Chapter 1: Chemical Neurotransmission
Modern psychopharmacology is largely the story of chemical neurotransmission.
❖ Anatomical versus chemical basis of neurotransmission
Neurotransmission can be described in many ways: anatomically, chemically, and
electrically.
Anatomical basis
Neurons and the connections between them (synapses), which is sometimes also
referred to as the anatomically addressed nervous system, a complex of hard-wired synaptic
connections between neurons. The anatomically addressed brain is a complex wiring
diagram, ferrying electrical impulses
Synapses can form on many parts of a neuron, not just from the axon of one neuron
to the dendrite of another (= axodendritic synapses), but also from the axon of one neuron to
the soma of another (= axosomatic synapses), and even from the axon of one neuron to the
axon of another (= axoaxonic synapses). These synapses are said to be ‘asymmetric’, as
communication is structurally designed to be in one direction. There are presynaptic
elements that differ from postsynaptic elements. A neurotransmitter is packaged in the
presynaptic nerve terminal, and then fired at the postsynaptic neuron to target its receptors.
Neurons are the cells of chemical communication in the brain. Neurons have many
sizes, lengths, and shapes that determine their functions, which is also influenced by
localization. When neurons malfunction, behavioral symptoms may occur. When drugs alter
neural function, behavioral symptoms may be relieved, worsened or produced.
General structure of a Neuron
All neurons have a cell body, which is known as the soma, and are set up structurally to
receive information from other neurons through dendrites. This happens sometimes via the
spines on the dendrites, and often through an elaborately branching tree of dendrites.
Neurons are also set up to send information to other neurons via an axon that forms
presynaptic terminals as the axon passes by (= en passant presynaptic axon terminals) or as
the axon ends (= presynaptic axon terminals)
Neurotransmission has an anatomical infrastructure, but it is fundamentally a
chemical operation. Complementary to the anatomically addressed nervous system, there is
the chemically addressed nervous system, which forms the chemical basis of
neurotransmission (how chemical signals are coded, decoded, transduced, and sent along
the way). Psychopharmacological agents target key molecules involved in
neurotransmission.
The neurobiologically informed clinician
Being ‘neurobiologically informed’ includes being able to translate exciting new findings on
brain circuitry, functional neuroimaging, and genetics into clinical practice, and potentially
improving the manner in which psychiatric disorders and their symptoms are diagnosed and
treated.
❖ Principles of Chemical Neurotransmission
Neurotransmitters
Modern psychopharmacology is largely the story of chemical neurotransmission.
❖ Anatomical versus chemical basis of neurotransmission
Neurotransmission can be described in many ways: anatomically, chemically, and
electrically.
Anatomical basis
Neurons and the connections between them (synapses), which is sometimes also
referred to as the anatomically addressed nervous system, a complex of hard-wired synaptic
connections between neurons. The anatomically addressed brain is a complex wiring
diagram, ferrying electrical impulses
Synapses can form on many parts of a neuron, not just from the axon of one neuron
to the dendrite of another (= axodendritic synapses), but also from the axon of one neuron to
the soma of another (= axosomatic synapses), and even from the axon of one neuron to the
axon of another (= axoaxonic synapses). These synapses are said to be ‘asymmetric’, as
communication is structurally designed to be in one direction. There are presynaptic
elements that differ from postsynaptic elements. A neurotransmitter is packaged in the
presynaptic nerve terminal, and then fired at the postsynaptic neuron to target its receptors.
Neurons are the cells of chemical communication in the brain. Neurons have many
sizes, lengths, and shapes that determine their functions, which is also influenced by
localization. When neurons malfunction, behavioral symptoms may occur. When drugs alter
neural function, behavioral symptoms may be relieved, worsened or produced.
General structure of a Neuron
All neurons have a cell body, which is known as the soma, and are set up structurally to
receive information from other neurons through dendrites. This happens sometimes via the
spines on the dendrites, and often through an elaborately branching tree of dendrites.
Neurons are also set up to send information to other neurons via an axon that forms
presynaptic terminals as the axon passes by (= en passant presynaptic axon terminals) or as
the axon ends (= presynaptic axon terminals)
Neurotransmission has an anatomical infrastructure, but it is fundamentally a
chemical operation. Complementary to the anatomically addressed nervous system, there is
the chemically addressed nervous system, which forms the chemical basis of
neurotransmission (how chemical signals are coded, decoded, transduced, and sent along
the way). Psychopharmacological agents target key molecules involved in
neurotransmission.
The neurobiologically informed clinician
Being ‘neurobiologically informed’ includes being able to translate exciting new findings on
brain circuitry, functional neuroimaging, and genetics into clinical practice, and potentially
improving the manner in which psychiatric disorders and their symptoms are diagnosed and
treated.
❖ Principles of Chemical Neurotransmission
Neurotransmitters
