Decoding parametric attributes of auditory working memories from human brain activity Auditory working memory (WM) refers to our capacity to maintain and manipulate relevant sound information to support communication and problem solving. Auditory WM dysfunctions are evidenced in individuals with speech perception disorders, language and reading impairments, and other disorders involving dysfunction of auditory cognition, such as central auditory processing disorders (CAPD). Better understanding of auditory WM would help develop more precise biomarkers and targeted interventions for these deficits. Evidence for neuronal activation related to auditory WM patterns have been found in laboratory animals as well as in non- invasive human neuroimaging studies, both in auditory cortices (AC) and elsewhere in the brain. Recent human fMRI data also provide some evidence on item-specific activation patterns in ACs and frontal cortices. However, exactly where in the brain auditory WM content is stored and, more importantly, how the memorized information is represented is still unclear. This research program pursues a better understanding of human auditory WM by attempting to infer its contents from the brain: Using state-of-the-art non-invasive neuroimaging and advanced signal-analysis methods we will search for cortical activation patterns that would predict item-specific WM information. We will examine brain function non-invasively with magneto- and electroencephalography (MEG/EEG), transcranial magnetic stimulation (TMS), and functional MRI (fMRI), and validate the findings using intracranial EEG (iEEG) measurements in presurgical patients. Recent studies suggest that, instead of persistent activation patterns, WM is supported by short-term synaptic facilitation, i.e., activity-silent population-level mechanisms. We hypothesize that these activity-silent representations could be decoded by analyzing the aftereffects of generic auditory impulse stimuli or TMS, which are utilized to ping the underlying cortical network during memory maintenance. We also hypothesize that although auditory WM likely involves co-operation of multiple brain regions, which are involved in articulatory-motor functions, perceptual categorization, or semantic processing, the retention of auditory-sensory attributes such as spectrotemporal modulation patterns critically depends on ACs. To examine WM of such auditory attributes, we will use tasks with dynamic ripple sound stimuli, which are spectrotemporally similar to human vocalizations but resist non-auditory processing strategies. The major significance of this project is that it will increase the understanding of auditory WM, a crucial cognitive function whose neuronal bases have remained elusive. The results may also help develop more precise tools for characterizing auditory WM dysfunctions in hearing and communication deficits as well as in disorders such as dyslexia, attention deficit/hyperactivity disorder (ADHD), and schizophrenia.
Auditory working memory (WM) refers to our capacity to maintain and manipulate relevant sound information to support communication and problem solving. Our research program pursues a better theoretical understanding of this crucial cognitive function using advanced multimodal neuroimaging methods, validated using intracranial recordings in pre-surgical patients. Our results may also help develop more precise tools for characterizing auditory WM dysfunctions in speech perception disorders, language and reading impairments, and other disorders involving dysfunction of auditory cognition, such as attention deficit/hyperactivity disorder (ADHD) and schizophrenia.
