The age-old doctrine that the entire adult organism is preformed within the egg or sperm, but only begins to grow to a visible size after fertilization occurs. It origins can be traced back at least to the pangenesis of Hippocrates of Cos (460 ca-377 BP), which held that everything necessary for development (or rather growth) is …
Category Archives: Uncategorized
Prefrontal-frontal-striatal loops
Neural circuits linking frontal areas of the brain with the sub-cortical area called the corpus striatum in the basal ganglia. This frontal-striatal circuitry can be roughly compartmentalised into cognitive, limbic and motor projections. More specifically: the dorsolateral prefrontal circuit (preparation to respond), the anterior cingulate circuit (generation of motivation) and the orbitofrontal circuit (emotional and limbic integration). …
Prediction and explanation
Prediction means to forecast or foretell some future event based either on an educated guess or informed knowledge, the latter being akin to prognosis. According to the deductive-nomological model, explanation and prediction have the same logical structure. In practice, however, these two scientific activities are by no means synonymous. An obvious difference is that what …
Predetermined epigenesis
The almost outmoded idea that the sequential development of structures and functions proceeds from the genetic through the neural to the behavioral and environmental levels in a unidirectional (bottom-up) fashion. See Epigenesis, Genetic determinism, Neuromaturation, Probabilistic epigenesis
Predicates (grammar)
Words that make a statement about their arguments. These typically include verbs, adjectives, and preposition in a sentence. A sentence has two parts: the subject and the predicate. The subject is what the sentence is about, and the predicate is a comment about the subject. See Arguments (grammar), Copula, Language development, Nominal group, Quantifier
Precocial
Precocial refers to the young of species who are relatively mature and mobile at birth or shortly thereafter, in contrast to those who are altricial where the young are born in a relatively helpless state that requires an ongoing investment in parental care (e.g., for nourishment and protection against predation). It is not a clear-cut …
Pre-reaching
Organized but incomplete reaching movements before functional reaching has developed. First identified by Colwyn Trevarthen and subsequently subjected to motion analysis by Claes von Hofsten they consist of arm movements toward an object with an open hand, which bring the hand in the vicinity of the object, but it does not contact it. Only seen in the newborn …
Precision
In statistics, the magnitude of the standard error or the associated confidence limits of a statistical estimate such as a mean or a correlation. When the standard error is small, estimates from different samples will be in close agreement, with the opposite also being the case. A distinction is made between prediction and accuracy. In this instance, …
Pre-eclampsia
Previously referred to as toxaemia, it is an abrupt pregnancy-induced hypertension, usually accompanied by edema of the face, feet and hands and proteineuria (protein in the urine). Occurring in about 3-5% of pregnancies, and thus one of the most prevalent complications of pregnancy, it is more common in the first pregnancy and typically becomes manifest …
Pragmatism
An approach to meaning first proposed by Charles S. Peirce 1839-1914) in 1878. He was concerned with the meaning of concepts, in particular scientific ones that affect the mind and not with those confined to the emotions or the senses. Peirce held that the meaning of such concepts was exhausted by the effects they have on our …