Neuronal correlates of sensory working memory in the auditory cortex of humans an monkeys

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Working memory (WM) refers to the processes used for temporarily storing information and is a fundamental prerequisite for our abilities to perform everyday functions. It involves a broad network of brain areas including sensory cortices. A role of early auditory cortex in auditory WM also appears likely because of the high accuracy of auditory WM. In a convergent approach with humans and non-human primates, we have conducted, in the current funding period, series of experiments requiring the performance of different tasks on the same stimulus material, sequences of two sounds separated by a delay. While subjects performed the tasks, single- and multiunit activity and local field potentials were recorded in monkey auditory and prefrontal cortices and magnetic fields in humans. Collectively, the results of these experiments demonstrate that differential activity in auditory cortex during the delay is partly due to true auditory WM and not only to other cognitive processes inevitably involved in such paradigms and intermingled with the memory process, such as anticipation of the second stimulus, preparation for motor response alternatives or expectation of a reward. Based on the successful realization of the initial research plan, we now propose to model the monkey and human data and to test, by means of new experiments (involving intracortical electrical stimulation in monkeys and magnetic field recordings in humans), predictions generated by the model. We will use the computational model of information processing in auditory cortex by May and colleagues. This model is ideally suited for the present purpose because it allows to simultaneously simulate neural activity and local field potentials on a mesoscopic scale and the generation of magnetic fields on a macroscopic level. It therefore provides a much-needed link between intra- and extracranial neural activity measures.