Neural activities of tactile cross-modal working memory in humans: an event-related potential study

Abstract

In the present study, we examined the neural mechanisms underlying crossmodal working memory by analyzing scalp-recorded event-related potentials (ERPs) from normal human subjects performing tactile-tactile unimodal or tactile-auditory crossmodal delay tasks that consisted of stimulus-1 (S-1, tactile), interval (delay), and stimulus-2 (S-2, tactile or auditory). We hypothesized that there are sequentially discrete task-correlated changes in ERPs representing neural processes of tactile working memory, and in addition, significant differences would be observed in ERPs between the unimodal task and the crossmodal task.In comparison to the ERP components in the unimodal task, two late positive ERP components (LPC-1 and LPC-2) evoked by the tactile S-1 in the delay of the crossmodal task were enhanced by expectation of the associated auditory S-2 presented at the end of the delay. Such enhancement might represent neural activities involved in crossmodal association between the tactile stimulus and the auditory stimulus. Later in the delay, a late negative component (LNC) was observed. The amplitude of LNC depended on information retained during the delay, and when the same information was retained, this amplitude was not influenced by modality or location of S-2 (auditory S-2 through headphones, or tactile S-2 on the left index finger). LNC might represent the neural activity involved in working memory. The above results suggest that the sequential ERP changes in the present study represent temporally distinguishable neural processes, such as the crossmodal association and crossmodal working memory.

Cooperative processing in primary somatosensory cortex and posterior parietal cortex during tactile working memory

“…The previous human electroencephalogram studies have indicated that two parietal event‐related potential components (located at about 300 and 600 ms, respectively, after the onset of tactile stimuli) are associated with cross‐modal information processing during WM (Ohara et al ., , ). Here, the causal contribution of SI and PPC to both unimodal and cross‐modal WM has been validated by stimulating them at the corresponding time points.…”

“…Here, the causal contribution of SI and PPC to both unimodal and cross‐modal WM has been validated by stimulating them at the corresponding time points. Furthermore, through comparisons in processing patterns of sensory information in the delay period between unimodal and cross‐modal tasks, the authors believe that cross‐modal information transfer does occur in the early delay, most likely during the period between 300 and 600 ms (Ohara et al ., , ).…”

The impact of social comparison on the neural substrates of reward processing: An event-related potential study

“…The LNC was commonly characterized as slow waveform, which showed modulation in late time course and reflected higher-order cognitive processes (e.g., Pfütze and Sommer, 2002;Pickering and Schweinberger, 2003;Perrin et al, 2005). Some previous studies also indicated that the LNC might be involved in working memory, such as temporarily storing, manipulating, and maintaining information (e.g., Baddeley, 1992;Ohara et al, 2008). In addition, previous studies had found that the striatum of humans exhibited a high degree of context dependency in reward processing (e.g., Elliott et al, 2000;Breiter et al, 2001;Knutson et al, 2001;Akitsuki et al, 2003;Delgado et al, 2004;Holroyd et al, 2004;Nieuwenhuis et al, 2005;Cromwell et al, 2005).…”