The retention of simultaneous tones in auditory short-term memory: a magnetoencephalography study

We used magnetoencephalography (MEG) to localize brain activity related to the retention of tones differing in pitch. Participants retained one or two simultaneously presented tones. After a two second interval a test tone was presented and the task was to determine if that tone was in memory. We focused on brain activity during the retention interval that increased as the number of sounds retained in auditory short-term memory (ASTM) increased. Source analyses revealed that the superior temporal gyrus in both hemispheres is involved in ASTM. In the right hemisphere, the inferior temporal gyrus, the inferior frontal gyrus, and parietal structures also play a role. Our method provides good spatial and temporal resolution for investigating neuronal correlates of ASTM and, as it is the first MEG study using a memory load manipulation without using sequences of tones, it allowed us to isolate brain regions that most likely reflect the simple retention of tones.