Brain regions sensory cortex

An inevitable consequence of ageing is an elevation of brain iron in specific brain regions, e.g. in the putamen, motor cortex, pre-frontal cortex, sensory cortex and thalamus, localized within H- and L-ferritin and neuromelanin with no apparent adverse effect. However, ill-placed excessive amounts of iron in specific brain cellular constituents, such as mitochondria or in specific regions brain, e.g. in the substantia nigra and lateral globus pallidus, will lead to neurodegenerative diseases (Friedreich s ataxia and Parkinson s disease (PD), respectively). We discuss here a few of the examples of the involvement of iron in neurodegenerative diseases. From more on iron metabolism see Crichton, 2001. 

Signals from pain receptors are transmitted to the brain where they are processed in the thalamus and then passed on to the sensory cortex where the sensation of pain originates. Receptors for endorphins (and for the opiates) are abundant in these regions and it is likely that a natural role of endorphins is to interfere with the transmission of impulses through these regions. The opiates appear to do the same, acting not so much to alter the pain threshold but altering the patient s attitude to pain. 

Tire neuronal events that occur within the cerebral cortex are extraordinarily complex and little understood 409 In what way the brain is able to initiate voluntary movement of muscles is obscure. However, it is established that the signals that travel out of the brain down the efferent fibers to the muscles arise from large motor neurons of the motor cortex,410 a region that extends in a band across the brain and adjacent to the sensory cortex (Fig. 30-14). The axons of these cells form the pyramidal tract that carries impulses downward to synapses in the spinal cord and from there to the neuromuscular junctions. These are specialized synapses at which acetycholine is released, carrying the signal to the muscle fibers themselves. Passing over the cell surface and into the... 

The cell bodies of third-order sensory neurons are located in the thalamus. These neurons transmit the pain signal to the somatosensory cortex. The function of this region of the brain is to localize and perceive the intensity of the painful stimulus. Further transmission of the signal to the association areas of the cerebral cortex is important for the perception and meaningfulness of the painful stimulus. 

Another brain imaging technique is magne-toencephalography (MEG).C n It has been uniquely valuable in mapping the sensory regions of the human cerebral cortex. Looking ahead, optical methods, which include use of infrared radiation, are also under development.0 They may not be adequate for study of the human brain but can be used for smaller animals, for studies of embryonic development, etc. 

---