The anatomical pathways for antennal sensory information in the central nervous system of the cricket, Gryllus bimaculatus

Abstract

Antennae are one of the major organs to detect chemo- and mechanosensory cue in crickets. Little is known how crickets process and integrate different modality of information in the brain. We thus used a number of different anatomical techniques to gain an understanding of the neural pathways extending from the antennal sensory neurons up to centers in the brain. We identified seven antennal sensory tracts (assigned as T1–7) utilizing anterograde dye filling from the antennal nerve. Tracts T1–T4 project into the antennal lobe (AL), while tracts T5 and T6 course into the dorsal region of the deutocerebrum or the suboesophageal ganglion, and finally, tract T7 terminates in the ventral area of flagellar afferent (VFA). By analyzing autofluorescence images of the AL, we identified 49 sexually isomorphic glomeruli on the basis of shape, relative position and size. On the basis of our sensory-tract data, we assigned the glomeruli into one of four separate groups. We then three-dimensionally reconstructed the internal structures in the AL (glomeruli) and the VFA (layers). Next in the protocerebrum, we identified both the tracts and their terminations from the AL and VFA. We found that 10 tracts originate in the AL, whereas there are at least eight tracts from the VFA. Several tracts from the AL share their routes with those from the VFA, but their termination areas are segregated. We now have a better anatomical understanding of the pathways for the antennal information in cricket

Variations on a Theme: Antennal Lobe Architecture across Coleoptera

“…domestica (A) and G . assimilis (B) s taining with phalloidin (Phal) revealed glomerular substructures (arrowheads), resembling the situation in Gryllus bimaculatus [51,88]. Staining with an antibody against tachykinin related peptide (TKRP) (magenta) and synapsin (Syn) (green) revealed irregular shaped and interconnected TKRP immunoreactive substructuring within the glomeruli of two Hemiptera species: G .…”

“…in the Gryllidae Gryllus bimaculatus . Ignell et al [51] and Yoritsune and Aonuma [88] described "microglomerular substructures" or "microglomerular clusters" within the "regular" glomeruli. Own stainings in the Gryllidae Gryllus assimilis and Acheta domesticus revealed also microglomerular substructures (Fig 6A and 6B arrowheads), showing that the observation in G .…”

“…Whether the substructures of the two hemipteran species are more similar to the substructures of G . bimaculatus , which are innervated by OSNs [51,88], or whether they are more similar to the substructures of Coleoptera, which lack innervations by OSNs, remains to date unknown.…”

Ca2+ imaging of cricket protocerebrum responses to air current stimulation

“…As suggested by the reduction of the spike responses in the antennae-removed experiments, these cells could be activated by mechanosensory input from antennae stimulated by air currents. Neuronal tracts from the primary projection area of mechanosensory afferents from the antennae-known as the ventral area of flagellar afferents [32,33]-terminated in the lateral protocerebrum, which corresponds to the lateral region of the VLNP [38]. Therefore, it is possible that the VLNP functions as an integrative center of input from mechanosensory sensilla and organs, including antennae and cerci.…”

Behavioural integration of auditory and antennal stimulation during phonotaxis in the field cricketGryllus bimaculatus(DeGeer)

“…Mechanosensory afferents coming from the cricket's antennae enter the brain via the antennal nerve and project to the deutocerebrum and the subesophageal ganglion (Rospars, 1988;Staudacher and Schildberger, 1999;Yoritsune and Aonuma, 2012). From the deutocerebrum, giant descending interneurons convey information to the ventral nerve cord (Gebhardt and Honegger, 2001;Schöneich et al, 2011).…”