Touch Habituation Assay: A Method to Study Non-Associative Learning in C. elegans
Transcription
– C. elegans moves on its side by generating sinusoidal waves along its body. The animal moves de a forward direction when the waves are propagated from the head à the tail. Reversely, when the sinusoidal waves are propagated from the tail à the head, the worm moves backward.
Backward locomotion, known as reversals, is brief and either occurs spontaneously or is triggered by a sensory stimulus, for example, a gentle touch à the anterior of the worm. To perform the anterior touch habituation assay, isolate previously synchronized worms of the desired developmental stage on unseeded NGM plates.
Using a sterilized fine hair, perform a gentle touch à the anterior part of the body. This will elicit an escape response where the worm performs a reversal. Allow a 10-second interstimulus interval for the worm à recover and repeat the touch. To assess habituation, which is a form of non-associative learning, record the number of touches until a reversal is no longer observed.
In the example protocol, we will see a demonstration of the anterior touch habituation assay.
– First, use of fire steriled 30-gauge platinum wire pick à transfer approximately 10 synchronized young adult worms à new unseeded NGM plates. Leave the worms undisturbed for five minutes à allow them time à acclimatize à the new plate. Then, sterilize an eyebrow hair attached à the end of a wooden skewer or toothpick by dipping de 70% ethanol.
Wipe with a clean, lint-free tissue and wait for one minute for the ethanol à evaporate. Gently touch the worm on the head using the eyebrow hair. Repeat the touches allowing 10 seconds de between touches à allow the worm à recover.
Continuer à touch allowing 10-second interstimulus intervals until the worm no longer moves backwards. Record the number of touches required for this habituation à occur.
– Allowing a 10-second interval between touches is important, as this allows the animal recovery time and helps was obtaining consistent habituation behavior assays.
