Page 70 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

How are we affected

by neurotransmitters?

Are our moods and emotions really just brain chemistry?

essages are passed from one nerve cell are normally associated with more addictive Schizophrenia Anxiety Happiness
to the next by chemical messengers behaviour types.
M called neurotransmitters. Each has a Noradrenaline is similar in structure to the
slightly different effect and by looking at what hormone adrenaline and is involved in the ‘fi ght
happens when neurotransmitter levels change, or flight’ response. In the brain, it keeps us alert

we are discovering that different combinations and focussed. In contrast, GABA reduces the
play a role in a range of complex emotions. activity of the nerves that it interacts with and is
Acetylcholine excites the nerve cells that it thought to reduce feelings of fear or anxiety.
touches, triggering more electrical activity. It Serotonin is sometimes known as the ‘happy Depression Love Fight or fl ight
plays a role in wakefulness, attention, learning hormone’ and transmits signals involved in body
and memory, and abnormally low levels are temperature, sleep, mood and pain. People with
found in the brains of people with dementia depression have been found to have lower
caused by Alzheimer’s disease. serotonin levels than normal, though raising
Dopamine is a chemical that also excites nerve serotonin levels with antidepressant medications
cells. It plays a vital role in the control of does not always help.
movement and posture, and low levels of There are many more neurotransmitters in the
dopamine underlie the muscle rigidity that exists brain and other chemicals like hormones can

in Parkinson’s disease. Dopamine is also used in also influence the behaviour of nerve cells. It is Dopamine Serotonin Oxytocin
Noradrenaline Adrenaline
the brain’s reward circuitry and is one of the these interactions that are thought to underlie
chemicals responsible for the good feelings that the huge range of human emotions.
Different levels of neurotransmitters have been
associated with different mental states
The synapse
Receptor Feelings
Neurotransmitters pass Nerve cells can only respond to a The combined activity
messages from one nerve specific neurotransmitter if they across this complex

cell to the next have the right corresponding system is what
receptors to detect it. underpins our thoughts,
feelings and emotions.
Incoming
signal
Neurotransmitter
release is only
triggered when
there is enough
electrical activity
in the nerve cell.

Neurotransmitters
These chemical messengers New signal
travel across the small gap -
called the synaptic cleft - and If a neighbouring nerve
stick to receptors on nearby receives the right
nerve cells. chemical messages it
will trigger a new
electrical signal.
Synapse
Nerve cells communicate by releasing
neurotransmitters at specialised
junctions called synapses.

Part of a network © BSIP SA / Alamy; Thinkstock
Each nerve cell makes thousands
of connections to its neighbours
and has its own mix of different
neurotransmitters and receptors.

70 How It Works