Normal Aging does Not Impair Orbitofrontal-Dependent Reinforcer Devaluation Effects

Domenic Hayden Cerri,Geoffrey Schoenbaum,Joshua L Jones,Michael A Mcdannald,Richard Z Haney,Teghpal Singh

doi:10.3389/fnagi.2011.00004

Domenic Hayden Cerri, Geoffrey Schoenbaum + Show 4 more

Open Access

https://doi.org/10.3389/fnagi.2011.00004

Copy DOI

Abstract

Normal aging is associated with deficits in cognitive flexibility thought to depend on prefrontal regions such as the orbitofrontal cortex (OFC). Here, we used Pavlovian reinforcer devaluation to test whether normal aging might also affect the ability to use outcome expectancies to guide appropriate behavioral responding, which is also known to depend on the OFC. Both young and aged rats were trained to associate a 10-s conditioned stimulus (CS+) with delivery of a sucrose pellet. After training, half of the rats in each age group received the sucrose pellets paired with illness induced by LiCl injections; the remaining rats received sucrose and illness explicitly unpaired. Subsequently, responding to the CS+ was assessed in an extinction probe test. Although aged rats displayed lower responding levels overall, both young and aged rats conditioned to the CS+ and developed a conditioned taste aversion following reinforcer devaluation. Furthermore, during the extinction probe test, both young and aged rats spontaneously attenuated conditioned responding to the cue as a result of reinforcer devaluation. These data show that normal aging does not affect the ability to use expected outcome value to appropriately guide Pavlovian responding. This result indicates that deficits in cognitive flexibility are dissociable from other known functions of prefrontal – and particularly orbitofrontal – cortex.

Highlights

Adaptive behavior requires the ability to rapidly update patterns of responding following shifts in contingencies
During the extinction probe test, both young and aged rats spontaneously attenuated conditioned responding to the cue as a result of reinforcer devaluation
These data show that normal aging does not affect the ability to use expected outcome value to appropriately guide Pavlovian responding.This result indicates that deficits in cognitive flexibility are dissociable from other known functions of prefrontal – and orbitofrontal – cortex

Summary

Introduction

Adaptive behavior requires the ability to rapidly update patterns of responding following shifts in contingencies. Normal aging is associated with a decline in this type of cognitive flexibility (Rapp and Heindel, 1994; Lamar and Resnick, 2004; Marschner et al, 2005; Weiler et al, 2008), and numerous studies in animals have demonstrated age-related deficits in flexible decision making processes thought to depend on prefrontal function (Zyzak et al, 1995; Schoenbaum et al, 2002a; Nicolle and Baxter, 2003; Smith et al, 2004; Joly et al, 2006; Brushfield et al, 2008; LaSarge et al, 2009; Mizoguchi et al, 2009, 2010; Simon et al, 2010) Prominent among these reports are deficits in reversal learning. Aged rats displaying reversal impairments exhibit fewer cue-selective neurons in OFC during a cued-odor discrimination task, and neurons that were cue-selective are markedly less flexible upon reversal (Schoenbaum et al, 2006b)

Methods

Results

Conclusion