Hello. I'm Tony Yaksh and I'm vice chair
for the Department of Anesthesiology at the University of California,
San Diego, and I'm Director of the Laboratory of anesthesiology research.
For almost 30 years,
we have had as a primary focus,
research related to the delivery and action of drugs in the spinal cord with
a particular emphasis on issues and pharmacology related to pain nociceptive processing.
Today I would like to give a brief overview of issues pertinent to spinal drug delivery,
particularly as it pertains to a technology, biology, and toxicology.
The idea of delivering drugs into the spinal cord reflects upon
a fundamental appreciation of the role played by that structure in pain transmission.
The idea that there were pathways leading from the outside to
the brain conceptually certainly goes back to Descarte, if not before.
In this iconic figure of the little boy with his foot proximal to the fire,
the notion was that the information that cause the individual
to have a grimace of his face reflected upon the transfer
of thermal energy to the foot and the activation of information
carrying pathways from the foot to the spinal cord to higher centers,
where the twitching of the pineal gland and the brain was believed to reflect
upon the nature of the pain condition of the stimulus of the outside world.
This notion of a specific pathway carrying information bounds as
its anatomical underpinnings the results from
early studies of 19th Century physiologists and anatomists.
Bell and Magendie, for example,
demonstrated that the dorsal root represented
a primary pathway by which afferent information made its way into the nervous system.
Brown-Sequard and Edinger and other anatomists pointed to the importance of
superficial long tracks in the lateral aspects of the cord for carrying such information.
It felt the Gower in 1888 who,
as a result of clinical observations in clinical case material,
made the prescient observation that pain traveled
as a crossed system in the ventral lateral quadrant of the spinal cord.
One such case, he noted that after ventral lateral tract injury,
that pain was found loss absent on the contralateral side,
whereas light touch was preserved bilaterally.
This observation pointed to the importance of specific pathways at the spinal level of
carrying sensory information relevant to different somatosensory experiences.