Rats ARE ticklish - but they only 'laugh' when they are in a good mood
http://www.dailymail.co.uk/sciencetech/article-3924300/Rats-ticklish-laugh-good-mood.html#v-7180138883129691345
How do you make a rat laugh? Just tickle it, say scientists (and if you don't believe them, watch their bizarre experiment)
- Researchers found neurons in rat brains linked to ticklishness and laughter
- When they stimulated these brain cells they made the animals chuckle
- Rats were only found to enjoy the sensation if they were already happy
- The findings suggest the somatosensory cortex may play a role in mood
Associated with the plague and demonised in novels such as George Orwell's 1984, rats don’t have the best of reputations.
But the vilified rodents are known to giggle.
Now scientists have found that rats ‘enjoy’ being tickled – but only if they were already in a good mood.
Researchers
at Humboldt University of Berlin identified neurons in rats’ brains
linked to ticklishness and laughter and by stimulating them, were able
to elicit a chuckle from the furry creatures.
The finding suggests the somatosensory cortex - the brain region where the neurons were located - may play some role in mood.
It was previously thought this brain region is primarily associated with the sense of touch.
The
study, published in the journal Science, builds on previous work in
which it was discovered tickling rats causes them to laugh at high
frequencies that are inaudible to humans.
While tickling is easy to do, how the sensation reaches our brain is unclear.
Know any good jokes? Rats love to
chuckle, according to a new study. Researchers captured footage of a rat
emitting ultrasonic vocalisations when it was tickled (still pictured)
To
investigate, Shimpei Ishiyama and Michael Brecht monitored neuron
activity in the rat somatosensory cortex before and during tickling.
They
found that consistent with earlier claims that tickling is rewarding,
the rats readily approached the tickling hand and performed ‘joy jumps’
as well as ultrasonic giggles when tickled.
The
experts observed that neural firing rates in the deep layers of the
somatosensory cortex increased along with laughter when the rats were
tickled.
To
test this correlation, they stimulated somatosensory cortex neurons
when the rats were not being tickled, which they found also resulted in
laughter.
However,
when the rats were in an anxious mood – as a result of being placed on a
high platform, for example - tickling-evoked laughter and neural firing
were suppressed.
The
authors believe their findings support Darwin's idea that ‘the mind
must be in a pleasurable condition’ for ticklish laughter to occur.
'TWO MICE WALK INTO A BAR...': THE SCIENCE OF HOW RATS LAUGH
Researchers have found that rats laugh at high frequencies inaudible to humans
Laughing
rodents may seem like a strange phenomenon, but researchers have found
that rats laugh at high frequencies inaudible to humans.
Their 50-kHz ultrasonic calls, known as chirps, are distinct from the other noises they make, Scientific American reported.
Researcher
Jaak Panksepp is thought to have been the first to discover that
chirping can be compared to laughter in humans, by tickling rats,
He
also found that the most ticklish rats - those that chirped the most -
were also the most naturally playful and that laughter in young rats
seems to increase bonding.
This
is because in his experiments, young rats actively sought out a hand
that had tickled them - presumably because the experience was enjoyable.
But
he stopped short of asserting rats have a sense of humour, simply
pointing out there seems to be similarities between laughter in children
when they play and the same activity in rats.
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