diff --git a/src/miv_simulator/config.py b/src/miv_simulator/config.py
index df588f1..430c10b 100644
--- a/src/miv_simulator/config.py
+++ b/src/miv_simulator/config.py
@@ -246,6 +246,7 @@ class ParametricSurface(BaseModel):
 
 class CellType(BaseModel):
     template: str
+    mechanism: Optional[Dict]
     synapses: Dict[
         Literal["density"],
         Dict[