Neuronal Integration Flashcards
What is divergence?
The axon from a single neuron branches many times, forming synaptic contacts with multiple target cells
Promotes coordinated effects
What is convergence?
Convergence allows a single target cell to integrate input from many presynaptic neurons
Allows integration of many diverse sources of information into a final output
What is presynaptic inhibition?
Inhibitory circuits filter or gate information flow within a system
E.g. reducing or preventing the reflex pathway
What is disinhibition?
The inhibition of an inhibitory neuron
Has a net excitatory effect
What is lateral inhibition?
Increases contrast between stimuli and helps to maintain the resolving power of a sensory system
E.g. center-surround receptive fields in the retina
What is feedback inhibition?
A type of self-regulation which limits the duration of activity within a system
E.g. motor neuron also synapses on a inhibitory interneuron
What is feedforward inhibition?
Used for regulation of other neurons
Enhances the effectiveness of the active pathway by suppressing output from the antagonistic pathway
E.g. reflex pathways controlling antagonistic muscles
What is a reverberating circuit?
Constructed from feedforward and feedback excitatory connections, allow for persistent activity in a system
Allow a response to outlast a stimulus; short-term memory
What are central pattern generators?
Generate oscillatory activity; formed by a network of interneurons with reciprocal inhibitory connections
Period (rate of cycling) can vary
E.g. alternating movements of limbs, breathing pattern
What occurs at the input zone of a neuron?
Signals consisting of graded potentials
Strength of signal is encoded by the amplitude of the potential - amplitude modulation
What occurs at the integration (or trigger) zone?
Graded potentials are converted into action potentials
Strength of signal is encoded by frequency of repitition - frequency modulation
In which zone are voltage-dependent calcium channels located?
The integration zone
What are high voltage activated (HVA) calcium channels?
VG calcium channels that require strong depolarization for their activation; typically only during an action potential
What are low voltage activated (LVA) calcium channels?
VG calcium channels that open at more modest levels of depolarization; typically between resting potential and threshold
Rapidly inactivated
Aka transient or T-type calcium channels
When is the inactivation of T-type calcium channels removed?
Hyperpolarization of the neuronal membrane potential
E.g. during an IPSP
