Developmental exposures to ambient ultrafine particles (UFPs) can produce multiple neuropathological and neurochemical changes that might contribute to persistent alterations in cognitive-type functions. The objective of the current study was to test the hypothesis that developmental UFP exposure produced impairments in learning, memory and impulsive-like behaviors and to determine whether these were selective and thus independent of deficits in other behavioral domains such as motor activity or motivation. Performance on measures of learning (repeated learning), memory (novel object recognition, NOR), impulsive-like behavior (differential reinforcement of low rate (DRL), schedule of reward and delay of reward (DOR)), motor activity (locomotor behavior) and motivation (progressive ratio schedule) were examined in adult mice that had been exposed to concentrated (10–20x) ambient ultrafine particles (CAPS) averaging approximately 45 ug/m³ particle mass concentrations from postnatal day (PND) 4–7 and 10–13 for 4 h/day. Given the number of behavioral tests, animals were tested in different groups. Results showed male-specific alterations in learning and memory functions (repeated learning, NOR and DRL) specifically during transitions in reinforcement contingencies (changes in rules governing behavior) that did not appear to be related to alterations in locomotor function or motivation. Females did not exhibit cognitive-like deficits at these exposure concentrations, but displayed behaviors consistent with altered motivation, including increases in response rates during repeated learning, significantly increased latencies to respond on the delay of reward paradigm, and reductions in the progressive ratio break point. Consistent with our prior findings, male-specific learning and memory-related deficits were seen and occurred even at relatively low level developmental UFP exposures, while females show alterations in motivational behaviors but not final performance. These findings add to the evidence suggesting the need to regulate UFP levels.

发育过程中暴露于环境超细颗粒（UFP）会产生多种神经病理学和神经化学变化，可能导致认知型功能的持续改变。本研究的目的是检验以下假设：发育性 UFP 暴露会对学习、记忆和冲动行为造成损害，并确定这些损害是否是选择性的，从而独立于运动活动或动机等其他行为领域的缺陷。学习（重复学习）、记忆（新物体识别，NOR）、类冲动行为（低速率差异强化（DRL）、奖励计划和奖励延迟（DOR））、运动活动（运动行为）的表现）和动机（渐进比例计划）在成年小鼠中进行了检查，这些小鼠从出生后第 4-7 天（PND）起就暴露于平均约 45 ug/m ³颗粒质量浓度的浓缩（10-20x）环境超细颗粒（CAPS）和10-13 点，每天 4 小时。鉴于行为测试的数量，动物被分成不同的组进行测试。结果显示，男性特有的学习和记忆功能（重复学习、NOR 和 DRL）发生了变化，特别是在强化意外事件（行为规则的变化）转变期间，这似乎与运动功能或动机的变化无关。在这些暴露浓度下，女性没有表现出类似认知的缺陷，但表现出与动机改变一致的行为，包括重复学习期间反应率的增加、对奖励范式延迟的反应潜伏期显着增加以及进步比率断点的减少。与我们之前的研究结果一致，即使在相对较低水平的发育性 UFP 暴露下，男性也会出现和发生特定的学习和记忆相关缺陷，而女性则表现出动机行为的改变，但最终表现没有改变。这些发现进一步证明了需要调节 UFP 水平。