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- Ericson, Ann-Charlott, 1965-
(författare)
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Synaptic organization of nociceptive relay nuclei in the cat and primate thalamus
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The fine structure of two thalamic nociceptive relay nuclei, the nucleus submedius (Sm) in the cat, and the posterior region in the owl monkey, was investigated using anatomical tract tracing techniques, immunohistochemical staining for neuroactive substances, and threedimensional reconstructions of synaptic circuitry. Ascending lamina I axons, labeled by anterograde transport of Phaseolus vulgaris leucoagglutinin, gave rise to two different types of termination in Sm: large, compact clusters of numerous boutons were predominant in the dense focus of the terminal field after a tracer injection at the site of nociceptive-specific neurons in lamina I, and boutons-of-passage type terminations were conspicuous in the periphery of a lamina I terminal field in Sm and predominant following a tracer injection at the site of thermoreceptive-specific neurons in lamina I. Three-dimensional reconstructions of a sample of these terminations, generated from series of ultrathin sections by using special software on a computer workstation, showed that all boutons of each cluster made synaptic contact with protrusions and branch points on a single dendrite. These contacts involved presynaptic dendrites (PSDs) in triadic arrangements. In contrast, the boutons-of-passage type terminations were generally characterized by contacts with PSDs, and some of the passing varicosities made simple such synaptic contacts. However, an intermediate termination pattern was also found in which boutons-of-passage fanned synaptic complexes with dendritic appendages involving PSD contacts. Postembedding immunogold-labeling techniques showed that the spinal and trigeminal terminals in Sm contained synaptic vesicle-associated glutamate, suggesting that glutamate is an excitatory neurotransmitter in these terminals. Corticothalamic tract terminals were also glutamatergic. Immunoreactivity to gamma-aminobutyric acid (GABA) was observed in PSDs originating from GABAergic intrinsic neurons and in axon tenninals supposed to originate from the reticular thalamic nucleus. A similar organization of glutamatergic and GABAergic elements was seen in the posterior thalamic region of owl monkeys. The different types of synaptic organization seen in Sm are consistent with the possibility that modality-selective nociceptive and thermoreceptive lamina I neurons terminate differentially in this nucleus and suggest a functional integration of cold and pain activity. The presentfindings provide evidence that such activity is transmitted by the excitatory amino acid glutamate and is modulated by inhibitory GABAergic mechanisms. Glutamate and GABA are also involved in the processing of ascending information in the posterior thalamic region of owl monkeys, showing that these substances are important for pain transmission in primates as well.
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- Ericson, Per G P, 1956-, et al.
(författare)
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Subspecific identity of prehistoric Baltic cormorants Phalacrocorax carbo
- 1997
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Ingår i: Ardea. - 0373-2266 .- 2213-1175. ; 85:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Cormorants of the subspecies Phalacrocorax carbo sinensis breed in large numbers in the Baltic Sea. They migrate to the Mediterranean region to winter and are then replaced in the Baltic by wintering individuals of the Norwegian population of the nominate subspecies carbo. Cormorants bred in the Baltic during prehistoric times too, but as evident from a comparison of skeletal measurements in present-day and prehistoric Cormorants, these individuals belonged to the nominate subspecies carbo. The Swedish subfossil record of the Cormorants available for study, does not include any remains small enough to suggest the presence of sinensis. Precisely when the subspecies sinensis immigrated into the Baltic is unknown, but it must have occurred sometime between 1500 and 1800 AD.
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- Ericson, Per G P, 1956-
(författare)
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Systematic relationships of the palaeogene family Presbyornithidae (Aves : Anseriformes)
- 1997
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Ingår i: Zoological Journal of the Linnean Society. - 0024-4082 .- 1096-3642. ; 121:4, s. 429-483
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Tidskriftsartikel (refereegranskat)abstract
- The early Tertiary (Paleocene and Eocene) family Presbyornithidae is one of the most completely known group of fossil birds. Essentially all parts of the skeleton are represented in the fossil record, allowing a thorough analysis of the phylogenetic position of the family. Forty-two families of nonpasserine birds representing the orders Ciconiiformes, Anseriformes, Galliformes, Gruiformes and Charadriiformes, were included in a cladistic analysis of 71 skeletal characters. The previously suggested anseriform affinity of the Presbyornithidae was confirmed. Furthermore, the family proved to be closer to the Anatidae than to the Anhimidae or Anseranatidae. The many postcranial similarities with certain charadriiform birds as the Burhinidae, obviously are plesiomorphies. By this observation, a better undestanding of character evolution in nonpasserine skeletal morphology is gained. The often suggested close relationship of anseriform and galliform birds is not confirmed by osteology. Instead, the Anseriformes and the Phoenicopteridae form a monophyletic clade that is the sister to the remaining ciconiiform birds. This result renders the Ciconiiformes sensu Wetmore (1960) polyphyletic. (C) 1997 The Linnean Society of London.
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- Ericson, Per G P, 1956-, et al.
(författare)
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The earliest record of house sparrows (Passer domesticus) in northern Europe
- 1997
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Ingår i: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 24:2, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- Remains of the house sparrow (Passer domesticus) recovered from a late Bronze Age (1200-800 sc) settlement in central Sweden are described. The house sparrow is conspicuously rare in prehistoric Europe, and this record constitutes the earliest from the northern part. The find predates the introduction of domestic fowl (Gallus gallus) to Sweden, a species with which the house sparrow has been assumed to be spread simultaneously. Instead, it is here suggested that house sparrows most likely spread over Europe along with the horse Equus caballus. (C) 1997 Academic Press Limited
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| 10. |
- Ericson, Per G P, 1956-
(författare)
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The skeletal evidence for a sister-group relationship of anseriform and galliform birds - A critical evaluation
- 1996
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Ingår i: Journal of Avian Biology. - : JSTOR. - 0908-8857 .- 1600-048X. ; 27:3, s. 195-202
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Tidskriftsartikel (refereegranskat)abstract
- The osteological basis for the proposed close phylogenetical relationship of anseriform and galliform birds is evaluated and found to be very weak. Out of eleven postulated synapomorphies in cranial morphology (Cracraft 1988), three must be excluded since they express variation that is already covered by any of the other eleven characters. Another six of the postulated synapomorhies either cannot be verified to occur in most anseriforms and galliforms, or have a wide distribution outside this group. A re-analysis of the combined morphological and biochemical data set of Cracraft and Mindell (1989) with the questionable osteological characters excluded, does not corroborate an anseriform-galliform sister-group relationship, but leaves the Neognathae unresolved.
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