Paroxysms and Synaptic Plasticity Flashcards
during learning, memories are stored as _____ within synaptic circuitry for later use
during learning, memories are stored as engrams within synaptic circuitry for later use
describe 3 types of amnesias
- Failure to produce engrams
- Deficit in encoding
- Losses of engrams
- Forgetting
- Failure in accessing engrams
- Deficit in retrieval
describe plasticity at hippocampal synapses
- with high-frequency stimulation, long-term potentiation (LTP) of synaptic responses commonly occurs
- low-frequency electrical stimulation causes long-term depression (LTD) of synaptic responses
describe calcium-dependence in synaptic plasticity
- high-frequency stimulation results in LTP
- large Ca influx leads to phosphorylation of GluR1 subunit of AMPA receptor that promotes delivery of AMPA receptors to membrane -> receptors inserted
- low frequency stimulation results in LTD
- small Ca influx
- receptors removed
- small Ca influx
describe the difference between phosphorylation vs dephosphorylatio in the hippocampus vs the cerebellum
describe seizures
- seizures reflect pathological paroxysyms with hypersynchronization of populations of neurons
- in rare instances (status epilepticus), the seizures may either last longer than 5 min. or may recur within 5 min. without the sufferer fully recovering during the interictal period
describe convulsions
motor manifestations of the seizures
describe epilepsy
chronically heightened susceptibility to seizures
describe epileptogenesus
transformation of a non‐epileptic brain into an epileptic brain
describe absence seizures
often brief, frequent and behaviorally unremarkable (immobility, staring, subtle facial twitching)
- commonly revealed by poor performance in school
- associated with spike and wave discharge triggered through thalamic circuitry
contrast clonic and tonic seizures
- clonic = repetitive flexion and extension of limbs or trunk
- tonic = sustained muscular contractions
describe focal (partial) seizures
arise from a localized pathological population of cells
- awareness may be preserved
- simple partial
- awareness may be disturbed
- complex partial often with aura
describe generalized vs focal seizures
describe different types of simple partial seizures
- discharge spatially restricted and unilateralized
- simple partial seizures
- parietal foci may trigger somatosensory experience
- frontal foci may trigger focal motor ouput that may progress according to the homunculus of Brodmann’s area 4 (Jacksonian march)
- autonomic output can accompany focal discharge from a variety of sites (unilateral sweating)
- simple partial seizures
describe different types of complex seizures
- complex partial seizures
- may arise from simple partial seizures
- foci (often limbic) generate aura or other indications of disturbed consciousness
- strong emotions are commonly experienced (fear)
- certain behaviors are often expressed in attemps to suppress aura or seizures
- patients variably responsive
- facial twitching often seen
which epileptic potentials are associated with:
- infantile spasms
- absence seizures
describe sodium channel blockers in treating epilespy
Na blocking agents tend to stabilize membranes through prolonged inactivation of voltage-gated sodium channels, which limits repetitive firing of APs
describe enhancement of GABAergic transmission drugs in treating epilepsy
- inhibition of GABA transaminase reduces metabolism of the transmitter
- blockage of GABA uptake increases synaptic longevity
- allosteric binding of benzos or barbiturates to the GABAA receptor complex enhances GABA-dependent conductance of Cl-
describe calcium channel blockers in treatment of epilepsy
reduced influx of Ca limits the capacity of pace-making thalamic cells to synchronize widespread cellular populations
