Neuroscience Letters 379 (2005) 127–131 The role of blind humans’ visual cortex in auditory change detection Teija Kujala a,b,c,∗ , Matias J. Palva d , Oili Salonen e , Paavo Alku f , Minna Huotilainen a,b,c , Antti J¨ arvinen f , Risto N¨ a¨ at¨ anen b,c a Helsinki Collegium for Advanced Studies, University of Helsinki, Finland b Cognitive Brain Research Unit, Department of Psychology, P.O. Box 9, FIN-00014 University of Helsinki, Siltavuorenpenger 20 C, Finland c Helsinki Brain Research Center, Helsinki, Finland d Department of Bio- and Environmental Sciences, University of Helsinki, Finland e Department of Radiology, Helsinki University Central Hospital, Finland f Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology, Espoo, Finland Received 8 September 2004; received in revised form 23 November 2004; accepted 21 December 2004 Abstract Several studies using brain imaging have demonstrated occipital-cortex activation in blind individuals during tactile and auditory tasks, suggesting that the visual cortex deprived of its normal input has adopted a new role in information processing. So far, however, at what stages of information processing and to which perceptual sub-processes this applies remains unclear. We determined the auditory functions of this cortical region in early-blind humans by means of functional magnetic resonance imaging. We found that these areas were not activated by the mere presence of sound, but were involved in the attentive processing of changes in the auditory environment, which is important in detecting potentially dangerous or other important events in the surroundings, for example. © 2004 Elsevier Ireland Ltd. All rights reserved. Keywords: Blindness; Neural plasticity; Crossmodal; Auditory A sensory-specific brain area may adopt a new function if it is deprived of its normal sensory input in deafness and blindness (for reviews, see [8,2,16]). For example, neurons in brain areas that normally process visual information become responsive to tactile [7] and auditory [18] stimuli in animals deprived of visual input after birth. Such cross-modal brain plasticity has also been shown in numerous studies in hu- man subjects (see, e.g., [3,9,23,26,20,14,22,5]). Moreover, it has been found that the occipital cortex of blind individuals indeed has a functional role in processing non-visual infor- mation: transient interference of the neural functioning in their occipital cortex with trans-cranial magnetic stimulation impairs Braille reading [3]. Occipital-cortex activation in the blind has been demon- strated during many different tasks using diverse stimuli, sug- gesting that it might be involved in various non-visual func- ∗ Corresponding author. Tel.: +358 9 191 23760; fax: +358 9 191 24509. E-mail address: teija.m.kujala@helsinki.fi (T. Kujala). tions. For example, it is activated during Braille reading [23], tactile discrimination [22], semantic processing [14], audi- tory localization [26], target-tone detection [9], and speech- listening tasks [20]. In contrast, it has been proposed that non-visual stimulation involving no task does not activate their visual areas [8,5]. Therefore, attention towards the non- visual stimuli seems to be a prerequisite for activating these brain areas. Auditory modality is essential for the blind in mediating important signals from the environment such as those indicat- ing a possible danger. Being very dependent on this modality, the blind are superior to the sighted in various auditory func- tions. For example, they are able to use echoes in order to navigate in their surroundings [24], and they are more effec- tive than the sighted in locating sound sources [17,10,11,21]. In order to fully use auditory modality as a means of de- tecting potentially important signals, one has to efficiently react to changes in the auditory environment. We addressed the role of blind humans’ occipital areas in the detection of 0304-3940/$ – see front matter © 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2004.12.070