A rounded outfolding or convolution on the surface of gray matter of the cerebral cortex of brain that lies between deep grooves or sulci (fissures). Each gyrus consists of a superficial part and another hidden from view in the floor and wall of a sulcus. See Anterior cingulate gyrus, Cerebral cortex (or pallium), Cingulate gyrus, …
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Gustation
Usually defined in one of two ways, one being the sense of taste and the other the act or process of tasting. In both cases, the tongue is the first port of call for sensing and processing gustatory influences. In general, gustation is the ability to respond to dissolved molecules and ions, in contrast to …
Guthrie test
A universal screening test in which a spot of blood is extracted by means of a heel prick, and which is carried out in the newborn period (usually on day 2) to detect treatable conditions such as phenylketonuria (PKU) or congenital hypothyroidism, conditions which can lead to irreversible brain damage, if not treated early. The …
Guilt
The emotional state of guilt or regret is produced when individuals evaluate their behaviour as failure (or having violated some moral standard), but focus on the specific features of the self or one the self’s action that led to the failure. Unlike shame, in which the focus is on the global self, with guilt the individual …
Guanine
A purine derivative, it is one of the major component bases of DNA, RNA and nucleotides. It pairs with cytosine in the DNA sequence. See Cytosine, DNA (deoxyribonucleic acid), Methylation, Nucleotide, Purines
Guidepost cells
Intermediate targets hypothesized to be located along the path from the periphery to the central nervous system that act as choice points for a developing axon through expressing unique surface molecules that are recognised by the filopodia of the growth cone. The floor plate of the spinal cord appears to be a class of specialised …
Growth models
An approach tostatistical analysis used in longitudinal and intervention research. Growthmodels can be used to: 1. study change in latent factors adjusting formeasurement error, 2. examine individual differences in the rate of changeacross time, and 3. assess the relationship between initial levels of thevariable of interest and subsequent rates of change in that variable. See …
Growth factors
Regulatory chemicals or proteins produced by specific cells or tissues (e.g., cells in the developing nervous system) that stimulate cellular growth, differentiation, or tissue development. Sometimes the term ‘growth factor’ is used interchangeably with ‘cytokine’, with cytokine denoting a neutral term that does not indicate what is being signalled. One example of a growth factor …
Growth hormone (or somatotropin)
A polypeptide or glycoprotein hormone produced by the anterior pituitary gland. It decreases the rate of carbohydrate uptake, enhances the mobilization of lipids from adipose tissue, and stimulates the production of insulin-like growth factors by the liver to enhance growth of muscle and bone, particularly through the engendering the release of somatomedin that influences the …
Growth cone
The actively growing, most distal, expanded part of a neurite or outgrowing axon extended from a neuron, and instrumental in target location. It moves in an ameboid-like fashion, with extensions called filopodia that grow (out) and retract (in) rapidly from the cone due to rapid polymerization and depolymerixation of internal actin filaments, respectively (see figure …