Neuropsychologia, Vol. 29, No. 7, pp. 695-702, 1991 Printed in Great Britain. C028-3932,‘91 $3.M)+0.00 0 1991Pergamon Press plc zyxwvutsr NOTE CONTRIBUTIONS OF OCCIPITAL AND TEMPORAL BRAIN REGIONS TO VISUAL AND ACOUSTIC IMAGERY-A SPECT STUDY GEORG GOLDENBERG,* Ivo PODREKA, MARGARETE STEINER, PATRICK FRANZEN and L~DER DEECKE Neurologische UniversitLtsklinik, Lazarettgasse 14, A 1090, Wien, Austria zyxwvutsrqponmlkjihgfe (Received 9 May 1990; accepted 4 March 1991) Abstract-Regional cerebral blood flow (rCBF) was assessed by means of HMPAO-SPECT in two experimental groups. In a control condition both groups listened to abstract words, in the experimental condition they heard five names of objects. One group was advised to form visual images of the objects, the other group was advised to form acoustic images of the sounds made by these objects. Post-experimental questionnaires revealed that most of the subjects in the acoustic imagery condition had had visual images in addition to the acoustic ones. Both imagery conditions lead to approximately equal increases of rCBF in the left inferior occipital region and in the left thalamus. Flow increases in both hippocampal regions and the right inferior and superior temporal regions were larger in the acoustic than in the visual imagery condition. It is concluded that only the activation of left inferior occipital and left thalamic regions can be interpreted as being related to modality-specific visual aspects of imagery. INTRODUCTION A CORE assumption of cognitive theories of visual imagery is that “seeing with the mind’s eye” employs cognitive representations and processes which are used in visual perception but not in non-imaginal thinking [Z, 4,5,8,12,14, 2&22]. Implicit in these theories is the consequence that visual imagery is based on the activity of modality-specific visual cortex. A number of physiological studies have supported this view by demonstraing that visual imagery is linked to activity in posterior regions of the brain [5-7,9-l 1,261, but the conclusion that visual areas are involved is not compelling. The physiological measurement methods applied do not permit an unquestionable distinction between the activity of visual cortex and of neighbouring regions. The creation of a mental visual image implies retrieval of information about the visual appearance of objects which is not needed for non-imaginal thinking. Differences in cerebral activation patterns between imagery and non-imaginal thinking may be referred to the additional demands on retrieval of information rather than to the modality-specific nature of the retrieved information. If visual imagery is based on the activity of modality-specific visual brain regions, its cerebral correlate should differ not only from that of non-imaginal thinking,but also from imagery in other modalities, as for example acoustic imagery. As a corollary of the assumption that visual imagery employs visual areas of the brain, one would expect acoustic imagery to be linked to the activity ofauditory cortex. Ifcerebral activation pattern are compared between subjects engaged in visual and in acoustic imagery, a double dissociation should occur: modality specific visual areas should be activated in visual but not in acoustic imagery, and modality specific acoustic areas should be activated in auditory but not in visual imagery. In the present study we compared regional cerebral blood flow (rCBF) patterns elicited by imagery of the visual appearance of objects to rCBF patterns elicited by imagery of the sounds made by the same objects. *Address all correspondence to: Univ.-Doz. Dr G. Goldenberg, Neurologische Universitltsklinik, Lazarettgasse 14, A 1090 Wien, Austria. 695