Catecholamine involvement in lateral hypothalamic self-stimulation : with special reference to the dorsal noradrenergetic system

Six experiments were undertaken to determine the involvement of the nigrostriatal dopamine (DA) pathway and the dorsal noradrenergic (NA) pathway in mediating lateral hypothalamic (LH) self-stimulation. All subjects were implanted with bipolar electrodes in the LH area and were trained to self-stimulate. Once this behavior had stabilized (20-30 days), lesions at various levels of the nigrostriatal DA system and the dorsal NA system were made via intracerebral injections of the catecholamine (CA) neurotoxin, 6-hydroxydopamine (6-OHDA) and/or electrolytic lesions. Testing for self-stimulation was resumed 24 hrs. after the lesions and continued for a period of 5 days. At the conclusion of testing, the animals were sacrificed and prepared for histological examination. -- Destruction of several CA systems by injections of 6-OHDA (8μg/4μl) in the cells of origin (A9) of the nigrostriatal DA system resulted in a strong suppression of LH self-stimulation (p<.025). Injections of 6-OHDA (8μg/4μl) anterior to the cells of origin (A6) of the dorsal NA system had little or no effect on LH self-stimulation (Experiment 2). 6-OHDA (4μg/μl) and electrolytic lesions of the dorsal NA bundle in combination with electrolytic lesions of A6 also failed to substantially affect LH self-stimulation (Experiments 3 & 5). The fourth experiment attempted to further examine the role of the dorsal NA system in LH self-stimulation by injections of procaine ( a local anesthetic), d-amphetamine and glutamate (a neural excitant) directly in A6. All three treatments resulted in considerable suppression of LH self-stimulation (p<.001) but these results were rendered questionable due to possible non-specific effects and methodological considerations. The sixth and final experiment revealed that self-stimulation is rapidly obtained from the region of A6 when a sensitive shaping procedure that maximizes behavioral arousal is employed. -- Together; these results suggest that LH self-stimulation is mediated by the nigrostriatal and mesolimbic DA systems alone or in combination with the dorsal NA system but the dorsal NA system itself does not seem necessary for maintenance of LH self-estimulation. Thus, noradrenergic theories of self-stimulation (e.g. Stein & Wise, 1971) must be reconsidered

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4 m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5 m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 yr, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit