Viral Vector-Based Techniques for Optogenetic Modulation In Vivo - Viral Vector Approaches in Neurobiology and Brain Diseases - page 292

18. Fiber optic implant:

● The implantable fi beroptic lightguide (IFL) can either be
inserted into the injection area or into a predicted projec-
tion area of that region [ 10 ]. The IFL we implant has a
metal or ceramic ferrule adapter which allows for optimal
optical coupling between the fi beroptic patch-cord and
the implanted fi ber.
● The length of the fi ber below the ferrule should be about
equal to the dorsoventral position of the target. It is rec-
ommended to cut the fi ber using a diamond knife: score
the optic fi ber with the diamond knife at the desired
length, lay the fi ber on a straight surface, and tape down
its tip. Holding the ferrule, pull lightly away from taped
tip. The fi ber should break at the scoreline (Fig. 1 -cI).
● Take into consideration that the tip of the fi ber should
be placed about 0.5 mm above the injection site in
order to be able to illuminate maximum volume of the
virally-transduced area.
● Replace the syringe holder arm with a cannula holder.
● Place the IFL in the cannula holder so that the fi ber tip is
pointing down towards the mouse head. Place the IFL
over bregma and reset the coordinates on the stereotax
(Fig. 1 -cII).
● Move the IFL to the target AP and ML coordinates. If the fi ber
implant area is the same as the injection site, the fi ber should be
above the previously drilled craniotomy (Fig. 1 -cIII). If the
fi ber implant area is different, proceed with drilling as men-
tioned above.
● Lower the IFL slowly to the DV coordinate. Make sure
that the dura mater has been fully removed from the
area before lowering the fi ber.
● Once the IFL has been inserted into the correct coordi-
nates, proceed with cementing. It is important not to
move the cannula guide yet.
19. Fix optic fi ber implant to skull.

Apply a layer of C&B metabond over the entire surface of
the skull, avoiding the craniotomy region ( see Note 9 ;
Fig. 1 -cIV).

●

Allow metabond to dry (5-10 min).

●

Apply a few thick layers of dental cement on the metabond
and around the fi ber and ferrule while leaving at least
5 mm from the top of the ferrule exposed (Fig. 1 -cV).
This is important in order to ensure suffi cient space for the
zirconia sleeve that will be attached to this area during the
experiments.

●