A form of chromosomal mutation, it is the process by which all or part of one chromosome becomes attached to another chromosome, and which can result in serious congenital disorders. Translocations can be balanced (no loss or gain of chromosomal material) or unbalanced (overall or partial loss of chromosomal material) . See Chromosome, Down‚was syndrome
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Transition
A quantitative or qualitative change in the state of a well-defined system that results in a marked alteration in the system‚was properties. The time taken to change should be markedly shorter that that spent in prior and subsequent states. See Bifurcation, Developmental acceleration, Microgenetic method, Phase transition (or shift), Quantitative and qualitative change, Ontogenetic development, …
Transient dystonia
A dysfunctional regulation of posture, where neck and trunk are over- or hyperextended (i.e., curved too much backward) . See Dystonia, Hypotonia, Overextension, Posture, Preterm infants
Transgene
A genetically engineered gene (i.e., a DNA sequence or combination of sequences) introduced into one or more cells of an organism so that it will exhibit a new property, the new property arising from the protein coded for by the transgene. If it is to be passed onto descendants, it must be incorporated into the …
Transforming growth factor (TGF)
A member of a family of polypeptide growth factors, which together with their receptors are involved in the induction of neural tissue from ectoderm . See Ectoderm, Germinal (or germ) layers, Induction (embryology)
Transformational grammar approach
A linguistic theory developed by Noam Chomsky in opposition to a behaviorist account of language based on the work of his teacher Zellig Harris (1909-1992), and initially formulated in his book Syntactic structures (1957). In essence, it provides a methodology for describing the relationships between sentences expressing similar concepts to underlying ‘deep structures’ by means …
Transcranial magnetic stimulation (TMS)
A non-invasive method that uses an externally applied coil to generate magnetic field impulses that stimulate neurones in a focused region of the underlying brain. TMS can elicit a clear physiological response (e.g., a muscle twitch on stimulation of the primary motor cortex), and can create a temporary ‘virtual lesion’ that interferes with ongoing brain …
Trajectory
motion path (e.g., in reaching for an object).
Trait
In biology, a particular character of a phenotype as opposed to a character mode. For example, in fruit flies, eye colour is a character mode, while a red eye colour is a trait. Traits can be auMethotosomal or sex-linked, and determined by a single locus or by polygenes. In psychology, the term is a theoretical …
Trace conditioning
A classical conditioning procedure in which the conditional stimulus occurs and terminates before the onset of the unconditional stimulus . See Classical conditioning