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Real-time Electrophysiology: Using Closed-loop Protocols to Probe Neuronal Dynamics and Beyond
Published on: June 24, 2015
Neurometabolic coupling in cerebral cortex reflects synaptic more than spiking activity
Ahalya Viswanathan1, Ralph D Freeman
1Group in Vision Science, School of Optometry, Helen Wills Neurosciences Institute, University of California, Berkeley, California 94720-2020, USA.
Nature Neuroscience
|September 11, 2007
Summary
Functional magnetic resonance imaging (fMRI) infers neural activity from blood oxygen changes. This study shows the blood oxygen-dependent (BOLD) signal is primarily driven by synaptic activity, not just neural spikes.
Area of Science:
- Neuroimaging
- Neurophysiology
- Metabolic imaging
Background:
- Functional magnetic resonance imaging (fMRI) infers neural activity using the blood oxygen-dependent (BOLD) signal.
- A key debate in fMRI research concerns whether the BOLD signal reflects synaptic activity or spiking activity.
Purpose of the Study:
- To investigate the relationship between synaptic activity, spiking activity, and the BOLD signal.
- To determine whether the BOLD signal is primarily driven by synaptic or spiking neural activity.
Main Methods:
- Utilized cat primary visual cortex for recordings.
- Employed a specialized stimulus to isolate synaptic activity without inducing spikes.
- Performed colocalized recordings of neural activity (local field potentials and spikes) and metabolic activity (tissue oxygen concentration).
Main Results:
- Observed a strong coupling between local field potentials (LFPs), indicative of synaptic activity, and changes in tissue oxygen concentration.
- This coupling persisted even in the absence of neural spiking activity.
- Demonstrated that metabolic changes, measured by oxygen levels, correlate with synaptic activity.
Conclusions:
- The blood oxygen-dependent (BOLD) signal in fMRI is more closely coupled to synaptic activity than to spiking activity.
- These findings have significant implications for interpreting fMRI data in neuroscience research.
- Suggests that fMRI primarily measures the metabolic consequences of synaptic transmission.
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