Exam 1 molecular neuro

Describe 3 main regions of a neuron and what differentiates them (1. Soma/cell body/perikaryon)

• contains the nucleus

• Keeps the neuron alive and maintains its functions.

• integrates signals received by the dendrites

• main site of protein production

Describe 3 main regions of a neuron and what differentiates them (2. Dendrites)

• Receive incoming signals from other neurons or sensory receptors.

• Usually highly branched.

• Contain many dendritic spines.

• Signals generally travel toward the cell body.

Describe 3 main regions of a neuron and what differentiates them (3. Axon)

• Carries electrical signals away from the cell body.

• Usually a single long projection

• Usually begins at the axon hillock/initial segment.

• Ends in axon terminals, which communicate with another cell.

cartoon of a typical neuron showing each region

What are spines?

• Small protrusions from dendrites

• Usually sites of excitatory synapses

• increase receptive surface area

• receive synaptic input and can change the strength of synaptic connections.

Pyramidal neurons

• Major excitatory neurons of the cerebral cortex

• Use glutamate

• roughly triangular cell body

• Large dendrite tree with an apical dendrite (reach very far away).

• Axon travels toward subcortical white matter (moves signals toward spine and brainstem for movement (face muscles and also voluntary movemet)

• All cortical output is carried by these neurons (electrical signals and neural messages sent from the cerebral cortex to other regions of the brain, the brainstem, or the spinal cord)

• These neurons are for long distance

Interneurons

• Mostly inhibitory and use GABA

• Found throughout the cortical layers (keep and control other neurons from firing, can calm down the signals, even from pyramidal neurons)

• Very diverse in structure and function

• Important types: Basket cells (If a pyramidal neuron is firing too fast and screaming its signal, these interneurons turn down the volume, keeping the electrical activity at a safe, stable level. Chandelier cells (By releasing GABA, the interneuron can completely veto and shut down the pyramidal neuron's output, no matter how excited the rest of the cell is.)

What are some molecular markers that differentiate subtypes of interneurons?

Parvalbumin (PV):

• Marker for PV interneurons

• Often fast-spiking

• Important for controlling timing and activity of neural circuits.

Somatostatin (SST)

• Marker for SST interneurons

• Often targets dendrites of other neurons.

VIP (vasoactive intestinal peptide)

• Marker for VIP interneurons

• Often inhibits other inhibitory interneurons, producing disinhibition

5 General Categories of neurons

• Inhibitory + local

  • GABAergic interneurons

  • Inhibit nearby neurons.

• Inhibitory + distant

  • Medium spiny neurons and Purkinje cells

  • Send inhibitory signals to neurons farther away.

• Excitatory + local

  • Spiny stellate cells

  • Excite nearby neurons.

• Excitatory + distant

  • Pyramidal neurons

  • Send excitatory signals to distant brain regions.

• Neuromodulatory

  • Examples: dopamine, serotonin, norepinephrine, and acetylcholine neurons

  • influence neurotransmission (changing how neurons respond to or communicate with other neurons)

Neurons

• Found in all regions of the brain (CNS and PNS)

• Main function: Neurotransmission (process by which neurons communicate with each other using electrical and chemical signals)/ generate electrical potential (activity)

• Effect on brain function: Coordinate info. and are behind thought, feelings, and behavior.

Astrocytes

• Found in the CNS

• Main function: Neurotransmitter uptake (regulates how much neurotransmitter is present and how long it remains active); Help maintain the environment around neurons

• Angiogenises (formation of new blood vessels from old ones)

• Effect on brain: Support homeostasis of neurons

Oligodendrocytes

• Found in the CNS only

• Main function: myelination of the neurons (axon) -

• Effect on brain: Speeds up neurotransmission

Microglia

• Found in the CNS (tissue microphages) - All regions of the brain and are in more grey than white matter

• Main function: play a role in tissue homeostasis (respond to injury, infection, inflammation, disease, and development

• Effect on brain: Immune cells of the CNS