Dissociable effects of top-down and bottom-up attention during episodic encoding.
It is well established that the formation of memories for life's experiences-episodic memory-is influenced by how we attend to those experiences, yet the neural mechanisms by which attention shapes episodic encoding are still unclear. We investigated how top-down and bottom-up attention contribute to memory encoding of visual objects in humans by manipulating both types of attention during fMRI of episodic memory formation. We show that dorsal parietal cortex-specifically, intraparietal sulcus (IPS)-was engaged during top-down attention and was also recruited during the successful formation of episodic memories. By contrast, bottom-up attention engaged ventral parietal cortex-specifically, temporoparietal junction (TPJ)-and was also more active during encoding failure. Functional connectivity analyses revealed further dissociations in how top-down and bottom-up attention influenced encoding: while both IPS and TPJ influenced activity in perceptual cortices thought to represent the information being encoded (fusiform/lateral occipital cortex), they each exerted opposite effects on memory encoding. Specifically, during a preparatory period preceding stimulus presentation, a stronger drive from IPS was associated with a higher likelihood that the subsequently attended stimulus would be encoded. By contrast, during stimulus processing, stronger connectivity with TPJ was associated with a lower likelihood the stimulus would be successfully encoded. These findings suggest that during encoding of visual objects into episodic memory, top-down and bottom-up attention can have opposite influences on perceptual areas that subserve visual object representation, suggesting that one manner in which attention modulates memory is by altering the perceptual processing of to-be-encoded stimuli.
Pubmed ID: 21880922 RIS Download
Adolescent | Adult | Analysis of Variance | Attention | Brain Mapping | Female | Humans | Image Processing, Computer-Assisted | Magnetic Resonance Imaging | Male | Mental Recall | Neural Pathways | Neuropsychological Tests | Oxygen | Parietal Lobe | Pattern Recognition, Visual | Photic Stimulation | Reaction Time | Recognition (Psychology) | Reproducibility of Results | Statistics as Topic | Young Adult