In rat S1, stimulation of connections that stay within a representation (NCB) yields inhibitory responses (IPSPs) that are larger than those evoked by stimulation of connections that cross into an adjacent representation (CB; Hickmott & Merzenich, 1997). Such differences may reflect the fact that there are fewer axons that cross a representational border than project within a representation (Mason et al, SFN Abstr. 2003). In this abstract we investigated whether inhibitory synapses have different properties between NCB connections and CB connections. The border between the forepaw and lower jaw representations was mapped in adult rats (>P90) using in vivo recording and marked with DiI. Coronal slices were taken from the marked region and maintained in vitro. Whole-cell recordings were obtained from layer 2/3 neurons close to the border. Filling solution with a high concentration of chloride (100 mM) was used to enhance IPSP amplitude. Horizontal connections within layer 2/3 were electrically stimulated; st...