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NEUROSCIENCE OF PSYCHOACTIVE SUBSTANCE USE AND DEPENDENCE

The region of the brain where it meets the spinal cord is called the
rhombencephalon or hindbrain, and is composed of the myelencephalon
(medulla) and metencephalon (pons and cerebellum) (Fig. 2.1). The medulla
is vital to sustaining life, and controls processes such as breathing, heartbeat
and blood flow. The medulla also contains receptors for the opioid drugs,
such as heroin and morphine, which is why these drugs can cause respiratory
depression and death. The pons is a relay station for signals being carried
from the cortex to the cerebellum, which is involved in body movements and
coordination.

Fig. 2.1 Central nervous system

Central sulcus
Precentral gyrus Postcentral gyrus
Basal ganglia

Frontal lobe Parietal
lobe
Forebrain
Cerebral
hemisphere

Diencephalon
Mid brain

Temporal lobe Occipital
lobe
Hindbrain
Midbrain
Pons
Brain stem
Medulla
Cerebellum Cervical

Spinal cord Thoracic

Lumbar
Sacral

Source: Reproduced from Kandel, Schwartz, & Jessell, 1995, with permission from the
publishers.

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