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In addition to examining how genetic mutations affect the actual structure of the brain, researchers in neurogenetics also examine how these mutations affect cognition and behavior. One method of examining this involves purposely engineering model organisms with mutations of certain genes of interest.
Miller and Sweatt demonstrated that rats trained in a contextual fear conditioning paradigm had elevated levels of mRNA for DNMT3a and DNMT3b in the hippocampus. [4] Fear conditioning is an associative memory task where a context, like a room, is paired with an aversive stimulus, like a foot shock; animals who have learned the association show higher levels of freezing behavior when exposed to ...
Alzheimer's disease (AD) is a chronic neurodegenerative disease that results in the loss of neurons and synapses in the cerebral cortex and certain subcortical structures, resulting in gross atrophy of the temporal lobe, parietal lobe, and parts of the frontal cortex and cingulate gyrus. [14] It is the most common neurodegenerative disease. [1]
Differentiated somatic cells of adult mammals generally replicate infrequently or not at all. Such cells, including, for example, brain neurons and muscle myocytes, have little or no cell turnover. Non-replicating cells do not generally generate mutations due to DNA damage-induced errors of replication.
Hering and Semon developed general theories of memory, the latter inventing the idea of the engram and concomitant processes of engraphy and ecphory. Semon divided memory into genetic memory and central nervous memory. [7] This 19th-century view is not wholly dead, albeit that it stands in stark contrast to the ideas of neo-Darwinism. In modern ...
The hippocampus is a structure in the brain that has been associated with various memory functions. It is part of the limbic system, and lies next to the medial temporal lobe. It is made up of two structures, the Ammon's Horn, and the Dentate gyrus, each containing different types of cells. [1]
[50] [51] [52] Mice defective in a gene (Pms2) that ordinarily corrects base mispairs in DNA have about a 100-fold elevated mutation frequency in all tissues, but do not appear to age more rapidly. [53] On the other hand, mice defective in one particular DNA repair pathway show clear premature aging, but do not have elevated mutation. [54]
Small-scale mutations affect a gene in one or a few nucleotides. (If only a single nucleotide is affected, they are called point mutations.) Small-scale mutations include: Insertions add one or more extra nucleotides into the DNA. They are usually caused by transposable elements, or errors during replication of repeating elements.