Learning and
Physiological Regulation
Within the cardiovascular system the
baroreflexes of the carotid sinus and aortic
arch are crucial to blood pressure
stabilization. Our research focuses on the
question of whether a mechanism of neural
plasticity, known as classical conditioning,
which is involved in drug tolerance,
digestive secretion, and adjustment of
critical visual tracking reflexes, is also
involved in activation and calibration of
the baroreflexes. Classical conditioning
itself is simply a repeating sequence of a
weak (conditioned) stimulus followed by a
stronger (unconditioned) stimulus. It has
been known since Pavlov that eventually, the
weaker stimulus produces reflex effects
closely resembling those of the stronger
stimulus. Mathematical models that we have
developed predict that classical
conditioning can significantly augment the
effectiveness of innate regulatory reflexes,
and in various ways tailor their action to
the needs of an individual's anatomy,
constitution and life experience. Our recent
research has established that the vascular
sympathoinhibitory and cardiac depressor
effects of the baroreflex can be
conditioned, and that the conditioned
responses satisfy the assumptions of the
models. Our experiments all use a unique
highly instrumented, CNS intact long-term
rat model. We are able to monitor blood
pressure, EKG, regional blood flow, brain
electrical activity, electrical activity of
individual skeletal and autonomic nerves,
and many other physiological variables
simulataneouly and accurately. At the same
time we can present various visual and
auditory stimuli, and activate selected
autonomic afferent nerves repeatedly.
Ongoing studies will extend the empirical
mechanisms and theoretical concepts of
traditional physiology to include classical
conditioning, and will specifically
determine whether there is a fundamental and
implicit role of conditioning in normal
blood pressure regulation. |
