Researchers found Human Tongue Has Sixth Sense of Taste

Researchers found Human Tongue Has Sixth Sense of Taste

Researchers have found that in addition to recognizing sweet, sour, salty, savory, and bitter tastes, our tongues can also pick up on carbohydrates, the nutrients that break down into sugar and form our main source of energy.

In the new study, to be published in Appetite, the researchers asked participants to squeeze a sensor held between their right index finger and thumb when shown a visual cue.

At the same time, the participants’ tongues were rinsed with one of three different fluids.

The first two were artificially sweetened—to identical tastes—but with only one containing carbohydrate; the third, a control, was neither sweet nor carb-loaded.
When the carbohydrate solution was used, the researchers observed a 30% increase in activity for the brain areas that control movement and vision.

This reaction, they propose, is caused by our mouths reporting that additional energy in the form of carbs is coming.

The finding may explain both why diet products are often viewed as not being as satisfying as their real counterparts and why carbohydrate-loaded drinks seem to immediately perk up athletes—even before their bodies can convert the carbs to energy.

Learning more about how this “carbohydrate sense” works could lead to the development of artificially sweetened foods, the researchers propose, “as hedonistically rewarding as the real thing.

The presence of carbohydrate in the human mouth has been associated with the facilitation of motor output and improvements in physical performance.

Oral receptors have been identified as a potential mode of afferent transduction for this novel form of nutrient signalling that is distinct from taste. In the current study oral exposure to carbohydrate was combined with a motor task in a neuroimaging environment to identify areas of the brain involved in this phenomenon. A mouth-rinsing protocol was conducted whilst carbohydrate (CHO) and taste-matched placebo (PLA) solutions were delivered and recovered from the mouths of 10 healthy volunteers within a double-blind, counterbalanced design. This protocol eliminates post-oral factors and controls for the perceptual qualities of solutions. Functional magnetic resonance imaging of the brain was used to identify cortical areas responsive to oral carbohydrate during rest and activity phases of a hand-grip motor task. Mean blood-oxygen-level dependent signal change experienced in the contralateral primary sensorimotor cortex was larger for CHO compared with PLA during the motor task when contrasted with a control condition. Areas of activation associated with CHO exclusively were observed over the primary taste cortex and regions involved in visual perception. Regions in the limbic system associated with reward were also significantly more active with CHO. This is the first demonstration that oral carbohydrate signalling can increase activation within the primary sensorimotor cortex during physical activity and enhance activation of neural networks involved in sensory perception.

Source –
Appetite - Volume 80, 1 September 2014, Pages 212–219

Source –

http://www.sciencedirect.com/science/article/pii/S0195666314002281

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Thursday, June 12, 2014

Tags – Human Taste sixth sense tongue