At Backyardbrains video lab we bring you our newest exciting preparation
the RoboRoach
To get started, you want to learn how to build your own electrodes
if you purchased a RoboRoach kit from us we included a few electrodes
pre-assembled for you
but as you become more advanced and doing more and more experiments
you're going to want to learn how to build your own
We take the common electrical component -the header- which you can buy from ??????
and cut them into three connector segments
then you want to carefully sand each side of the header
so that it will become gritty which will make it easier to clue
which you'll understand
very soon why we do that
I've sped up the sanding process in the interest of time
To interface with the cockroach's nervous system we use
very fine silver wire from A-M Systems. This is 0.003 inches in diameter
and you want to cut three separate pieces of each approximately being 1
to 1/4 inches in length
Use a lighter, now burn off approximately 1/8th inch of the teflon insulation
off the silver wire segments you just made. This requires a bit of finesse
as if you hold the wire to close you can actually melt the silver.
Do this for both ends of each wire segment you cut
Now to solder the fines??? of a wire
to a connector, we use a standard
Radio Shack product with two percent silver in it
we make the silver wire into a loop
and we lay all three across the three connector segments
now grab your favorite soldering iron
and solder the three wires to the three connectors. Make sure each connection is
distinct, and that there are no shorts
and voilá!
you've now made your electrode
Now it's time for the biology
Take your colony of cockroaches,
grab your largest discoid
and put him in the ice water.
The ice water serves as the anesthetic.
After a few minutes, he will stop moving and will be ready for the next step.
Now the reason cockroaches are such experts at getting into very very small places
is that their whole body is covered with a very slippery wax, which is
very very difficult to glue to.
Thus, we're going to sand a little bit of this wax off of his pronotum.
Now we're going to glue the connector
The super glue we enjoy enjoy is the Loctite Super glue control gel. It's not as runny as
normal cyanoacrylate and very very easy to control
Glue a little bit on his pronotum
Now carefully place the connector onto the cockroach
with the solder points pointing towards the anterior end.
The conection will be strong enough within one to two minutes
Now for the hardest step of the surgery. I have not figured out an easier way
to do this.
You need to put your ground wire
into the thorax of the cockroach
Carefully splay one of his wings and secure it with silly putty.
Now wipe off the excess water from the ice water anesthesia off his thorax
with a q-tip
Now again, since we're at a glue step,
we're going to lightly sand the waxy coating of the thorax with a small bit of
sandpaper
And with our q-tip we're going to again soak up the excess moisture from the
ice water anesthesia
Now with a small needle -you can buy these at the drugstore-
you want to lightly poke the exoskeleton of his thorax.
Now very carefully place the lefternmost wire.
Park it
in the small hole you just made
in the thorax
This is a very very hard step to do
as the wire will easily crumple on itself.
You may find this takes multiple attempts to get it parked.
Now with a splinter of wood
take a small piece of super glue
and place it on the wire just above
where it goes into
the thorax
You may find using a magnifying glass helps you,
while i was shooting this video it was easier for me not to use it.
So I've put just a little bit of glue right above where it's parked
and then with my forceps
I'm carefully lowering
the wire
about one to three millimeters below the surface so that it's in contact
with the saline
of the body
I've put a little bit more super glue on top of where I just inserted it.
Remove the silly putty
and fold the wing back over to its natural position.
Now's a good time to put the cockroach back in ice water anesthesia for a
couple minutes.
Now it's time to insert the antennae- stimulating wires.
Using your forceps splay the antenna out
and then with your scissors, cut the antenna down to with only 1/8th to
1/4 inch left.
The antennae are hollow fluid-filled structures with a nerve running down
the center.
Now you're going to position
the middle-most wire to go into the cockroach left side
park it just into the antenna -don't put up all the way in.
Now, as you did before, apply a little bit of super glue to the wire just above
where you parked it
and then using your forceps
put the wire approximately two to four millimeters into the antenna. The point is
to get the super glue just inside the inner ring of the antenna so it sticks
on the inside
otherwise it will slip out very easily.
Put some more super glue around the antenna-wire interface
and now put the cockroach back in the ice anesthesia
After a couple minutes, repeat for the remaining antenna and the remaining wire.
Be careful not to touch the super glue with your fingers
as it will very easily glue to you instead of the cockroach or the silver.
Now you're almost done!
Put the cockraoch back in the ice water anesthesia
and wait a couple minutes before proceeding to the next step.
Nw it's time to clean up all the excess wire so the cockroach
can't pull the wires out.
Carefully,
pull back all the wires until they are in a nice loop
on top of the connector.
It's important that the distance between the antennae
and the connector
be as short as possible
so the cockroach can't reach his forearm in between the loop and potentially
pull the wires out.
This is a principal failure point
that took a while to figure out.
Notice I have made my best effort to have all the excess wire tightly compact an organized
on top of the connector.
Now to hold
the excess wire in place
place a dab of hot glue on top of the connector.
Now to make the hot glue spread evenly on the connector and hold all the wires
in place,
I've coated the end of my forceps with baking soda
and pressed the forceps gently onto the hot glue.
The baking soda prevents the hot glue from sticking to the forceps.
After a couple seconds I gently lifted the forceps and it comes off quite easily.
Look how nice and organized it is now.
But how do I know if my surgery was any good?
If i have a SpikerBox
I can actually try to record the neural responses in the antennae;
that tells me the surgery was successful.
I've plugged in my little adapter into the connector.
I'll then plug in my micro clips, one to the ground and one to the left antenna
and turn the SpikerBox on. It sounds a bit noisy, so I'm going to turn off all the
fluorescent lights to reduce line?? interference.
That semi-random popping you're hearing is the spiking, or action potentials
of the living neurons in the antenna.
I'll try the other side and check as well.
The other side sounds good as well, great neural response.
Now it's time for the cockroach to recover.
I'll simply put him in his cockroach house and wait usually overnight.
However, if I'm teaching in a classroom and I want him to recover faster
I have a tub of warm water and I put the cockroach
on top of the warm water and it'll recover
within maybe half an hour.
Now to test your RoboRoach!
Take your RoboRoach circuit and turn it on by pushing the switch
all the way to the right.
Make sure your transmitter's on the B-channel
and press the L and R buttons.
If the lights on either side turn on, you know it's working.
It's time to plug in the cockroach.
Notice that nice wing-flapping behavior when I pick him up by the connector.
That's a fairly stereotyped behavior that students like to observe to wonder
about the mechanics of wing flapping.
Now that he is on the table, simply plug in the connector, gently.
But how do we get it to stay on the cockroach? Take your hot glue again and put a small tab on
the underside
and then stick the package firmly on the center
of the cockroach
It's not too hot -don't worry, the cockroach is fine.
Now place the cockroach on the floor
and when he starts running
start stimulating the left and right sides and see what you observed
How long do the behaviors last? Does he always turn left and right
upon stimulation?
Does the cockroach appear to show any sort of learning or adaptation upon
repeated stimulation?
Are you competing with any other sorts of behaviors?
There are many types of questions you can ask about stimulation
and neural responses with this simple prep.
When you're done with your experiment, it's time for the cockroach to go back into his house to eat and rest.
Put him in the refrigerator to slow him down a bit
and then with your forceps, carefully ease the connector
from the stimulator package
and slowly peel it off
and put the cockroach back in his house.
So after that unsightly scar on my hand -I was changing the oil of my Tercel?? last weekend
busted knuckles.
Now you can start asking independent questions of your own.
For example, from your neural engineering class, are biphasic pulses better than
direct voltage?
Here I've designed a RoboRoach where I am solely providing positive three volts
to the antennae
and you can notice there's very little effect on the cockroach turning???
This tells us that pulses designed to mimic action potentials are actually more effective.
Now here's a confusing result. We have a different species of cockroach, the Giant
South American Fusca cockcoach, and when you stimulate his left and right antennae he simply stops...
...it's more of a break.
Why is this? Is there behavioral reason?
Or a stimulation reason?
And eventually the cockroach just ignores it and keeps walking
upon simulation.
We're still trying to figure this out.
Good luck on your surgeries.
You can purchase a RoboRoach Prototyping Kit on our website, backyardbrains.com.
We'd love to hear you suggestions on improving the technique
as well as anything you learn.
Backyard Brains, Neuroscience for everyone!