1. Neurons, Communication and
Transduction
Adapted from Steven Stahl MD, PHD

2. BASIC ANATHOMY AND PHYSIOLOGY

3. Anatomy and Physiology of The
Neuron

4. Synaptic Neurotransmission and
Neurodevelopment
• Neurogenesis, neuronal selection and
migration occur before birth.
• Differentiation, myelination and
synaptogenesis continue throughout entire
life
• Competitive elimination is a process of brain
restructuring that occurs in adolescence.

5. Neuronal organelles

6. Protein synthesis
• Peripheral proteins (proteins who live in the
cytoplasm) are made on free polysomes and
transported into the axon and dendrites.
• Integral or secretory proteins (proteins that
are inserted into a membrane) are made on
the rough endoplasmic reticulum, transported
to the Golgi apparatus where they are packed
into vesicles – ready for transport.

7. Peripheral protein synthesis

8. Synthesis of Membrane and Secretory
Proteins

9. Some Protein Synthesis Occurs in The
Dendrites

10. BASIC NEUROTRANSMISSION

11. Classic Neurotransmission

12. Retrograde Neurotransmission
• The postsynaptic neuron can communicate
with the presynaptic neuron (such is the case
with endogenous canabinoids, NO and NGF).

13. Volume Neurotransmission
• Neurotransmission can occur without a
synapse(by diffusion of the neurotransmitter
to sites that are distant from its own synapse).

14. Volume Neurotransmission of
Dopamine in The Prefrontal Cortex
• There are few dopamine reuptake pumps in
the prefrontal cortex. The excess dopamine
diffuses and finds receptors on other neurons.

15. Volume Neurotransmission to
Autoreceptors on Monoamine
Neurons
• Autoreceptors are situated on the same
neuron and cause inhibition of transmission.
• For instance dopamine diffuses out of the
synapse in the prefrontal cortex and
stimulates the autoreceptors on the same
neuron, thus inhibiting dopaminergic
transmission.

16. Inhibitory Volume Transmission

17. SIGNAL TRANSDUCTION

18. Signal Transduction
• Refers to communication between the
genome of the presynaptic neuron and the
genome of the postsynaptic neuron.
• It can happen both ways: the genome of the
postsynaptic neuron can also communicate
back with the genome of the presynaptic
neuron.
• Signal transduction is a slow process taking
hours or days.

19. Signal Transduction is a Two Way
Street

20. Signal Transduction Cascade
• The cascade of events that take place after the
stimulation of the postsynaptic receptors.
• The third messenger can be a KINASE which adds
phosphate groups to proteins to create
phosphoproteins.
• The third messenger can also be a PHOSPHATASE
which removes phosphate groups from
phosphoproteins
• The balance between kinases and phosphatases
determines the downstrean chemical activity.

21. Four Types of Signal Transduction
Cascade
• G protein linked systems
• Ion channel-linked systems
• Hormone linked systems
• Neurotrophin-linked systems
Neurotransmitters activate G protein linked
systems and ion channel linked systems. Both of
these systems activate genes in the cell nucleus.

22. Signal Transduction Cascades
• The G protein linked system works through a cascade involving cAMP and Protein
kinase A.
• The ion channel systems works through Calcium and calcium modulin kinase.
Both of these systems activate genes in the cell nucleus by phosphorylating a
protein there called CREB (cAMP response element-binding protein).
• Certain hormones (like estrogen and steroids) enter the neuron, bind to their
receptors in the cytoplasm, forming a hormone nuclear receptor complex. This
complex enters the nucleus and interact with hormone response elements (HRE)
to trigger activation of specific genes.
• The neurotrophin system activates a series of kinase to trigger gene
expression, which may control synaptogenesis and neuron survival. Ras is a G
protein, Raf is a kinase, MAPK is mitogen activated protein kinase and GSK3 is
glycogen synthase kinase 3.

23. Four Most Important Signal
Transduction Cascades