| 1. |
- Adden, Andrea, et al.
(författare)
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The brain of a nocturnal migratory insect, the Australian Bogong moth
- 2020
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 528:11, s. 1942-1963
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Tidskriftsartikel (refereegranskat)abstract
- Every year, millions of Australian Bogong moths (Agrotis infusa) complete an astonishing journey: In Spring, they migrate over 1,000 km from their breeding grounds to the alpine regions of the Snowy Mountains, where they endure the hot summer in the cool climate of alpine caves. In autumn, the moths return to their breeding grounds, where they mate, lay eggs and die. These moths can use visual cues in combination with the geomagnetic field to guide their flight, but how these cues are processed and integrated into the brain to drive migratory behavior is unknown. To generate an access point for functional studies, we provide a detailed description of the Bogong moth's brain. Based on immunohistochemical stainings against synapsin and serotonin (5HT), we describe the overall layout as well as the fine structure of all major neuropils, including the regions that have previously been implicated in compass-based navigation. The resulting average brain atlas consists of 3D reconstructions of 25 separate neuropils, comprising the most detailed account of a moth brain to date. Our results show that the Bogong moth brain follows the typical lepidopteran ground pattern, with no major specializations that can be attributed to their spectacular migratory lifestyle. These findings suggest that migratory behavior does not require widespread modifications of brain structure, but might be achievable via small adjustments of neural circuitry in key brain areas. Locating these subtle changes will be a challenging task for the future, for which our study provides an essential anatomical framework.
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| 2. |
- Agardh, E., et al.
(författare)
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Gamma‐aminobutyric acid‐ and glutamic acid decarboxylase‐immunoreactive neurons in the retina of different vertebrates
- 1987
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967. ; 258:4, s. 622-630
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Tidskriftsartikel (refereegranskat)abstract
- The localization of gamma‐aminobutyric acid (GABA)‐ and L‐glutamate 1 carboxy‐lyase (GAD)‐immunoreactive neurons was compared in the skate, frog, pigeon, chicken, rabbit, and man. Horizontal cells show both GABA and GAD immunoreactivity in the skate, frog, and bird. Certain amacrine cells show GABA and GAD immunoreactivity in all species. The distribution of GABA‐ and GAD‐immunoreactive cell bodies and cell processes was very similar, if not identical, in the skate and man. In the other species, cell populations with GAD immunoreactivity also showed GABA immunoreactivity. However, in the bird, frog, and rabbit, the GABA‐immunoreactive amacrine cells were at least twice as numerous as the GAD‐immunoreactive cells. In birds, the distributions of the GAD and GABA immunoreactivities were different in the sublayers of the inner plexiform layer. The reason for the difference is currently unknown. GABA‐immunoreactive bipolar‐like cells were seen in the frog.
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| 6. |
- Beetz, M Jerome, et al.
(författare)
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Topographic organization and possible function of the posterior optic tubercles in the brain of the desert locust Schistocerca gregaria
- 2015
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 1096-9861 .- 0021-9967. ; 523:11, s. 1589-1607
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Tidskriftsartikel (refereegranskat)abstract
- Migrating desert locusts, Schistocerca gregaria, are able to use the skylight polarization pattern for navigation. They detect polarized light with a specialized dorsal rim area in their compound eye. After multistage processing, polarization signals are transferred to the central complex, a midline-spanning brain area involved in locomotor control. Polarization-sensitive tangential neurons (TB-neurons) of the protocerebral bridge, a part of the central complex, give rise to a topographic arrangement of preferred polarization angles in the bridge, suggesting that the central complex acts as an internal sky compass. TB-neurons connect the protocerebral bridge with two adjacent brain areas, the posterior optic tubercles. To analyze the polarotopic organization of the central complex further, we investigated the number and morphologies of TB-neurons and the presence and colocalization of three neuroactive substances in these neurons. Triple immunostaining with antisera against Diploptera punctata allatostatin (Dip-AST), Manduca sexta allatotropin (Mas-AT), and serotonin (5HT) raised in the same host species revealed three spatially distinct TB-neuron clusters, each consisting of 10 neurons per hemisphere: cluster 1 and 3 showed Dip-AST/5HT immunostaining, whereas cluster 2 showed Dip-AST/Mas-AT immunostaining. Five subtypes of TB-neuron could be distinguished based on ramification patterns. Corresponding to ramification domains in the protocerebral bridge, the neurons invaded distinct but overlapping layers within the posterior optic tubercle. Similarly, neurons interconnecting the tubercles of the two hemispheres also targeted distinct layers of these neuropils. From these data we propose a neuronal circuit that may be suited to stabilize the internal sky compass in the central complex of the locust
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| 7. |
- Beggs, J, et al.
(författare)
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Synaptology of trigemino- and spinothalamic lamina I terminations in the posterior ventral medial nucleus of the macaque
- 2003
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 459:4, s. 334-354
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Tidskriftsartikel (refereegranskat)abstract
- We used the electron microscope to examine lamina I trigemino- and spinothalamic (TSTT) terminations in the posterior part of the ventral medial nucleus (VMpo) of the macaque thalamus. Lamina I terminations were identified by anterograde labeling with biotinylated dextran, and 109 boutons on 38 terminal fibers were closely studied in series of ultrathin sections. Five unlabeled terminal boutons of similar appearance were also examined in detail. Three-dimensional, volume-rendered computer models were reconstructed from complete series of serial sections for 29 boutons on 10 labeled terminal fibers and one unlabeled terminal fiber. In addition, postembedding immunogold staining for GABA was obtained in alternate sections through 23 boutons. Lamina I TSTT terminations in VMpo generally have several large boutons (mean length = 2.16 ╡m, mean width = 1.29 ╡m) that are densely packed with vesicles and make asymmetric synaptic contacts on low-order dendrites of VMpo neurons (mean diameter 1.45 ╡m). They are closely associated with GABAergic presynaptic dendrites (PSDs), and nearly all form classic triadic arrangements (28 of 29 reconstructed boutons). Consecutive boutons on individual terminal fibers make multiple contacts with a single postsynaptic dendrite and can show evidence of progressive complexity. Dendritic appendages that enwrap and invaginate the terminal bouton constitute additional anatomic evidence for secure, high-fidelity synaptic transfer. These observations provide direct ultrastructural evidence supporting the hypothesis that VMpo is a lamina I TSTT thalamocortical relay nucleus in primates that subserves pain, temperature, itch, and other sensations related to the physiological condition of the body.
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| 9. |
- Beramendi, Ana, et al.
(författare)
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Neuromuscular junction in abdominal muscles of Drosophila melanogaster during adulthood and aging
- 2007
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 501:4, s. 498-508
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Tidskriftsartikel (refereegranskat)abstract
- The neuromuscular junction (NMJ) of Drosophila melanogaster has been established as a productive model for the study of synaptogenesis, synaptic plasticity, vesicle recycling, and other synaptic functions in embryos and larvae. It also has potential for the study of long-term plasticity during adult life and degenerative processes associated with aging. Here we provide a detailed description of the morphology and ultrastructure of the NMJ on abdominal dorsal longitudinal muscles throughout adult life from eclosion to senescence. In contrast to the case in the larva, the predominant type of terminals in these muscles in the adult fly consists of only two or three branches with tightly packed synaptic boutons. We observed qualitative and quantitative changes as mean bouton size increased gradually during adulthood, and the largest boutons were present in the old fly. The length of nerve branches first increased and thereafter decreased gradually during most of adult life. Branch diameter also decreased progressively, but branch number did not change. The subsynaptic reticulum became progressively thinner, and “naked” boutons were found in old flies. Ultrastructural traits gave indications of an age-associated increment in autophagy, larger synaptic vesicles, and impaired endocytosis. We propose that NMJ aging in the fly correlates with impaired endocytosis and membrane dynamics. This view finds a functional correlate in flies carrying a temperature-sensitive mutation in shibire that reversible blocks endocytosis; age significantly reduces the time required for complete paralysis and increases the time of recovery, thus confirming the age-dependent alteration in vesicle dynamics.
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