Neuronal representation of individual heroin choices in the orbitofrontal cortex
Addiction Biology. 2017-07-13; 23(3): 880-888
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1. Addict Biol. 2018 May;23(3):880-888. doi: 10.1111/adb.12536. Epub 2017 Jul 13.
Neuronal representation of individual heroin choices in the orbitofrontal cortex.
Guillem K(1)(2), Brenot V(1), Durand A(1)(2), Ahmed SH(1)(2).
(1)Université de Bordeaux, Institut des Maladies Neurodégénératives, France.
(2)CNRS, Institut des Maladies Neurodégénératives, France.
Drug addiction is a harmful preference for drug use over and at the expense of
other non-drug-related activities. We previously identified in the rat
orbitofrontal cortex (OFC) a mechanism that influences individual preferences
between cocaine use and an alternative action rewarded by a non-drug reward (i.e.
sweet water). Here, we sought to test the generality of this mechanism to a
different addictive drug, heroin. OFC neuronal activity was recorded while rats
responded for heroin or the alternative non-drug reward separately or while they
chose between the two. First, we found that heroin-rewarded and sweet
water-rewarded actions were encoded by two non-overlapping OFC neuronal
populations and that the relative size of the heroin population represented
individual drug choices. Second, OFC neurons encoding the preferred action-which
was the non-drug action in the large majority of individuals-progressively fired
more than non-preferred action-coding neurons 1 second after the onset of choice
trials and around 1 second before the preferred action was actually chosen,
suggesting a pre-choice neuronal competition for action selection. Together with
a previous study on cocaine choice, the present study on heroin choice reveals
important commonalities in how OFC neurons encode individual drug choices and
preferences across different classes of drugs. It also reveals some drug-specific
differences in OFC encoding activity. Notably, the proportion of neurons that
non-selectively encode both the drug and the non-drug reward was higher when the
drug was heroin (present study) than when it was cocaine (previous study). We
will discuss the potential functional significance of these commonalities and
differences in OFC neuronal activity across different drugs for understanding
© 2017 Society for the Study of Addiction.