Di Domenico, C. | Search bioRxiv

bioRxiv2026

The Brain Encodes Pure Logic Beyond Natural Language And At The Boundaries With Mathematics

You are not not reading this sentence. True, because you are. It's the law of double negation, a logical rule that states that a statement that is not not true is itself true. The development of pure logic - the study of the properties of formal systems, irrespective of their content - represents one of the most abstract intellectual achievements of human culture. Yet its neural correlates remain vastly unexplored. Is pure logic represented in a linguistic format like natural language, in an abstract symbolic format like other formal systems such as mathematics, or as a fully distinct domain of knowledge? To address this question, we monitored the brain activity of professional logicians and matched controls while they evaluated the truth of spoken statements of pure logic, and compared these activations to those elicited by language and mental arithmetic. We show that pure logic recruits left-lateralized brain circuits that are completely distinct from those involved in language processing. Those circuits only partially overlap with those involved in mathematics. These findings highlight an independent neural pathway for abstract thought and indicate that the brain's capacity to process structured rules of formal systems is implemented beyond language and at the boundaries with mathematics.

neuroscience↗

bioRxiv2025

Non-neuronal signal fluctuations in Alzheimer's disease and in mild cognitive impairment

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) permits the investigation neural activity thanks to the neurovascular coupling mechanism. However, neural activity accounts for only a portion of the observed BOLD signal fluctuations, as the vasculature integrates multiple physiological inputs that contribute to the response. Research focusing on isolating the vascular components of the BOLD signal revealed that markers of cerebrovascular health, such as cerebrovascular reactivity (CVR), serve as valuable biomarkers for neurodegenerative diseases. This study examines the relationship between vascular metrics and noise in a cohort comprising individuals with Alzheimers disease (AD), mild cognitive impairment (MCI), and healthy controls (HC). Vascular responses were assessed using three functional contrasts during a hypercapnic challenge: arterial spin labeling (ASL) to measure cerebral blood flow (CBF) reactivity, vascular space occupancy (VASO) to quantify cerebral blood volume (CBV) reactivity, and BOLD imaging. Noise metrics were derived from multi-echo BOLD resting-state data by isolating the TE-independent components of the signal. Mean correlation coefficients for noise vs ASL-CVR are: (-0.12 {+/-} 0.06) for HC, (-0.14 {+/-} 0.08) for MCI, (-0.11 {+/-} 0.05) for AD. Mean correlation coefficients for noise vs BOLD-CVR are: (0.25 {+/-} 0.11) for HC, (0.24 {+/-} 0.07) for MCI, (0.23 {+/-} 0.11) for AD. Mean correlation coefficients for noise vs VASO-CVR are: (0.13 {+/-} 0.10) for HC, (0.13 {+/-} 0.07) for MCI, (0.12 {+/-} 0.12) for AD. These results suggest that TE-independent noise relates to the three vascular contrasts to varying extents and directions, with no significant differences across groups. Further analysis within specific functional networks revealed group differences in specific networks. The observed cortical correlations between noise and vascular features provide important insights into brain function and the progression of neurodegenerative diseases, offering a potential avenue to disentangle vascular and neural contributions in brain network and connectivity studies.

neuroscience↗