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.

This study utilizes tritiated muscimol binding and electron microscope autoradiography (Ilford L4 emulsion and phenidone development) to localize γ-aminobutyric acid (GABA) receptor sites in the cerebellum of the rat. In the cerebellar cortex, silver grains were associated with somata and dendrites of basket and stellate cells in the molecular layer, with somata and primary and secondary dendritic shafts of Purkinje cells, axons and terminals of basket cells in the pinceau or basket, initial axonal segments and myelinated axons of Purkinje cells, and dendrites of granule and Golgi cells in the granular layer, and with somata and dendritic shafts of large and small cells in the cerebellar nuclei. These data correspond well to the light-microscope-autoradiographic observations in the cerebellum previously reported [Chan-Palay, V. (1978) Proc. Natl. Acad. Sci. 75, 1024-1028]. Label over GABA receptor sites can be localized to the plasma membranes between pre- and postsynaptic elements at synaptic junctions, of which 88.9% of the samples are axodendritic and the remaining 11.1% are axosomatic. GABA receptor sites are also found along axonal membranes of the GABA-containing basket cell within the basket surrounding Purkinje cells, where true axo-axonal synapses are rare. It is speculated that GABA receptors in the basket may suggest a possibility of the basis for synchronization, either self-inhibition or facilitation within the basket formation, or presynaptic suppression of inhibitory action of basket cell on Purkinje cell.

Ultrastructural localization of γ-aminobutyric acid receptors in the mammalian central nervous system by means of [3H]muscimol binding

The rapid Golgi reaction produces initially a red and secondarily a black precipitate in certain neurons, neuroglia, and endothelial cells of nerve tissue. High voltage electron microscopy shows that the red impregnation is a dense, intracellular, fibrillar meshwork of rodlets with a filamentous substructure. The black impregnation is due to the superimposition of very dense globular and polyhedral crystals that stud the surface of the underlying red fibrillar network. When present in quantity, these globules conglomerate to form a crust over the impregnated structure. This can cause distortion in the shape of the structure and considerable overestimation of its size in light microscope studies of black Golgi material.

High voltage electron microscopy of rapid golgi preparations. Neurons and their processes in the cerebellar cortex of monkey and rat.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/cne.900790204

Neurosecretion V. The origin of neurosecretory granules from the nuclei of nerve cells in fishes

Neurosecretion. VIII. The nissl substance in secreting nerve cells

Immunocytochemical evidence is presented for the existence of choline acetyltransferase (ChoAcTase), cysteine sulfinic acid decarboxylase (CSADCase), tyrosine hydroxylase (TyrOHase), and glutamic acid decarboxylase (GluDCase) in large motor neurons of the hypoglossal nucleus and the spinal cord and in nerve terminals of motor end plates in tongue and skeletal muscle of five mammalian species, including man. These enzymes, which are responsible for the synthesis of acetylcholine (AcCho), taurine, dopamine, and gamma-aminobutyrate (GABA), respectively, were detected by immunocytochemical studies with monoclonal or polyclonal antibodies raised against the enzymes. Electron microscopy of the neuromuscular junctions showed that the immunoreactivity in each case was confined to the cytoplasmic matrix of presynaptic nerve terminals. Immunoreactivity obtained for each enzyme antibody varied with the species. It was highest in fresh, unfixed muscle and lowest in aldehyde-fixed specimens. Negative controls were obtained with preimmune sera and antisera preabsorbed with pure ChoAcTase, CSADCase, or GluDCase antigen. Double-labeling studies with ChoAcTase antibodies and acetylcholinesterase (AcChoEase) antibodies, AcChoEase enzyme activity, or alpha-bungarotoxin binding indicated that ChoAcTase, AcChoEase, and AcCho receptors were colocalized at the same end plates.

Sanford L. Palay

Papers

Ultrastructural localization of γ-aminobutyric acid receptors in the mammalian central nervous system by means of [3H]muscimol binding

High voltage electron microscopy of rapid golgi preparations. Neurons and their processes in the cerebellar cortex of monkey and rat.

Neurosecretion V. The origin of neurosecretory granules from the nuclei of nerve cells in fishes

Neurosecretion. VIII. The nissl substance in secreting nerve cells

Synthesizing enzymes for four neuroactive substances in motor neurons and neuromuscular junctions: light and electron microscopic immunocytochemistry