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conditions), and right-click the mouse button when they heard a change to no key
(
atonal
condition). As the participants were non-musicians, the task was explained
as clicking in response to a given type of change so as to avoid misunderstandings
of the meaning of the terms
. That is, they were instructed
to indicate any change from one key to another by clicking on the left button of a
mouse and a change towards a sequence with no key by clicking on the right
button. Subjects were given an initial practice period in order to ensure that they
understood the task.
The results of the behavioural tasks are shown in Table
1.3
, which gives the
percentage of trials that contained a left- or right-click for each condition. Second-
level one-way analysis of variance (ANOVA) was performed for the left-click and
right-click results, respectively, across all participants.
Distant
,
close
and
initial
conditions had a signi
'
tonal
'
,
'
atonal
'
and
'
key
'
cantly higher number of left-click responses than for con-
ditions
same
and
atonal
. Conversely, the
atonal
condition had a signi
cantly higher
amount of right mouse clicks than for
distant
,
same
and
atonal
conditions. These
results con
rm that the participants were able to perform the behavioural task
satisfactorily and show that
the participants had some awareness of the tonal
structure of the stimuli.
As for the fMRI scanning, functional volumes were collected with 3 Tesla
scanner using echo planar imaging. A more detailed description of the data
acquisition procedures and analysis methods is beyond the scope of this chapter. In
summary, each stimulus block lasted 8 s and was immediately followed by the next
stimulus block. Analysis was performed with a general
linear model (GLM)
(Friston et al.
2006
).
Group analysis revealed a cluster of fMRI activation around the auditory cortex
(especially in the left hemisphere) showing a systematic increase in blood-oxygen-
level-dependent (BOLD) amplitude with increasing distance in key. We have found
a number of signi
cant active neural clusters associated with the processing of
tonality, which represent a diverse network of activation, as shown in Table
1.4
and
Fig.
1.9
.
We note the strong presence of medial structures, in particular
cingulate cortex
(label 5 in Fig.
1.8
and Table
1.4
) and
caudate nucleus
(label 4 in Fig.
1.8
and
Table
1.4
) in response to key changes. Also signi
cant is the bilateral activation for
key changes of the
transverse temporal gyrus
also known as Heschl
'
s gyrus (labels
Table 1.3
Behavioural results, showing the percentage of trials that contained a left- or right-
click aggregated over all participants in the experiment
Condition
Left-click
Right-click
Distant
89.453
11.328
Close
83.594
0.7812
Same
26.563
3.5156
Initial
68.62
4.2969
Atonal
14.193
83.984
