Scatter polarization
The term cortical spreading depression ( spreading depression ) or Cortical cortical spreading depression ( cortical spreading depression ) refers to a regularly occurring neurological phenomenon that by a slowly spreading depolarization of the cerebral cortex is characterized (Cortex).
This phenomenon, which u. a. can be registered with the help of functional magnetic resonance imaging (fMRI) or by means of an electrocorticogram (ECoG) is associated with the pathogenesis of migraine and stroke . Spreading depression usually begins spontaneously at one point and progresses at a characteristic rate of 3 to 5 millimeters per minute. In migraines, it strides a few centimeters as a localized wave segment through areas of the furrowed cerebral cortex. In the case of a stroke, the spreading depression starts in the vicinity of the infarct tissue and possibly circles it several times. As a rule, it is limited to one hemisphere . In the affected areas , the cell membranes of the neurons and glial cells depolarize , and the electrically measurable activity practically collapses.
The development and spread of the Spreading Depression is linked to the release of potassium ions into the extracellular space . A malfunction of ion channels for calcium , sodium and potassium as well as a malfunction of ionotropic glutamate receptors can also be involved. Potassium ions cause depolarization that spreads over an area of the cerebral cortex. A slow spread of this depolarization across the visual center is regarded as an electrophysiological correlate of wandering ciliated scotomas , which can often be observed during a migraine aura . A spreading depression was first described in 1944 by the Brazilian Aristides Leão . Despite more than 5 decades of active research in various animal models, the occurrence of spreading depression in the human brain has long been controversial. The first clinical studies with electrocorticographic recordings in the vicinity of brain injuries in neurosurgical patients were able to provide positive evidence.
literature
- Aristides P. Leão (1944). Spreading depression of activity in the cerebral cortex. J. Neurophysiol. 7 : 359-390
- George G. Somjen (2001). Mechanisms of Spreading Depression and Hypoxic Spreading Depression-Like Depolarization. Physiol. Rev. 81 : 1065-1096. PMID 11427692
- Anthony J. Strong, et al. (2002). Spreading and synchronous depressions of cortical activity in acutely injured human brain. Stroke 33 : 2738-43 PMID 12468763
Web links
- Natalie R. Ebert: Cortical spreading ischaemia as a consequence of free hemoglobin and increased potassium concentration in the subarachnoid space induces cortical infarctions in rats. Diss.
- braintsunamis.com - Spreading Depolarization and Spreading Ischemia
Individual evidence
- ↑ Santos E et al. 2014 doi : 10.1016 / j.neuroimage.2014.05.021