A Brain System for Auditory Working Memory.
The brain basis for auditory working memory, the process of actively maintaining sounds in memory over short periods of time, is controversial. Using functional magnetic resonance imaging in human participants, we demonstrate that the maintenance of single tones in memory is associated with activation in auditory cortex. In addition, sustained activation was observed in hippocampus and inferior frontal gyrus. Multivoxel pattern analysis showed that patterns of activity in auditory cortex and left inferior frontal gyrus distinguished the tone that was maintained in memory. Functional connectivity during maintenance was demonstrated between auditory cortex and both the hippocampus and inferior frontal cortex. The data support a system for auditory working memory based on the maintenance of sound-specific representations in auditory cortex by projections from higher-order areas, including the hippocampus and frontal cortex.


CONCLUSIONS
In this work, we demonstrate a system for maintaining sound in working memory based on activity in auditory cortex, hippocampus, and frontal cortex, and functional connectivity among them. Specifically, our work makes three advances from the previous work. First, we robustly demonstrate hippocampal involvement in all phases of auditory working memory (encoding, maintenance, and retrieval): the role of hippocampus in working memory is controversial. Second, using a pattern classification technique, we show that activity in the auditory cortex and inferior frontal gyrus is specific to the maintained tones in working memory. Third, we show long-range connectivity of auditory cortex to hippocampus and frontal cortex, which may be responsible for keeping such representations active during working memory maintenance.
Auditory Group, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom, Wellcome Trust Centre for Neuroimaging, London WC1N 3BG, United Kingdom, sukhbinder.kumar@ncl.ac.uk.
Sukhbinder
S
Kumar
Institute of Cognitive Neuroscience, London, United Kingdom, Institute of Neurology, UCL Neuroscience, London WC1N 3AR, United Kingdom.
Sabine
S
Joseph
Human Brain Research Laboratory, Department of Neurosurgery, The University of Iowa, Iowa City, Iowa 52242.
Phillip E
PE
Gander
UCL Ear Institute, London WC1X 8EE, United Kingdom, and.
Nicolas
http://orcid.org/0000-0003-1495-561X
N
Barascud
Department of Psychology, Bucknell University, Lewisburg, Pennsylvania 17837.
Andrea R
AR
Halpern
Auditory Group, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom, Wellcome Trust Centre for Neuroimaging, London WC1N 3BG, United Kingdom.
Timothy D
TD
Griffiths
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000378:metabolism*; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D001931:Brain Mapping / Q000379:methods; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000378:metabolism*
MVPA; auditory cortex; fMRI; hippocampus; working memory