1,721,543 research outputs found
Differential representation of drug-seeking within ventral pallidal subregions
No full textVentral pallidum (VP) neurons exhibit changes in firing rate (FR) immediately prior to and/or following cocaine-reinforced responses. We first aimed to determine whether the changes in FR surrounding cocaine-seeking responses were coincident with behaviors such as approaching the manipulandum, responding on the manipulandum, and retreating away from the manipulandum. Second, we aimed to determine whether changes in FR during cocaine-seeking behaviors differed between VP subregions. Prior to recordings, animals exhibited both task and skill learning, replicating previous results using this operant. 171 single-units in the ventromedial VP (VPvm) and 48 in the dorsolateral VP (VPdl) were recorded in welltrained animals during cocaine self-administration. Baseline FR and waveform characteristics did not differ between subregions. VPdl neurons exhibited a greater absolute change in FR over VPvm neurons during approaches as well as approaches divided into cued and uncued conditions. VPdl neurons exhibited a greater absolute change in FR over the VPvm during responses as well as responses divided into those cued/reinforced and uncued/unreinforced conditions. VPdl neurons were more likely to exhibit a similar change in FR during approach and response than VPvm neurons. VPvm neurons were heterogeneous, changing FRs during approach or response alone, or both. No differences were found between subregions during retreat behavior. VPdl neurons exhibited a greater absolute change in FR over the VPvm for retreats in which the pump was activated prior to or during a retreat, but not for retreats when the pump was not activated. Given that VPdl neurons exhibited a greater change in FR than VPvm neurons during approach and response, VPdl may be involved in the expression of drug-seeking behaviors through projections to "motoric" regions such as subthalamic nucleus and substantia nigra. Furthermore, because VPdl neurons were more likely to continue their change of FR from approach through response while VPvm were more selective (e.g., approach alone, response alone), it is suggested that cocaine-seeking behaviors are differentially represented within VP subregions. The VPvm projects primarily to the mediodorsal thalamus and ventral tegmental area. Heterogeneous firing patterns within the VPvm may be involved in maintaining a representation of behavioral characteristics or sequences of self-administration behaviors.Ph. D.Includes bibliographical referencesby David Hamilton Roo
The Diary of Sir David Hamilton, 1709-1714, edited by Philip Roberts, 1975
No full textLevier Daniel. The Diary of Sir David Hamilton, 1709-1714, edited by Philip Roberts, 1975. In: Dix-huitième Siècle, n°8, 1976. Les Jésuites. p. 457
Genesis of the gold-bearing breccia bodies at the Lebong Tandai mine, Sumatra
No full textThe Lebong Tandai mine, located in the foothills of the Barisan mountains on the Indonesian island of Sumatra, is a volcanic-hosted, low-sulphidation epithermal gold deposit of Neogene age. The mineralization occurs as a series of moderately- to steeply-dipping, tabular quartz-cemented breccia bodies which are highly transgressive to the bedding in the host rocks. Vertical and horizontal dimensions of the breccia bodies are 100-700m and widths average 2m. The contact between the breccias and the host rocks is commonly planar, displaying striations which indicate either dip-slip or strike-slip movement, although some surfaces provide evidence for both senses of movement. In places, the hangingwall contact comprises a zone of quartz stockwork, which may be up to 1m in width, where the intensity of the quartz veining decreases away from the mineralisation. The breccias comprise sub-angular to sub-rounded clasts, up to 1m in diameter, of the wallrocks and earlier quartz-cemented breccias, although the average clast size is 20cm. The quartz cement of the breccias in places is massive and structureless, although more commonly it displays cockade or colloform banding of quartz and chlorite. Ore minerals are confined to the quartz cement of the breccias, occurring either as disseminated polymineralic aggregates or cockade or colloform bands concentric around the breccias clasts. The ore minerals commonly form 1-2% of the breccias, although sulphide-rich breccias, in which virtually the entire cement is composed of ore-minerals, occur at the west end of the mine. The ore-minerals are predominantly base-metal sulphides, mainly pyrite, chalcopyrite, galena and sphalerite, with precious metals occurring primarily as electrum and acanthite. Additional silver-bearing phases include hessite, cervelleite and pearceite-polybasite. Although at least three brecciation and quartz cementation events have occurred, sulphide and precious metal mineralisation was confined to the final event.</p
The magnetic fabric and depositional environments of loess deposits
No full textThe method of defining the bulk sedimentary fabric by equating it with the magnetic fabric (the anisotropy of magnetic susceptibility) has been to yield reliable, well-defined results for moderately to strongly magnetic samples. Highly weathered horizons occurring within fresh sediment can be identified by results which are not sufficiently precise to define an ordered grain fabric.Two end-member styles of magnetic fabric have been observed in the results of measurements on long, continuous sections of terrestrial silt. These styles are sufficiently different to enable the distinction between various modes of formation not immediately apparent from the bulk sedi-mentology.The sedimcntological characteristics of the silts have been used to confirm the primary evidence from the magnetic fabric for the origins of the deposits. It is, therefore, postulated that the first, constrained, style of magnetic fabric represents subaqueous deposition from a moving body of water, whilst the second, more random, style represents deposition from a succession of dust-falls, ie. the fabric of a primary aeolian loess.</p
David Hamilton, 73, of Green Lake, was scammed by Toronto-based con artists into
No full textDavid Hamilton, 73, of Green Lake, was scammed by Toronto-based con artists into paying 110. A reverse scam set up by the Securities Division of the Maine Department of Professional and Financial Regulation helped Hamilton recover his money
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