Functional Groups of Neurons - 11.6

Neuronal Pools

groups of interneurons within the CNS

Neuronal Pool composition

• these pools are a tangled mats of neurological cells, dendrites, and axons in the brain

• the soma are found in other parts of the CNS

Functions of Neuronal Pools

connections between neuronal pools allow for complex mental activity, such as:

• planned movement

• cognition

• personality

• etc.

What are input neurons?

each neuronal pool begins with one or more neurons called input neurons, which initiate the series of signals

• branches to multiple neurons in the pool

• can generate EPSPs that bring the trigger zone closer to threshold

• AP’s are possible but are determined by the # of contacts an input neuron makes with the postsynaptic neuron

• Spatial summation because the input neuron is connected to multiple postsynaptic neurons

What are Neural Circuits?

the patterns of a synaptic connection between neural pools (how neuronal pools are connected)

• each neuronal pool in a circuit receives input from other pools, then produces output that travels to additional pools

What are the 2 types of Neural Circuits?

1. Diverging Circuit

2. Converging Circuit

What are Diverging Circuits?

one axon on an input neuron branches to make contact with multiple postsynaptic neurons

• found in neurons that transmit sensory stimuli which originates from the spinal cord to the different neuronal pools of the brain for processing

What are Converging Circuits?

multiple axon terminals from many input neurons converge into a single postsynaptic neuron, allowing for spatial summation of synapses

• opposite of diverging, it converges (hence the name)

• important in controlling skeletal muscle movement

• interneurons in the spinal cord receive input from neurons in different regions of the brain, which converges to synapse on the motor efferent neurons that stimulate skeletal muscle contraction