Left posterior parietal cortex participates in both task preparation and episodic retrieval (original) (raw)

Optimal memory retrieval depends not only on the fidelity of stored information, but also on the attentional state of the subject. Factors such as mental preparedness to engage in stimulus processing can facilitate or hinder memory retrieval. The current study used functional magnetic resonance imaging (fMRI) to distinguish preparatory brain activity before episodic and semantic retrieval tasks from activity associated with retrieval itself. The use of a catch-trial imaging paradigm permitted separation of neural responses to preparatory task cues and memory probes. Episodic and semantic task preparation engaged a common network, including the bilateral intraparietal sulcus (IPS), left fusiform gyrus (FFG), and pre-SMA. In the subsequent retrieval phase, the left IPS participated in a frontoparietal network which responded differentially to old and new stimuli. In contrast, the right IPS was influenced only by preparatory cues, with minimal modulation during memory retrieval. Preparatory activity in the left IPS and its sensitivity to old/new differences indicate that this brain region participates both in task preparation and in episodic retrieval. This dual response profile suggests the left IPS as a possible interface between systems for domain-general attentional control and episodic retrieval.