Electrophysiology and anatomy of medulla interneurons in the optic lobe of the cockroach, Periplaneta americana

Abstract

1. Medulla interneurons of the optic lobe of P. americana were studied to determine their spectral properties. These neurons exhibited tonic firing which changed with monochromatic broadfield illumination of the ipsilateral eye. The response patterns of these neurons were analyzed by inferring their relation to the ultraviolet (UV) and green (G) photoreceptor groups of the eye. Their anatomy was described after injection of Lucifer yellow. 2. Broadband neurons received either excitatory or inhibitory input from both UV and G receptors. These neurons were not strictly sensitive to luminosity levels and had large cell bodies in the central rind of the medulla and wide dendritic arbors in the medulla neuropil. 3. Narrow band neurons received input from predominantly one receptor type. Their spectral sensitivity curves were more finely tuned than those of the primary receptors presumably due to neural interactions within the optic lobe. 4. Color opponent neurons were inhibited by UV and excited by G inputs in their sustained response. Under certain conditions, some of these neurons also showed G inhibition. These neurons suggested the presence of a subsystem involved in color vision. 5. Broadband, narrow band and color opponent properties were seen in some single neurons when tested over a 5-6 log unit range of intensity. The responses of some of these neurons changed when stimulus duration was increased. These findings indicated that functional classification for these neurons was dependent on stimulus intensity and duration. 6. Polarizational sensitivity was tested in preliminary experiments. Two neurons responded to the movement and direction of polarized light.

Neurons of the Central Complex of the LocustSchistocerca gregariaare Sensitive to Polarized Light

“…Little is known about the central processing of polarized light information in the insect brain. Polarization-sensitive interneurons have been reported in the optic lobe of the cockroaches Periplaneta americana and Leucophaea maderae (Kelly and Mote, 1990;Loesel and Homberg, 2001), the locust S. gregaria (Homberg and Würden, 1997), and the desert ant Cataglyphis bicolor (Labhart, 2000), but an in-depth analysis only exists for the cricket Gryllus campestris (Labhart, 1988(Labhart, , 1996Labhart and Petzold, 1993;Labhart et al, 2001;Petzold, 2001). As in the locust central complex, POL neurons in the optic lobe of the cricket, cockroach, locust, and ant showed polarization opponency.…”

Polarization-Sensitive and Light-Sensitive Neurons in Two Parallel Pathways Passing Through the Anterior Optic Tubercle in the Locust Brain

“…Polarization-sensitive interneurons (POL neurons), found in several areas of the insect brain, are involved in signaling the orientation of the animal relative to the sky polarization pattern (Homberg 2004;Labhart and Meyer 2002;Wehner 2003). POL neurons were studied in peripheral visual neuropils of the optic lobe in cockroaches (Kelly and Mote 1990;Loesel and Homberg 2001), crickets (Labhart et al 2001), and ants (Labhart 2000). More recently in the desert locust and cricket, POL neurons were discovered in the central complex (Sakura and Labhart 2005;Vitzthum et al 2002), a neuropil in the median protocerebrum involved in spatial orientation, right-left maneuvering, and other aspects of motor control (reviewed by Homberg 2004;Strauss 2002).…”

Immunolocalization suggests a role of the histamine‐gated chloride channel PxHCLB in spectral opponent processing in butterfly photoreceptors

“…Therefore, the medulla has been the most plausible candidate where the first stage of color processing takes place (Kelber, 2016). In line with this assumption, spectral opponency, a key feature in color processing, had been reported in the medulla and/or higher visual centers in several insect species (Kelly & Mote, 1990;Kien & Menzel, 1977;Osorio, 1986;Paulk, Phillips-Portillo, Dacks, Fellous, & Gronenberg, 2008;Yang, Lin, & Hung, 2004). Rather unexpectedly, photoreceptors showing spectral opponency have also been found even at the level of the retina in butterflies (Chen, Arikawa, & Yang, 2013;Horridge, Mar celja, Jahnke, & Mati c, 1983;Mati c, 1983).…”

“…Color processing had long been considered to start in the medulla (Kelly & Mote, 1990;Kien & Menzel, 1977;Osorio, 1986;Paulk et al, 2008;Yang et al, 2004). However, spectral opponency has occasionally Axons of lvfs terminate in layer 4b (b,e).…”