This is an extract of our Brain Evolution And Development document, which we sell as part of our Behavioural Neurobiology Notes collection written by the top tier of University Of Manchester students.
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Brain Evolution and Development Aim to understand body evolutionary development by observation, and the idea of modification of repeated structures. Invertebrate and vertebrate nervous systems Vertebrates have multipolar neurons and a dorsal nerve cord compared with invertebrates, which have unipolar neurons and a ventral nerve cord (except for cnidaria, which have a two-layered nerve net and bipolar and multipolar neurons. The ventral nerve cord in the annelid worm is not uniformly shaped - it has repeated swellings in each segment. So not only are structures such as food organs repeated, but so is the nervous system. NB. The term 'ganglia' only really refers to invertebrates Vertebrate nervous systems The prototype of the vertebrate nervous system is the lancelet (amphioxus), which is a small fish-like creature, a primordial chordate, that contains the four key features of a vertebrate -
1. Pharangeal slits
2. Dorsal nerve cord
4. post-anal tail Although the larval form is mobile, the adult is a sedentary filter feeder, which burrows in its substrate. Main regions of the mammalian CNS Major divisions of the Forebrain (prosencephalon) o telencephalon (contains cerebrum and basal ganglia) o diencephalons (contains thalamus and hypothalamus) Brainstem o Midbrain (mesencephalon) is comprised of two colliculi o Hindbrain (rhomboencephalon) contains the pons, the cerebellum and the medulla Spinal cord There are also fluid-filled areas called ventricles. Full of cerebral spinal fluid, and metabolic products. There are two ventral ventricles, then two further ones in the back and middle. Damage to the ventricles can be severe if the flow of fluid is stopped. They contain cells lined with cilia to rapidly move fluid. Hydrocephalus for example can be caused by ventricle damage. Damage to the brain stem = death. The lower down the CNS is damaged, the more chance of lethal consequences.
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