Emotion has a profound impact on animal behavior. In fact, the same neural mechanisms of learning that evolved to guide animals toward natural rewards also regulate mood. The goal of my research program is to understand the neural regulation of emotion, or affect, and the control it exerts over adaptive and, in the case of obesity and drug-seeking, maladaptive behavior.

To that end, I examine the role of brain nuclei in hedonic and motivational processing by recording changes in neuronal cell firing rates. These studies have revealed that patterned firing rate changes of nucleus accumbens neurons reflect the devaluation of a natural reward as it comes to predict, and is devalued by, future cocaine availability. I also use fast-scan cyclic voltammetry to examine dopamine transmission in this brain region. Dopamine release can be seen in response to a sweet taste that increases the firing rate of dopamine neurons. However, when this sweet taste is devalued by cocaine availability, dopamine concentration is transiently reduced. The dynamic nature of this conditioned switch in affect and the neural code reveals a mechanism by which cues may induce negative affect and subsequent drug-seeking behavior.

Selected Publications

• Wheeler, R.A., Roitman, M.F., Grigson, P.S., Carelli, R.M. Single neurons in the nucleus accumbens track relative reward. International Journal of Comparative Psychology. 2005 18; 320-332.
• Wheeler, R.A., Carelli R.M. The neuroscience of pleasure. J Neurophysiol. 2006 Aug 2.
• Wheeler, R.A., Twining, R.C., Jones, J.L., Slater, J.M., Grigson, P.S., Carelli, R.M. Behavioral and electrophysiological indices of negative affect predict cocaine self-administration. Neuron. 2008 Mar13;57(5) 774-85.
• Grigson, P.S., Twining, R.C., Freet, C.S., Wheeler, R.A., & Geddes, R.I. Drug-induced suppression of CS intake: Reward, aversion, and addiction. In: Conditioned Taste Aversion: Behavioral and Neural Processes, S. Reilly & T. Schachtman, Editors. Oxford University Press. NY, NY.
• Wheeler, R.A., Carelli, R.M. Dissecting motivational circuitry to understand substance abuse. Neuropharmacology. 2009;56 Suppl 1:149-59.
• Roitman, M.F., Wheeler R.A., Wightman R.M., Carelli R.M. Real-time chemical responses in the nucleus accumbens differentiate rewarding and aversive stimuli. Nat Neurosci. 2008 Dec;11(12):1376-7.
• Jones, J.L., Day J.J., Aragona B.J., Wheeler R.A., Wightman R.M., Carelli R.M. Basolateral Amygdala Modulates Terminal Dopamine Release in the Nucleus Accumbens and Conditioned Responding. Biol Psychiatry. 2009 Dec 29.
• Wheeler, R.A., Aragona, B.J., Fuhrmann, K.A., Day, J.J, Jones, J.L., Wightman, R.M., Carelli, R.M. Cocaine cues drive opposing context-dependent shifts in reward processing and emotional state. Submitted.
• Park, J., Wheeler, R.A., Fontillas, K., Keithley, R.B., Carelli, R.M., Wightman, R.M. The bed nucleus of the stria terminalis as a reward-aversion integrator. Submitted.