diff --git a/hnn_core/network.py b/hnn_core/network.py
index c703f4511b..54b09bbf1c 100644
--- a/hnn_core/network.py
+++ b/hnn_core/network.py
@@ -1260,6 +1260,8 @@ def clear_connectivity(self, src_types=None):
         ----------
         src_types : list | None
             Source types of connections to be removed
+            None - Remove all connections other than those which have an
+            external drive as a source type
         """
         if src_types is None:
             src_types = list()