Discovering

INDIVIDUAL RESEARCHER

Joseph F. Cheer , Ph.D.
Assistant Professor
e-mail: cheerj@mail.amc.edu

Education

2000 - Ph.D. from The University of Nottingham (UK)

Current Research

Research in my lab is aimed at understanding the physiological function of the endogenous cannabinoid system with a particular emphasis on normal motivated behaviors as well as its potential therapeutic role in pathological states such as addiction. Endogenous cannabinoids such as arachidonoylethanolamide (anandamide from the sanskrit word "ananda" meaning bliss) and 2-arachidonoylglycerol (2-AG) and their binding to central cannabinoid receptors (CB1) in the brain and spinal cord make up this recently described signaling system. These molecules have been involved in a wide spectrum of physiological states ranging from reinforcement processing to pain perception and executive function. Our research employs state-of-the-art electrophysiological (ensemble recordings) and electrochemical (fast-scan cyclic voltammetry) techniques to extract neurobiological correlates of key aspects of behavior in real-time. We have also implemented the use of a microsensor that can simultaneously record extracellular single-unit activity and neurotransmitter release. These techniques are used in conjunction with pharmacological tools such as systemic administration, microinjection and iontophoresis to examine how endogenous cannabinoids modulate the encoding of motivated behavior. We are specifically interested in the dopaminergic projection from the ventral tegmental area to the nucleus accumbens. Dopaminergic neurons burst fire in response to rewards and play a key role in the prediction of the availability of reward. We have shown that exogenous cannabinoids potently modulate the activity of dopaminergic neurons, in particular their ability to burst fire and to produce transient increases in dopamine concentration in the nucleus accumbens, suggesting that endogenous cannabinoids are indeed important mediators of reward encoding in behaving animals. Thus, understanding the interactions between endogenous cannabinoid and dopaminergic signaling in the nucleus accumbens during reward-related behavior is likely to yield unprecedented insight on the pathogenesis of addiction. For more information please visit our website: The Cheer Lab at AMC

References

1. Cheer JF; Heien MLAV; Ariansen JL; Aragona BJ, Carelli RM and Wightman RM. (2007) Coordinated accumbal dopamine release and neural activity drive goal-directed behavior. Neuron 54: 237-244



2. Cheer JF; Wassum KM; Sombers LA; Heien MLAV; Ariansen JL; Aragona BJ; Phillips PEM and Wightman RM (2007) Phasic dopamine release evoked by abused substances requires cannabinoid receptor activation. Journal of Neuroscience 27: 791-795



3. Cheer JF*; Heien MLAV*; Garris PA; Carelli RM and Wightman RM (2005) Simultaneous dopamine and single-unit recordings reveal accumbens GABAergic responses: implications for intracranial self-stimulation. Proceedings of the National Academy of Sciences of the United States of America 102: 19150-19155 *These authors contributed equally



4. Heien MLAV; Khan AS; Ariansen JL; Cheer JF; Phillips PEM; Wassum KM and Wightman RM (2005) Principal component regression resolves dopamine fluctuations in the brain of behaving rats revealed from in vivo voltammetry. Proceedings of the National Academy of Sciences of the United States of America 102: 10023-10028



5. Cheer JF; Wassum K; Heien MLAV; Phillips PEM and Wightman RM (2004) Cannabinoids enhance subsecond dopamine release in the nucleus accumbens of awake rats. Journal of Neuroscience 24: 4393-4400