Emotions: From neuropsychology to functional imaging

Recent developments in functional imaging techniques, such as Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI), allow us to characterize more precisely the functional neuroanatomy mediating emotional responding. This corpus of studies has led to the development of affective neuroscience. First, we present a summary of the studies aimed at understanding the underlying mechanisms of the emotional response, which were conducted prior to the use of the brain imaging techniques. Then, this paper reviews the studies investigating the neural substrates implicated in the processing of facial expressions and those implicated in the production of experimentally induced emotional responses. This review of the literature includes a meta‐analysis of eight studies using PET and one fMRI study reporting the neural correlates of experimentally induced emotions in healthy individuals. The methods and results of these studies are described through figures drawn from the reported Talairach's coordinates depicting the cerebral regions activated in relation to different experimental conditions. The implications of the results and the role of the cerebral structures that have been identified are discussed. As regards the studies on the neural bases of the processing of facial expressions of emotion, there are separable neural circuits that are involved in mediating responding to differing categories of facial expressions of emotion. Fearful expressions have relatively consistently been found to activate the amygdala, as, occasionally, have sad and happy expressions. The anterior insula and the putamen seem to be particularly involved in disgust expression recognition, whereas the facial expression of anger seems to be predominantly associated with anterior cingular and orbitofrontal cortex activity. Among the cerebral structures that have appeared to be activated by experimentally induced emotions, the anterior cingulate cortex seems to play a specific role in representing subjective emotional responses.     

The Interaction of Mood and Rumination in Depression: Effects on Mood Maintenance and Mood-Congruent Autobiographical Memory

Rumination is a response to distress in which individuals focus repetitively on their feelings and the causes and consequences of those feelings. When induced to ruminate, dysphorics exhibit more negative mood and recall more negative memories, but these effects are not seen in nondysphorics. This pattern of results could be due to trait-like differences between dysphoric and nondysphoric individuals, or to the high levels of negative affect that dysphorics are experiencing at the time of rumination. The purpose of this study was to evaluate the effects of pre-rumination mood on post-rumination mood and subsequent memory. Participants scoring high or low in depressive symptoms were assigned to either a positive or negative emotion induction prior to ruminating and completing an autobiographical memory task. Analysis of self-reported mood indicates that both emotion inductions were effective. Surprisingly, all participants returned to baseline mood levels following the rumination induction, and emotion induction had no effect on the negativity of the memories recalled. Dysphorics recalled significantly more negative memories than nondysphorics, regardless of whether positive, neutral, or negative memories were specifically prompted. Our results indicated that the prolonged experience of dysphoria may have greater effects on post-rumination mood and memory than the transitory experience of sadness.     

Developmental shifts in fMRI activations during visuospatial relational reasoning

To investigate maturational plasticity of fluid cognition systems, functional brain imaging was undertaken in healthy 8-19 year old participants while completing visuospatial relational reasoning problems similar to Raven's matrices and current elementary grade math textbooks. Analyses revealed that visuospatial relational reasoning across this developmental age range recruited activations in the superior parietal cortices most prominently, the dorsolateral prefrontal, occipital-temporal, and premotor/supplementary cortices, the basal ganglia, and insula. There were comparable activity volumes in left and right hemispheres for nearly all of these regions. Regression analyses indicated increasing activity predominantly in the superior parietal lobes with developmental age. In contrast, multiple anterior neural systems showed significantly less activity with age, including dorsolateral and ventrolateral prefrontal, paracentral, and insula cortices bilaterally, basal ganglia, and particularly large clusters in the midline anterior cingulate/medial frontal cortex, left middle cingulate/supplementary motor cortex, left insula-putamen, and left caudate. Findings suggest that neuromaturational changes associated with visuospatial relational reasoning shift from a more widespread fronto-cingulate-striatal pattern in childhood to predominant parieto-frontal activation pattern in late adolescence.     

Gender differences in acute and chronic stress in Wistar Kyoto (WKY) rats

While females are considered more susceptible to depressive behavior, this assertion is not strongly supported by the experimental literature. Since stress contributes to depressive behavior, male and female Wistar Kyoto (WKY) rats were exposed to either one session (acute stress) or 5 sessions (chronic stress) of restraint plus cold in order to study depressive behavior in male and female rats. After their respective treatment exposure, rats were tested in the open field test (OFT) and for retention of a passive-avoidance (P-A) task. One stress session resulted in significant immobility in the OFT for males, whereas 5 sessions were required to produce similar immobility in female rats. Acute stress interfered with the retention of the P-A response for males, while both acute and chronic stress produced poor P-A responses in female rats. Food consumption decresed, progressively, as a function of stress sessions, in female rats, whereas feeding in males returned to control levels after five stress days. Both acute and chronic stress exacerbated the stress ulcer response in male rats, but not in female rats. Chronic, but not acute, stress resulted in an increase in serotonin transporter mRNA levels in the dorsal raphe nucleus of both male and, female rats. The general consensus from these data suggested that female rats were more vulnerable to chronic stress and consequently supported the notion that females may be more susceptible to stress induced behavioral depression.     

Heightened sensitivity to facial expressions of emotion in borderline personality disorder

Individuals with borderline personality disorder (BPD) have been hypothesized to exhibit significant problems associated with emotional sensitivity. The current study examined emotional sensitivity (i.e., low threshold for recognition of emotional stimuli) in BPD by comparing 20 individuals with BPD and 20 normal controls on their accuracy in identifying emotional expressions. Results demonstrated that, as facial expressions morphed from neutral to maximum intensity, participants with BPD correctly identified facial affect at an earlier stage than did healthy controls. Participants with BPD were more sensitive than healthy controls in identifying emotional expressions in general, regardless of valence. These findings could not be explained by participants with BPD responding faster with more errors. Overall, results appear to support the contention that heightened emotional sensitivity may be a core feature of BPD.     

A first examination of the relationships between primed subconscious goals, assigned conscious goals, and task performance

The authors conducted 2 studies of subconscious goal motivation. First, the authors ran a pilot study to establish the effects of priming of subconscious goals on a performance task frequently used in goal setting research. Second, the authors conducted the main study in which the authors examined the effects of both priming of subconscious goals and assigned conscious goals on the same performance task. The authors found significant main effects of both manipulations and a significant interaction between subconscious and conscious goals. The effects of conscious difficult and do-best goals were enhanced by subconscious goals, although conscious easy goals were not affected. All effects from the main study still held after 1 day.     

Grammatical gender effects on cognition: implications for language learning and language use

In 4 experiments, the authors addressed the mechanisms by which grammatical gender (in Italian and German) may come to affect meaning. In Experiments 1 (similarity judgments) and 2 (semantic substitution errors), the authors found Italian gender effects for animals but not for artifacts; Experiment 3 revealed no comparable effects in German. These results suggest that gender effects arise as a generalization from an established association between gender of nouns and sex of human referents, extending to nouns referring to sexuated entities. Across languages, such effects are found when the language allows for easy mapping between gender of nouns and sex of human referents (Italian) but not when the mapping is less transparent (German). A final experiment provided further constraints: These effects during processing arise at a lexical-semantic level rather than at a conceptual level.     

Responding to the emotions of others: dissociating forms of empathy through the study of typical and psychiatric populations

Empathy is a lay term that is becoming increasingly viewed as a unitary function within the field of cognitive neuroscience. In this paper, a selective review of the empathy literature is provided. It is argued from this literature that empathy is not a unitary system but rather a loose collection of partially dissociable neurocognitive systems. In particular, three main divisions can be made: cognitive empathy (or Theory of Mind), motor empathy, and emotional empathy. The two main psychiatric disorders associated with empathic dysfunction are considered: autism and psychopathy. It is argued that individuals with autism show difficulties with cognitive and motor empathy but less clear difficulties with respect to emotional empathy. In contrast, individuals with psychopathy show clear difficulties with a specific form of emotional empathy but no indications of impairment with cognitive and motor empathy.