1 Classification of Neurons and Neuron Types

What are neuropil?

Dense tangle of neuronal and glial processes

What is the difference between afferent and efferent?

Afferent are sensory inputs towards the CNS, efferent are motor outputs away from the CNS

What are the three types of signals?

Excitatory, inhibitory, and modulatory

What are interneurons?

Short axons that participate in local circuit function

What are macrocircuits?

Involve a population of neurons that project from one brain region to another

What are microcircuits?

Reflect local cell-cell interactions within a particular brain region

What circuits involve projecting from one brain region to another?

Macro

What circuits involve local cell-cell interactions?

Micro

What are the main segments of a neuron?

Cell body, axon and dendrites

What parts of neurons do some lack?

Axons and dendrites

What factors define anatomical classes of neurons? (5)

• Location of neuron in nervous system

• dendritic and axonic morphology

• synaptic connectivity

• cellular components

  • molecular signatures

What are the four main classes of neurons?

Sensory, motor, principal, and interneurons

What is the full name of S neurons?

Sensory afferent

What is the role of sensory neurons?

Transform an input/stimulus into electrical and chemical signals to inform the nervous system of internal/external environmental events

What kind of input/stimulus can sensory neurons transform into signals?

Chemical, physical or pressure

Where can sensory neurons collect information from?

Eyes, nose, tongue and skin

What is the full name for M neurons?

Motor efferent

What is the role of motor neurons?

Responsible for the direct or indirect control of effector organs such as muscles and glands

What are the axons of motor neurons? What is their role

Efferent nerve fibers that carry signals away from the CNS to produce movements

What do motor neurons typically look like?

Very short dendrites that stick very close to the cell body and a very long axon

What are the two main classifications of principal neurons?

Pyramidal and non-pyramidal

What are cortical pyramidal neurons important for?

Making connections with sensory and motor neurons as it has an important integrative role

Why is it important that interneurons outnumber principal cells?

Interneurons help with inhibition and modulation to it helps keep principal cells under control

What are the five main kinds of interneurons?

• Excitatory

• soma and proximal dendrite-targeting cells

• dendrite targeting cells

• dendrite and tuft-targeting cells

• axon-targeting cells

What is the relationship between interneurons and pyramidal cells? Why?

Lots of outputs to pyramidal cells and not many inputs from pyramidal cells. This is because principal neurons want to project to other principal neurons

What are the three main kinds of non-pyramidal cells?

Stellate, granule, Purkinje

What system is important with non-pyramidal cells? What occurs when there are disruptions to this system?

System is important for coordinated muscular movement and disruptions are thought to be involved in movement disorders