Access session cookie in scrapy spiders

I am trying to access the session cookie within a spider. I first login to a social network using in a spider:

    def parse(self, response):

        return [FormRequest.from_response(response,
                formname='login_form',
                formdata={'email': '...', 'pass':'...'},
                callback=self.after_login)]

In after_login, I would like to access the session cookies, in order to pass them to another module (selenium here) to further process the page with an authentificated session.

I would like something like that:

     def after_login(self, response):

        # process response
        .....

        # access the cookies of that session to access another URL in the
        # same domain with the autehnticated session.
        # Something like:
        session_cookies = XXX.get_session_cookies()
        data = another_function(url,cookies)

Unfortunately, response.cookies does not return the session cookies.

How can I get the session cookies ? I was looking at the cookies middleware: scrapy.contrib.downloadermiddleware.cookies and scrapy.http.cookies but there doesn't seem to be any straightforward way to access the session cookies.

Some more details here bout my original question:

Unfortunately, I used your idea but I dind't see the cookies, although I know for sure that they exists since the scrapy.contrib.downloadermiddleware.cookies middleware does print out the cookies! These are exactly the cookies that I want to grab.

So here is what I am doing:

The after_login(self,response) method receives the response variable after proper authentication, and then I access an URL with the session data:

  def after_login(self, response):

        # testing to see if I can get the session cookies
        cookieJar = response.meta.setdefault('coo