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Cold reaction

Scientists have discovered the body’s ultimate “thermostat”. Fighting low temperatures to keep ourselves warm – within a narrow range of temperature in which our internal systems work optimally — is no mean job. Our body manages this well, but through a series of complex processes, according to new research.

Interestingly, the researchers at the Oregon Health & Science University in the US found that the body relies not just on sensory organs such as the skin, eyes and ears to get a sense of the outside temperature. It has a parallel mechanism which works as efficiently as the senses — perhaps even better — for alerting the brain to external conditions, Kazuhiro Nakamura and Shaun Morrison write in a coming issue of Nature Neuroscience.

For instance, there is a mechanism that tells the body when to perform one of the most basic defences against the cold: shivering. Shivering — which is actually heat production in the skeletal muscles — requires quite some energy. It is hence usually the last strategy used by the body to maintain its internal temperature in extreme cold, when all other options, including restricting blood flow to the skin, have run out.

The study, however, showed that the brain wiring that detects the need for — and ultimately triggers — shivering is not the same as the sensory pathway for conscious cold detection, as was previously thought. It works subconsciously, they observed.

“Our perception of temperature sensation (that is, our feeling “cold” or “hot”) is easily affected by other sensory inputs from the eyes, ears, etc. For example, when a person is facing something scary (such as a wolf), he or she would not feel cold even if the environmental temperature is pretty low. But even during such a situation, the body has to maintain its internal temperature in an appropriate range for survival,” Nakamura told KnowHow.

The research conducted in rats showed that signals collected from the skin are sent to a hitherto little known brain area called the parabrachial nucleus for processing and the information is subsequently passed on to another part of the brain — called the preoptic area — which decides when the body should start shivering.

A good example of how redundancy is at work in Nature!

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