task when the fundamental frequency was present. Patients with more anterior right tem-
poral lobe damage, or those with similar damage on the left were unimpaired. Both stud-
ies thus point to a specificity for basic aspects of pitch processing, indicating a special role
for areas in or adjacent to the right primary auditory cortex in these functions. Several
other studies have added weight to this idea, although the degree of anatomical specificity
has not always been possible; nonetheless, many authors have observed that the right tem-
poral cortex plays a particularly important role for processing of pitch and of spectral
pattern information.^7 –^11
More recently, functional imaging studies have begun to add important new evidence to
our emerging view of the functional organization of the human brain. Among the many
advantages of techniques, such as positron emission tomography (PET) and functional
magnetic resonance imaging (fMRI), is that they provide a noninvasive means of obtain-
ing anatomically accurate information about the cerebral areas that change their neural
activity as a function of stimulus or task parameters. Thus, these techniques provide criti-
cal complementary evidence to the data derived from more traditional behavioural stud-
ies. However, whereas activation studies can identify the sites of neural activity associated
with a particular function, they cannot determine the degree to which necessary computa-
tions are carried out. Conversely, only lesion techniques or stimulation techniques (such as
transcranial magnetic stimulation, see, Chapter 26, this volume) can provide information
about essential areas, but they are constrained by various other limitations. Clearly, when-
ever converging evidence can be obtained from a variety of methods, the conclusions that
can be drawn will be correspondingly stronger.
Several recent studies have examined pitch processing using functional imaging tech-
niques. One relevant piece of evidence in favour of a special role for the right auditory
cortex in pitch processing comes from PET studies of pitch production. Perry et al.^12
compared a condition in which subjects repeatedly produced a single vocal tone of con-
stant pitch to a control in which they heard synthetic tones at the same rate. Increased cere-
bral blood flow (CBF) was noted in several motor areas, but within the superior temporal
gyrus (STG), only right-sided activations were noted in both primary and secondary audi-
tory cortices. The authors interpret this finding as a reflection of the specialization of the
right auditory cortex for pitch perception. They argue that accurate perception of the pitch
of one’s own voice is required during singing in order to use feedback to maintain the
desired pitch. Additional findings in favour of this conclusion come from regression analy-
ses performed on these data, in which the accuracy of the subjects’singing was measured,
and the degree of pitch excursion was covaried against CBF in the whole brain volume.^13
Strikingly, a region of covariation was identified in the right HG, such that increased CBF
was observed with increasing pitch deviation. This result confirms the special role played
by this region in pitch processing and suggests that a feedback mechanism may indeed be
operative to maintain consistency of vocalized pitch.
Processing of pitch patterns
The initial phase of pitch analysis set the stage for processing of pitch patterns. The relation-
ships between individual tones form the basis for the most fundamental aspect of musical
236