**3.3 Musical imagery**

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Shah (2004) also showed that the primary auditory cortex was not activated during auditory verbal imagery. Relative to the resting condition, imagining hearing a syllable (e.g., Ka, Ta, Pa) yielded activation in the bilateral superior temporal gyri, including the planum temporale, and the dorsal bank of the superior temporal sulcus. By exploring the fMRI correlates of auditory verbal imagery associated with the phonological processing of words, Aleman et al. (2005) confirmed the lack of activation of the primary auditory cortex. Participants were presented with bi-syllabic words and were required to indicate the syllable that carried the stress, discriminating between weak-initial words and strong-initial words. In the perceptual condition, words were delivered by headphones, whereas in the imagery condition, words were presented on a screen and participants were instructed to imagine hearing the word being spoken by another person. Results revealed that both perceptual and imagery conditions activated the bilateral supplementary motor area, bilateral post-central gyrus, bilateral insula, the left inferior frontal gyrus (Broca's area), the posterior left superior temporal sulcus/superior temporal gyrus, and the left intra-parietal sulcus/superior parietal lobule. Kim et al. (2008) reported a deactivation in the left superior temporal cortex (BA 22/42) and anterior cingulated cortex during auditory verbal imagery of another's remarks expressed toward self, which were derogatory in content, relative to auditory verbal imagery of another's remarks expressed toward self, which were nonderogatory and neutral in content. In addition, activation was found in both medial frontal cortex, left inferior frontal cortex, both pre-central gyrus, both inferior parietal lobule, right occipital-temporal cortex, left occipital cortex, both posterior insula, and both amigdala.

This type of auditory imagery can occur spontaneously or deliberately when recalling the sound produced by environmental objects or auditory sources, such as the ringing of the phone, the shot of a gun, or sound produced by animals. In this direction, Olivetti Belardinelli et al. (2004a) investigated the neural correlates of mental imagery in different sensory modalities, including the auditory modality, by contrasting imagery sentences (e.g., hearing a shot) with abstract sentences (e.g., the power of reason). Relative to the abstract condition, there was no activation found in the primary auditory cortex during auditory imagery. There was, however, activity in the left middle temporal gyrus (BA 22/37), left inferior temporal gyrus (BA 37), left inferior-middle frontal gyrus, left inferior parietal lobule, and left insula. Using the same methodology, Olivetti Belardinelli et al. (2009) found a bilateral activation in the Heschl's gyrus comparing high-vivid participants with low-vivid participants in generating auditory images of environmental sounds, and in the right hemisphere of the same gyrus regressing the vividness scores of auditory images onto the bold signal. These activations, however, were not significant at the corrected threshold for multiple comparisons. Significant activations were found in the left middle frontal gyrus, right angular gyrus, right posterior cingulate, and left lingual gyrus. Authors explained the lack of significant modality-specific activation in the Heschl's gyrus in the light of the interference of the scanner noise on the auditory image formation process, which may have led to signal decrease solely in the primary auditory cortex, as showed by Gaab et al. (2007). Nonetheless, Bunzeck et al. (2005) used the fMRI technique and did not find any activation of the primary auditory cortex during imagery of familiar complex environmental sounds, either. Compared to watching a silent scrambled movie of familiar scenes (control condition), watching familiar scenes and listening to the corresponding sounds (perception

**3.2 Auditory imagery of environmental sounds** 

Musical imagery is a type of auditory imagery that relies upon the capacity to mentally conceptualize songs, tunes, and general musical input. Musical imagery processes the tempo, temporal extension (Halpern, 1988), pitch (loudness) (Intons-Peterson Russell & Dressel, 1992), and timbre (sound quality of different instruments or voices) of real music (Pitt & Crowder, 1992). The first event-related fMRI study showed activation in the bilateral primary and secondary auditory areas in the superior temporal gyri when participants imagined a single computer-generated note (Yoo et al., 2001). The results also revealed significant activation in the medial and inferior frontal gyri, precuneus, middle frontal gyri, superior temporal gyri, and anterior cingulate gyri. This suggests that fMRI may be sensitive at least to the activation caused by simple internally generated sounds. This study, however, had no control conditions or task validation, and did not isolate timbre. Halpern et al. (2004) examined musical imagery of timbre relative to the visual imagery control. They found that the former activated the posterior temporal cortex, but not the primary auditory cortex, whereas the perception condition (judgments of the timbres of sounds) activated primary and secondary auditory areas with some right-sided asymmetry.

No activation was found in the primary auditory cortex during musical imagery, even in musicians. Langheim et al. (2002) asked to musicians to imagine musical performances for 30 seconds alternated with resting periods. Relative to the resting condition, musical imagery activated supplementary motor and pre-motor areas, right superior parietal lobule, right inferior frontal gyrus, bilateral mid-frontal gyri, and bilateral lateral cerebellum. Yet, Lotze et al. (2003) did not find any activation of the primary auditory cortex when asking amateurs and professional violinists to mentally perform Mozart's "Violin concerto in G major" (KV216). During the musical imagery condition, professionals recruited the supplementary motor area, the superior premotor cortex, anterior areas (Larsell's lobule HVI) in the left cerebellar hemisphere, and bilateral superior parietal areas. Latter Zatorre et al. (2010) carried out two fMRI experiments with musicians. Participants were presented with the first few notes of a familiar tune (Experiment 1) or its title (Experiment 2), followed by a string of notes that was either an exact or an inexact reversal. The task was to judge whether the second string was correct or not by mentally reversing all its notes, which required both maintenance and manipulation of the represented string. During the reversal process, neither experiment showed activation of the primary auditory cortex, but both showed activation of the superior parietal lobe (intraparietal sulcus). Ventrolateral and dorsolateral frontal cortices were also activated, consistent with the memory load required during the task. Authors interpreted these results in the context of other mental transformation tasks, such as mental rotation in the visual domain, which are known to recruit the intraparietal sulcus region.

Kraemer et al. (2005) conducted the only fMRI study that showed activation in the primary auditory cortex. In this study, participants were asked to listen to excerpts of songs with

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representation of the external imagery or third person perspective, in which information processing involves the visualization of spatial components of the perceived world (Ruby &

Various studies using fMRI have yielded contrasting results regarding the involvement of primary motor cortex during motor imagery. On one hand, the first studies revealed bilateral supplementary motor area and pre-motor activations, without an increase in signal intensity in the primary motor cortex (pre-central gyrus – BA 4) or somatosensory cortex during self-paced complex finger movements (Rao et al., 1993) or sequential finger opposition movements (Tyszka et al., 1994). However, using stance and locomotion (walking and running) imagery condition (Jahn et al., 2004), complex imagery actions (e.g., running) (Olivetti Belardinelli et al., 2004a), mental training-related changes on a fingertapping task (Nyberg et al., 2006), and fingers or objects movements imagery task (Lorey et al., 2010), there was no reported activity in the primary motor cortex. Even when participants were instructed to imagine using a common tool, such as the brush for an action related to the hair, activity was observed in the pre-motor cortex, posterior part of the parietal cortex, and cerebellum, but not in the primary motor cortex (Higuchi et al., 2007). On the other hand, there was activity in the primary motor cortex more reduced for motor imagery than for actual performance (Fieldman et al., 1993). In particular, the primary motor cortex was activated during the mental execution of movements with either the left or right hand (Dechent et al., 2004; Lotze et al., 1999; Porro et al., 1996; Roth et al., 1996), when participants were instructed to imagine a right-hand self-paced button press sequence before (novel condition) and after (skilled condition) one week of intensive physical practice (Lacourse et al., 2005), when participants imagined dancing Tango after five training days (Sacco et al., 2006), when participants were instructed to imagine complex everyday movements (e.g., eating a meal, swimming) (Szameitat et al., 2007), or situations involving actions cued by appropriate motor phrases (e.g., to cut) (Tomasino et al., 2007). Sharma, Jones, Carpenter, & Baron (2008) likewise revealed that both the anterior and posterior primary motor area can be bilaterally activated when imaging a finger opposition sequence (2, 3, 4, 5; paced at 1 hz). According to these authors, the role of the primary motor area and its subdivisions may be non-executive, perhaps related to spatial encoding. Recently, Olivetti Belardinelli et al. (2009) demonstrated that primary motor cortex can be activated in high-vivid participants rather than in low-vivid participants, but did not confirm the same activation when motor imagery vividness was regressed onto the BOLD signal, showing activation for only the left pre-central gyrus (BA 6), the right medial frontal gyrus (BA 6), and the inferior parietal lobule. Nevertheless, even considering the studies showing the activation of the primary motor area during motor imagery, it should be noted that the majority of these experiments did not employ electrophysiological monitoring to exclude muscle contractions during scanning. To exclude this possible confounding factor, Takashi et al. (2003) employed electromyographic monitoring within the scanner while participants performed sequential finger-tapping movements in response to visually presented number stimuli in either a movement or an imagery mode of performance. Results revealed that the movement condition activated the primary sensory and motor areas, parietal operculum, anterior cerebellum, caudal pre-motor areas, and area 5 that had mild-to-moderate imageryrelated activity, whereas the motor imagery condition yielded the activation of the precentral sulcus at the level of middle frontal gyrus (BA 6/44), and the posterior superior parietal cortex/pre-cuneus (BA 7), and bilateral cerebellum. Moreover, activity of the

Decety, 2001).

lyrics and instrumentals with no lyrics. Each piece of music was pre-rated by subjects as either familiar or unknown. Short sections of music (lasting for 2–5 s) were extracted at different points during the soundtrack and replaced with silent gaps. Participants were instructed to continue imaging the musical selection. Results revealed that imaging the continuation of familiar songs induced greater activation in auditory association areas than imaging the continuation of unknown songs (in both songs with lyrics and without lyrics). Moreover, when familiar songs contained no lyrics, cortical activity extended into the left primary auditory cortex. However, authors revealed that neural activation during lyrics were in the auditory association areas, whereas with instrumental music, neural activity extended to the primary auditory cortex.
