Prelude. Cycle 1. Introduction. Cycle 2. Structure defines function. Cycle 3. Diversity of cortical functions is provided by inhibition. Cycle 4. Windows on the brain. Cycle 5. A system of rhythms: from simple to complex dynamics. Cycle 6. Synchronization by oscillation. Cycle 7. The brain's default state: self-organized oscillations in rest and sleep. Cycle 8. Perturbation of the default patterns by experience. Cycle 9. The gamma buzz: gluing by oscillations in the waking brain. Cycle 10. Perceptions and actions are brain state-dependent. Cycle 11. Oscillations in the "other cortex:" navigation in real and memory space. Cycle 12. Coupling of systems by oscillations. Cycle 13. The tough problem. References.

Rhythms of the brain

https://www.cell.com/cell/pdf/S0092-8674(00)80783-7.pdf

Subventricular Zone Astrocytes Are Neural Stem Cells in the Adult Mammalian Brain

The epithelia of a number of glands and cavitary organs of the rat and guinea pig have been surveyed, and in all cases investigated, a characteristic tripartite junctional complex has been found between adjacent cells. Although the complex differs in precise arrangement from one organ to another, it has been regularly encountered in the mucosal epithelia of the stomach, intestine, gall bladder, uterus, and oviduct; in the glandular epithelia of the liver, pancreas, parotid, stomach, and thyroid; in the epithelia of pancreatic, hepatic, and salivary ducts; and finally, between the epithelial cells of the nephron (proximal and distal convolution, collecting ducts). The elements of the complex, identified as zonula occludens (tight junction), zonula adhaerens (intermediary junction), and macula adhaerens (desmosome), occupy a juxtaluminal position and succeed each other in the order given in an apical-basal direction. The zonula occludens (tight junction) is characterized by fusion of the adjacent cell membranes resulting in obliteration of the intercellular space over variable distances. Within the obliterated zone, the dense outer leaflets of the adjoining cell membranes converge to form a single intermediate line. A diffuse band of dense cytoplasmic material is often associated with this junction, but its development varies from one epithelium to another. The zonula adhaerens (intermediate junction) is characterized by the presence of an intercellular space ( approximately 200 A) occupied by homogeneous, apparently amorphous material of low density; by strict parallelism of the adjoining cell membranes over distances of 0.2 to 0.5 micro; and by conspicuous bands of dense material located in the subjacent cytoplasmic matrix. The desmosome or macula adhaerens is also characterized by the presence of an intercellular space ( approximately 240 A) which, in this case, contains a central disc of dense material; by discrete cytoplasmic plaques disposed parallel to the inner leaflet of each cell membrane; and by the presence of bundles of cytoplasmic fibrils converging on the plaques. The zonula occludens appears to form a continuous belt-like attachment, whereas the desmosome is a discontinuous, button-like structure. The zomula adhaerens is continuous in most epithelia but discontinuous in some. Observations made during experimental hemoglobinuria in rats showed that the hemoglobin, which undergoes enough concentration in the nephron lumina to act as an electron-opaque mass tracer, does not penetrate the intercellular spaces beyond the zonula occludens. Similar observations were made in pancreatic acini and ducts where discharged zymogen served as a mass tracer. Hence the tight junction is impervious to concentrated protein solutions and appears to function as a diffusion barrier or "seal." The desmosome and probably also the zonula adhaerens may represent intercellular attachment devices.

/pdf/junctional-complexes-in-various-epithelia-9u1kkdzfat.pdf

Junctional complexes in various epithelia

Delayed neuronal death in the gerbil hippocampus following ischemia

http://www.back-in-business-physiotherapy.com/images/files/DescendingControl.pdf

Descending control of pain.

High voltage electron microscopy was applied to sections of cerebellar cortex prepared by the Golgi method and embedded in epoxy resin. The silver chromate deposit in the cells consists of a fine, fibrillar meshwork upon which dense globules of various sizes may be superimposed. At the light microscope level finer images are obtained from specimens in which the fibrillar meshwork is incrusted with the fewest globules or are without incrustation. The varicosities in nerve fibres display light circular patches which represent the sites of synaptic junctions. The velamentous processes of neuroglial cells are also well demonstrated in these preparations.

High voltage electron microscopy of the central nervous system in Golgi preparations

Morphological plasticity in the sympathetic chain

In 1874 GOLGI described two kinds of distinctive large nerve cells in the granular layer of the human cerebellar cortex. Although their cell bodies had been noted by others (e.g., by DENISSENKO, 1877), their processes had never been seen before, and their discovery was one of the many first fruits of his impregnation method that he was able to harvest long before other histologists became interested in it. The first kind of nerve cell had a long, fusiform perikaryon that lay directly beneath the layer of Purkinje cell bodies and extended transversely across the folium. The major dendrites issued from opposite poles of the perikaryon, and, continuing the longitudinal axis of the cell body, they ran for long distances before bifurcating and turning upward into the molecular layer or downward into the granular layer. GOLGI was unable to observe their terminations. The second kind of cell that he described was irregularly rounded or polygonal, almost as large as the Purkinje cell, and furnished with numerous dendrites that, in contrast to those of the fusiform cells, tended predominantly to run into the molecular layer.

The Golgi Cells

gamma-Aminobutyric acid (GABA) receptors were visualized in mouse spinal cord explant cultures by [3H]muscimol autoradiography over certain small neurons of the dorsal horn grey matter, in the interneuronal neuropil of dorsal and ventral horns, and (rarely) in small clusters on processes of anterior horn cells. Specificity was indicated in control experiments by inhibition of binding by [3H]muscimol after pretreatment with GABA or a GABA analogue, 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP, isoxazole 16), or with receptor antagonists bicuculline and picrotoxin. Unlabeled muscimol exchanged effectively with [3H]muscimol and produced autoradiographic label in locations indistinguishable from those found in experiments with [3H]muscimol alone. Pretreatment with the GABA uptake and transport inhibitors (-)-nipecotic acid and guvacine did not affect binding with [3H]muscimol. These experiments indicate that explant culture systems can be used for demonstration of functional receptors.

https://www.pnas.org/content/pnas/75/12/6281.full.pdf

gamma-Aminobutyric acid receptors visualized in spinal cord cultures by [3H]muscimol autoradiography.

RAMON y CAJAL (1888b) discovered the climbing fiber during his study of the cerebellar cortex of birds. In view of the difficulties electron microscopists had in identifying this nerve fiber nearly a century later, his first account is interesting.

Sanford L. Palay

Papers

High voltage electron microscopy of the central nervous system in Golgi preparations

Morphological plasticity in the sympathetic chain

The Golgi Cells

gamma-Aminobutyric acid receptors visualized in spinal cord cultures by [3H]muscimol autoradiography.

The Climbing Fiber