This pattern obtains over different kinds of imagery tasks and different brain-imaging techniques, including SPECT ( Goldenberg et al., 1989) and ERP ( Farah et al., 1989) as well as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) mentioned above. Many studies investigating visual imagery have found evidence that visual association areas (and sometimes primary areas) are engaged during visual imagery tasks. To the extent that brain areas known to be associated with sensory processing are active during imagery tasks, we may conclude that the brain efficiently uses similar areas both to process information initially, as well as to reactivate it for further processing.įor the case of visual imagery, several studies have indeed found the hypothesized activation in visual cortical areas during imagery tasks ( Kosslyn et al., 1993). More directly, a number of researchers have employed brain-imaging technology to observe the brain areas that are active while participants perceive or imagine stimuli. Farah reviewed evidence from brain-damaged patients who show parallel deficits in visual imagery and perception skills after damage to particular brain areas ( Farah, 1988). To investigate the nature of mental imagery further, researchers have turned to physiological evidence that imagery and perception may share actual neural structures. For instance, although similarity of response patterns in perceived and imagined tasks may indicate shared mental structures, the similarity may be coincidental or epiphenomenal. However, these behavioral methods have their limitations in helping us decide whether perception and imagery share similar mental structures. Purely behavioral methods have shown intriguing similarities between performance on perceptual and imaginal versions of the same task ( Farah, 1989) or facilitation by an imagined stimulus on performance of a task involving a perceived stimulus ( Hubbard and Stoeckig, 1988). Cognitive psychologists have wondered whether this experience is fundamentally different to the more abstract mentation used in recalling facts or solving arithmetic problems. The SMA seems to be involved specifically in image generation, implicating a motor code in this process.Ĭognitive scientists are interested in the mental structures that underlie the experience of imagery, or mental acts in which we seem to re-enact the experience of perceiving an object when the object is no longer available. Retrieval from musical semantic memory is mediated by structures in the right frontal lobe, in contrast to results from previous studies implicating left frontal areas for all semantic retrieval. We conclude that areas of right auditory association cortex, together with right and left frontal cortices, are implicated in imagery for familiar tunes, in accord with previous behavioral, lesion and PET data. Subtraction of activation in the control condition from that in the reimagine condition, intended to capture imagery of unfamiliar sequences, revealed activation in SMA, plus some left frontal regions. Isolating retrieval of the real tunes by subtracting activation in the reimagine task from that in the real-tune imagery task revealed activation primarily in right frontal areas and right superior temporal gyrus. Subtraction of the activation in the control task from that in the real-tune imagery task revealed primarily right-sided activation in frontal and superior temporal regions, plus supplementary motor area (SMA). Subjects either imagined the continuation of nonverbal tunes cued by their first few notes, listened to a short sequence of notes as a control task, or listened and then reimagined that short sequence. The present study used positron emission tomography (PET) to examine the cerebral activity pattern associated with auditory imagery for familiar tunes.
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