Lab Projects: Neurophysiology

Neurophysiological Basis of Behavioral Sensitization and tolerance following chronic psychic stimulant administration

The work in this area focuses on uncovering the brain structures responsible for the development and expression of behavioral sensitization. Repeated treatment with stimulants (Ritalin, amphetamine, codeine) is believed to cause release of dopamine and norepinephrine from areas like the prefrontal cortex, nucleus accumbens, ventral tegmental area, and caudate-putamen recordings of neuronal activity from these areas are studied. Our overall objective is to investigate behavioral and neurophysiological aspects of behavioral sensitization and tolerance as the fundamental mechanisms underlying the effect of long-term sequelae of methylphenidate (Ritalin) administration, which is the drug of choice for the treatment of ADHD. The neurophysiological studies investigate brain sites considered to be essential in the induction and expression of sensitization and/or tolerance to psychostimulants. In addition we are making an effort to develop non-invasive electrophysiological procedures to differentiate between ADHD and non-ADHD subjects.

Pain Suppression Mechanisms

Since the discovery that profound analgesia can be produced by focal electrical stimulation of midbrain structures (e.g., periaqueductal gray, dorsal raphe), it has become increasingly apparent that analgesia is in part related to opioid agonists that interact with a variety of receptors and endogenous opioids. Pain modulation is a dynamic process which involves continuous interactions among complex ascending and descending pathways. Our pain research focuses on defining the sites responsible for the modulation of pain.

Mechanisms of Drug Abuse

In addition to behavioral studies on the effects of drugs of abuse, our laboratory uses electrophysiological techniques to uncover the mechanisms, actions, and modulators of drug abuse. For example, we have shown that noninvasive, subthreshold auricular electrical stimulation (AES) may be used as a treatment to reduce the severity of precipitated and of abrupt opiate withdrawal, and explored the mechanism of irradiation-induced on changes in opiate withdrawal.