CakePHP社交网站的模型关联

I'm sorry. I thought about it but I can't come to a better title since I don't know how to describe this problem in one sentence.

Anyway, I am building a news feed just as Facebook where users can post a wall message and other users can comment on it.

I have 3 Tables in the database

profiles Table which contains the file name for their profile picture. posts table which contains details about posts and comments table for comments.

I have the below code in my Post model

    public $belongsTo = 'Profile';
    public $hasMany = 'Comment';

by doing that I can get the comments associated with each posts. But I am not able to get the profile picture from profiles table for "commenter". I tried

    public $belongsTo = 'Profile;

in the Comment model too but it's not working.