Connectome of the lamina reveals the circuit for early color processing in the visual pathway of a butterfly.

Connectomics has become a standard neuroscience methodology in a few model animals, with the visual system being a popular target of study. Combining connectomics with circuit and behavioral physiology, recent studies on the color vision of the fruit fly Drosophila melanogaster have focused on the mechanisms underlying early wavelength processing in the optic ganglia. However, the color vision capabilities of D.

Morphology and receptive field organization of a temporal processing region in Apteronotus albifrons.

The timing system of weakly electric fishes is vital for many behavioral processes, but the system has been relatively unexplored in Apteronotus albifrons. This paper describes the receptive fields of phase-locked neurons in the midbrain of A. albifrons, in combination with neuroanatomy and electron microscopy (EM) to delineate a phase-locked area in this fish, the magnocellular mesencephalic nucleus (MMN).

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

Spectrally opponent responses, that is, wavelength-dependent inversions of response polarity, have been observed at the level of photoreceptors in butterflies. As inter-photoreceptor connections have been found in the butterfly Papilio xuthus, and histamine is the only neurotransmitter so far identified in insect photoreceptors, we hypothesize that histaminergic sign-inverting synapses exist in the lamina between different spectral receptors as a mechanism for spectral opponency as in the medulla of Drosophila. Here, we localized two histamine-gated chloride channels, PxHCLA (Drosophila Ort homolog) and PxHCLB (Drosophila HisCl1 homolog), in the visual system of Papilio xuthus by using specific antisera.

Not flying blind: a comparative study of photoreceptor function in flying and non-flying cockroaches.

Flying is often associated with superior visual performance, as good vision is crucial for detection and implementation of rapid visually guided aerial movements. To understand the evolution of insect visual systems it is therefore important to compare phylogenetically related species with different investments in flight capability. Here, we describe and compare morphological and electrophysiological properties of photoreceptors from the habitually flying green cockroach and the American cockroach , which flies only at high ambient temperatures.

Combined pigmentary and structural effects tune wing scale coloration to color vision in the swallowtail butterfly Papilio xuthus.

Butterflies have well-developed color vision, presumably optimally tuned to the detection of conspecifics by their wing coloration. Here we investigated the pigmentary and structural basis of the wing colors in the Japanese yellow swallowtail butterfly, Papilio xuthus, applying spectrophotometry, scatterometry, light and electron microscopy, and optical modeling. The about flat lower lamina of the wing scales plays a crucial role in wing coloration.

Spectrally tuned structural and pigmentary coloration of birdwing butterfly wing scales.

The colourful wing patterns of butterflies play an important role for enhancing fitness; for instance, by providing camouflage, for interspecific mate recognition, or for aposematic display. Closely related butterfly species can have dramatically different wing patterns. The phenomenon is assumed to be caused by ecological processes with changing conditions, e.

Time disparity sensitive behavior and its neural substrates of a pulse-type gymnotiform electric fish, Brachyhypopomus gauderio.

Roles of the time coding electrosensory system in the novelty responses of a pulse-type gymnotiform electric fish, Brachyhypopomus, were examined behaviorally, physiologically, and anatomically. Brachyhypopomus responded with the novelty responses to small changes (100 μs) in time difference between electrosensory stimulus pulses applied to different parts of the body, as long as these pulses were given within a time period of ~500 μs. Physiological recording revealed neurons in the hindbrain and midbrain that fire action potentials time-locked to stimulus pulses with short latency (500-900 μs).

Rhabdom evolution in butterflies: insights from the uniquely tiered and heterogeneous ommatidia of the Glacial Apollo butterfly, Parnassius glacialis.

The eye of the Glacial Apollo butterfly, Parnassius glacialis, a 'living fossil' species of the family Papilionidae, contains three types of spectrally heterogeneous ommatidia. Electron microscopy reveals that the Apollo rhabdom is tiered. The distal tier is composed exclusively of photoreceptors expressing opsins of ultraviolet or blue-absorbing visual pigments, and the proximal tier consists of photoreceptors expressing opsins of green or red-absorbing visual pigments.

Glass scales on the wing of the swordtail butterfly Graphium sarpedon act as thin film polarizing reflectors.

The wings of the swordtail butterfly Graphium sarpedon (the Common Bluebottle) have blue/green-colored patches that are covered on the underside by two types of scales: white and glass scales. Transmission and scanning electron microscopy revealed that the white scales are classically structured: the upper lamina, with prominent ridges and large open windows, is well separated by trabeculae from a flat, continuous lower lamina. In the glass scales, the upper lamina, with inconspicuous ridges and windows, is almost flat and closely apposed to the equally flat lower lamina.

Eyes with basic dorsal and specific ventral regions in the glacial Apollo, Parnassius glacialis (Papilionidae).

Recent studies on butterflies have indicated that their colour vision system is almost species specific. To address the question of how this remarkable diversity evolved, we investigated the eyes of the glacial Apollo, Parnassius glacialis, a living fossil species belonging to the family Papilionidae. We identified four opsins in the Parnassius eyes--an ultraviolet- (PgUV), a blue- (PgB), and two long wavelength (PgL2, PgL3)-absorbing types--and localized their mRNAs within the retina.

Pathway-specific utilization of synaptic zinc in the macaque ventral visual cortical areas.

Synaptic zinc is an activity-related neuromodulator, enriched in hippocampal mossy fibers and a subset of glutamatergic cortical projections, exclusive of thalamocortical or corticothalamic. Some degree of pathway specificity in the utilization of synaptic zinc has been reported in rodents. Here, we use focal injections of the retrograde tracer sodium selenite to identify zinc-positive (Zn+) projection neurons in the monkey ventral visual pathway.

Confocal mapping of cortical inputs onto identified pyramidal neurons.

Using a confocal microscopy protocol, we carried out a microcircuitry investigation of cortical connections in monkey temporal cortex. Inputs were labeled by BDA injections in posterior area TE, and potential postsynaptic pyramidal neuron targets were labeled with EGFP, by injection of retrogradely transported adenovirus. We scored the number and distribution of putative contacts onto dendritic compartments of neurons in different layers.

Neuronal sensitivity to microsecond time disparities in the electrosensory system of Gymnarchus niloticus.

To perform the jamming avoidance response (JAR), the weakly electric fish Gymnarchus detects time disparities on the order of microseconds between electrosensory signals received by electroreceptors in different parts of the body surface. This paper describes time-disparity thresholds of output neurons of the electrosensory lateral line lobe (ELL), where the representation of timing information is converted from a time code to a firing-rate code. We recorded extracellular single-unit responses from pyramidal cells in the ELL to sinusoidally modulated time disparity with various depths (0-200 micros).

Unitary giant synapses embracing a single neuron at the convergent site of time-coding pathways of an electric fish, Gymnarchus niloticus.

Phase-locking neurons in the electrosensory lateral line lobe (ELL) of a weakly electric fish, Gymnarchus niloticus, fire an action potential in response to each cycle of the sinusoidal electrosensory signal (350-500 Hz) created by the fish's own electric organ. The exact firing times of the phase-locking neurons are altered (time-shifted) by capacitance of electrolocation objects or by electric organ discharges of other individuals. The magnitude of the time shifts depends on the location of the neurons' receptive field on the skin; thus, time disparities arise between the firing of phase-locking neurons.