Nerve circuits are usually analyzed in terms of the axon, the long fiber of the nerve cell. It now appears that there are many circuits involving only the nerve cell's shorter extensions, the dendrites. (Author/BB)

What shade of gray a surface appears is related to the perceived distribution of light and shadow, which in turn depends on the perceived spatial relation between the surface and its neighbors. (Author/ BB)

Explains the mechanisms and describes the processes that underlie gravitropism in roots. Reviews experimental efforts and investigative results that explored the causes of root behavior. (ML)

Describes the nature and action of hematopoietic proteins which regulate the production of specific sets of blood cells. Discusses the production of these hematopoietins by recombinant-DNA methods in an effort to enable physicians to treat patients by eliciting production of specific types of blood cells. (CW)

Examines research related to the retina's coding of visual input with emphasis on the organization of two kinds of ganglion cell receptive fields. Reviews current techniques for examining the shapes and arrangement in the retina of entire populations of nerve cells. (ML)

Only a few substances serve as signals within cells; this indicates that internal signal pathways are remarkably universal. The variety of physiological and biochemical processes regulated by known messengers is discussed along with chemical structures, pathways, inositol-lipid cycles, and cell growth regulation. (DH)

Historically described are research studies which led to the current explanation of the two kinds of intracellular transport-axoplasmic flow and axoral transport. Models explaining their fundamental mechanism and the kinds of materials they convey are presented. (BT)

Discusses the irregularity and unpredictability of the human body. Presented are pictures showing the fractallike structures and research findings on the mechanism for chaos in the human body. Lists four further reading materials. (YP)

Discusses the use of radioactive isotopes to graphically represent changes in the amount of blood flowing in areas of the human cerebral cortex, reflecting changes in the activity of those areas. Numerous illustrations are included. (Author/MA)

Chemical messengers mediate long-range hormonal communication and short-range neural communication between cells. Background information on peptides, steroids, neuropeptides, and specialized enzymes is given. Investigations reveal that the two systems have many common intercellular messenger molecules. (DH)

Describes the decline in people's ability to focus their eyes as their age increases. Discusses probable causes of this effect including changes in the eye's geometry and biochemistry. Diagrammatically illustrates age related changes in the lens of the human eye. (CW)

Investigates memory storage and molecular nature of associative-memory formation by analyzing Pavlovian conditioning in marine snails and rabbits. Presented is the design of a computer-based memory system (neural networks) using the rules acquired in the investigation. Reports that the artificial network recognized patterns well. (YP)