Allow normal scrolling when scrolling up

Using fullpage.js, is it possible to enable normal scrolling when scrolling up but keep the default "one slide per scroll" functionality when scrolling down?

I tried the following but doesn't seem to work:
```
$('.full-page').fullpage({
onLeave: function(index, nextIndex, direction) {

if (direction == 'down') {
$.fn.fullpage.setAllowScrolling(true);
}

else {
$.fn.fullpage.setAllowScrolling(false);
}
}
});
```