Single-neuron activity and tissue oxygenation in the cerebral cortex

Area of Science:

• Neuroscience
• Biophysics
• Medical Imaging

Background:

• Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) infers neural activity from hemodynamic changes.
• The spatial resolution of BOLD fMRI in relation to cortical columns remains debated.

Purpose of the Study:

• To determine if hemodynamic changes are regulated at a spatial scale sufficient for resolving functional columns in the cerebral cortex.
• To investigate the coupling between neural activity and oxidative metabolism at a high spatial resolution.

Main Methods:

• Simultaneous measurements of tissue oxygenation and single-cell neural activity were performed in the visual cortex.
• Neuronal spike rates and local tissue oxygenation levels were recorded concurrently.
• The relationship between oxygenation changes and neuronal function (orientation selectivity, ocular dominance) was analyzed.

Main Results:

• Increases in neuronal spike rate were immediately followed by decreases in tissue oxygenation.
• Decreases in tissue oxygenation were utilized to predict the orientation selectivity and ocular dominance of adjacent neurons.
• A direct coupling between neural activity and oxidative metabolism was established.

Conclusions:

• Hemodynamic changes associated with neural activity occur at a spatial scale capable of resolving columnar structures.
• High-resolution fMRI holds potential for localizing neural activity at the columnar level.
• The findings support a tighter link between metabolism and neural function than previously resolved by imaging techniques.