The
detection of movement and vibrations is critical to most species. Whether
you’re a mammal, reptile or a fish you have hairs that amplify the motion and
convert it to an electrical signal in the brain. To make this work, each hair
has a little bundle of organelles on the end, rather like a brush.
We use
these little brushes to listen to endless political debates and we know our
heads are spinning from these by more little brushes, which normally help us to
maintain our equilibrium.
Fish have
their little brushes hidden along their lateral line, which makes them very
sensitive to variations in water movement. Very useful for proper shoaling
behavior, but doesn’t help in paying attention to political debates, not that
it matters to most fish as they have very short memories, which would probably
make their vote predicable should they ever get registered.
If our
hair bundles are going to work well for us, we want them to give us a clear
signal when the volume is very low, but turn it down when the volume is very
high. In other words we need them to be non-linear. Too much of a good thing
and we may get them mussed up leaving us with a ringing in the ears.
Those
little hair bundles have to be very versatile depending on the their location
and end-use. A recent paper by Ó Maoiléidigh et al published in the proceedings of
the National Academy of Science has used a simple mechanical model that behaves
in a similar fashion to hair bundles (1). The key is that the response can be
widely varied by altering the loading of parts of the model in an analogous
manner to the variation of situations that hair bundles find themselves
occupying.
Now we know how we are using similar technology to fish or frogs
are we going to shoal to the polls or sit stubbornly on our own pad and croak?
