Week 9: Neuroplasticity Flashcards
What is the classical pathway of LTP?
- release of serotonin → synthesis of cAMP
- activation of PKA → if pathway is repeatedly stimulated, amplitude of EPSP is constant
- CREB phosphorylation at Ser133
- Gene Transcription → structural changes
How are effects in postsynaptic neurons triggered?
- action potential
- voltage dependent Ca2+ channels open
- increase in intracellular Ca2* in presentation terminal
- release of neurotransmitters
What kind of postsynaptic currents are triggered?
excitatory effects
- increases probability of postsynaptic spiking
- positive membrane potential deflection → generates excitatory postsynaptic potentionals (EPSPs)
Inhibitory effects
- decreases probability of postsynaptic spiking
- negative membrane potential deflection → produces inhibitory postsynaptic potentials (IPSPs)
What is short-term facilation?
= Synaptic efficacy release for brief periods
- Ca2+ accumulation in presynaptic terminal after AP
- increases amount of released neurotransmitter in subsequent AP if soon enough
What is short term depression?
= temporary decrease in synaptic strength that occurs when neurons are repeatedly activated
Mechanisms:
- depletion of synaptic vesicles → high frequency of AP deplies the vesicles available over time
- decreases Ca2+ → inactivation of Ca2+ channels
- endocannabinoids → retrograde signal that closes calcium channels
What is the role of the eCBs in synaptic plasticity?
- the endogenous cannabinioid system strengthens and weaken neural connections that underlies learning and memory by sending retrograde signals to presynaptic neurons
What happens when THC enters the brain?
- floods of CB1 receptors that normally respond to precise localized signals from eCBs
→ receptor desensitization and internalization
→ disrupts short- and long-term plasticity mechanisms
What is maladaptive plasticity?
Plasticity in NS that leads to a disruption of the function
What are different disorders caused by maladaptive plasticity?
Physical
- phantom limb pain
- tinnitus
- chronic pain
- musicians dystonia
Psychological
- Addiction
- OCD
- chronic stress
What is Musician‘s Dystonia?
- focal dystonia : painless loss of muscular control localised to a specific body part
- occupational dystonia: task-specific focal dystonia
- results from musical training
- involuntary contractions due to co-activation of flexor and extensor muscles
What influences Neuroplasticity in the prenatal period?
- maternal diet
- exposure to toxins
- infections during pregnancy
What influences Neuroplasticity during infancy and childhood?
- nutrition
- social interaction
- environmental factors
What influences Neuroplasticity during Adulthood?
- aging (neurodegeneration)
- life - style: diet, physical exercise, sleep quality, stress
- cognitive stimulation and socialisation
- traumas and health conditions
How does pregnancy influence Neuroplasticity?
- changes in cortical volume of mother:
- decrease during pregnancy, increase post-partum
- scheduled c-section greater cortical increase
- no significant connection with sleep deprivation, stress or ppd
What is brain stimulation and how does it work?
= Applications of controlled electrical or magnetic stimuli which induces electric current to the brain in order to excite or inhibit neural activity
Why do we use brain stimulation?
- excitation / inhibition of targeted regions
- modulation of abnormal firing
- synaptic changes (LTP/ LTD)
- functional reorganisation
Electroconvulsive Therapy
What?
- electric current → seizure
- anaesthesia to avoid pain
When?
- treatment resistent, acute or life threatening stages
Cons
- anesthesia
- anterograde and retrograde amnesia
Transcranial direct current stimulation (tDCS)
What?
- milder stimulation than ECT
- no anesthesia
When?
- milder conditions
- gradual improvement suffices
Cons
- modest improvement
- short-lived effects
Transcranial Magnetic Stimulation (TMS)
What?
- electric coil above scalp → magnetic field → electric current in the brain
When?
- non-invasive
- targeted
Cons
- expensive
-many sessions needed for response
neuroprosthetics
- field that combines neuroscience and engineering
- develop devices that interface with nervous system
- to restore lost functions or enhance brain activity
- deep brain stimulation and vagal nerve stimulation
Optogenetics
- technique that involves use of light to activate or inhibit genetically engineered cells that have been made sensititive to light
- gene encoding a light-sensitive protein is introduced to specific neuron
- neurons can be activated or inhibited by shining light
- precise manipulation of neuronal activity by light control
- can promote Neuroplasticity
Novel pharmacology
- serotonergic psychedelics
- ketamine
