diff --git a/publications/serializers.py b/publications/serializers.py
index 4a4b7d6..17b373d 100644
--- a/publications/serializers.py
+++ b/publications/serializers.py
@@ -20,9 +20,18 @@ class PublicationSerializer(serializers.ModelSerializer):
         return getattr(obj, 'average_score', 0)
     
     def validate(self, attrs):
-        content_type = attrs.get('content_type')
-        image = attrs.get('image')
-        video = attrs.get('video')
+        content_type = attrs.get(
+            'content_type',
+            getattr(self.instance, 'content_type', None)
+        )
+        image = attrs.get(
+            'image',
+            getattr(self.instance, 'image', None)
+        )
+        video = attrs.get(
+            'video',
+            getattr(self.instance, 'video', None)
+        )
 
         errors = {}