Abnormal Psychology

112 CHAPTER 4

4.1 • Using Medication to Change

Brain Functioning Medications can alter

events at the synapse, and thereby change brain

functioning. A medication can (a) mimic the effects

of a neurotransmitter substance (that is, act as an

agonist); (b) bind to receptors and thereby prevent

neurotransmitter molecules from binding (that is,

act as an antagonist); (c) cause extra amounts of a

neurotransmitter to be released from the terminal

button into the synapse; or (d) partially block

reuptake of leftover neurotransmitter molecules

in the synaptic cleft (that is, act as a reuptake

inhibitor). Drugs can also alter the level or activity

of other substances that are produced in glial cells

that surround a synapse, which in turn infl uence the

amount of neurotransmitter in the synaptic cleft.

Figure 4.1g 4

Axon of

sending neuron

(a)

(b)

(c)

(d)

Synaptic

cleft

Agonist

drug molecules

Receptor

sites

Dendrite of

receiving neuron

Neurotransmitter

molecules

Neurotransmitter

molecules

Neurotransmitter

molecules

Reuptake

blocked

Antagonist

drug molecules

Neural impulse Neural impulse

Neural impulse blocked

Neural impulse Neural impulse

Neural impulse

Neural impulse Neural impulse

Reuptake

channels

• binding to a receptor site, which prevents the neurotransmitter in the synapse from bind-
  ing to the receptor (or causes less of it to bind); such medications are called antagonists.


• causing the release of extra amounts of a neurotransmitter from the terminal
  button into the synapse.


• increasing or decreasing the level or activity of other substances that activate or
  inactivate a neurotransmitter.

Antagonists
Medications that bind to a receptor site on
a dendrite (or cell body) and prevent the
neurotransmitter in the synapse from binding
to that receptor or cause less of it to bind.