L5 - Synapses and Neural Integration Flashcards Preview

PSYC1020 - Introduction to Psychology - Minds, Brains and Behaviour > L5 - Synapses and Neural Integration > Flashcards

Flashcards in L5 - Synapses and Neural Integration Deck (7):
1

Neuron Signals:

  • Electrical Signals
    • Within-neuron: Action Potential, electrical signal from axon hillock, along axon, to pre-synaptic axon terminal
  • Chemical Signals
    • Between-neurons: Neurotransmitter signal across synapse

2

The Synapse:

3

Neurotransmitters:

Amino Acids

  • Glutamate: Excitatory – used in 90% of synaptic transmissions
  • Gamma-aminobultyric acid: Inhibitory – used in 9% of synaptic transmissions

Monomines and Acetylcholine (the other 1%)

  • Cholinergic System
    • Uses Acetylcholine (Striatum)
    • Important for arousal, vigilance and memory
    • Reduced activity implicated in Alzheimer’s
  • Dopaminergic System
    • Uses Dopamine (Substantia Nigra)
    • Important for motor control
    • Reduced activity linked to Parkinson’s
  • Noradrenergic System
    • Uses Norephinephrine (Locus cerelus of the brainstem)
    • Important for attention and executive control
    • Reduced activity implicated in ADHD
  • Serotonergic System
    • Uses Serotonin (Raphe Nuclei of the brainstem)
    • Important for sleep, aggression and memory
    • Reduced Activity implicated in depression

4

“Lock and key” - neurotransmitter receptors:

  • Each receptor only binds to a specific type of neurotransmitter
  • Neurotransmitters only “activate” their specific type of receptor
  • Important for drug effects
    • Drugs can act on specific receptors to cause specific effects (eg. L-DOPA for Parkinson’s disease replaces dopamine in the brain)

5

Anti-Depressant Drugs - Serotonin

6

Ligand-Gated ion channels:

  • Neurotransmitter receptors open ion channels when neurotransmitter binds
  • Different neurotransmitters bind to and open different ion channels (Na+, K+,Cl-) to change membrane potential in different ways
  • Receptor binding:
    • Can cause depolarisation (less negative) e.g. Na+ flows in
    • Can cause hyperpolarisation (more negative) e.g. K+ flows out or Cl- flows in

7

Excitatory and Inhibitory Post Synaptic Potentials:

  • Excitatory (EPSP) and inhibitory (IPSP) post synaptic potentials feed into the dendrites of a neuron
  • The influence of EPSP and ISPS vary depending on the strength of the synaptic connection between the neurons
  • Graded potential: The resulting potential at the axon hillock determined on the sum and timing of inputs (EPSPs and IPSPs).
    • Depolarisation: Less negative and closer to 0 (and the AP threshold) - Excitatory
    • Hyperpolarisation: More negative and further from 0 - Inhibitory
  • If enough excitatory inputs occur together close enough in time, membrane potential will exceed AP threshold level and the neuron will fire an AP
  • Neural integration: The summation of all sensory or higher inputs to determine motor output