Biology subjects

Krasovec, I. M.

Publications and source records attributed to Krasovec, I. M..

2 recordsLinked to original sources

bioRxiv2026

Functional neural signatures of navigation impairment in early Alzheimer's Disease

Spatial navigation is impaired early in Alzheimers disease (AD), but the neural computations affected by AD pathology remain unclear. We combined virtual-reality navigation with fMRI in aged controls, preclinical AD, and early AD participants, relating navigation activity to cerebrospinal fluid biomarkers and genetic risk. Early AD was associated with dissociable alterations: amyloid-{beta}-linked hippocampal hyperactivity during memory-demanding navigation, tau-linked reductions in hexadirectional modulation near the entorhinal cortex, and altered object-centered representations in posterior cingulate and entorhinal-adjacent regions. Object-centered changes related to how participants encoded and retrieved target locations. Hippocampal hyperactivity was the earliest, most robust effect and the only functional measure distinguishing preclinical individuals from controls. These findings connect AD biomarkers to distinct spatial computations in humans and reveal navigation-based functional signatures of neural dysfunction before overt dementia.

neuroscience↗

bioRxiv2025

Egocentric body-axis-related and allocentric clover-like tuning of object vector representations supports human spatial cognition

Vector-based spatial coding has been demonstrated in rodents, yet its neural basis in humans and its contribution to navigation remain poorly understood. Using a novel spatial updating task, we show that egocentric directional signals peak when objects are located behind the navigator, while distance signals emerge only when objects are out of view, suggesting a mnemonic role for vision-independent spatial mapping. Allocentric signals form a clover-shaped, four-axis pattern aligned to visual features, with improved navigation accuracy along its axes. Parallel rodent recordings further show the clover pattern arises from averaged activity of allocentric vectorial neurons, suggesting conserved cross-species mechanisms. Together, our findings uncover vector-based representations in the human brain, potentially serving as a neural reference axis to anchor objects to internal maps and support navigation.

neuroscience↗