laughter than we know. by human right at least in the brain it's just so. when a rat loves it's not audible to the human ear the rat emits a series of high frequency chuckles in the range of fifty kilo heads to hear a rattle off uses an ultrasound detector tests we can stimulate their. stimulating specific parts of the brain. and every place you stimuli that you get a rat laughter which is kind of should you choose the animal likes it the animal will turn on the stimulation themselves so now we know it's a positive emotion. from. jason how this animal charge for a good response has actually been surfing when you're older you know that we go.