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[1] [2] In Ancient Greece, interest in the brain began with the work of Alcmaeon, who appeared to have dissected the eye and related the brain to vision. He also suggested that the brain, not the heart, was the organ that ruled the body (what Stoics would call the hegemonikon) and that the senses were
Many neurons migrating along the anterior-posterior axis of the body use existing axon tracts to migrate along in a process called axophilic migration. [18] An example of this mode of migration is in GnRH-expressing neurons , which make a long journey from their birthplace in the nose, through the forebrain, and into the hypothalamus. [ 19 ]
Area of the human body surface innervated by each spinal nerve Even mammals , including humans, show the segmented bilaterian body plan at the level of the nervous system. The spinal cord contains a series of segmental ganglia , each giving rise to motor and sensory nerves that innervate a portion of the body surface and underlying musculature.
The 3 ′ (3 prime end) genes in the Hox cluster are induced by retinoic acid in the hindbrain, whereas the 5 ′ (5 prime end) Hox genes are not induced by retinoic acid and are expressed more posteriorly in the spinal cord. Hoxb-1 is expressed in rhombomere 4 and gives rise to the facial nerve.
Brain-to-body size scales allometrically. [1] This means that as body size changes, so do other physiological, anatomical, and biochemical connections between the brain and body. [2] Small-bodied mammals tend to have relatively large brains compared to their bodies, while larger mammals (such as whales) have smaller brain-to-body ratios.
Cortical white matter increases from childhood (~9 years) to adolescence (~14 years), most notably in the frontal and parietal cortices. [8] Cortical grey matter development peaks at ~12 years of age in the frontal and parietal cortices, and 14–16 years in the temporal lobes (with the superior temporal cortex being last to mature), peaking at about roughly the same age in both sexes ...
A millimeter-sized sea animal could hold clues to the evolution of the human nervous system. While placozoans are simple animals only as big as a grain of sand, the blobs have unique cells that ...
Neurons formed in the ventricular zone migrate to their final locations in one of the six layers of the cortex. [1] The process occurs from embryonic day 10 to 17 in mice and between gestational weeks seven to 18 in humans. [2] The cortex is the outermost layer of the brain and consists primarily of gray matter, or neuronal cell bodies.