Neuro Ch 3

  1. Parts of a neuron
    • dendrites: collect info 
    • soma: integrate incoming signal (cell body)
    • axon: conducts signals 
    • axon terminal: output of signals
    • * myelin sheath: increase conduction speed of action potential
  2. synapses
    • point of communication and communication between cells
    • presynaptic, synaptic, postsynaptic
  3. neuron via function
    • sensory: incoming/arriving signals, afferent. 
    • motor: outgoing/exiting signals, efferent 
    • interneuron: lie between sensation and action, but not motor or sensory

    • - projection interneuron - long to other regions
    • - local interneuron - stay within a brain region
  4. neuron via shape
    • via shape:
    • multipolar: multiple dendrites (most common)
    • bipolar: have a single dendrite at
    • one end and a single axon on the other monopolar:
  5. Glial cells
    • support cells that maintain an optimal environment for neurons
    • 1.oligodendrocytes
    • 2. Schwann cells
    • 3. astrocytes
    • 4. microglia
  6. oligodendrocytes
    myelination in the CNS
  7. Schwann cells
    myelination in the PNS
  8. astrocytes
    physical structural support, maintain balance of chemicals outside neurons, repair injury, contribute nutrients, regulate local blood flow
  9. microglia
    immune defence; search for infectious agents, consume and destroy them to prevent disease and inflammation
  10. neurotransmitters
    • how neurons communicate
    • chemicals released when a neuron is active

    released by axon of presynaptic into synaptic cleft where they diffuse, affect dendrites in postsynaptic
  11. types of neurotransmitters
    • acetylcholine 
    • monoamines 
    • amino acids
  12. acetylcholine
    • the main excitatory neurotransmitter in the PNS
    • at neuromuscular joints it causes muscle contractions
  13. Monoamines
    important in sleep, appetite, mood, anxiety, and other homeostatic, motivational, and emotional functions

    dopamine, epinephrine, and norepinephrine, serotonin, melatonin
  14. catecholamines
    dopamine, epinephrine, norepinephrine collectively
  15. amino acid neurotransmitters
    • glutamate: main excitatory neurotransmitter in the CNS
    • aspartate: excitatory neurotransmitter
    • GABA (gamma-aminobutyric acid): inhibitory neurotransmitter
    • glycine: inhibitory neurotransmitter
  16. types of receptors
    ionotropic and metabotropic
  17. ionotropic receptor
    • work by causing direct flow of ions into or out of the cell
    • allow particular ion to pass
  18. metabotropic receptor
    • work indirectly by triggering a cascade of signals inside the cell
    • G protein, effector, second messanger
    • slower than ionotropic
  19. G protein
    trelay information from the neurotransmitter receptor to proteins (effectors) inside the cell; these proteins in turn relay, amplify, and transform the signal
  20. second messengers
    • modulate the activity
    • of ion channels, activate or deactivate enzymes in
    • the cell, or change gene expression
  21. clearing away neurotransmitters
    • degradation: enzymes break it up
    • diffusion: neurotransmitter moves away from the synaptic cleft
    • re-uptake: specialised protein transporters in cell membranes pull the neurotransmitter back into the cell
  22. potential difference
    • difference concentrations of ions cause differences in potential/voltage across the membrane
    • postsynaptic potential
  23. excitatory postsynaptic potential (EPSP)
    • positive ions enter the cell
    • when the membrane potential of the postsynaptic cell changes so that the inside of the cell becomes less negative relative to the outside
  24. inhibitory postsynaptic potential (IPSP)
    • when the membrane potential of the postsynaptic cell changes so that the inside of the cell becomes more negative relative to the outside
    • when positive leave or negative ions enter
  25. action potential
    • aka nerve impulse, is a rapid change in a
    • neuron’s membrane potential, used to transmit information from the cell body to the axon terminals
    • all or nothing
    • generated at axon hillock at -55 - -60 mV
  26. integrating signals
    • individual postsynaptic potentials are small but summate at the soma to have an effect on the cell
    • two EPSPs together sum to a larger voltage change,  EPSP and an IPSP same moment cancel out

    temporal and spatial summation
  27. temporal summation
    when postsynaptic potentials arrive at the cell body at about the same time; their effects can be summed because of their temporal proximity (close together in time to cause strong enough force)
  28. spatial summation
    postsynaptic potentials that originated at different branches of the dendrites will converge at the cell body (different place but converge at the same time to cause strong enough force)
  29. refractory period
    • prevent action potentials from going backwards
    • period where Na+ channels more resistant to opening
  30. saltatory conduction
    • noncontinuous ‘leaping’ of the
    • action potential from node to node
  31. psychoactive drug
    drugs that alter neurotransmission 

    • agonist: increases or mimics activity of neurotransmitter 
    • antagonist: decreases activity of neurotransmitter
  32. rate coding
    • selectivity of a neuron can be quantified by examining its firing rate for different stimuli (e.g., # action potentials / sec)
    • preferred stimuli fire more often
    • ignores when spikes happen, and ‘sums up’ how many there are
  33. temporal coding
    • looks at temporal structure of spikes
    • the arrangement of spikes in time can vary for different stimuli, even if overall firing rate does not
  34. local coding
    • all stimuli in the outside world become represented uniquely by different neurons, highly selective, "grandmother" 
    • inefficient, inflexible, and prone to loss
  35. population coding
    • distributed representations —
    • coalitions of neurons working together
    • neuron can participate n many different coalitions
    • any given concept is represented
    • by the pattern of activity across
    • many neurons not just individual
Card Set
Neuro Ch 3
cognitive neuroscience chapter 3