HIGH-SPEED VOLTAGE-SENSITIVE DYE IMAGING OF AN IN-VIVO INSECT BRAIN

We have developed an improved optical recording technique with high sp atio-temporal resolution to investigate neural activity from an in viv o insect brain. Optical images were acquired from hawk moth antennal l obe (AL) neurons. When activity was elicited by electrical stimulation of the antennal nerve using a stereoscopic microscope, depolarization followed by hyperpolarization was consistently recorded in the AL. Wh en gamma-aminobutyric acid (GABA)-mediated synaptic transmission was b locked by the picrotoxin, the typical hyperpolarization was greatly re duced while no changes were observed in the depolarization. This sugge sts that the hyperpolarization results from inhibitory postsynaptic po tentials (IPSPs) originating from GABA-sensitive chloride channels on the AL neurons.