diff --git a/brainpy/dyn/synapses/abstract_models.py b/brainpy/dyn/synapses/abstract_models.py
index 6a7c59dc3..b279c1766 100644
--- a/brainpy/dyn/synapses/abstract_models.py
+++ b/brainpy/dyn/synapses/abstract_models.py
@@ -348,8 +348,7 @@ def update(self, _t, _dt):
           post_vs = post_vs - pre_spike
         post_vs = self.g_max * post_vs
       else:
-        post_vs = bm.expand_dims(pre_spike, 1) * self.g_max
-        post_vs = post_vs.sum(axis=0)
+        post_vs = pre_spike @ self.g_max
     elif isinstance(self.conn, One2One):
       post_vs = pre_spike * self.g_max
     else:
@@ -667,8 +666,7 @@ def update(self, _t, _dt):
           post_vs = post_vs - self.g
         post_vs = self.g_max * post_vs
       else:
-        post_vs = bm.expand_dims(self.g, 1) * self.g_max
-        post_vs = post_vs.sum(axis=0)
+        post_vs = self.g @ self.g_max
     elif isinstance(self.conn, One2One):
       post_vs = self.g_max * self.g
     else:
@@ -1230,8 +1228,7 @@ def update(self, _t, _dt):
         if not self.conn.include_self:
           post_g = post_g - self.g
       else:
-        post_g = bm.expand_dims(self.g, 1) * self.g_max
-        post_g = post_g.sum(axis=0)
+        post_g = self.g * self.g_max
     elif isinstance(self.conn, One2One):
       post_g = self.g_max * self.g
     else:
diff --git a/brainpy/dyn/synapses/biological_models.py b/brainpy/dyn/synapses/biological_models.py
index 5726e7f14..b93bd2e2d 100644
--- a/brainpy/dyn/synapses/biological_models.py
+++ b/brainpy/dyn/synapses/biological_models.py
@@ -206,8 +206,7 @@ def update(self, _t, _dt):
         if not self.conn.include_self:
           post_g = post_g - self.g
       else:
-        post_g = bm.expand_dims(self.g, 1) * self.g_max
-        post_g = post_g.sum(axis=0)
+        post_g = self.g @ self.g_max
     else:
       if self.conn_type == 'sparse':
         post_g = bm.pre2post_sum(self.g, self.post.num, self.post_ids, self.pre_ids)