TABLE 1.
Drivers and Modulators in LGN plus layer 5 Drivers
| Criteria | Retinal (Driver) | Layer 5 to HO (Driver) | Modulator: layer 6 | Modulator: PBR | Modulator: TRN & Int |
|---|---|---|---|---|---|
| Criterion 1 | Determines relay cell receptive field | * Determines relay cell receptive field | Does not determine relay cell receptive field | Does not determine relay cell receptive field | Does not determine relay cell receptive field |
| Criterion 2 | Activates only ionotropic receptors | Activates only ionotropic receptors | Activates metabotropic receptors | Activates metabotropic receptors | TRN: Activates metabotropic receptors; Int: † |
| Criterion 3 | Large EPSPs | Large EPSPs | Small EPSPs | † | TRN: small IPSPs; Int: † |
| Criterion 4 | Large terminals on proximal dendrites | Large terminals on proximal dendrites | Small terminals on distal dendrites | Small terminals on proximal dendrites | Small terminals; TRN: distal; Int: proximal |
| Criterion 5 | Each terminal forms multiple contacts | Each terminal forms multiple contacts | Each terminal forms single contact | Each terminal forms single contact | Each terminal forms single contact |
| Criterion 6 | Little convergence onto target | * Little convergence onto target | Much convergence onto target | † | † |
| Criterion 7 | Very few synapses onto relay cells (~5%) | Very few synapses onto relay cells (~5%) | Many synapses onto relay cells (~30%) | Many synapses onto relay cells (~30%) | Many synapses onto relay cells (~30%) |
| Criterion 8 | Often thick axons | Often thick axons | Thin axons | Thin axons | Thin axons |
| Criterion 9 | Glutamatergic | Glutamatergic | Glutamatergic | Cholinergic | GABAergic |
| Criterion 10 | Synapses show paired-pulse depression (high p) | * Synapses show paired-pulse depression (low p) | Synapses show paired-pulse facilitation | † | † |
| Criterion 11 | Well localized, dense terminal arbors | Well localized, dense terminal arbors | Well localized, dense terminal arbors | Sparse terminal arbors | Well localized, dense terminal arbors |
| Criterion 12 | Branches innervate subtelencephalic targets | Branches innervate subtelencephalic targets | Subcortically known to innervate thalamus only | † | Subcortically known to innervate thalamus only |
| Criterion 13 | Innervates dorsal thalamus but not TRN | Innervates dorsal thalamus but not TRN | Innervates dorsal thalamus and TRN | Innervates dorsal thalamus and TRN | TRN: both; Int: dorsal thalamus only |
*
Very limited data to date
†
No relevant data available