Caffeine may influence the way the brain responds to touch - medicalxpress

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Many people begin each day with a steaming cup of joe to shake off the morning fog and jump-start their brain. Whether it's a shot of espresso or a frothy latte, that caffeine hit is famous for boosting alertness. However, new research published in the journal Clinical Neurophysiology reveals that coffee may be doing more than just waking us up. It could be changing how the brain connects what we feel to how we move.

Beyond the morning buzz

Researchers led by a team from Aarhus University Hospital in Denmark wanted to look at how a typical dose of caffeine affects a brain process called short-latency afferent inhibition (SAI). In simple terms, this is when a sensation in your body, such as a touch on your wrist, reduces the brain's response in the motor cortex, helping control how strongly muscles are activated. It is like a filtering system that keeps your movements smooth and controlled, which prevents the brain from overreacting to every single touch.

The scientists recruited 20 healthy adults for their experiment. Each received either 200 mg of caffeine (equivalent to a typical daily consumption) delivered in chewing gum for faster absorption or a placebo gum. The study was double-blind, so neither the participants nor the researchers knew which gum was administered during the test.

Then they stimulated the motor cortex with magnetic pulses and measured SAI using two different techniques. The traditional method (conventional amplitude, A-SAI) uses a fixed magnetic pulse and measures the size of the resulting twitch. The second technique (threshold tracking, T-SAI) automatically adjusts the pulse strength to maintain a constant muscle response.

With the first technique, researchers found that caffeine increased the brain's ability to reduce muscle response after a touch. This effect was most pronounced between 19 and 21 milliseconds after stimulation. With the second technique, no significant caffeine boost was detected.

"Caffeine enhances SAI as evaluated with the conventional A-SAI protocol, but not with the threshold-tracking method," commented the team in their paper.

Modifying brain chemistry

The research team believes that caffeine likely works by blocking adenosine receptors, which may lead to an increase in acetylcholine, a chemical messenger that helps control sensory-motor integration.

"Caffeine's effect may result from its modulation of the cholinergic system, providing insights into both its physiological action and brain disorder pathophysiology," noted the researchers.

Ultimately, one of the world's favorite beverages isn't just giving us an energy boost in the morning. It could also subtly change how sensory signals influence motor areas of the brain.

by Paul Arnold, Medical Xpress

edited by Stephanie Baum, reviewed by Robert Egan 

Source: Caffeine may influence the way the brain responds to touch