Viral Vector-Based Techniques for Optogenetic Modulation In Vivo - Viral Vector Approaches in Neurobiology and Brain Diseases - page 297

7. If diffi cult to detect, it is possible to apply a bit of pressure with
tweezers on one of the skull bones in order to better empha-
size the sutures under the stereomicroscope. Another possibil-
ity is to apply a bit of sterile 4 % H 2 O 2 with a cotton swab.
After several seconds, wash the skull with sterile saline to stop
the reaction. Suture lines should become more visible after
~10 s of treatment.
8. If necessary, adjust skull position to align lambda and bregma.
The medial-lateral position can be adjusted by moving the ear
bars simultaneously without releasing the pressure on the
skull. If lambda is too high or too low relative to bregma,
adjust the mouse's snout by raising/lowering the tooth bar.
9. Metabond acts as a bonding material between the scalp and
the dental cement. A thick layer should be spread on the scalp
around the implanted fi ber and around the bottom part of the
ferrule. Contact between metabond and the exposed craniot-
omy can be eliminated by applying a layer of aqueous gel or
petroleum jelly (Vaseline) into the craniotomy prior to inser-
tion of the IFL.
10. It is advisable to measure the light power output of the optical
system by using a portable light power meter (e.g., Thorlabs
P-1000D). This can be done using an IFL similar to the
implanted one, in order to account for light power losses at all
points of optical coupling in the path.

Acknowledgments

We thank the entire Yizhar lab for helpful comments and discus-
sions on the manuscript and protocol. This work was supported
by grants from the Israeli Science Foundation (ISF grant
1351/12) and by the Israeli Center of Research Excellence
(I-CORE) in Cognition (I-CORE Program 51/11). Ofer Yizhar
is the incumbent of the Gertrude and Philip Nollman Career
Development Chair.

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