A fetal condition characterised by a specific pattern of growth, mental development and physical birth defects, caused by excessive exposure to alcohol in utero. The distinctive and often severe effects associated with FAS are more commonly expressed in milder or incomplete form, referred to as fetal alcohol effects or fetal alcohol spectrum disorder. First described …
Category Archives: Uncategorized
Fetal breathing movements
First identified in 1888, they are rhythmical, but paradoxical, chest wall and abdominal movements, which are the precursors of postnatal respiration. Appearing for the first time between the gestational ages of 10-16.5 weeks, they do not result in gas exchange with the lungs, and their early onset in prenatal life suggests they serve to promote …
Fetal akinesia deformation sequence (FADS)
A specific pattern of abnormal fatal growth and physical defects that result from a period of reduced motor activity or akinesia during fetal development. The causes are quite disparate and poorly understand as the abnormality is clinically and genetically varied group of features that includes intrauterine growth restriction, short umbilical cord, arthrogryposis (a rare congenital …
Continue reading “Fetal akinesia deformation sequence (FADS)”
Feedforward
An anticipatory process in which trends in the input signal lead to modulations of the output signal that prevent or suppress subsequent errors. An example is the provision of an efferent copy to the extra-ocular muscles during a saccade that suppresses the sensation of movement, which would otherwise be generated by the motion of images …
Fertilization (or syngamy)
The union of male and female gametes during the process of sexual reproduction to form a zygote (see figure below). A sperm at the moment of entering an ovum to fertilize it. See Acrosome, Gametes, Spermatogonia, Spermatoza, Zygote
Feedback
Information about the results of a process that is used to change the process itself. There are two types of feedback. Negative feedback, invented by Harold S. Black (1898-1983) in 1927 to stabilize vacuum tube amplifiers, is a circular or closed-loop causal process in which the system’s output is returned to its input, which is …
Fasciculation
A small, localised, rapid and involuntary muscle contraction or twitch involving contiguous groups of skeletal muscle fibers visible beneath the skin. Many twitches are evident in the face (see face below) as, for example in Tourette’s syndrome. It is triggered by a spontaneous discharge of a bundle of muscle fibers or filaments. Random facial muscle …
Fatty acid
Long-chain monobasic (carboxylic) acids or lipids that occur naturally in the form of glycerides (an ester of glycerol) in fats and fatty oils, and particularly important for the myelination process in early brain development. Some fatty acids are saturated in that each carbon bond is connected to its carbon neighbours by single bonds, while unsaturated …
Fantasy play
Pretend enactment of themes that commonly occurs in early childhood, with a tendency for the themes to be different between boys and girls. Some evidence suggests that for 3-4 year-olds that boys tend to indulge in more (active) fantasy play. Girls will make dolls the object of their play, while boys have a preference for …
False negative
Individuals classified initially as normal who eventually turn out to be abnormal. In contrast, those categorized initially as normal who turn out to be normal on re-examination are true negatives. See Efficacy, False positive, Indices of efficacy