| Popis: |
The central complex is a group of midline neuropils found in all arthropods. In insects, circuits within the central complex play a role in processing visual and tactile information. Activity recorded in the central complex is correlated with and often precedes changes in step frequency and turning movement. Electrolytic lesions in the central complex adversely affect various locomotory behaviors. However, questions exist about collateral damage to areas outside of the central complex as the lesion probe was inserted. To address this issue, we developed a reversible chemical block of neural activity in the central complex using the anesthetic procaine. Black and white moving stripes induced an optomotor turning response in the cockroach, Blaberus discoidalis. After documenting the response in a normal individual, we injected a solution of 10% or 20% procaine into the central complex. Subjects with anesthetized central complex had a significant decrease in optomotor response up to 30 minutes after injections. Controls injected with saline showed no deficit. As the effects of the anesthetics diminished, the cockroach regained the ability to turn. While the optomotor response processing happens mostly within the cockroach brain, most escape circuitry is located in the thoracic ganglia. Nevertheless, the brain has been shown to influence escape response. We, therefore, extended our analysis to examine the effects of the procaine injection into the central complex on escape. Subjects with reduced output from the central complex showed little deficit in escape speed. Electrophysiological recording showed that procaine reduced firing activity in the central complex. |
