Fig. 10e). To investigate the presence of functional synapses in migrated Dlxi1/2b::eGFP+ neurons, we performed whole-cell voltage clamp recordings in sliced hSS-hCS. We found that Dlxi1/2b::eGFP+ that migrated into hCS display both excitatory postsynaptic currents (EPSCs, downward deflecting) and IPSCs (upward deflecting) (Fig. 4h). Moreover, after migration into hCS, these cells primarily receive EPSCs rather than IPSCs and their synaptic input increases approximately 3-fold (Fig. 4i; Extended Data Fig. 10f; Supplementary Table 5). In parallel, glutamatergic neurons from hCS, which exhibit only EPSCs before assembly, also begin receiving IPSCs and show an overall increase in synaptic input following the migration of interneurons from hSS (Fig. 4j; Extended Data Fig. 10g). Lastly, to assess the functional integration of hCS and hSS neurons into neural networks, we applied electrical stimulation to the hCS side of assembled hSS-hCS to trigger glutamate release from excitatory neurons in the vicinity of the stimulation electrode while simultaneously recording EPSCs and IPSCs in Dlxi1/2b::eGFP+ cells that migrated into hCS (Extended Data Fig. 10h, i). We found that electrical simulation evoked EPSCs (eEPSCs) immediately following simulation (> 5 ms); this was followed by presumed multisynaptic IPSCs (< 15 ms) that were sensitive to gabazine. Together, these data demonstrate
