an  title="" class="an ">&ensp;</span>on <span  title="" class="an ">&ensp;</span>monoamine <span  title="" class="an ">&ensp;</span>release <span  title="" class="an ">&ensp;</span>when <span  title="" class="an ">&ensp;</span>no <span  title="" class="an ">&ensp;</span>reward <span  title="" class="an ">&ensp;</span>is <span  title="" class="an ">&ensp;</span>to <span  title="" class="an ">&ensp;</span>be <span  title="" class="an ">&ensp;</span>obtained <span  title="" class="an ">&ensp;</span>It <span  