These findings suggest some key brain areas in the distributed neural circuits underlying
the perceptual/cognitive representation of central aspects of musical rhythm. These data
suggest that distinct brain areas subserve musical meter, tempo, pattern, and duration. In
addition, the results confirm that the neural subsystems underlying pitch discrimination
are distinct from those subserving the elements of rhythm discrimination. The differences
in activated brain areas for nonmusicians and musicians likely reflect differences in strat-
egy, perceptual skill, and cognitive representation of the components of musical rhythm
and pitch.
Neurology of pitch discrimination
In the foregoing review of neuroimaging and neurological studies of music, the cerebellum
appears to be involved in some way in nonmotor, nonsomatic sensory or cognitive pro-
cessing. This kind of conclusion is supported by many other recent neuroimaging and neu-
rological findings.37–45,73Such findings challenge classical motor theories of cerebellar
function and have created an environment in which researchers are increasingly question-
ing the extent to which the cerebellum is involved in motor control. Although in most
cases, new alternative proposals are described as an extension of the role of the cerebellum
in motor coordination itself, others, who have been driven primarily by new neuroimaging
results, are proposing radically different functions for this structure.
James Bower and I, and our colleagues, have been using neuroimaging of tactile and
cutaneous sensory and motor tasks to test the hypothesis that the cerebellum is involved in
monitoring and optimizing the acquisition of information in various sensory modali-
ties.72–74A direct prediction of this hypothesis is that damage to the cerebellum will impair
performance on sensory tasks, especially those in which successful performance depends
on sensory information processing at a very fine time scale. We evaluated this prediction
for auditory perception by examining for the first time the effect of global cerebellar degen-
eration on auditory pitch discrimination in (nonmusician) patients.^75 This strictly audi-
tory task does not depend on overt motor behaviour, as do other sensory tasks.
Fifteen patients and 15 healthy control subjects (matched in age and education) per-
formed a pitch discrimination task measuring difference thresholds. The patients suffer
from pancerebellar degeneration caused by hereditary, idiopathic, paraneoplastic, or
postinfectious pancerebellitis. The degree of cerebellar degeneration in these patients, as
confirmed by examinations of pancerebellar ataxia and anatomical imaging, ranged from
minimal to severe, and included mild- and moderate-grade cases of ataxia. Patients and
controls mostly had normal loudness thresholds; some had mild hearing loss in the
4000–8000 Hz range.
On each pitch discrimination trial, subjects decided whether a comparison tone was
higher or lower than a preceding 500 Hz standard. All tones had suprathreshold loudness
(80 dB) and 400 ms duration; the standard was followed 400 ms later by the comparison
pitch. The tones were composed of the fundamental, three times the fundamental fre-
quency at a 50 per cent amplitude, and five times the fundamental at a 25 per cent ampli-
tude. The difference threshold estimation procedure used was PEST.76,77Subjects
performed 60 trials, with threshold trials from above and below the standard pitch, mixed
260