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Regional temperature changes in the brain during somatosensory stimulation
Hubert K F Trübel1, Laura I Sacolick, Fahmeed Hyder
1Department of Diagnostic Radiology, Magnetic Resonance Research Center, Yale University, New Haven, Connecticut 06510, USA.
Summary
Brain temperature (Tt) increases slowly during neuronal activity due to changes in cerebral blood flow (CBF) and metabolism (CMRO2). Increased CMRO2 is the primary driver of this temperature rise.
Area of Science:
- Neuroscience
- Physiology
- Biophysics
Background:
- Brain temperature (Tt) variations are linked to cerebral blood flow (CBF) and metabolic rate (CMRO2).
- Understanding these dynamics is crucial for interpreting functional brain imaging and temperature regulation.
Purpose of the Study:
- To investigate the relationship between neuronal activity, brain temperature, CBF, and CMRO2.
- To determine the primary drivers of brain temperature changes during functional challenges.
Main Methods:
- Multimodal measurements in anesthetized rats using magnetic resonance, optical imaging, temperature sensing, and electrophysiology.
- Forepaw stimulation to induce localized neuronal activity.
Main Results:
- Neuronal activation caused localized increases in Tt (approx. 0.2%), CBF (approx. 95%), and CMRO2 (approx. 73%).
- Tt increase showed a slower time-to-peak (42+/-11 secs) compared to CBF and CMRO2.
- Increased CMRO2 (Qm) was the main contributor to net heat, overriding potential cooling effects from CBF (Qf) and conduction (Qc).
Conclusions:
- Brain temperature rises slowly during physiological stimulation, primarily driven by metabolic rate.
- Cerebral blood flow's cooling effect is secondary to metabolic heat production in influencing brain temperature.
- Findings have implications for functional neuroimaging in humans and understanding thermoregulation.