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Tickling and the Brain
By Dr. Silvia Helena Cardoso
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Tickling
Fascinating instance of the
Normal
child
Congenitally blind
child
Chimpanzee
• Connection between playfulness, laughter
and social bonding
• Almost always produces laughter
• Tickling and laughter evolved in part to help
us relate to others
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Anatomy of Tickling
Brain
Skin
Axon
Sensory cortex
(Area that registers touch)
Thalamus
Touch
receptors
Spinal cord
Anterior Spinothalamic Tract
Nerve cell
Sensory ganglion
Tickling stimulates touch receptors in the skin. These receptors, when stimulated carry
information in sensory neurons that goes to the spinal cord.
Then this information travels up to the sensory cortex via the thalamus.
The sensory cortex is involved in processing information from the skin.
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The big enigma of
We do not laugh when we tickle ourselves,
only when other people tickle us.
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Why is it impossible to tickle ourselves?
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Cerebellum
Brain region that helps to
control voluntary movement and
balance
Predicts the sensory consequences of
movements - supplying the brain with
information that reduces the sensation of touch
information.
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Charles Darwin
1809 -1882
“For tickling to be effective, you must not
know the precise point of stimulation in
advance”
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.
Somatosensory
cortex
Cerebellum
When you try to tickle yourself, your cerebellum sends to
your somatosensory cortex precise information on the
position of the tickling target and therefore what sensation
to expect.
.
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Robotic arm
Experiment using robotic arms to
tickle people. It is as effective as real
people in provoking laughter.
Subject tickling himself. He couldn’t make
himself laugh.
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fMRI
Touch’s area
Somatosensory
cortex
Part of the
brain that
registers
touch
To compare brain activity when a
subject's hand was tickled by an
experimenter or by himself.
fMRI detected more neuronal
activity in somatosensory cortex,
when people were tickled than
when they tickled themselves.
Somatosensory cortex helps interpret external stimuli
registered by nerve endings that sense touch. 10