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Articles by A. W Johnson
Total Records ( 2 ) for A. W Johnson
  H. S Crombag , A. W Johnson , A. M Zimmer , A Zimmer and P. C. Holland

Cannabinoid CB1 receptor is abundantly expressed throughout the CNS and is implicated in numerous physiological and behavioral functions, including appetite and feeding. In the present study, wild-type and CB1 heterozygous and homozygous knockout mice were tested on an instrumental outcome-selective devaluation task to assess changes in acquired instrumental response levels for a distinct food reward following selective satiation. Deletion of CB1 receptor, as well as reduction in CB1 expression (HET), produced deficits in outcome-selective instrumental devaluation. These results identify a critical role for CB1 receptor in the ability of animals to represent, update, and/or use sensory-specific outcome representations to alter appetitive behaviors.

  A. W Johnson , S Han , A. M Blouin , J Saini , P. F Worley , M. J During , P. C Holland , J. M Baraban and I. M. Reti

Neuronal activity regulated pentraxin (Narp) is a secreted protein that regulates -amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPAR) aggregation and synaptogenesis. Mapping of Narp-positive neurons in brain has revealed it is prominently expressed in several limbic system projection pathways. Consistent with this localization pattern, Narp knockout mice show deficits in using the current value of a reinforcer to guide behavior, a critical function of the limbic system. To help assess whether this behavioral deficit is due to impairment of synaptogenesis during development or in modulating synaptic signaling in the mature brain, we have used a dominant negative Narp viral construct which blocks trafficking of endogenous Narp to axons. Focal injection of this viral construct into the medial prefrontal cortex (mPFC) of adult mice, a region containing Narp-positive projection neurons, blocked reinforcer devaluation. Thus, these results indicate that Narp released from mPFC neurons plays a key role in mediating synaptic changes underlying instrumental reinforcer devaluation.

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