Summation Process

• What is the definition of summation in neurons?

  It determines if a neuron sends a signal
• What is the result of positive ions flowing into the neuron?

  The membrane undergoes depolarization
• What does EPSP stand for?

  Excitatory Postsynaptic Potential
• Which ions are involved in IPSPs?

  K+ and Cl-
• What is the effect of inhibitory signals on a neuron?

  Decreases likelihood to fire
• How do signals combine in Spatial Summation?

  They combine their effects at the axon hillock
• What is Spatial Summation?

  Multiple signals arrive at different locations
• How do IPSPs affect a neuron's firing probability?

  They decrease it by causing hyperpolarization
• How does summation lead to neuron firing?

  • Multiple subthreshold depolarizations occur.
  • These depolarizations build up during summation.
  • When the threshold is reached, rapid depolarization initiates.
  • This is followed by repolarization.
• What is the timing characteristic of Temporal Summation?

  Signals arrive sequentially within a short time frame
• What are the characteristics of IPSPs?

  • Signals: Inhibitory
  • Channels: K+ and Cl-
  • Membrane Change: Hyperpolarization
  • Effect: Decreases firing chance
• What happens when excitatory signals reach the threshold potential?

  An action potential is triggered.
• What is the role of summation in neuron firing?

  It integrates all incoming signals.
• What type of signals do IPSPs represent?

  Inhibitory signals
• What is Temporal Summation?

  Successive signals arrive at the same location
• What are the key features that differentiate Spatial and Temporal Summation?

  • Signals Combine:
  • Spatial: Across dendrites
  • Temporal: Over time
  • Location:
  • Spatial: Different sites
  • Temporal: Same site
  • Timing:
  • Spatial: Simultaneous
  • Temporal: Sequential
• What are the effects of excitatory and inhibitory signals on a neuron?

  • Excitatory Signals:
  • Increase likelihood to fire
  • More likely to produce action potential
  • Inhibitory Signals:
  • Decrease likelihood to fire
  • Less likely to produce action potential
• What happens to the membrane potential after EPSPs occur?

  It returns to resting potential
• What does it mean when a neuron is more likely to fire?

  It indicates a higher chance of action potential
• What effect do EPSPs have on a neuron?

  They make a neuron more likely to fire
• What is the effect of excitatory signals on a neuron?

  Increases likelihood to fire
• What happens if excitatory signals are stronger than inhibitory signals?

  The neuron fires an action potential
• What are EPSPs?

  Small membrane potential changes in neurons
• How are IPSPs similar to EPSPs?

  Both are brief electrical changes in neurons
• What role do IPSPs play during signal integration in neurons?

  They help integrate incoming signals during summation
• How does summation affect a neuron's action potential?

  It decides if the neuron fires based on signals
• What is the membrane change associated with IPSPs?

  Hyperpolarization
• What are the steps involved in the generation of EPSPs?

  1. Excitatory signals stimulate ligand-gated channels
  2. Na+ and Ca2+ channels open
  3. Positive ions flow into neuron
  4. Membrane undergoes depolarization
  5. Potential moves toward threshold (-55mV)
• What ions flow into the neuron during EPSPs?

  Na+ and Ca2+
• How long do EPSPs last?

  Only a few milliseconds
• What is the threshold potential for a neuron to fire?

  -55mV
• What does it mean when a neuron is less likely to fire?

  It indicates a lower chance of action potential
• What is the effect of IPSPs on neuronal firing chance?

  It decreases the firing chance