Grundlagen zur genauen Beschreibung von Komplexaugen

“…3) and counting the 'dots' covered by the dendritic fan, we obtain for each row of the retino-topic projection the corresponding ommatidia from which these cells receive input. Such eye maps were constructed from the dendritic fields of the V-cells V1-V3 and V5-V9 and the corresponding input area on the eye is shown in Figure 9A-G. We have used a regular hexagonal array in this illustration, despite the fact that the array of ommatidia in the eyes of Musca, Calliphora and Phaenicia is not regular and divergence angles vary from the anterior to the posterior part of the eye (Washizu, 1965;Gemperlein, 1969;Braitenberg, 1970;Beersma et al, 1975;Franceschini, 1975;Eckert, unpublished results). The abscissa and ordinate in Figure 9 both are shown in numbers of rows and columns, respectively; the abscissa gives in addition the angle/3 between the most anterior ommatidium and an ommatidium along the equatorial horizontal row.…”

Section: Dendritic Fieldsmentioning

confidence: 99%

Anatomical and physiological properties of the vertical cells in the third optic ganglion ofPhaenicia sericata (Diptera, Calliphoridae)

Eckert

Bishop

1978

J. Comp. Physiol.

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Summary. Intracellular recording and dye injection (Procion Yellow) techniques were applied to a set of nine giant, homolateral cells of the lobula plate of dipterans (Phaenicia, Sarcophaga) -the ' big vertical cells ' (or V-cells) of Pierantoni (1974).Anatomical Findings. The V-cells can be divided into 4 distinctly different groups which, in principle, agree with the classification (though into 3 groups) given by Strausfeld (1976a). In each case, the cell body lies in the caudal cell body layer of the optic pedunculus with the cell axon extending at the caudal surface of the lobula plate. The axons run through the optic pedunculus and terminate in the ventrolateral part of the protocerebrum. The large bifurcated dendrites and their small dendritic branches form a fan which lies in a frontal plane perpendicular to the columnar arrangement of this ganglion and penetrate the whole dorso-ventral region of the lobula plate. The highest density of dendritic branches is found in the anterior part of the retino-topic projection. It decreases gradually towards the projection of the posterior retina in the medial lobula plate. The dendritic field widths (Fig. 9) extend approximately 60 degrees in the horizontal and 200 degrees in the vertical direction; thus, there is a considerable degree of overlap in the horizontal direction. The posterior Vcells V6 to V8 possess a more extended horizontal field width in the dorsal part of the eye. These anatomical findings were verified by physiological measurements of the receptive field widths.Physiological Findings. The anterior V-cells (V1 to V3) are directionally sensitive to vertical movement: upward and downward pattern motion causes hyperpolarizing and depolarizing DC-membrane potential shifts, respectively. The lateral and posterior V-cells (V4 to V8) exhibit an additional sensitivity to horizontal movement giving rise to depolarizing and hyperpolarizing DC-membrane potential shifts with progressive and regressive pattern motion, respectively (Fig. 14). The directional sensitivity of V9 is not known. All V-cells respond to monocular, ipsilateral stimulation only. In addition to their directional sensitivity to moving patterns they respond to light intensity changes with a strong increase in the fluctuations of the transmembrane potential (which is proportional to the logarithm of the intensity). The average DC-membrane potential changes only very slightly (+ 3 mV) to a hundredfold increase in light intensity. These graduated potentials are sometimes accompanied by small, rapid spike-like potentials. Regular action potentials have never been observed under natural conditions, but can be elicited by hyperpolarizing current injection. The ionic basis of the observed potential behaviour is discussed.On physiological and anatomical grounds, the Vcells are believed to be output elements of the lobula plate with connections to descending neurones of the ventral nerve cord (Strausfeld and Obermayer, 1976) and to heterolateral elements. The anatomical and physiological properties of...

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“…5, have been obtained by Braitenberg (1967), Gemperlein (1969) and Braitenberg and Hauser-Holschuh (1972). A more detailed discussion on the latter reports in relation to our measurements on a series of other diptera will be presented elsewhere.…”

Section: G Discussionmentioning

confidence: 88%