A phase of NREM sleep, often considered along with stage 4 sleep as ‘slow wave sleep’, with about two brain wave cycles per second or slower. See Behavioral state, Behavioral state concept, EEG stage 2 sleep, EEG stage 4 sleep, Electroencephalogram (EEG), Locus coeruleus (or ceruleus), NREM sleep, Sleep architecture
Author Archives: Brian Hopkins
EEG stage 4 sleep
A phase of NREM sleep in humans that has a higher voltage associated with the wave than stage 3 and is the most resistant to arousals; a person requires the most amount of stimuli (noise) to awaken from this stage of sleep. See Behavioral state, Behavioral state concept, Electroencephalogram (EEG), REM sleep, Sleep architecture
EEG stage 2 sleep
Considered to be NREM light sleep, follows stage 1 in both children and adults with brain wave forms occurring about 12-14 cycles per second of low voltage but mixed frequencies, and marked by K-complexes and sleep spindles; arousal threshold is a bit higher than what is needed to awaken a person from stage 1 sleep. …
Edward’s syndrome
Sometimes referred to as trisomy 18 as it arises as a consequence of an extra copy of chromosome 18 (see figure below). It occurs in about 1 in every 3000 to 5000 births, affecting girls more than boys. As with Down’s syndrome (after which it is the second most common trisomy), the risk of conceiving …
EEG stage 1 sleep
Considered to be NREM, (or quiet sleep), a transitional stage from wake to sleep wherein a person is close to being awake, but whose eyes exhibit slow, rolling movements, while the recorded brain waves are about 8 to 13 cycles per second. See Behavioral state, Behavioral state concept, EEG stage 2 sleep, EEG stage …
Ectoderm
The outermost primary germ layer that originates during gastrulation (see figure below), which gives rise to the nervous system and outer integument (i.e., outer protective covering such as skin and cuticle). Ectoderm, along with mesoderm and entoderm, is one of three main layers formed in the gastrula during the stages of gastrulation (A-D). There are …
Education
A term with many definitions. As a general definition, take, for example, that provided by John Dewey (1859-1952) in his book Democracy and education (1966), which refers to it as that reconstruction or reorganization of experience adding to the meaning of experience, and which increases the ability to direct the course of subsequent experience. A …
Ecosystem
The association of plants and animals together with the physical features of the habitat. There are about ten general types of ecosystems in the world and these are known as biomes. See Ecology, Environment, Evolutionary niche theory, Habitat (ecology), Niche (ecology)
Ecological validity
How well a study generalises to or represents everyday, real life. Studies with high ecological validity can be generalized beyond the setting in which they were carried out. See External validity, Generalization, Internal validity
Ecology
A term invented by Ernst H. Haeckel (1834-1919) in 1866 and which now denotes the interdisciplinary study of the relationships among organisms and their environments, including both living and non-living components. It addresses three levels of organisation: the individual, the population and community levels. See Community, Ecological psychology, Ecological systems theory, Ecosystem, Environment, Habitat (ecology), Levels …