Attention to Auditory Location and Pitch: A Behavioral, ERP, and fMRI Study

Abstract:
Within the visual system, several studies have described different subsystems that are active during attention to location, motion, and color. In the current experiment, we examined whether differentiation of attention systems exists in the auditory modality by comparing cortical activation to the same physical stimuli when subjects attended to auditory location, to pitch, or to concurrently presented visual stimuli. We presented bands of noise with different center frequencies from various locations using Virtual Auditory Space (VAS) technology. Using ERPs, cross-modal attention effects were found on short-latency components for both visual and auditory stimuli. Location attention effects were similar to those found using free-field sounds and included an enhanced negativity around 100ms for sounds from attended locations. The effects of attention to pitch were longer in latency and had distinct scalp distributions. fMRI revealed greater hemodynamic responses in appropriate sensory areas for attention to auditory and visual modalities. Attention to location was accompanied by an increased hemodynamic response in dorsal cortical regions including right parietal areas previously associated with spatial processing in other modalities. Attention to pitch was associated with a greater response in more ventral regions including those along the occipital/temporal border. These results will be discussed in the context of recently hypothesized ventral and dorsal auditory projections.