Refer to the rostral cerebral region (see figure below) superior to the Sylvian fissure and anterior to the Rolandic fissure, and encompass approximately 24-33 percent of the adult human brain. They have a protracted period of development, and it is only between the ages of 6 and 10 years that they show adult-like structure and …
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Frontal eye fields (FEF)
Anatomically, it is Brodmann’s area 8, together with parts of areas 6 and 9, situated in the prefrontal cortex, just rostral to the premotor cortex, in the prefrontal and frontal gyrii that projects to the caudate nucleus in the basal ganglia. Together with the superior colliculus (both of which discharge immediately prior to saccades), it …
Friendship
A positive social relationship between unrelated individuals who are well known to one another. This broad definition does not capture the developmental history of friendships. For pre-schoolers and elementary school children, friendships are based on having playmates within the context of group acceptance while friendships during adolescence are intimate and intense and susceptible to peer …
Frontal cortex
The front third of the cortex, which has the motor cortex as its posterior boundary. Involved in aspects of motor planning, working memory, organization of behavior with respect to future goals (i.e., executive functions). See Attention deficit hyperactivity disorder (ADHD), Brain damage studies, Cerebellum and basal ganglia, Cerebral cortex (development), Cortical lobes, Dorsolateral prefrontal cortex …
Fricative
Also called a spirant, it is a speech sound (i.e., consonant) characterized by a long interval of turbulence noise (called ‘frication’) due to forcing air through a constricted passage, and which sounds like hissing. Achieved by narrowing the passage of the mouth by placing two articulators close together so as to make the airflow turbulent, …
Frames, then content (FC) hypothesis
This hypothesispredicts that within and across syllable patterns are based on rhythmicmandibular oscillations without independent tongue movements in infants fromthe onset of babbling (e.g. /bÉ™/, /di/, /gu/ ). The term ‘frame’ concerns how regular the oscillation of the mandibular is that results in rhythmical syllable-like structure whereas ‘contents’ applies to the period in development when …
Frequency
The rate of oscillation in a sound (or other) wave in a specified time period. More technically, it is the number of times that a wave repeats itself in one second, which is expressed in hertz (Hz) or cycles per second (e.g., middle C has a frequency of 256 Hz, and alpha waves as measured …
Fragile X syndrome
One of the most common inherited causes of mental retardation (second after Down’s syndrome) and autism as well as being associated with attention deficit hyperactivity disorder, and that has an incidence of about 1 in 2000-4000 for males and 1 in 5000-8000 for females. The syndrome was first discovered in 1943 through the combined efforts …
Fovea
A small depression or pit in the center of macula lutae of the retina, and thus referred to as the fovea centralize or central fovea. The macula (also called the macula retinae or the spot of Soemmering) is a minute oval-shaped yellowish area (and thus sometimes referred to as the yellow spot) about 2.5 mm …
Fractals
Geometrical objects typified by some form of self-similarity. In other words, when magnified to an appropriate scale, parts of a fractal appear similar to the whole. Examples of approximate fractals are coastlines of islands, continents and terrain features. In non-linear dynamical systems that exhibit deterministic chaos, the so-called strange attractors are typically fractals. See Attractor, …