Table 1.
Ketamine Effect.
| Parameter | Parameter Estimate (Ep) | Posterior Probability (Pp) | |
|---|---|---|---|
| Rate Constants: | |||
| 1 | AMPA rate constant - IN* | −0.0981 | 0.6344 |
| 2 | AMPA rate constant - AC* | −0.0647 | 0.5202 |
| 3 | GABA rate constant - IN | 0 | |
| 4 | GABA rate constant - AC | 0 | |
| 5 | NMDA rate constant -IN | 0 | |
| 6 | NMDA rate constant - AC | 0 | |
| Membrane Capacitance | |||
| 7 | Membrane Capacitance - SS | 0 | |
| 8 | Membrane Capacitance - SPY** | −0.5777 | 1 |
| 9 | Membrane Capacitance - II | 0 | |
| 10 | Membrance Capacitance - DPY | 0 | |
| Extrinsic Connectivity | |||
| 11 | AMPA Forward Connectivity: AI to AC | 0 | |
| 12 | AMPA Forward Connectivity: AC to AI | 0 | |
| 13 | AMPA Backward Connectivity: AI to AC | 0 | |
| 14 | AMPA Backward Connectivity: AC to AI* | −0.2598 | 0.605 |
| 15 | NMDA Forward Connectivity: AI to AC | 0 | |
| 16 | NMDA Forward Connectivity: AC to AI | 0 | |
| 17 | NMDA Backward Connectivity: AI to AC | 0 | |
| 18 | NMDA Backward Connectivity: AC to AI | 0 | |
| Intrinsic Connectivity (one each for AI and AC) | |||
| 19 | Excitatory - SS to SPY | 0 | |
| 20 | Excitatory - SS to II | 0 | |
| 21 | Excitatory - SPY to DPY | 0 | |
| 22 | Excitatory - DPY to II | 0 | |
| 23 | Inhibitory - II to SS | 0 | |
| 24 | Inhibitory - II to SPY | 0 | |
| 25 | Inhibitory - II to DPY | 0 | |
| 26 | Inhibitory Self-Connection - SS | 0 | |
| 27 | Inhibitory Self-Connection - SPY | 0 | |
| 28 | Inhibitory Self-Connection - II | 0 | |
| 29 | Inhibitory Self-Connection -DPY | 0 |
Parametric empirical Bayes was used to identify the mixing of parameters that contributed to ketamine’s effect. Note that the timing of data collection (6–9 hours following ketamine administration) is past the half-life of ketamine. We defined meaningful parameters as those with a probability (Pp) of greater than 0.95. A single parameter, the membrane capacitance of superficial pyramidal cells (which are thought to be the primary contributor to the MEG signal), was found to significantly contribute to ketamine’s effect. In addition, other parameters modeling AMPA effects, including the AMPA rate constants in insula (IN) and anterior cingulate (AC) and AMPA backward connectivity between AC and AI were found to contribute to ketamine’s effect, though not at the significance level we defined. SPY=superficial pyramidal cells, SS=spiny stellate cells, II=inhibitory interneurons, DPY=deep pyramidal cells.
Pp>0.5
Pp>0.95