Types of cortical neuroplasticity
This article needs additional citations for verification. In earlier centuries, scientists believed that animals were like mechanical devices that transformed the energy of sensory stimuli into motor responses. Nerve cell bodies look more or less like other body cells, although they do have certain characteristic features. Somatic efferent neurons are motor neurons that conduct impulses from the spinal cord to skeletal muscles. The cell body of a neuron frequently gives rise to multiple dendrites, but never to more than one axon, although the axon may branch hundreds of times before it terminates. Free nerve ending Nociceptors.
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Hamilton 5 Peter L. It is continuous with the spinal cord at the foramen magnum. All the ascending sensory and descending motor nerve fibers connecting the brain and spinal cord pass through the medulla Source: Cerebrum - 1 - largest portion of the human brain 2 - consists of 2 hemispheres divided by a fissure Source: According to 'instructions' from the premotor cortex P , an area in the motor cortex controller, or CT sends impulses to the controlled object CO; a body part.
The visual cortex VC mediates feedback from the body part to the motor cortex. The dashed arrow indicates that the body part is copied as an 'internal model' in the cerebellum. In the forward-model control system, control of the body part CO by the motor cortex CT can be precisely performed by referring to the internal feedback. In the inverse-model control system, feedback control by the motor cortex CT is replaced by the inverse model itself Ito Cortex matures faster in youth with superior IQs -- Children and teens with superior IQ's are distinguished by how fast the thinking part of their brains thickens and thins as they grow up.
It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations. Although most previous MRI studies of brain development compared data from different children at different ages, Shaw et al. Most were scanned two or more times at two-year intervals.
The resulting scans were divided into three equal groups and analyzed based on IQ test scores: The smartest 7-year-olds tended to start out with a relatively thinner cortex that thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially thicker cortex peaked by age 8, with gradual thinning thereafter. Those in the high range showed an intermediate trajectory see below.
Although the cortex was thinning in all groups by the teen years, the superior group showed the highest rates of change. Like the brain, the spinal cord consists of gray matter and white matter. The spinal cord is also responsible for spinal reflexes. Reflex - rapid and unconscious response to changes in the internal or external environment needed to maintain homeostasis Reflex arc - the neural pathway over which impulses travel during a reflex.
The components of a reflex arc include: The dorsal root is sensory all neurons conduct impulses into the spinal cord while the ventral root is motor all neurons conduct impulses out of the spinal cord. The dorsal root has a ganglion that contains the cell bodies of the sensory neurons that pass through the dorsal root. Other neurons are 'visceral', and these conduct impulses to or from 'visceral' structures smooth muscle, cardiac muscle, and glands.
Somatic efferent neurons are motor neurons that conduct impulses from the spinal cord to skeletal muscles. These neurons are multipolar neurons, with cell bodies located in the gray matter of the spinal cord. Somatic efferent neurons leave the spinal cord through the ventral root of spinal nerves.
These neurons are collectively referred to as enteroceptors or visceroceptors. These neurons make up the Autonomic Nervous System. Some visceral efferent neurons begin in the brain; others in the spinal cord.