Effects of Prenatal Cannabis Vapor Exposure on Cognitive Flexibility
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Cannabis is the most commonly used illicit substance among pregnant women, yet the effects of prenatal cannabis exposure on cognitive wellbeing remain largely unknown. With recreational cannabis laws now in effect in 8 states and counting, there is growing concern that prenatal cannabis exposure could increase dramatically in the coming years. Thus, there is an urgent need to better understand the impact of maternal cannabis exposure on cognition. We investigated whether chronic exposure to vaporized cannabis during pregnancy alters cognitive flexibility in male and female offspring. Female dams were passively exposed to vaporized cannabis extract (50 or 400mg/mL; 1 puff every 2 min for 1 hr, twice daily) or vehicle vapor throughout mating and gestation. Beginning at postnatal day 50, offspring were trained to press a lever that was paired with delivery of a cue light to receive a food reward. Next, rats had to disregard the previously learned strategy in favor of an egocentric spatial strategy (i.e., ignore the cue and always press the left, or right, lever). Finally, rats were tested in a reversal task that required them to press the lever opposite of the previous task. The number of trials to criterion and errors, along with error type (perseverative, regressive, or never reinforced) and spatial reference of distractor (i.e., toward or away from cue) were tabulated and compared across groups. Preliminary results indicate that prenatal cannabis exposure did not significantly affect cue discrimination learning or reversal learning, but impaired strategy shifting. Moreover, cannabis-exposed offspring made more never reinforced and regressive errors, which indicates an inability to obtain and maintain the new optimal strategy. These data indicate that prenatal cannabis exposure may lead to deficits in cognitive flexibility in adulthood.