Temporal dynamics of parietal activity during word-location binding

Most of human cognitive activity involves, to a greater or lesser extent, the integration of information from different modalities, a process also referred to as 'binding'. Although the neural basis of several forms of binding has been extensively investigated, the neurobiological mechanisms of the encoding phase of integration of words and their spatial location have not been previously investigated. This process is at the core of what Baddeley proposed in his revised model as episodic buffer. In the current experiment, the authors used magnetoencephalography to investigate the spatiotemporal patterns of brain activity related to encoding words, locations, and the integration of both types of information using a working memory paradigm. The spatiotemporal analysis showed a preferential activation of superior parietal lobe (SPL) during the integration of information, which was modulated by performance in the task. These findings are in agreement with proposals suggesting that SPL participates in binding processes by encoding and maintaining a detailed, complex integrated representation in working memory (WM). Considering Baddeley's episodic buffer, it appears that the same mechanisms involved in integrating information within one subsystem (i.e., visuospatial buffer) also support the integration of information between previously considered independent subsystems (i.e., verbal and visuospatial buffers).