limits and research

Limits

fMRI offers high spatial resolution (1-2mm), but suffers from low temporal resolution. The BOLD signal reflects hemodynamic changes in blood flow and oxygenation. This process occurs over several seconds, meaning that fMRI cannot capture fast neural dynamics ( e.g., an AP is on the ms scale, whilst the temporal resolution of fMRI is 1-2 seconds). 

Furthermore, BOLD signals are influenced by blood flow, volume, oxygenation, vascular reactivity and metabolic states. This introduces noise unrelated to neural activity. Signals can also be confounded by physiological artifacts like head motion or heartbeat. 

Unlike NIBS techniques, fMRI can show brain regions correlated with tasks or stimuli, but cannot establish causation. 

Studies example

Research shows that deceptive answers can produce distinguishable patterns in the BOLD signal compared to truthful responses. Activity during lying and truth telling is often compared, revealing heightened activity in regions like the prefrontal cortex and parietal lobes during deception. 

However, Results are not universally reliable. False positives can occur due to stress or cognitive load unrelated to lying. It would also be impractical in real life scenarios, as it would imply staying still for extended periods. Additionally, it would have a poor real-time detection of lies.