Recent Publications from the Laboratory of Fear Learning

Two papers were recently published by faculty from the Department of Anatomy and Neurobiology at the School of Medicine. Both studies were partially supported by the RCMI Program.

The effects of yohimbine and amphetamine on fear expression and extinction in rats  was recenty published in the Psychopharmacology. Authors include David Muller, faculty in the Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine; Lening A. Olivera-Figueroa, faculty in the Clinical Psychology Program, Ponce School of Medicine; Daniel S. Pine, researcher in the Section on Development and Affective Neuroscience, NIMH Intramural Research Program, and Gregory J. Quirk, Director of the Laboratory of Fear Learning, and faculty in the Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine.

The research team evaluated the effectiveness of yohimbine and amphetamine in enhancing fear extinction. In addition to freezing, they measured bar-press suppression, which is less sensitive to changes in locomotion to answer two research questions: Do psychostimulants reduce fear during extinction training when drug is present? Does learning extinction with psychostimulants result in better extinction retention?

The other article, published in Biological Psychiatry, is titled Systemic propranolol acts centrally to reduce conditioned fear in rats without impairing extinction. Authors include José Rodríguez-Romaguera, from the Department of Psychology Undergraduate Program, University of Puerto Rico Rio Piedras Campus, and Francisco Sotres-Bayon, Devin Mueller, and Gregory J. from the Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine.

The purpose of this study was two-fold: to assess the effects of propranolol on expression of conditioned fear, and to assess the effects of propranolol on extinction memory. The investigators also assessed the effect of systemic propranolol on the activity of neurons in the prelimbic region of the medial pre-frontal cortex, an area implicated in the expression of conditioned fear. Clarifying the effects of systemic propranolol on the expression and extinction of conditioned fear could have clinical significance, because extinction is the basis of exposure-based therapies for the treatment of anxiety disorders.

Citations:

Mueller D, Olivera-Figueroa LA, Pine DS, Quirk GJ. The effects of yohimbine and amphetamine on fear expression and extinction in rats. Psychopharmacology (Berl). 2009 Feb 26. doi:10.1007/s00213-009-1491-x
The paper is available online at: http://www.springerlink.com/content/a46m556w21145v02/ 

Rodriguez-Romaguera J, Sotres-Bayon F, Mueller D, Quirk GJ. Systemic Propranolol Acts Centrally to Reduce Conditioned Fear in Rats Without Impairing Extinction. Biol Psychiatry. 2009 Feb 24. doi:10.1016/j.biopsych.2009.01.009
The paper is available online at:
http://www.journals.elsevierhealth.com/periodicals/bps/article/S0006-3223(09)00034-1/abstract