Surface electrodes record and label brain neurons in insects

Abstract

We used suction electrodes to reliably record the activity of identified ascending auditory interneurons from the anterior surface of the brain in crickets. Electrodes were gently attached to the sheath covering the projection area of the ascending interneurons and the ringlike auditory neuropil in the protocerebrum. The specificity and selectivity of the recordings were determined by the precise electrode location, which could easily be changed without causing damage to the tissue. Different nonauditory fibers were recorded at other spots of the brain surface; stable recordings lasted for several hours. The same electrodes were used to deliver fluorescent tracers into the nervous system by means of electrophoresis. This allowed us to retrograde label the recorded auditory neurons and to reveal their cell body and dendritic structure in the first thoracic ganglion. By adjusting the amount of dye injected, we specifically stained the ringlike auditory neuropil in the brain, demonstrating the clusters of cell bodies contributing to it. Our data provide a proof that surface electrodes are a versatile tool to analyze neural processing in small brains of invertebrates. We show that surface suction electrodes can be used to monitor the activity of auditory neurons in the cricket brain. They also allow delivering electrophoretically a fluorescent tracer to label the structure of the recorded neurons and the local neuropil to which the electrode was attached. This new extracellular recording and labeling technique is a versatile and useful method to explore neural processing in invertebrate sensory and motor systems.

Response properties of spiking and non-spiking brain neurons mirror pulse interval selectivity

“…It is still not certain if the auditory brain neurons represent individuals or functional types. Surface electrode labeling of the ring-like auditory neuropil reveal three cluster with about 54 cell bodies, which could be linked to auditory processing ( Kostarakos and Hedwig, 2017 ).…”

An auditory-responsive interneuron descending from the cricket brain: a new element in the auditory pathway

“…Not only does it contain the axonal arborization of the ascending, calling song frequency-sensitive auditory interneuron, AN1, but several local auditory interneurons that have a critical role in pattern recognition also have their arborizations confined to this neuropil region. (Kostarakos and Hedwig 2012 , 2017 ; Schöneich et al 2015 ). The second ascending auditory interneuron, AN2, which is most strongly responsive to auditory frequencies higher than calling song, also has an extensive arborization within the ring neuropil.…”

Photoreceptive reaction spectrum effect and phototactic activity intensity of locusts’ visual display characteristics stimulated by spectral light

“…Previous researchers have carried out basic investigations on the spectral sensitivity of locusts' phototaxis and visual orientation model. In a study of locusts' visual sensitivity spectrum [3][4][5][6][7][8][9] , Vishnevskaya et al [3] considered that the visual pigments in the retinal cells of a locust's compound eye are sensitive to the spectrum with 430 nm and 515 nm of peak wavelength. Jiang [4] revealed that locusts' screening pigments have two sensitive spectral bands, 400-520 nm and 365-390 nm.…”