Fig. 3.

Identification of neurons contributing to activity in I2 n., R n.1, and n.2,1. A, B, Simultaneous extra- and intracellular recordings during patterned activity elicited by stimulation of n.2,3. Cell B31/32 fires in phase with I2 n., cell B9 fires in phase with activity in n.2,1 (A), and cell B8 fires in phase with the large unit activity in R n.1 (B).C, A one-for-one relationship between intracellularly recorded action potentials from B31/32 and extracellular activity recorded from I2 n. (circle, C1) and antidromically activated action potentials in B31/32 elicited by stimulation of I2 n. C2 demonstrated thatB31/32 projects through I2 n. Four oscilloscope traces triggered by intrasomatic action potentials recorded fromB31/32 (C1) and six traces triggered by nerve stimulation (C2) were superimposed.D, A similar study as in C indicated that neuronB9 sends axons in both ipsilateral (i) and contralateral (c) n.2,1 (n.2,1i, n.2,1c;circles in D1 indicate the time-locked extracellular action potentials). Six oscilloscope traces triggered by intrasomatic action potentials recorded from B9(D1) and five traces triggered by nerve stimulation (D2) were superimposed. E, CellB8 projects bilaterally through the ipsilateral and contralateral R n.1 (R n.1i, R n.1c;circles in E1 indicate the time-locked extracellular action potentials). Five oscilloscope traces triggered by intrasomatic action potentials recorded from B8(E1) and four traces triggered by nerve stimulation (E2) were superimposed.