The pupil as a measure of emotional arousal and autonomic activation

Pupil diameter was monitored during picture viewing to assess effects of hedonic valence and emotional arousal on pupillary responses. Autonomic activity (heart rate and skin conductance) was concurrently measured to determine whether pupillary changes are mediated by parasympathetic or sympathetic activation. Following an initial light reflex, pupillary changes were larger when viewing emotionally arousing pictures, regardless of whether these were pleasant or unpleasant. Pupillary changes during picture viewing covaried with skin conductance change, supporting the interpretation that sympathetic nervous system activity modulates these changes in the context of affective picture viewing. Taken together, the data provide strong support for the hypothesis that the pupil's response during affective picture viewing reflects emotional arousal associated with increased sympathetic activity.     

The influence of subliminal emotional words on functional hemispheric asymmetry

The P300 component of the evoked potential was recorded over both hemispheres in order to study interhemispheric differences in the process of perception of subliminal verbal stimuli. The stimuli--subliminal words, neutral and emotional--were presented at random to the left or right visual fields. In response to an unrecognized emotional word, the amplitude of P300 wave increased diffusely over both hemispheres as compared to that to a neutral word, with no changes in interhemispheric differences. The interhemispheric difference changed considerably in the presence of an 'unaccountable' emotion caused by a subliminal word. This suggests a unilateral activation of the right hemisphere and a predominant role of this hemisphere in the cortical organization of the unconscious function 'unaccountable' emotion.     

Estrogen modifies arousal but not memory for emotional events in older women

Emotional arousal and the affective content of events influence memory. These effects shift with age such that older people find negative information less arousing and remember proportionately more positive events compared to the young. The emotional enhancement of memory is mediated by medial temporal lobe limbic structures and the prefrontal cortex, which are both affected by sex hormones. We examined whether hormone use (estrogen or estrogen and progesterone) in older women modulated perceptions of valence and arousal, and subsequent memory for emotional images or stories. Their performance was compared to younger women. Hormone use in older women resulted in higher arousal for negative images and stories but memory was not affected. We hypothesize that estrogen modifies the influence of the amygdala and the prefrontal cortex on emotion, but that age-related changes in the hippocampus prevent the enhancement of emotional memory in older women.     

Direct and indirect semantic priming with neutral and emotional words in schizophrenia: Relationship to delusions

Introduction. Evidence is accumulating that suggests that semantic networks are abnormal in schizophrenia. Methods. To investigate this further, we examined priming in 42 schizophrenics and 28 normal controls on a lexical decision task involving three different prime-target conditions all at 700 ms stimulus onset asynchrony (SOA): directly semantically related, indirectly semantically related, and unrelated; and three types of emotional pairings: positive, negative, and neutral. Two schizophrenic groups were compared: nondeluded (no current delusions) and deluded. Results. Schizophrenic patients did not demonstrate significant direct priming overall, whereas controls did. However, when material was examined according to emotional pairing, the controls and deluded subjects demonstrated significant priming to neutral word pairs. Neither schizophrenic group showed direct priming with positive and negative word pairings, the deluded subjects showing inhibition of priming with negative stimuli. Controls failed to show direct priming with negative stimuli. Indirect priming was obtained in all groups. The absence of direct priming and indirect priming with negative material in deluded subjects was particularly striking. The results point to quantitative and qualitative abnormalities in semantic networks in schizophrenia. Conclusions. We propose that delusions may be the result of intact, unusual (indirect) associations in contrast to poorer normal (semantic) associations; a particular bias being shown toward material of a negative valence.     

The effect of age on memory for emotional faces

Prior studies of emotion suggest that young adults should have enhanced memory for negative faces and that this enhancement should be reduced in older adults. Several studies have not shown these effects but were conducted with procedures different from those used with other emotional stimuli. In this study, researchers examined age differences in recognition of faces with emotional or neutral expressions, using trial-unique stimuli, as is typically done with other types of emotional stimuli. They also assessed the influence of personality traits and mood on memory. Enhanced recognition for negative faces was found in young adults but not in older adults. Recognition of faces was not influenced by mood or personality traits in young adults, but lower levels of extraversion and better emotional sensitivity predicted better negative face memory in older adults. These results suggest that negative expressions enhance memory for faces in young adults, as negative valence enhances memory for words and scenes. This enhancement is absent in older adults, but memory for emotional faces is modulated in older adults by personality traits that are relevant to emotional processing.     

The influence of APOE status on episodic and semantic memory: data from a population-based study

In a prospective cohort study, the authors demonstrated a more pronounced epsilon4-related deficit for participants 70 years of age and older in tasks assessing episodic recall. Apolipoprotein E (APOE) and age interacted for episodic memory tasks, whereas the interaction for semantic memory tasks was between APOE and test wave. Heterozygotes of epsilon4 between middle-age and young-old participants performed at a higher level than noncarriers of this allele in recall tasks. A dose effect was found such that carriers of 2 epsilon4 alleles failed more profoundly in acquiring and recollecting episodic information than carriers of 1 epsilon4 allele, who in turn failed more than carriers of non-epsilon4 alleles. The pattern of findings observed for older epsilon4 carriers suggests that these individuals have particular difficulty when the executive task demands are high. Several factors (e.g., smaller hippocampal volumes, less effective neural repair mechanisms) may account for these findings. On the basis of the data obtained, the authors argue that analyses of the effect of specific genes in cognition should be accompanied by assessment of performance at a specific level, with due attention to the individual's age.     

The effects on cardiovascular autonomic control of repetitive arousal from sleep

STUDY OBJECTIVES: To quantitatively assess autonomic cardiovascular control in normal young adults following exposure to repetitive acoustically-induced arousals from sleep. DESIGN: Respiration, R-R interval (RRI) and noninvasive measurements of continuous arterial blood pressure were monitored in subjects during the transition from relaxed wakefulness to stable Stage 2 sleep. These measurements were made under undisturbed conditions or conditions in which transient arousals were induced repetitively by acoustic stimulation. A mathematical model was used to partition the fluctuations in RRI into a component ("RSA") correlated with respiration and a component ("A representing baroreflex control of heart rate. The magnitudes and forms of each component before and after exposure to repetitive arousals were compared SETTING: Sleep disorders laboratory in a university setting. PATIENTS OR PARTICIPANTS: Ten healthy young adults (5 male, 5 female) with an average age of 20.4 +/- 2.0 y and mean body-mass index of 23.8 +/- 2.9 kg/m2. INTERVENTIONS: Each subject participated in multiple sleep studies consisting of 4 conditions with 2 nights in each condition. The first condition consisted of undisturbed sleep (control), while in the other 3 conditions, the subjects were aroused from sleep by repetitive auditory stimuli applied continuously over a duration of 50 minutes, with periodicities of 30 seconds, 1 minute, and 2 minutes of sleep. MEASUREMENTS AND RESULTS: Exposure to repetitive arousal (RA) did not alter mean heart rate or blood pressure. However, ABR and RSA gains estimated using the model, increased from the onset of Stage 1 sleep to the start of stable Stage 2 sleep under the control condition, but remained unchanged in all RA conditions. There were also significant increases in low-frequency oscillations of systolic blood pressure in the RA conditions versus no change in the control condition. CONCLUSIONS: Exposure to RA over durations approximating an hour produces cumulative effects on autonomic control that are subtle and can only be detected when advanced signal processing methods are employed. More specifically, the increases in ABR and RSA gains that accompany increasing sleep depth in normal sleep are prevented from occurring.     

Evaluating semantic similarity and relatedness over the semantic grouping of clinical term pairs

IntroductionThis article explores how measures of semantic similarity and relatedness are impacted by the semantic groups to which the concepts they are measuring belong. Our goal is to determine if there are distinctions between homogeneous comparisons (where both concepts belong to the same group) and heterogeneous ones (where the concepts are in different groups). Our hypothesis is that the similarity measures will be significantly affected since they rely on hierarchical is-a relations, whereas relatedness measures should be less impacted since they utilize a wider range of relations. In addition, we also evaluate the effect of combining different measures of similarity and relatedness. Our hypothesis is that these combined measures will more closely correlate with human judgment, since they better reflect the rich variety of information humans use when assessing similarity and relatedness.MethodWe evaluate our method on four reference standards. Three of the reference standards were annotated by human judges for relatedness and one was annotated for similarity.ResultsWe found significant differences in the correlation of semantic similarity and relatedness measures with human judgment, depending on which semantic groups were involved. We also found that combining a definition based relatedness measure with an information content similarity measure resulted in significant improvements in correlation over individual measures.AvailabilityThe semantic similarity and relatedness package is an open source program available from http://umls-similarity.sourceforge.net/. The reference standards are available at http://www.people.vcu.edu/∼{}btmcinnes/downloads.html.     

The disparate effects of Alzheimer's disease and Huntington's disease on semantic memory.

Alzheimer's disease (AD) and Huntington's disease (HD) impair performance on semantic memory tasks, but researchers disagree on whether AD and HD cause these impairments in the same manner. According to one view, AD disrupts the storage of semantic memories, whereas HD disrupts the retrieval of semantic memories. Dissenters argue that AD, like HD, disrupts retrieval. In this study, participants generated category exemplars (e.g., kinds of fruits) for 1 min, and response latencies were examined. Relative to healthy controls, the 12 AD patients produced a larger proportion of responses earlier in the recall period, consistent with the view that AD patients quickly exhaust their limited supply of items in storage. By contrast, the 12 HD patients produced a larger proportion of their responses late in the recall period, consistent with the view that HD slows retrieval.     

Pre-learning stress differentially affects long-term memory for emotional words, depending on temporal proximity to the learning experience

Stress exerts a profound, yet complex, influence on learning and memory and can enhance, impair or have no effect on these processes. Here, we have examined how the administration of stress at different times before learning affects long-term (24-hr) memory for neutral and emotional information. Participants submerged their dominant hand into a bath of ice cold water (Stress) or into a bath of warm water (No stress) for 3 min. Either immediately (Exp. 1) or 30 min (Exp. 2) after the water bath manipulation, participants were presented with a list of 30 words varying in emotional valence. The next day, participants' memory for the word list was assessed via free recall and recognition tests. In both experiments, stressed participants exhibited greater blood pressure, salivary cortisol levels, and subjective pain and stress ratings than non-stressed participants in response to the water bath manipulation. Stress applied immediately prior to learning (Exp. 1) enhanced the recognition of positive words, while stress applied 30 min prior to learning (Exp. 2) impaired free recall of negative words. Participants' recognition of positive words in Experiment 1 was positively associated with their heart rate responses to the water bath manipulation, while participants' free recall of negative words in Experiment 2 was negatively associated with their blood pressure and cortisol responses to the water bath manipulation. These findings indicate that the differential effects of pre-learning stress on long-term memory may depend on the temporal proximity of the stressor to the learning experience and the emotional nature of the to-be-learned information.     

Preservation of memory for people in semantic memory disorder: Further category-specific semantic dissociation

ML, a 70-year-old right-handed woman, presented with a history of semantic memory difficulties and a profound anomia affecting both proper nouns and common nouns following a left-hemisphere CVA some years earlier. She was found to show a striking contrast between her ability to make fine-grained semantic distinctions between objects and animals, on the one hand, and famous faces and names, on the other. Although she was impaired on a series of picture and word semantic comprehension tests when the stimuli consisted of exemplars of object and animal categories, her performance was intact when the materials comprised famous faces and names, suggesting a dissociation between the representation of person-specific knowledge and other categories of semantic information. A number of cases have been reported in which person-specific knowledge has been selectively impaired, but we would suggest that our case provides the clearest evidence so far of the reverse dissociation, in which person-specific knowledge is selectively preserved. We speculate on possible differences in the ways in which person-specific knowledge may be represented, relative to information about objects and animals.     

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 neural basis of semantic memory: evidence from semantic dementia

Semantic dementia (SD) is a syndrome of progressive impairment in semantic memory. Fifty-eight brain regions were measured in seven post mortem SD cases, ten normal controls and two disease controls (diagnosis frontotemporal dementia and motor neuron disease, FTD–MND). Manual segmentation of the whole brain has not previously been undertaken in a series of SD cases, either post mortem or during life. Widespread volume loss relative to controls was found in SD, with anterior temporal lobe regions bearing the brunt (>60% atrophy of temporopolar and perirhinal cortices bilaterally). Comparison of regional volumes in SD and FTD–MND found greater atrophy in SD only in temporopolar and perirhinal volumes. The sole region showing atrophy relative to controls in FTD–MND but not SD was motor cortex. Posterior temporal and frontal regions were not consistently affected and no significant asymmetry of atrophy was found. In summary, whole-brain regional evaluation in SD, in comparison with normal controls and FTD–MND, found anterior temporal atrophy encompassing the perirhinal cortex with relative sparing of adjacent posterior temporal regions.     

Measures of semantic similarity and relatedness in the biomedical domain

Measures of semantic similarity between concepts are widely used in Natural Language Processing. In this article, we show how six existing domain-independent measures can be adapted to the biomedical domain. These measures were originally based on WordNet, an English lexical database of concepts and relations. In this research, we adapt these measures to the SNOMED-CT ontology of medical concepts. The measures include two path-based measures, and three measures that augment path-based measures with information content statistics from corpora. We also derive a context vector measure based on medical corpora that can be used as a measure of semantic relatedness. These six measures are evaluated against a newly created test bed of 30 medical concept pairs scored by three physicians and nine medical coders. We find that the medical coders and physicians differ in their ratings, and that the context vector measure correlates most closely with the physicians, while the path-based measures and one of the information content measures correlates most closely with the medical coders. We conclude that there is a role both for more flexible measures of relatedness based on information derived from corpora, as well as for measures that rely on existing ontological structures.     

The relationship between physiological arousal and cortical and autonomic responses to postural instability

Postural instability evokes cortical and autonomic reactions in addition to the primary compensatory response, and it is hypothesized that these responses may be related to underlying affective influences such as tonic physiological arousal. The purpose of this study was to determine whether perturbation-evoked cortical potentials (N1 and P2) and electrodermal responses (EDRs) were related to each other or to tonic electrodermal level (EDL). Ten healthy individuals received sixty perturbations while standing at ground level (LOW) and at the edge of an elevated platform (HIGH), where an unsuccessful reaction could lead to a fall from a height of 160 cm. Postural responses, tonic EDLs and N1 potentials were all significantly larger (p ≤ 0.01) at the HIGH height relative to LOW. EDR amplitudes did not show a main effect of condition, but habituated less at the HIGH height (interaction p = 0.04). P2 potentials were not different between conditions (p > 0.05). There was no statistically significant relationship between the magnitude of change in N1 amplitude between conditions and the change in EDR amplitude between conditions (R = 0.25, p = 0.5), between magnitude of N1 change and magnitude of EDL change (R = −0.23, p = 0.25), or between magnitude of EDR change and EDL change (R = −0.51, p = 0.16). Altered cortical and autonomic responses at the HIGH height were independent of elevated physiological arousal. These findings have implications for understanding the role of cortical and autonomic responses in compensatory balance control, and alleviate concerns about the potential influence of underlying arousal on electrodermal reactivity.