A diamond-shaped, membrane-covered ‘soft-spot’ situated at the front of the top of an infant’s head that corresponds to the junction of the frontal, saggital and coronal sutures. These fibrous sutures allow movements of the skull plates during delivery through the birth canal, and for brain growth during the first year. Typically, this fontanelle closes (or …
Category Archives: Uncategorized
Anterior cingulate gyrus
A structure in the prefrontal cortex (see figure below) and limbic system that is closely associated with executive attention and executive function. It is activated during conditions of irritation or anger, with extraverted people showing a higher level of activation in the anterior cingulate cortex. In contrast, introverts have less activation in this cortex, but …
Anterior commissure
A small, round bundle of nerve fibers connected to the corpus callosum that crosses the midline of the brain near anterior limit of the third ventricle (see figure below). One of three groups of commissural fibers, it connects, like the corpus callosum, the right and left cerebral hemispheres. Its smaller anterior part has fibers that …
Antenatal
The period during pregnancy from conception to the onset of labor. See Embryo, Fetus
Antagonist muscle
A muscle acting in opposition to the action produced by the prime mover or agonist, and which is responsible for returning a limb to its initial position. The biceps and the triceps muscles are, for example, antagonist muscles. Thus, when bending the elbow, an action of the biceps, the triceps is the antagonist. In healthy …
Antecedent-consequent relationships
In its weakest form, it is assumed that a precursor or antecedent is simply a forerunner to some later-occurring event in development, without the implication that there is a functional connection between them. In the stronger form, a precursor is a necessary condition for that later event, which would not occur without it. In human …
Anoxia
Total lack of oxygen in inspired gases or in arterial blood, which may cause irreversible damage to nerve cells in the brain. Anoxic anoxia results from defective oxygenation of the blood, in particular the cerebral cortex, and ischemic (reduced blood) anoxia from slow peripheral circulation as can follow a congestive cardiac failure. Hypoxic-ischemic insult follows …
Animistic thinking
Allegedly typical of ‘primitive’ thinking, it refers to the belief that inanimate objects like rocks possess a soul; the term is often used to refer to magical thinking more generally. Such thinking is a characteristic of children during the Piagetian pre-operational stage of development. See Appearance-reality distinction, Biological knowledge, Theory of the child’s mind (ToM)
Anlage
An embryonic primordium (clustering of cells) or developmental precursor from which a specific part or organ of the embryo develops. See Embryo, Embryogenesis
Anhedonia
A loss of interest in and withdrawal from all regular and pleasurable activities, often associated with depression. In short, it is an inability to experience pleasure. According to Freud, using his tripartite distinction between the id, ego and superego, deficits in the development of the id could lead to anhedonia. It has been suggested that …