Older adults catch up to younger adults on a learning and memory task that involves collaborative social interaction.

Learning and memory abilities tend to decline as people age. The current study examines the question of whether a learning situation that emphasises collaborative social interaction might help older persons overcome age-related learning and memory changes and thus perform similarly to younger persons. Younger and Older participants (n = 34 in each group) completed the Barrier Task (BT), a game-like social interaction where partners work together to develop labels for a set of abstract tangrams. Participants were also administered standard clinical neuropsychological measures of memory, on which the Older group showed expected inferiority to the Younger group. On the BT, the Older group performed less well than the Younger group early on, but as the task progressed, the performance of the Older group caught up and became statistically indistinguishable from that of the Younger group. These results can be taken to suggest that a learning milieu characterised by collaborative social interaction can attenuate some of the typical memory disadvantages associated with being older.

Empathy in hippocampal amnesia.

Empathy is critical to the quality of our relationships with others and plays an important role in life satisfaction and well-being. The scientific investigation of empathy has focused on characterizing its cognitive and neural substrates, and has pointed to the importance of a network of brain regions involved in emotional experience and perspective taking (e.g., ventromedial prefrontal cortex, amygdala, anterior insula, cingulate). While the hippocampus has rarely been the focus of empathy research, the hallmark properties of the hippocampal declarative memory system (e.g., representational flexibility, relational binding, on-line processing capacity) make it well-suited to meet some of the crucial demands of empathy, and a careful investigation of this possibility could make a significant contribution to the neuroscientific understanding of empathy. The present study is a preliminary investigation of the role of the hippocampal declarative memory system in empathy. Participants were three patients (1 female) with focal, bilateral hippocampal (HC) damage and severe declarative memory impairments and three healthy demographically matched comparison participants. Empathy was measured as a trait through a battery of gold standard questionnaires and through on-line ratings and prosocial behavior in response to a series of empathy inductions. Patients with hippocampal amnesia reported lower cognitive and emotional trait empathy than healthy comparison participants. Unlike healthy comparison participants, in response to the empathy inductions hippocampal patients reported no increase in empathy ratings or prosocial behavior. The results provide preliminary evidence for a role for hippocampal declarative memory in empathy.

Myopia for the future or hypersensitivity to reward? Age-related changes in decision making on the Iowa Gambling Task.

It has been shown that older adults perform less well than younger adults on the Iowa Gambling Task (IGT), a real-world type decision-making task that factors together reward, punishment, and uncertainty. To explore the reasons behind this age-related decrement, we administered to an adult life span sample of 265 healthy participants (Mdn age = 62.00 +/- 16.17 years; range [23-88]) 2 versions of the IGT, which have different contingencies for successful performance: A'B'C'D' requires choosing lower immediate reward (paired with lower delayed punishment); E'F'G'H' requires choosing higher immediate punishment (paired with higher delayed reward). There was a significant negative correlation between age and performance on the A'B'C'D' version of the IGT (r = -.16, p = .01), while there was essentially no correlation between age and performance on the E'F'G'H' version (r = -.07, p = .24). In addition, the rate of impaired performance in older participants was significantly higher for the A'B'C'D' version (23%) compared with the E'F'G'H' version (13%). A parsimonious account of these findings is an age-related increase in hypersensitivity to reward, whereby the decisions of older adults are disproportionately influenced by prospects of receiving reward, irrespective of the presence or degree of punishment.

Distributed neural system for general intelligence revealed by lesion mapping.

General intelligence (g) captures the performance variance shared across cognitive tasks and correlates with real-world success. Yet it remains debated whether g reflects the combined performance of brain systems involved in these tasks or draws on specialized systems mediating their interactions. Here we investigated the neural substrates of g in 241 patients with focal brain damage using voxel-based lesion-symptom mapping. A hierarchical factor analysis across multiple cognitive tasks was used to derive a robust measure of g. Statistically significant associations were found between g and damage to a remarkably circumscribed albeit distributed network in frontal and parietal cortex, critically including white matter association tracts and frontopolar cortex. We suggest that general intelligence draws on connections between regions that integrate verbal, visuospatial, working memory, and executive processes.

Poor decision making among older adults is related to elevated levels of neuroticism.

BACKGROUND: A well-studied index of reasoning and decision making is the Iowa Gambling Task (IGT). The IGT possesses many features important to medical decision making, such as weighing risks and benefits, dealing with unknown outcomes, and making decisions under uncertainty. PURPOSE: There exists a great deal of individual variability on the IGT, particularly among older adults, and the present study examines the role of personality in IGT performance. We explored which of the five-factor model of personality traits were predictive of decision-making performance, after controlling for relevant demographic variables. METHODS: One hundred and fifty-two healthy cognitively intact adults (aged 26-85) were individually administered the IGT and the NEO Five-Factory Inventory. RESULTS: In the older adults, but not the younger, higher NEO neuroticism was associated with poorer IGT performance. CONCLUSIONS: Our findings are discussed in the context of how stress may impact cognitive performance and cause dysfunction of neural systems in the brain important for decision making.

Bolus isoproterenol infusions provide a reliable method for assessing interoceptive awareness.

Interoception, defined as the perception of internal body states, plays a central role in classic and contemporary theories of emotion. In particular, deviations from baseline body states have been hypothesized to be integral to the experience of emotion and feeling. Consequently, reliable measurement of interoception is critical to the testing of emotion theories. Heartbeat perception tasks have been considered the standard method for assessing interoceptive awareness, primarily due to their non-invasive nature and technical feasibility. However, these tasks are limited by the fact that above chance group performance rates on heartbeat detection (or the frequency of 'good detectors') are rarely higher than 40%, meaning that such tasks (as they are typically utilized) do not obtain a measure of interoceptive awareness in the majority of individuals. Here we describe a novel protocol for inducing and assessing a range of deviations in body states via bolus infusions of isoproterenol, a non-selective beta adrenergic agonist. Using a randomized, double-blinded, and placebo-controlled experimental design, we found that bolus isoproterenol infusions elicited rapid and transient increases in heart rate and concomitant ratings of heartbeat and breathing sensations, in a dose-dependent manner. Our protocol revealed changes in interoceptive awareness in all 15 participants tested, thus overcoming a major limitation of heartbeat detection tasks. These findings indicate that bolus isoproterenol infusions provide a reliable method for assessing interoceptive awareness, which sets a foundation for further investigation of the role of interoceptive sensations in the experience of emotion.

Gastric myoelectrical activity as an index of emotional arousal.

Autonomic nervous system parameters such as electrodermal activity, heart rate, and facial EMG have been utilized extensively as measures of emotional arousal. One measure that has rarely been employed in this setting is gastric myoelectrical activity, despite the fact that "gut feelings" have an obvious and even profound role in everyday emotional life. It has been shown that the gastrointestinal system changes wall tonus and contraction rate during stressful tasks. However, the effects of emotionally salient stimuli on gastrointestinal motility have scarcely been studied. In the current study, emotional film clips designed to elicit happiness, disgust, fear, sadness, or no emotion (neutral) were presented to 16 normal participants. Electrogastrogram (EGG), skin conductance, and heart rate were measured while the participants viewed the film clips, and participants rated subjective arousal intensity and pleasantness of the film clips. We found that emotional film clips reliably induced the intended subjective feeling states. Also, EGG peak amplitudes in fear, disgust, sadness and happiness were higher than in the no emotion condition. There was a strong positive correlation (r=0.64) between EGG peak amplitude and subjective ratings of arousal. This is the first evidence that gastric myoelectrical activity is strongly correlated with arousal ratings to emotionally salient stimuli, and it suggests that EGG may add useful information about how the body contributes to the phenomenology of emotion and feeling.

The Iowa Gambling Task and the somatic marker hypothesis: some questions and answers.

A recent study by Maia and McClelland on participants' knowledge in the Iowa Gambling Task suggests a different interpretation for an experiment we reported in 1997. The authors use their results to question the evidence for the somatic marker hypothesis. Here we consider whether the authors' conclusions are justified.

The ability to decide advantageously declines prematurely in some normal older persons.

The prefrontal region of the brain, including the ventromedial sector which supports reasoning and decision-making, may undergo disproportionate aging in some older persons, but the empirical evidence is decidedly mixed. To help resolve this, we tested 80 neurologically and psychiatrically healthy Younger (aged 26-55) and Older (aged 56-85) adults on a "Gambling Task", which provides a close analog to real-world decision-making by factoring in reward, punishment, and unpredictability, yielding a sensitive index of ventromedial prefrontal function. A subset of the Older group manifested a decision-making impairment on the Gambling Task, in spite of otherwise intact cognitive functioning. This finding raises the possibility of disproportionate aging of the ventromedial prefrontal cortex in these individuals. Our finding has important societal and public policy implications (e.g., choosing medical care, allocating personal wealth), and may also help explain why many older individuals are targeted by and susceptible to fraudulent advertising.

Neural systems behind word and concept retrieval.

Using both the lesion method and functional imaging (positron emission tomography) in large cohorts of subjects investigated with the same experimental tasks, we tested the following hypotheses: (A) that the retrieval of words which denote concrete entities belonging to distinct conceptual categories depends upon partially segregated regions in higher-order cortices of the left temporal lobe; and (B) that the retrieval of conceptual knowledge pertaining to the same concrete entities also depends on partially segregated regions; however, those regions will be different from those postulated in hypothesis A, and located predominantly in the right hemisphere (the second hypothesis tested only with the lesion method). The analyses provide support for hypothesis A in that several regions outside the classical Broca and Wernicke language areas are involved in name retrieval of concrete entities, and that there is a partial segregation in the temporal lobe with respect to the conceptual category to which the entities belong, and partial support for hypothesis B in that retrieval of conceptual knowledge is partially segregated from name retrieval in the lesion study. Those regions identified here are seen as parts of flexible, multi-component systems serving concept and word retrieval for concrete entities belonging to different conceptual categories. By comparing different approaches the article also addresses a number of method issues that have surfaced in recent studies in this field.

The amygdala's role in long-term declarative memory for gist and detail.

In humans, the emotional nature of stimuli appears to have a complex influence on long-term declarative memory for those stimuli: Whereas emotion enhances memory for gist, it may suppress memory for detail. On the basis of prior studies, the authors hypothesized that the amygdala helps mediate the above 2 effects. Long-term memory for gist and for visual detail of aversive and neutral scenes was assessed in 20 subjects with unilateral amygdala damage and 1 rare subject with bilateral amygdala damage. Comparisons with 2 control groups (15 brain-damaged and 47 healthy) provided evidence that bilateral, but not unilateral, damage to the amygdala results in poorer memory for gist but superior memory for visual details. The pattern of findings provides preliminary support for the idea that the amygdala may help filter the encoding of relevant information from stimuli that signal threat or danger.

Emotion recognition from faces and prosody following temporal lobectomy.

The anteromedial temporal lobe has been found to participate in processing emotion, but there are unresolved discrepancies in the literature. To address this issue, the authors investigated recognition of emotion from faces and from prosody in 26 participants with unilateral temporal lobectomy (15 left, 11 right) and in 50 brain-damaged controls. Participants with right, but not left, temporal lobectomy did significantly worse in recognizing fear from facial expressions. There were no group differences in recognizing emotional prosody. Neither IQ nor basic perceptual function accounted for task performance; however, there was a moderate negative correlation between extent of amygdala damage and overall performance. Consistent with some prior studies, these findings support a role for the right anteromedial temporal lobe (including amygdala) in recognizing emotion from faces but caution in drawing conclusions from small group samples.

Severe developmental prosopagnosia in a child with superior intellect.

Developmental prosopagnosia, a lifelong inability to learn and recognize familiar faces, has rarely been reported, and there are even fewer cases that have been studied during childhood. Of the cases studied during childhood, significant "apperceptive" features to the face recognition defect have been noted. We had an opportunity to conduct extensive standard and experimental neuropsychological, psychophysiological, and neuroanatomical studies in a five-year-old child with severe developmental prosopagnosia. The subject was intellectually gifted (FSIQ = 130), but had a marked discrepancy between verbal and nonverbal abilities (VIQ = 140, PIQ = 110). Although some visual perceptual weaknesses were apparent, the subject's face recognition defect was found to cnform most closely to the "associative" type, and he did not have visual recognition deficits for any categories of nonunique entities. A novel finding was that the child's covert recognition of familiar faces based on an autonomic index was normal, suggesting that as in some adult-onset cases, the brain is capable of acquiring some information about familiar faces, even without conscious recognition. The child also had normal judgments of facial emotional expressions. Our report extends the understanding of the neuropsychological features of developmental prosopagnosia, and may help narrow the search for neuroanatomical correlates of this condition, which have yet to be identified.

A role for left temporal pole in the retrieval of words for unique entities.

Both lesion and functional imaging studies have implicated sectors of high-order association cortices of the left temporal lobe in the retrieval of words for objects belonging to varied conceptual categories. In particular, the cortices located in the left temporal pole have been associated with naming unique persons from faces. Because this neuroanatomical-behavioral association might be related to either the specificity of the task (retrieving a name at unique level) or to the possible preferential processing of faces by anterior temporal cortices, we performed a PET imaging experiment to test the hypothesis that the effect is related to the specificity of the word retrieval task. Normal subjects were asked to name at unique level entities from two conceptual categories: famous landmarks and famous faces. In support of the hypothesis, naming entities in both categories was associated with increases in activity in the left temporal pole. No main effect of category (faces vs. landmarks/buildings) or interaction of task and category was found in the left temporal pole. Retrieving names for unique persons and for names for unique landmarks activate the same brain region. These findings are consistent with the notion that activity in the left temporal pole is linked to the level of specificity of word retrieval rather than the conceptual class to which the stimulus belongs.

Neural correlates of naming actions and of naming spatial relations.

Ina [(15)O] water PET experiment, 10 normal subjects retrieved words denoting actions (performed with or without an implement), and another 10 normal subjects retrieved words denoting the spatial relations between objects. Our objective was to test the following hypothesis: that the salient neural activity associated with naming actions and spatial relations occurs in left frontal operculum and left parietal association cortices, but not in the left inferotemporal cortices (IT) or in the right parietal association cortices. There were two control tasks, one requiring a decision on the orientation of unknown faces (a standard control task in our laboratory) and another requiring the retrieval of words denoting the concrete entities used in the action and spatial relations tasks. In accordance with the hypothesis, both naming actions and spatial relations (using the face orientation task as control activated the left frontal operculum; naming actions also activated the left parietal lobe. However, sectors of the left posterior IT were also engaged in both naming actions and spatial relations. When the naming of concrete entities was subtracted from the naming of actions performed with such entities, area MT in the posterior temporo-occipital region was activated bilaterally. On the other hand, when naming of the concrete entities was subtracted from the naming of spatial relations, left parietal activation was found, and when two tasks of naming spatial relations were contrasted to each other bilateral parietal activation was seen, right when abstract stimuli were used and left when concrete objects were used. The activity in posterior IT is thought to be related to object processing and possibly name retrieval at a subconscious level.

Hemispheric perception of emotional valence from facial expressions.

The authors previously reported that normal subjects are better at discriminating happy from neutral faces when the happy face is located to the viewer's right of the neutral face; conversely, discrimination of sad from neutral faces is better when the sad face is shown to the left, supporting a role for the left hemisphere in processing positive valence and for the right hemisphere in processing negative valence. Here, the authors extend this same task to subjects with unilateral cerebral damage (31 right, 28 left). Subjects with right damage performed worse when discriminating sad faces shown on the left, consistent with the prior findings. However, subjects with either left or right damage actually performed superior to normal controls when discriminating happy faces shown on the left. The authors suggest that perception of negative valence relies preferentially on the right hemisphere, whereas perception of positive valence relies on both left and right hemispheres.

Verbal and nonverbal emotional memory following unilateral amygdala damage.

The amygdala is involved in the normal facilitation of memory by emotion, but the separate contributions of the left and right amygdala to memory for verbal or nonverbal emotional material have not been investigated. Fourteen patients with damage to the medial temporal lobe including the amygdala (seven left, seven right), 18 brain-damaged, and 36 normal controls were exposed to emotional and neutral pictures accompanied by verbal narratives. Memory for both narratives and pictures was assessed with a free recall test 24 h later. Subjects with left amygdala damage failed to show the normally robust enhancement of memory for verbal and nonverbal emotional stimuli. The group with right amygdala damage showed the normal pattern of facilitation of memory by emotion for both verbal and nonverbal stimuli despite an overall reduction in memory performance. Furthermore, subjects with left amygdala damage were disproportionately impaired on memory for emotional narratives as compared with memory for emotional pictures. The latter finding offers partial support for a lateralized and material-specific pattern of the amygdala's contribution to emotional memory.

A neural basis for the retrieval of words for actions.

Although much has been learned in recent years about the neural basis for retrieving words denoting concrete entities, the neural basis for retrieving words denoting actions remains poorly understood. We addressed this issue by testing two specific anatomical hypotheses. (1) Naming of actions depends not only on the classical implementation structures of the left frontal operculum, but also on mediational structures located in left premotor/prefrontal areas. (2) The neural systems subserving naming of actions and naming of concrete entities are segregated. The study used the lesion method and involved 75 subjects with focal, stable lesions in the left or right hemispheres, whose magnetic resonance data were analysed with a three-dimensional reconstruction method. The experimental tasks were standardised procedures for measuring action and object naming. The findings offered partial support for the hypotheses, in that: (1) lesions related to impaired action naming overlapped maximally in the left frontal operculum and in the underlying white matter and anterior insula; and (2) lesions of the left anterior temporal and inferotemporal regions, which produce impairments in naming of concrete entities, did not cause action naming deficits. A follow-up analysis indicated that action naming impairments, especially when they were disproportionate relative to concrete entity naming impairments, were not only associated with premotor/prefrontal lesions, but also with lesions of the left mesial occipital cortex and of the paraventricular white matter underneath the supramarginal and posterior temporal regions.