Brain mechanisms underlying reality monitoring for heard and imagined words.

Using functional MRI, we investigated reality monitoring for auditory information. During scanning, healthy young adults heard words in another person's voice and imagined hearing other words in that same voice. Later, outside the scanner, participants judged words as "heard," "imagined," or "new.

Negative effects of item repetition on source memory.

In the present study, we explored how item repetition affects source memory for new item-feature associations (picture-location or picture-color). We presented line drawings varying numbers of times in Phase 1. In Phase 2, each drawing was presented once with a critical new feature.

The cognitive neuroscience of true and false memories.

Of central relevance to the recovered/false memory debate is understanding the factors that cause us to believe that a mental experience is a memory of an actual past experience. According to the source monitoring framework (SMF), memories are attributions that we make about our mental experiences based on their subjective qualities, our prior knowledge and beliefs, our motives and goals, and the social context. From this perspective, we discuss cognitive behavioral studies using both objective (e.

Medial prefrontal cortex activity when thinking about others depends on their age.

This functional magnetic resonance imaging study examined medial prefrontal cortex (mPFC) activity as young and older participants rated an unknown young and older person, and themselves, on personality characteristics. For both young and older participants, there was greater activation in ventral mPFC (anterior cingulate) when they made judgments about own-age than other-age individuals. Additionally, across target age and participant age, there was greater activity in a more anterior region of ventral mPFC (largely medial frontal gyrus, anterior cingulate) when participants rated others than when they rated themselves.

Similar and dissociable mechanisms for attention to internal versus external information.

We compared two attentional executive processes: updating, which involved attending to a perceptually present stimulus, and refreshing, which involved attending to a mentally active representation of a stimulus no longer perceptually present. In separate blocks, participants either replaced a word being held in working memory with a different word (update), or they thought back to a just previously seen word that was no longer perceptually present (refresh). Bilateral areas of frontal cortex, supplementary motor area, and parietal cortex were similarly active for both updating and refreshing, suggesting that a common network of areas is recruited to bring information to the current focus of attention.

Age-group differences in medial cortex activity associated with thinking about self-relevant agendas.

In this functional magnetic resonance imaging (fMRI) study, we compared young and older adults' brain activity as they thought about motivationally self-relevant agendas (hopes and aspirations, duties and obligations) and concrete control items (e.g., shape of USA).

The influence of self-regulatory focus on encoding of, and memory for, emotional words.

We investigated self-regulatory focus (Higgins, 1997, 1998) as one source of variation in encoding of, and memory for, emotional words. Participants wrote about their hopes and aspirations (promotion focus) or duties and obligations (prevention focus). In a subsequent incidental encoding task during functional magnetic resonance imaging (fMRI), participants evaluated emotional (positive and negative) and neutral words as either good or bad.

Neuroimaging evidence for agenda-dependent monitoring of different features during short-term source memory tests.

A short-term source monitoring procedure with functional magnetic resonance imaging assessed neural activity when participants made judgments about the format of 1 of 4 studied items (picture, word), the encoding task performed (cost, place), or whether an item was old or new. The results support findings from long-term memory studies showing that left anterior ventrolateral prefrontal cortex (PFC) is engaged when people make source attributions about reflectively generated information (cognitive operations, conceptual features). The findings also point to a role for right lateral PFC in attention to perceptual features and/or familiarity in making source decisions.

Dissociating medial frontal and posterior cingulate activity during self-reflection.

Motivationally significant agendas guide perception, thought and behaviour, helping one to define a 'self' and to regulate interactions with the environment. To investigate neural correlates of thinking about such agendas, we asked participants to think about their hopes and aspirations (promotion focus) or their duties and obligations (prevention focus) during functional magnetic resonance imaging and compared these self-reflection conditions with a distraction condition in which participants thought about non-self-relevant items. Self-reflection resulted in greater activity than distraction in dorsomedial frontal/anterior cingulate cortex and posterior cingulate cortex/precuneus, consistent with previous findings of activity in these areas during self-relevant thought.

Refreshing one of several active representations: behavioral and functional magnetic resonance imaging differences between young and older adults.

We explored age-related differences in executive function during selection of a target from among active representations. Refreshing (thinking briefly of a just-activated representation) is an executive process that foregrounds a target relative to other active representations. In a behavioral study, participants saw one or three words, then saw a cue to refresh one of the words, saw one word again and read it, or read a new word.

A brief thought can modulate activity in extrastriate visual areas: Top-down effects of refreshing just-seen visual stimuli.

Current models of executive function hold that the internal representations of stimuli used during reflective thought are maintained in the same posterior cortical regions initially activated during perception, and that activity in such regions is modulated by top-down signals originating in prefrontal cortex. In an event-related functional magnetic resonance imaging study, we presented participants with two pictures simultaneously, a face and a scene, immediately followed either by a repetition of one of the pictures (perception) or by a cue to think briefly of one of the just-seen, but no longer present, pictures (refreshing, a reflective act). Refreshing faces and scenes modulated activity in the fusiform face area (FFA) and parahippocampal place area (PPA), respectively, as well as other regions exhibiting relative perceptual selectivity for either faces or scenes.

Refreshing: a minimal executive function.

Executive functions include processes by which important information (e.g., words, objects, task goals, contextual information) generated via perception or thought can be foregrounded and thereby influence current and subsequent processing.

Mental rubbernecking to negative information depends on task context.

We previously demonstrated mental rubbernecking during the simple cognitive act of refreshing a just activated representation. Participants saw two neutral and one negative word presented simultaneously and, 425 msec later, were cued to mentally refresh (i.e.

A functional magnetic resonance imaging investigation of short-term source and item memory for negative pictures.

We investigated the hypothesis that arousal recruits attention to item information, thereby disrupting working memory processes that help bind items to context. Using functional magnetic resonance imaging, we compared brain activity when participants remembered negative or neutral picture-location conjunctions (source memory) versus pictures only. Behaviorally, negative trials showed disruption of short-term source, but not picture, memory; long-term picture recognition memory was better for negative than for neutral pictures.

Emotional arousal can impair feature binding in working memory.

To investigate whether emotional arousal affects memorial feature binding, we had participants complete a short-term source-monitoring task-remembering the locations of four different pictures over a brief delay. On each trial, the four pictures were all either high arousal, medium arousal, or low arousal. Memory for picture-location conjunctions decreased as arousal increased.

Using fMRI to investigate a component process of reflection: prefrontal correlates of refreshing a just-activated representation.

Using fMRI, we investigated the functional organization of prefrontal cortex (PFC) as participants briefly thought of a single just-experienced item (i.e., refreshed an active representation).

An fMRI investigation of short-term source memory in young and older adults.

Using functional magnetic resonance imaging (fMRI) and a working memory procedure, we compared source memory judgments (format and location) with old-new judgments in young and older adults. Consistent with previous fMRI findings, for young adults, an area of left dorsolateral prefrontal cortex showed greater activity during format than old-new judgments made immediately, as well as those made after a brief, filled delay. In contrast, for older adults, activity in this area was not greater during format than old-new judgments at either retention interval.

Neural correlates of evaluation associated with promotion and prevention regulatory focus.

Higgins (1997, 1998) proposed two self-regulatory or motivational systems--one sensitive to gains (promotion) and one sensitive to losses (prevention). To examine the interaction of motivation and cognition, participants made good/bad or abstract/concrete judgments about concepts during fMRI scanning. After scanning, participants rated the extent to which each stimulus was good and bad and completed a questionnaire that measured promotion/prevention orientation.

Implicit and explicit evaluation: FMRI correlates of valence, emotional intensity, and control in the processing of attitudes.

Previous work suggests that explicit and implicit evaluations (good-bad) involve somewhat different neural circuits that process different dimensions such as valence, emotional intensity, and complexity. To better understand these differences, we used functional magnetic resonance imaging to identify brain regions that respond differentially to such dimensions depending on whether or not an explicit evaluation is required. Participants made either good-bad judgments (evaluative) or abstract-concrete judgments (not explicitly evaluative) about socially relevant concepts (e.

Separable neural components in the processing of black and white faces.

In a study of the neural components of automatic and controlled social evaluation, White participants viewed Black and White faces during event-related functional magnetic resonance imaging. When the faces were presented for 30 ms, activation in the amygdala-a brain region associated with emotion-was greater for Black than for White faces. When the faces were presented for 525 ms, this difference was significantly reduced, and regions of frontal cortex associated with control and regulation showed greater activation for Black than White faces.

Prefrontal cortex activity associated with source monitoring in a working memory task.

Using functional magnetic resonance imaging (fMRI), we investigated prefrontal cortex (PFC) activity during remembering specific source information (format, location judgments) versus remembering that could be based on undifferentiated information, such as familiarity (old/new recognition [ON], recency judgments). A working memory (WM) paradigm with an immediate test yielded greater activation in the lateral PFC for format and location source memory (SM) tasks than ON recognition; this SM-related activity was left lateralized. The same regions of PFC were recruited in Experiment 2 when information was tested immediately and after a filled delay.

An age-related deficit in prefrontal cortical function associated with refreshing information.

Older adults are slower than young adults to think of an item they just saw, that is, to engage or execute (or both) the simple reflective operation of refreshing just-activated information. In addition, they derive less long-term memory benefit from refreshing information. Using functional magnetic resonance imaging (fMRI), we found that relative to young adults, older adults showed reduced refresh-related activity in an area of dorsolateral prefrontal cortex (left middle frontal gyrus, Brodmann's Area 9), but not in other refresh-related areas.

FMRI evidence for an organization of prefrontal cortex by both type of process and type of information.

Neuroimaging evidence is conflicting regarding whether human prefrontal cortex (PFC) shows functional organization by type of processes engaged or type of information processed. Most studies use complex working or long-term memory tasks requiring multiple processes and the combinations of processes recruited for different materials may vary. Using functional magnetic resonance imaging (fMRI) and simple tasks suggested by a component process approach, we found activity in left PFC when participants thought about (refreshed) a just-seen item and in right PFC when participants noted whether an item had been presented previously.

Second thoughts versus second looks: an age-related deficit in reflectively refreshing just-activated information.

Age-related deficits in memory are greater as encoding and retrieval tasks require more reflective (self-generated or executive) processing. One problem in developing more specific models of age-related changes in cognition is that the tasks studied tend to be complex and vary in the combinations of component cognitive processes they recruit. Here we report an age-related deficit in one of the most elementary, but critical, components of reflection: refreshing a just-activated representation.

Neuroimaging a single thought: dorsolateral PFC activity associated with refreshing just-activated information.

Neuroimaging studies of human working memory (WM) show conflicting results regarding whether dorsolateral prefrontal cortex (PFC) contributes to maintaining information in consciousness or is recruited primarily when information must be manipulated. Using functional magnetic resonance imaging (fMRI), we looked at a minimal maintenance process--thinking back to a single, just-seen stimulus (refreshing). We found greater activity in left dorsolateral PFC (BA9) when participants refreshed a word compared to reading a word once or a second time.