Howard Fields, MD, PhD


Neural Circuitry of Motivation

My research group studies the neurobiology of motivation, both pain and pleasure. We are interested in how addictive drugs alter behavior. In particular, our current research focuses on how opioids contribute to motivated behaviors and addiction. There are several distinct opioid receptors: mu, kappa, and delta, and endogenous opioids: endorphins, enkephalins, dynorphins and endomorphins. Our goal is to determine how each of these endogenous opioids and their receptors regulate motivation and reinforcement. We use both behavioral pharmacology and electrophysiology in awake behaving rodents. We also use in vitro electrophysiology in the relevant brain regions to identify the synaptic mechanisms that control neuron firing and consequently behavior. We also use immunocytochemical and tract tracing methods to answer questions of circuitry.

Our current focus is on a circuit that includes the midbrain dopaminergic regions and their downstream targets in the nucleus accumbens and medial prefrontal cortex. We are studying opioid control of these midbrain dopaminergic neurons and their neighboring non-dopamine neurons. We have found that opioid actions differ depending upon the projection target of the neuron under study. We are also studying dopamine inputs to nucleus accumbens neurons in awake behaving rats.

Laboratory members are also engaged in studying the neural basis of decision making in humans using behavioral testing and functional MRI. We plan to apply this approach to the study of addiction in humans.

Lab Members

Neil Schwartz, PhD
Postdoctoral Fellow

Kelly Lei, PhD
Postdoctoral Fellow

Maggie Waung, PhD
Postdoctoral Fellow

Ben Alter, PhD
Staff Research Associate

George Luu, PhD
Staff Research Associate

Catriona Miller
Laboratory Manager

Dawn Weinstein
Nurse Practitioner

Jocelyn Breton
Graduate Student

Joseph Driscoll
Graduate Student

Lab Website