Summary of tonic LC-mediated effects on stimulus-evoked latencies of VPM thalamic and BF cortical neurons
| Thalamus | Cortex | |
|---|---|---|
| Mean latency | ||
| Increased | 15/40 (37.5%) | 10/54 (18.2%) |
| Decreased | 23/40 (57.5%) | 41/54 (75.9%) |
| No effect | 2/40 (5.0%) | 3/54 (5.6%) |
| Latency variance | ||
| Increased | 16/40 (40.0%) | 10/54 (18.5%) |
| Decreased | 21/40 (52.5%) | 42/54 (77.8%) |
| No effect | 3/40 (7.5%) | 2/54 (3.7%) |
| Modal latency | ||
| Increased | 12/40 (30.0%) | 14/54 (25.9%) |
| Decreased | 27/40 (67.5%) | 37/54 (68.5%) |
| No effect | 1/40 (2.5%) | 3/54 (5.6%) |
Responses of thalamic and cortical cells were examined to determine whether changes in temporal properties of the whisker pad stimulus-evoked discharge were observed during periods of tonic LC stimulation. As described in Materials and Methods, mean latency and latency variance indicate the average latency of the first spike of the response and its variance over multiple stimulus presentations. Modal latency is the latency of the statistical mode of the stimulus-evoked response. Response latencies of thalamic or cortical neurons were classified as increased or decreased if a significant change in these measures was observed at any frequency or current of LC stimulation.