Scientists have found that part of rat brains that processes ticklishness. Tickling the rats caused neurons in that region to fire. The rats also seemed to giggle hysterically, emitting rapid-fire, ultrasonic squeaks.

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Scientists have found that part of rat brains that processes ticklishness. Tickling the rats caused neurons in that region to fire. The rats also seemed to giggle hysterically, emitting rapid-fire, ultrasonic squeaks.