How To Uncheck Default Checkbox When Another Is Checked - Angular

I need to have the first value "none" checked as default and then unchecked when any of the other options are checked. I have found the way to do this using the ng-model but I'm using ng-model to build an object for email. Is there a way that I can do this using an angularish style?

<div class="activate-mail-subsection">
         <label>Allergies</label><br>
         <div class="checkbox mailorder-checkbox">
            <input name="allergies" class="checkbox"  type="checkbox" ng-model="mailorder.allergies.none" tabindex="1"/> None
        </div>
         <div class="checkbox mailorder-checkbox">
             <input name="allergies" class="checkbox"  type="checkbox" ng-model="mailorder.allergies.codeine" tabindex="1"/> Codeine
         </div>
         <div class="checkbox mailorder-checkbox">
             <input name="allergies" class="checkbox"  type="checkbox" ng-model="mailorder.allergies.sulfa" tabindex="1"/> Sulfa
         </div>
         <div class="checkbox mailorder-checkbox">
             <input name="allergies" class="checkbox"  type="checkbox" ng-model="mailorder.allergies.asprin" tabindex="1"/> Asprin
         </div>
         <div class="checkbox mailorder-checkbox">
             <input name="allergies" class="checkbox"  type="checkbox" ng-model="mailorder.allergies.penicillin" tabindex="1"/> Penicillin
         </div>
            <div class="checkbox mailorder-checkbox">
                <label>Other</label>
                <input name="allergies" class="form-control health-profile-text" type="text" ng-model="mailorder.allergies.other" tabindex="1"/>
            </div>
        </div>

Here is the object

  $scope.mailorder = {
    allergies: {none: true, codeine: false, sulfa: false, aspirin: false, penicillin: false, other: ''},
};