30 • CHAPTER 2 Cognitive Neuroscience
covers the brain (Fischl & Dale, 2000). The cortex is
the wrinkled covering you see when you look at an
intact brain (● Figure 2.7). Localization of function
has been demonstrated for many different cognitive
functions. We fi rst consider perception.LOCALIZATION FOR PERCEPTION
One of the most basic demonstrations of localiza-
tion of function is the primary receiving areas for the
senses, shown in Figure 2.7. These are the fi rst areas
of the cerebral cortex to receive signals from each of
the senses. For example, when sound stimulates recep-
tors in the ear, the resulting electrical signals reach the
auditory receiving area in the temporal lobe.
The primary receiving area for vision occupies
most of the occipital lobe, and the area for the skin
senses—touch, temperature, and pain—is located
in the parietal lobe. The areas for taste and smell
are located on the underside of the temporal lobe
(smell) and in a small area within the frontal lobe
(taste). The frontal lobe receives signals from all of
the senses and plays an important role in percep-
tions that involve the coordination of information
received through two or more senses.
The primary receiving areas were initially identi-
fi ed by noting the effects of brain damage. For exam-
ple, it was noted that damage to the occipital lobe
caused by battlefi eld injuries caused blindness. Another source of brain damage is stroke—
disruption of the blood supply to the brain, usually due to a blood clot. As with battlefi eld
injuries, the perceptual effects of strokes are linked to each of the sensory receiving areas.
In addition to the primary receiving areas, other areas also serve specifi c sensory func-
tions. People who have suffered damage to a certain area in the temporal lobe on the lower
right side of the brain (not the auditory area, which is higher up in the temporal lobe) have
a condition called prosopagnosia—an inability to recognize faces. People with prosopag-
nosia can tell that a face is a face, but can’t recognize whose face it is, even for people they
know well such as friends and family members. In some cases, people with prosopagnosia
look into a mirror and, seeing their own image, wonder who the stranger is looking back
at them! What is special about this condition is that the problem is restricted to using the
sense of vision to recognize faces. The person can recognize other objects, can recognize
people based on their voices or mannerisms, and have normal memory and general cogni-
tive functioning (Burton et al., 1991; Hecaen & Angelergues, 1962; Parkin, 1996).
Localization of function has also been demonstrated by recording from neurons in
different areas of the brains of animals (mainly monkeys). Neurons in the occipital lobe
respond to stimulation of the eye with light, neurons in the temporal lobe to sound, neurons
in another area in the temporal lobe to faces, and so on. In addition, a technique called
brain imaging has been used to demonstrate localization of function in the human cortex.A widely used technique for measuring brain activity in humans is brain imaging, which allows
researchers to create images that show which areas of the brain are activated as awake humans
carry out various cognitive tasks. One of these techniques, positron emission tomography (PET),
was introduced in the 1970s (Hoff man et al., 1976; Ter-Pogossian et al., 1975). PET takes advan-
tage of the fact that blood fl ow increases in areas of the brain that are activated by a cognitive task.
To measure blood fl ow, a low dose of a radioactive tracer is injected into a person’s bloodstream.● FIGURE 2.7 The human brain, showing the locations of the primary
receiving areas for the senses: vision = occipital lobe; skin senses =
parietal lobe (dotted area); hearing = temporal lobe (located within the
temporal lobe, approximately under the hatched area). Areas for taste
and smell are not visible. The frontal lobe responds to all of the senses
and is involved in higher cognitive functioning.Temporal lobeOccipital lobeParietal lobeSpinal cordFrontal lobeCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.