Weak correlations between hemodynamic signals and ongoing neural activity during the resting state

Area of Science:

• Neuroscience
• Physiology
• Biomedical Engineering

Background:

• Spontaneous fluctuations in hemodynamic signals are commonly used to infer neural activity during rest.
• Understanding the origins of these signals is crucial for accurate brain activity monitoring.

Purpose of the Study:

• To investigate the relationship between neural activity and cerebral blood volume (CBV) fluctuations during rest and behavioral states.
• To determine the drivers of spontaneous hemodynamic signals in the somatosensory cortex.

Main Methods:

• Simultaneous measurement of neural activity and CBV in awake, head-fixed mice.
• Recording during rest, whisker stimulation, and volitional whisking.
• Pharmacological blockade of neural and noradrenergic pathways.

Main Results:

• Neurovascular coupling remained consistent across different behavioral states.
• Volitional movements, not sensory input, drove large spontaneous CBV changes during rest.
• Hemodynamic signals during rest showed weak correlation with neural activity.
• Spontaneous CBV fluctuations persisted even when neural activity and specific receptors were blocked, suggesting non-neuronal origins.

Conclusions:

• Spontaneous hemodynamic signals are a complex interplay of behavior, neural activity, and non-neuronal processes.
• Relying solely on spontaneous hemodynamic signals for neural activity inference may be limited.
• Further research is needed to fully elucidate the non-neuronal contributions to hemodynamic signals.