medial geniculate nucleus preferentially responds to auditory transients

The medial geniculate nucleus (MGN), the auditory relay in the thalamus, is composed of three anatomical subdivisions: the ventral, dorsal and medial or magnocellular division. The functional differences among these nuclei have not been studied in humans, and in particular, the function of the magnocellular division is poorly understood in mammals in general. We anatomically segmented the MGN using proton-density-weighted magnetic resonance images (MRI) and measured the functional responses of the MGN to sustained and transient sounds, using functional MRI (fMRI). We observed that voxels in the ventromedial portion of the MGN, corresponding to the magnocellular division, exhibited a strong preference to transient sounds, whereas the remainder of the MGN showed no preference between sustained and transient sounds. We concluded that the magnocellular neurons in the MGN parallel the magnocellular neurons in its visual counterpart, the lateral geniculate nucleus (LGN), and constitute an information stream specialized for encoding stimuli dynamics. Significance statementThe medial geniculate nucleus is the auditory relay in the thalamus. It is composed of three anatomical divisions, of which the function of the magnocellular division is poorly understood. We show, using functional magnetic resonance imaging (fMRI) in humans, that the magnocellular neurons are strongly activated by transient auditory stimuli, similar to the magnocellular neurons in the lateral geniculate nucleus, the visual thalamic relay, which are rapidly adapting and specialized to encode visual transients. These results confirm that the auditory system represents stimuli using parallel information streams, employing similar encoding strategies as in other sensory modalities.

neuroscience↗

bioRxiv2022

Dyslexia linked to profound impairment in the magnocellular medial geniculate nucleus

The neurological basis of dyslexia, a common reading disorder, remains unclear but is hypothesized to be caused by either dysfunction of the magnocellular system in the brain, abnormal temporal processing, and/or deficient phonological skills. Using functional magnetic resonance imaging, we measured activity in the magnocellular portion of the medial geniculate nucleus, the auditory relay in the thalamus, and observed profoundly attenuated responses to non-linguistic transient but not sustained sounds in every subject with dyslexia we tested, compared to normal readers. Our finding unifies these three hypotheses and identifies a core deficit causing dyslexia.

neuroscience↗

bioRxiv2021

The impact of COVID-19 vaccination campaigns accounting for antibody-dependent enhancement

BackgroundCOVID-19 vaccines are approved, vaccination campaigns are launched, and worldwide return to normality seems within close reach. Nevertheless, concerns about the safety of COVID-19 vaccines arose, due to their fast emergency approval. In fact, the problem of antibody-dependent enhancement was raised in the context of COVID-19 vaccines. Methods and findingsWe introduce a complex extension of the model underlying the pandemic preparedness tool CovidSim 1.1 (http://covidsim.eu/) to optimize vaccination strategies with regard to the onset of campaigns, vaccination coverage, vaccination schedules, vaccination rates, and efficiency of vaccines. Vaccines are not assumed to immunize perfectly. Some individuals fail to immunize, some reach only partial immunity, and - importantly - some develop antibody-dependent enhancement, which increases the likelihood of developing symptomatic and severe episodes (associated with higher case fatality) upon infection. Only a fraction of the population will be vaccinated, reflecting vaccination hesitancy or contraindications. The model is intended to facilitate decision making by exploring ranges of parameters rather than to be fitted by empirical data. We parameterized the model to reflect the situation in Germany and predict increasing incidence (and prevalence) in early 2021 followed by a decline by summer. Assuming contact reductions (curfews, social distancing, etc.) to be lifted in summer, disease incidence will peak again. Fast vaccine deployment contributes to reduce disease incidence in the first quarter of 2021, and delay the epidemic outbreak after the summer season. Higher vaccination coverage results in a delayed and reduced epidemic peak. A coverage of 75% - 80% is necessary to prevent an epidemic peak without further drastic contact reductions. ConclusionsWith the vaccine becoming available, compliance with contact reductions is likely to fade. To prevent further economic damage from COVID-19, high levels of immunization need to be reached before next years flu season, and vaccination strategies and disease management need to be flexibly adjusted. The predictive model can serve as a refined decision support tool for COVID-19 management.

immunology↗