Figure 1.

Effects of medial prefrontal cortex (mPFC) inactivation on odor span capacity in rats. (A) Schematic of the apparatus and procedure for the odor span task (see text for details; schematic based on Dudchenko et al. 2000, 2012). Odors are denoted with letters. On subsequent trials, the bowl (black circle) containing novel odor is rewarded (+) while the other stimuli are not rewarded (−). Rats are tested on a series of trials until an error is made. The number of bowls on the platform when an error is made minus one is recorded as the span. Note that a given odor is moved to a different position on the platform for each trial so that spatial cues cannot be used to solve the task. (B) Placements (black dots) of the infusion needle tips for rats in the mPFC inactivation and odor span experiment (n = 13). Infusion sites were located in both the prelimbic and infralimbic areas of the mPFC and impinged on the dorsal peduncular cortex in four subjects. The distance each plate is anterior to bregma is indicated in millimeters. (C) Mean (+ standard error of the mean) odor spans during the 7 d of training immediately prior to testing for rats in the mPFC inactivation experiment. (D) Mean spans for the rats following each treatment of the mPFC inactivation experiment. Musc/baclo refers to the muscimol/baclofen treatment to temporarily inactivate the mPFC. (E) Correlation between spans and latencies to the first choice in the olfactory span task for rats treated with muscimol/baclofen. (^*) Indicates a significant difference from all other groups (P < 0.05).