Bidirectional alterations in brain temperature profoundly modulate spatiotemporal neurovascular responses in-vivo

Abstract

Neurovascular coupling (NVC) is a mechanism that, amongst other known and latent critical functions, ensures activated brain regions are adequately supplied with oxygen and glucose. This biological phenomenon underpins non-invasive perfusion-related neuroimaging techniques and recent reports have implicated NVC impairment in several neurodegenerative disorders. Yet, much remains unknown regarding NVC in health and disease, and only recently has there been burgeoning recognition of a close interplay with brain thermodynamics. Accordingly, we developed a novel multi-modal approach to systematically modulate cortical temperature and interrogate the spatiotemporal dynamics of sensory-evoked NVC. We show that changes in cortical temperature profoundly and intricately modulate NVC, with low temperatures associated with diminished oxygen delivery, and high temperatures inducing a distinct vascular oscillation. These observations provide novel insights into the relationship between NVC and brain thermodynamics, with important implications for brain-temperature related therapies, functional biomarkers of elevated brain temperature, and in-vivo methods to study neurovascular coupling.

Establishment and external validation of a nomogram for predicting 28-day mortality in patients with skull fracture

“…There were several reasons that may be responsible for our findings. One possible explanation was that when body temperature drops, it can cause vasoconstriction and bradycardia, affecting the perfusion and oxygen delivery to vital organs (25). Another reason was perhaps that hypothermia can result in coagulation abnormalities, heightening the risk of bleeding (26).…”

Effects of focal cortical cooling on somatosensory evoked potentials in rats

“…For either V p-n , V n , or V p , the relationship between the amplitude and the temperature showed an inverted U-curve, where the SEP amplitudes increased by cooling up to approximately 27.5 °C and then decreased by further cooling (cf. Boorman et al, 2023; Gotoh et al, 2020). This temperature-dependent pattern was modulated by the administration of the GABA A receptor antagonist, gabazine.…”

Arousal state transitions occlude sensory-evoked neurovascular coupling in neonatal mice

“…We did not measure body temperature, and the neonates likely had lowered body temperature during imaging. Cooling of the adult brain below ~20 °C results in large reduction of neural activity and a profound decrease in the hemodynamic response 68 , but neonates separated from their mother typically maintain a temperature above 30 °C 69 . Circadian rhythms can also affect temperature, but brain temperature in adults changes only by a few tenths of a degree over minutes 70 , so it is hard to attribute the rapid constrictions upon awakening seen here to any temperature change.…”

“…Circadian rhythms can also affect temperature, but brain temperature in adults changes only by a few tenths of a degree over minutes 70 , so it is hard to attribute the rapid constrictions upon awakening seen here to any temperature change. However, cooling of a few degrees in adults causes a slowing of the hemodynamic repsonse 68 , and may account for the slower dynamics of neonates compared to adults.…”