Parietal and frontal contributions to episodic encoding of location.

Specific contributions of frontal and parietal regions to visuospatial encoding and attention remain controversial. This study used fMRI to examine associative encoding of sequentially-presented spatial cues and object stimuli. The cue preceded the centrally-displayed object by a jittered-delay-interval to better isolate attempt and success in episodically integrating pure location information with separately presented objects. Superior parietal response was modulated by attempted location binding, while superior/middle frontal response was predictive of successful location binding.

The timing of associative memory formation: frontal lobe and anterior medial temporal lobe activity at associative binding predicts memory.

The process of associating items encountered over time and across variable time delays is fundamental for creating memories in daily life, such as for stories and episodes. Forming associative memory for temporally discontiguous items involves medial temporal lobe structures and additional neocortical processing regions, including prefrontal cortex, parietal lobe, and lateral occipital regions. However, most prior memory studies, using concurrently presented stimuli, have failed to examine the temporal aspect of successful associative memory formation to identify when activity in these brain regions is predictive of associative memory formation. In the current study, functional MRI data were acquired while subjects were shown pairs of sequentially presented visual images with a fixed interitem delay within pairs. This design allowed the entire time course of the trial to be analyzed, starting from onset of the first item, across the 5.5-s delay period, and through offset of the second item. Subjects then completed a postscan recognition test for the items and associations they encoded during the scan and their confidence for each. After controlling for item-memory strength, we isolated brain regions selectively involved in associative encoding. Consistent with prior findings, increased regional activity predicting subsequent associative memory success was found in anterior medial temporal lobe regions of left perirhinal and entorhinal cortices and in left prefrontal cortex and lateral occipital regions. The temporal separation within each pair, however, allowed extension of these findings by isolating the timing of regional involvement, showing that increased response in these regions occurs during binding but not during maintenance.

Activity in the hippocampus and neocortical working memory regions predicts successful associative memory for temporally discontiguous events.

Models of mnemonic function suggest that the hippocampus binds temporally discontiguous events in memory (Wallenstein, Eichenbaum, & Hasselmo, 1998), which has been supported by recent studies in humans. Less is known, however, about the involvement of working memory in bridging the temporal gap between to-be-associated events. In this study, subsequent memory for associations between temporally discontiguous stimuli was examined using functional magnetic resonance imaging. In the scanner, subjects were instructed to remember sequentially presented images. Occasionally, a plus-sign was presented during the interstimulus interval between two images, instructing subjects to associate the two images as a pair. Following the scan, subjects identified remembered images and their pairs. Images following the plus-sign were separated into trials in which items were later recognized and the pair remembered, recognized and the pair forgotten, or not recognized. Blood-oxygen-level-dependent responses were measured to identify regions where response amplitude predicted subsequent associative- or item memory. Distinct neocortical regions were involved in each memory condition, where activity in bilateral frontal and parietal regions predicted memory for associative information and bilateral occipital and medial frontal regions for item information. While activity in posterior regions of the medial temporal lobe showed an intermediate response predicting memory for both conditions, bilateral hippocampal activity only predicted associative memory.

Outpatient morning report: a new educational venue.

Increasingly, medical educators are looking for ways to train residents and medical students in outpatient medicine. One novel idea, outpatient morning report, draws upon the concept of inpatient morning report and applies a similar conference format to the outpatient setting. The authors describe outpatient morning report and comment on its successful use in their institution.