Images of MOR and Fos immunostained tissue.

<p>(a) Image of MOR immunoreactivity in the striatum. (b) Placement of templates used for analysis of Fos expression in the dorsal caudate-putamen and nucleus accumbens core and shell. (c) Left, closeup image of MOR immunostained tissue displaying the patch and matrix compartments. Middle, closeup image of Fos expression. Right, overlay of the left and middle images demonstrating Fos expression in patch compartments.</p

General timeline of experimental phases.

<p>General timeline of experimental phases.</p

Pavlovian Conditioning using a tone CS.

<p>PCA Index scores were correlated with CS lever contacts during PCA (panel A) but not with CS magazine entries during the last day of tone conditioning (panel B). During tone conditioning (panel C), only goal-tracking was observed and did not differ between sign- and goal-trackers. When allowed to nose-poke for the tone in a conditioned reinforcement test (panel D), STs and GTs did not differ in the number of nose-pokes. Data are represented as mean (± SEM).</p

Proximal auditory stimuli (either tone or white noise) are more reinforcing than distal stimuli.

<p>Rats made more food-cup entries during the proximal stimulus presentation during training (panel A), and performed more nose-pokes for the proximal stimulus (panel B). Data are represented as mean (± SEM). There were no significant differences between sign-trackers (ST) and goal-trackers (GT).</p

Pavlovian Conditioned Approach (PCA).

<p>Rats (n = 47) were classed as sign-trackers (ST), intermediates (IN) or goal-trackers (GT) based on CS-evoked behaviors during 5 days of Pavlovian training. Values represent mean (± SEM) number of lever deflections (panel A), food cup entries (panel B), probability of approaching the lever (panel C), or food cup (panel D), and latency to contact the lever (panel E) or make a food cup entry (panel F).</p

The lever, but not the auditory, component of a compound CS are differentially reinforcing in sign-trackers (ST), but not goal-trackers (GT).

<p>Rats nose-poked for either the lever component or the auditory component of the compound CS in separate conditioned reinforcement tests. STs, GTs, and intermediates (IN) did not differ in nose-pokes that were reinforced by the tone component of the CS (panel A), but STs made more nose-pokes for the lever component (panel B). STs approached the lever more often than GTs during the conditioned reinforcement test (Panel C). The PCA index was significantly correlated with the reinforcing efficacy of the lever component of the CS, but not the auditory component (Panels D and E). Asterisks indicate significant differences compared to goal-trackers (p<0.05). Data are represented as mean (± SEM).</p

Stress potentiates the conditioned reinforcing properties of reward paired cues equally in sign trackers (ST) and goal trackers (GT).

<p>Nosepoke responses in sessions immediately before and after an ip injection of sterile water (SW) or the pharamacological stressor yohimbine (YOH). Responding after administration of yohimbine was significantly greater than responding after administration of sterile water, but increased equally in STs and GTs after both sterile water and yohimbine injections.</p

Amphetamine enhances the reinforcing efficacy of an auditory stimulus equally in sign-trackers (ST), goal-trackers (GT), and intermediates (IN).

<p>Amphetamine increased the number of nose-pokes into the active (reinforced by the tone-cue) port. Amphetamine did not have systematic effects on nose-poke responding into the inactive port. Data are represented as mean (± SEM). There were no significant differences between STs and GTs. Asterisks denotes a significant increase compared to the saline-treated rats (0.00 dose).</p

Fos expression in the patch and matrix compartments of the dorsomedial caudate-putamen as a function of pretreatment, challenge, and bregma level.

<p>Left panels (a and c), Fos expression across rostral-caudal levels. Right panels (b and d), Fos expression collapsed across levels. Asterisk denotes significant interaction between pretreatment and challenge (values = Mean±SEM).</p

Fos expression in the patch and matrix compartments of the dorsolateral caudate-putamen as a function of pretreatment, challenge, and bregma level.

<p>Left panels (a and c), Fos expression across rostral-caudal levels. Right panels (b and d), Fos expression collapsed across levels. Asterisk denotes significant interaction between pretreatment and challenge (values = Mean±SEM).</p