What is the approximate delay of the hemodynamic response after neuronal activity?

What is the approximate delay of the hemodynamic response after neuronal activity?

• A. 0 seconds
• B. 1 second
• C. 4-6 seconds
• D. 30 seconds

Answer: (C)

Neural activity triggers a vascular response that lags behind the firing. The blood flow change takes a few seconds to rise and reach its peak, with the typical peak occurring about 4–6 seconds after neurons fire. So the approximate delay to the hemodynamic response is 4–6 seconds. An instant change would be unrealistic, and a peak at 1 second or as late as 30 seconds misses the usual timing of the neurovascular response.

Neural activity triggers a vascular response that lags behind the firing. The blood flow change takes a few seconds to rise and reach its peak, with the typical peak occurring about 4–6 seconds after neurons fire. So the approximate delay to the hemodynamic response is 4–6 seconds. An instant change would be unrealistic, and a peak at 1 second or as late as 30 seconds misses the usual timing of the neurovascular response.