361the location of a particular instrument on the stage helps the conductor to pinpoint the
source of errors. Training this ability obviously helps, as has been found in a recent study
with event-related brain potentials.^41 Conductors show greater differentiation between
positions in peripheral auditory space than nonmusicians or pianists. As attention has been
shown to increase brain activation in nonprimary auditory cortex,^42 attentional modula-
tion during rehearsal would be expected to sharpen conductors’ skills by modulating the
activity of brain regions encoding auditory space. This situation is not unlike that of blind
individuals focusing completely on nonvisual events, although in this situation attention
only provides the initial vehicle that leads to permanent change. At the single-neuron level,
cells have been found in area CL of the monkey’s nonprimary auditory cortex that are
selective to both the content and the location of complex sounds.^29 Such cells could well
provide the neural substrate for the above effects.
Sensitive periods of auditory cortical plasticity
Auditory cortical plasticity can be demonstrated in everyday processes as musical learning,
and it becomes even more overtly obvious in the reorganization of auditory cortex across
areal borders after early blindness. Age certainly plays an important role in these plastic
changes, as the age of onset of musical training as well as the age of onset of blindness have
both been shown to be critical for the extent of reorganization. Learning a musical instrument
Figure 23.4Results of functional magnetic resonance imaging during anticipatory imagery of music. The axial
sections from individual subjects are displayed in radiological coordinates showing the left side of the brain on
the right and vice versa. Imagery leads to activation of anterior regions of auditory cortex in the right hemisphere
(in conjunction with right inferior frontal regions; panel on the left of the figure). This emphasizes the role of
sensory cortices in mental imagery. However, brain regions outside auditory cortex, such as the cerebellum (left
cerebellar hemisphere; middle panel) and the anterior cingulate bilaterally (right panel), are also activated,
demonstrating their role in cognitive processing. (See Plate 20 in colour section.)