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TESE (Background information (Bliss & Collingridge, 1993 (The role of…

- - - - In summary, the available evidence suggests that under normal conditions Ca2+ permeates NMDA channels to provide a transient signal which is necessary for the induction of L TP. It is probable that this signal is restricted to the vicinity of activated spines and is amplified by release from intracellular stores.
    - - Signal transduction mechanisms.
        
        Several different Ca2+ -sensitive enzymes have been proposed to play a part in converting the probable induction signal (entry of Ca2+ through the NMDA channel) into persistent modifications of synaptic strength. These include the protease calpain 76, phosphatases such as calcineurin77, phospholipases and protein kinases.
        
        Most interest has focused on phosphorylation cascades and, in particular, the role of protein kinases. The first kinase to be implicated in LTP was the Ca2+ / phospholipid-dependent protein kinase (PKC) 78-80.
        
        It seems that activation of PKC is not sufficient to induce LTP but is a necessary factor and may be specifically involved in the conversion of STP to LTPl (that is in the consolidation or stabilization of LTP).
        
        Several inhibitor studies have also indicated a role for calmodulin and the Ca2+ / calmodulin-dependent protein kinase CaMKII in LTP 84·88·94-96. Knockout of the gene encoding aCaMKII, an isoform which is heavily enriched in postsynaptic densities, severely impairs, though it does not always completely block, the ability of slices to exhibit LTP 97
  - - - The major neurotransmitters fall into one of three chemical categories: (1) amino acids , (2) amines , and (3) peptides.
      - Neurotransmitter release is triggered by the arrival of an action potential in the axon terminal. The depolarization of the terminal membrane causes voltage-gated calcium channels in the active zones to open.
        
        The resulting elevation in [Ca 2] i is the signal that causes neurotransmitter to be released from synaptic vesicles by a process called exocytosis.
  - - - Delta rhythms are slow, less than 4 Hz, are often large in amplitude, and are a hallmark of deep sleep.
      - Theta rhythms are 4–7 Hz and can occur during both sleeping and waking states.
      - Alpha rhythms are about 8–13 Hz, are largest over the occipital cortex, and are associated with quiet, waking states
      - Beta rhythms are about 15–30 Hz.
      - Gamma rhythms are relatively fast, ranging from about 30–90 Hz, and signal an activated or attentive cortex.
      - Spindles , brief 8–14 Hz.
      - Ripples , brief bouts of 80–200 Hz oscillations.