A novel major output target for pheromone-sensitive projection neurons in male moths

The male-specific macroglomerular complex (MGC) in the moth antennal lobe contains circuitry dedicated to pheromone processing. Output neurons from this region project along three parallel pathways, the medial, mediolateral, and lateral tracts. The MGC-neurons of the lateral tract are least described and their functional significance is unknown. We used mass-staining, calcium imaging, and intracellular recording/staining to characterize the morphological and physiological properties of these neurons in Helicoverpa armigera. All lateral-tract MGC neurons targeted the column, a small region within the superior intermediate neuropil. We identified this region as the major converging site for lateral-tract neurons responsive to pheromones and plant-odors. The lateral-tract MGC-neurons consistently responded with a faster onset than the well-described medial-tract neurons. Different from the medial-tract MGC neurons encoding odor quality important for signal identification, those in the lateral tract seem to convey a robust and rapid, but fixed signal – potentially important for fast control of hard-wired behavior.

Representation of the temporal raphe within the optic tract of the cat

The retinal topography of the cat's optic tract was determined by means of injections of the enzyme horseradish peroxidase (HRP) into the tract. This analysis was accomplished by the subtraction of all HRP injection sites not labeling a defined retinal area from those injection sites which resulted in ganglion cell labeling (Venn diagram analysis). Using this method, the following correspondences were demonstrated for the ipsilateral and contralateral projections: superior retina represented in medial optic tract; inferior retina in lateral tract; and area centralis in a dorsocentral location (which was part of a larger area representing the visual streak). The temporal raphe was represented in the ipsilateral tract as a band curving from the area centralis region toward the dorsomedial border of the tract. Contralateral fibers from a region superior to the optic disc were found to be displaced with respect to the general retinal representation in the optic tract and this appeared to be related to retinal development. The ratio of contralateral to ipsilateral fibers was determined and found to be nonuniform within the tract.Injection of HRP into the optic tract of the cat also allowed the axons from labeled retinal ganglion cells to be traced within the retina and optic disc. Axons from ganglion cells lying temporal to the raphe curve around the area centralis enter the optic disc on the lateral and inferior aspects. Ganglion cells lying nasal to the raphe send their axons more directly to enter the optic disc on its superior aspect. A schema is proposed whereby the retina is mapped onto the optic tract.

Observations on the ciliary currents of the jelly-fish Aurelia aurita L.

SUMMARYThe jelly-fish Aurelia aurita possesses external and internal ciliary currents that play a large part in food collection and in the transport of food, reproductive products and excretory matter.Adults feed on relatively small organisms, which are collected in mucus on all external surfaces and eventually passed to the inner surfaces of the oral arms.The inner surfaces of the oral arms bear two ciliated tracts which operate simultaneously in opposite directions. The lateral tract carries food materials proximally towards the gastric pouches, but is capable of rejecting inedible matter. The basal tract carries excretory matter distally, away from the gastric pouches and canals to the exterior.Rejection reactions are also found in the gastric pouches and radial canals, parts of which have currents moving in opposite directions on the roof and on the floor. These opposing currents appear to be derived from the system in the ephyra stage, where the circulation in the wide gastric cavity and blind-ending canals is maintained partly by centripetal currents on the floor and centrifugal currents on the roof.The directions of the main currents remain constant throughout the larval stages to the adult, although slight variations are introduced by morphological changes. The currents also remain the same during spawning, when the eggs and sperm leave the gastric pouches by the normal excretory path.Many of the ciliary currents found in Aurelia are present in other semaeostome and rhizostome medusae, but only in Aurelia do the umbrella surfaces and currents play a large part in food collection.

V.–Distribution of the Cells in the Intermedio-Lateral Tract of the Spinal Cord

The term intermedio-lateral tract was introduced in 1859 (Phil. Trans., 1859, p. 445) by Lockhart Clarke to designate a tract or column of nerve cells in the spinal cord, which he had previously described in 1851 (Phil. Trans., 1851, ii. p. 613) as occupying that portion of the lateral margin of the grey matter which is intermediate between the anterior and posterior cornua. According to Clarke's original account, the column in question was very transparent in appearance, and resembled somewhat the substantia gelatinosa of the posterior horn. It was found in the upper part of the lumbar enlargement, extended upwards through the dorsal region, where it distinctly increased in size, to the lower part of the cervical enlargement. Here it disappeared almost entirely. In the upper cervical region it was again seen, and could be traced upwards into the medulla oblongata, where, in the space immediately behind the central canal, it blended with its fellow of the opposite side. In the more complete account of the tract published in 1859 (p. 446), its component cells are described as in part oval, fusiform, pyriform, or triangular, and as being smaller and more uniform in size than those of the anterior cornua. In the mid-dorsal region, where they are least numerous, they are found only near the lateral margin of the grey matter, with the exception of some cells which lie among the white fibres beyond the margin of the grey substance. In the upper dorsal region the tract is larger, and not only projects further outwards into the lateral column of the white fibres, but also tapers inwards across the grey substance, almost to the front of Clarke's column. In the cervical enlargement it gradually disappears, although it seems to contain, in part at least, a few scattered cells resembling those of the intermedio-lateral tract of the dorsal region. In the upper cervical region, as already stated, it is again seen occupying a lateral horn similar to that found in the dorsal region. It is composed of the same kind of cells, and can be followed up into the medulla, where it is said to give origin to some of the fibres of the vagus and the spinal accessory.