Disable yellow background of comments

I would like to turn off the strong yellow background of the comments before a function. For example:

/**
  *  This is a comment with a strong, distracting yellow background.
  */
function this_is_a_function() {
    // This comment looks normal.
    drupal_exit();
}

I'm using vim with the "desert" colorscheme with "background=dark", therefore the highlighted comment is very distracting. How could I turn it off?

Thank you!