Otto Friedrich Karl Deiters (1834–1863)Deiters, Vera S.; Guillery, R.W.
doi: 10.1002/cne.23316pmid: 23436306
Otto Deiters, for whom the lateral vestibular nucleus and the supporting cells of the outer auditory hair cells were named, died in 1863 aged 29. He taught in the Bonn Anatomy Department, had an appointment in the University Clinic, and ran a small private practice. He published articles on the cell theory, the structure and development of muscle fibers, the inner ear, leukaemia, and scarlet fever. He was the second of five surviving children in an academic family whose private correspondence revealed him to be a young man with limited social skills and high ambitions to complete a deeply original study of the brainstem and spinal cord. However, first his father and then his younger brother died, leaving him and his older brother responsible for a suddenly impecunious family as he failed to gain academic promotion. Otto died of typhus two years after his younger brother's death, leaving his greatest scientific achievement to be published posthumously. He showed that most nerve cells have a single axon and several dendrites; he recognized the possibility that nerve cells might be functionally polarized and produced the first illustrations of synaptic inputs to dendrites from what he termed a second system of nerve fibers. J. Comp. Neurol. 521:1929–1953, 2013. © 2013 Wiley Periodicals, Inc.
Postsynaptic muscarinic m2 receptors at cholinergic and glutamatergic synapses of mouse brainstem motoneuronsCsaba, Zsolt; Krejci, Eric; Bernard, Véronique
doi: 10.1002/cne.23268pmid: 23184757
In many brain areas, few cholinergic synapses are identified. Acetylcholine is released into the extracellular space and acts through diffuse transmission. Motoneurons, however, are contacted by numerous cholinergic terminals, indicating synaptic cholinergic transmission on them. The muscarinic m2 receptor is the major acetylcholine receptor subtype of motoneurons; therefore, we analyzed the localization of the m2 receptor in correlation with synapses by electron microscopic immunohistochemistry in the mouse trigeminal, facial, and hypoglossal motor nuclei. In all nuclei, m2 receptors were localized at the membrane of motoneuronal perikarya and dendrites. The m2 receptors were concentrated at cholinergic synapses located on the perikarya and most proximal dendrites. However, m2 receptors at cholinergic synapses represented only a minority (<10%) of surface m2 receptors. The m2 receptors were also enriched at glutamatergic synapses in both motoneuronal perikarya and dendrites. A relatively large proportion (20–30%) of plasma membrane–associated m2 receptors were located at glutamatergic synapses. In conclusion, the effect of acetylcholine on motoneuron populations might be mediated through a synaptic as well as diffuse type of transmission. J. Comp. Neurol. 521:2008–2024, 2013. © 2012 Wiley Periodicals, Inc.
Identification of distinct tyraminergic and octopaminergic neurons innervating the central complex of the desert locust, Schistocerca gregariaHomberg, Uwe; Seyfarth, Jutta; Binkle, Ulrike; Monastirioti, Maria; Alkema, Mark J.
doi: 10.1002/cne.23269pmid: 23595814
The central complex is a group of modular neuropils in the insect brain with a key role in visual memory, spatial orientation, and motor control. In desert locusts the neurochemical organization of the central complex has been investigated in detail, including the distribution of dopamine‐, serotonin‐, and histamine‐immunoreactive neurons. In the present study we identified neurons immunoreactive with antisera against octopamine, tyramine, and the enzymes required for their synthesis, tyrosine decarboxylase (TDC) and tyramine β‐hydroxylase (TBH). Octopamine‐ and tyramine immunostaining in the central complex differed strikingly. In each brain hemisphere tyramine immunostaining was found in four neurons innervating the noduli, 12–15 tangential neurons of the protocerebral bridge, and about 17 neurons that supplied the anterior lip region and parts of the central body. In contrast, octopamine immunostaining was present in two bilateral pairs of ascending fibers innervating the upper division of the central body and a single pair of neurons with somata near the esophageal foramen that gave rise to arborizations in the protocerebral bridge. Immunostaining for TDC, the enzyme converting tyrosine to tyramine, combined the patterns seen with the tyramine‐ and octopamine antisera. Immunostaining for TBH, the enzyme converting tyramine to octopamine, in contrast, was strikingly similar to octopamine immunolabeling. We conclude that tyramine and octopamine act as neurotransmitters/modulators in distinct sets of neurons of the locust central complex with TBH likely being the rate‐limiting enzyme for octopamine synthesis in a small subpopulation of TDC‐containing neurons. J. Comp. Neurol. 521:2025–2041, 2013. © 2012 Wiley Periodicals, Inc.
Scene from above: Retinal ganglion cell topography and spatial resolving power in the giraffe (Giraffa camelopardalis)Coimbra, João Paulo; Hart, Nathan S.; Collin, Shaun P.; Manger, Paul R.
doi: 10.1002/cne.23271pmid: 23595815
The giraffe (Giraffa camelopardalis) is a browser that uses its extensible tongue to selectively collect leaves during foraging. As the tallest extant terrestrial mammal, its elevated head height provides panoramic surveillance of the environment. These aspects of the giraffe's ecology and phenotype suggest that vision is of prime importance. Using Nissl‐stained retinal wholemounts and stereological methods, we quantitatively assessed the retinal specializations in the ganglion cell layer of the giraffe. The mean total number of retinal ganglion cells was 1,393,779 and their topographic distribution revealed the presence of a horizontal visual streak and a temporal area. With a mean peak of 14,271 cells/mm2, upper limits of spatial resolving power in the temporal area ranged from 25 to 27 cycles/degree. We also observed a dorsotemporal extension (anakatabatic area) that tapers toward the nasal retina giving rise to a complete dorsal arch. Using neurofilament‐200 immunohistochemistry, we also detected a dorsal arch formed by alpha ganglion cells with density peaks in the temporal (14–15 cells/mm2) and dorsonasal (10 cells/mm2) regions. As with other artiodactyls, the giraffe shares the presence of a horizontal streak and a temporal area which, respectively, improve resolution along the horizon and in the frontal visual field. The dorsal arch is related to the giraffe's head height and affords enhanced resolution in the inferior visual field. The alpha ganglion cell distribution pattern is unique to the giraffe and enhances acquisition of motion information for the control of tongue movement during foraging and the detection of predators. J. Comp. Neurol. 521:2042–2057, 2013. © 2012 Wiley Periodicals, Inc.
Diversity of thalamorecipient spine morphology in cat visual cortex and its implication for synaptic plasticityda Costa, Nuno Maçarico
doi: 10.1002/cne.23272pmid: 23184851
A feature of spine synapses is the existence of a neck connecting the synapse on the spine head to the dendritic shaft. As with a cable, spine neck resistance (Rneck) increases with increasing neck length and is inversely proportional to the cross‐sectional area of the neck. A synaptic current entering a spine with a high Rneck will lead to greater local depolarization in the spine head than would a similar input applied to a spine with a lower Rneck. This could make spines with high Rneck more sensitive to plastic changes since voltage sensitive conductances, such as N‐methyl‐D‐aspartic acid (NMDA) channels can be more easily activated. This hypothesis was tested using serial section electron microscopic reconstructions of thalamocortical spine synapses and spine necks located on spiny stellate cells and corticothalamic cells from area 17 of cats. Thalamic axons and corticothalamic neurons were labeled by injections of the tracer biotinylated dextran amine (BDA) in the dorsal lateral geniculate nucleus (dLGN) of anesthetized cats and spiny stellates were filled intracellularly in vivo with horseradish peroxidase. Twenty‐eight labeled spines that formed synapses with dLGN boutons were collected from three spiny stellate and four corticothalamic cells and reconstructed in 3D from serial electron micrographs. Spine length, spine diameter, and the area of the postsynaptic density were measured from the 3D reconstructions and Rneck of the spine was estimated. No correlation was found between the postsynaptic density size and the estimated spine Rneck. This suggests that forms of plasticity that lead to larger synapses are independent of spine neck resistance. J. Comp. Neurol. 521:2058–2066, 2013. © 2012 Wiley Periodicals, Inc.
Neural pathways mediating control of reproductive behavior in male Japanese quailWild, J. Martin; Balthazart, Jacques
doi: 10.1002/cne.23275pmid: 23225613
The sexually dimorphic medial preoptic nucleus (POM) in Japanese quail has for many years been the focus of intensive investigations into its role in reproductive behavior. The present study delineates a sequence of descending pathways that finally reach sacral levels of the spinal cord housing motor neurons innervating cloacal muscles involved in reproductive behavior. We first retrogradely labeled the motor neurons innervating the large cloacal sphincter muscle (mSC) that forms part of the foam gland complex (Seiwert and Adkins‐Regan [1998] Brain Behav Evol 52:61–80) and then putative premotor nuclei in the brainstem, one of which was nucleus retroambigualis (RAm) in the caudal medulla. Anterograde tracing from RAm defined a bulbospinal pathway, terminations of which overlapped the distribution of mSC motor neurons and their extensive dorsally directed dendrites. Descending input to RAm arose from an extensive dorsomedial nucleus of the intercollicular complex (DM‐ICo), electrical stimulation of which drove vocalizations. POM neurons were retrogradely labeled by injections of tracer into DM‐ICo, but POM projections largely surrounded DM, rather than penetrated it. Thus, although a POM projection to ICo was shown, a POM projection to DM must be inferred. Nevertheless, the sequence of projections in the male quail from POM to cloacal motor neurons strongly resembles that in rats, cats, and monkeys for the control of reproductive behavior, as largely defined by Holstege et al. ([1997], Neuroscience 80:587–598). J. Comp. Neurol. 521:2067–2087, 2013. © 2012 Wiley Periodicals, Inc.
Expression patterns of Pax6 and Pax7 in the adult brain of a urodele amphibian, Pleurodeles waltlJoven, Alberto; Morona, Ruth; González, Agustín; Moreno, Nerea
doi: 10.1002/cne.23276pmid: 23224769
Expression patterns of Pax6, Pax7, and, to a lesser extent, Pax3 genes were analyzed by a combination of immunohistochemical techniques in the central nervous system of adult specimens of the urodele amphibian Pleurodeles waltl. Only Pax6 was found in the telencephalon, specifically the olfactory bulbs, striatum, septum, and lateral and central parts of the amygdala. In the diencephalon, Pax6 and Pax7 were distinct in the alar and basal parts, respectively, of prosomere 3. The distribution of Pax6, Pax7, and Pax3 cells correlated with the three pretectal domains. Pax7 specifically labeled cells in the dorsal mesencephalon, mainly in the optic tectum, and Pax6 cells were the only cells found in the tegmentum. Large populations of Pax7 cells occupied the rostral rhombencephalon, along with lower numbers of Pax6 and Pax3 cells. Pax6 was found in most granule cells of the cerebellum. Pax6 cells also formed a column of scattered neurons in the reticular formation and were found in the octavolateral area. The rhombencephalic ventricular zone of the alar plate expressed Pax7. Dorsal Pax7 cells and ventral Pax6 cells were found along the spinal cord. Our results show that the expression of Pax6 and Pax7 is widely maintained in the brains of adult urodeles, in contrast to the situation in other tetrapods. This discrepancy could be due to the generally pedomorphic features of urodele brains. Although the precise role of these transcription factors in adult brains remains to be determined, our findings support the idea that they may also function in adult urodeles. J. Comp. Neurol. 521:2088–2124, 2013. © 2012 Wiley Periodicals, Inc.
Quantitative analysis of axon bouton distribution of subthalamic nucleus neurons in the rat by single neuron visualization with a viral vectorKoshimizu, Yoshinori; Fujiyama, Fumino; Nakamura, Kouichi C.; Furuta, Takahiro; Kaneko, Takeshi
doi: 10.1002/cne.23277pmid: 23595816
The subthalamic nucleus (STN) of the basal ganglia plays a key role in motor control, and STN efferents are known to mainly target the external segment of the globus pallidus (GPe), entopeduncular nucleus (Ep), and substantia nigra (SN) with some axon collaterals to the other regions. However, it remains to be clarified how each STN neuron projects axon fibers and collaterals to those target nuclei of the STN. Here we visualized the whole axonal arborization of single STN neurons in the rat brain by using a viral vector expressing membrane‐targeted green fluorescent protein, and examined the distribution of axon boutons in those target nuclei. The vast majority (8–9) of 10 reconstructed STN neurons projected to the GPe, SN, caudate‐putamen (CPu), and Ep, which received, on average ± SD, 457 ± 425, 400 ± 347, 126 ± 143, and 106 ± 100 axon boutons per STN neuron, respectively. Furthermore, the density of axon boutons in the GPe was highest among these nuclei. Although these target nuclei were divided into calbindin‐rich and ‐poor portions, STN projection showed no exclusive preference for those portions. Since STN neurons mainly projected not only to the GPe, SN, and Ep but also to the CPu, the subthalamostriatal projection might serve as a positive feedback path for the striato‐GPe‐subthalamic disinhibitory pathway, or work as another route of cortical inputs to the striatum through the corticosubthalamostriatal disynaptic excitatory pathway. J. Comp. Neurol. 521:2125–2146, 2013. © 2012 Wiley Periodicals, Inc.