The neural substrates of cognitive empathy.

Neuroscientific research has consistently found that the perception of an affective state in another activates the observer's own neural substrates for the corresponding state, which is likely the neural mechanism for "true empathy." However, to date there has not been a brain-imaging investigation of so-called "cognitive empathy", whereby one "actively projects oneself into the shoes of another person," imagining someone's personal, emotional experience as if it were one's own. In order to investigate this process, we conducted a combined psychophysiology and PET and study in which participants imagined: (1) a personal experience of fear or anger from their own past; (2) an equivalent experience from another person as if it were happening to them; and (3) a nonemotional experience from their own past.

Interoceptive awareness in experienced meditators.

Attention to internal body sensations is practiced in most meditation traditions. Many traditions state that this practice results in increased awareness of internal body sensations, but scientific studies evaluating this claim are lacking. We predicted that experienced meditators would display performance superior to that of nonmeditators on heartbeat detection, a standard noninvasive measure of resting interoceptive awareness.

Basic emotions are associated with distinct patterns of cardiorespiratory activity.

The existence of specific somatic states associated with different emotions remains controversial. In this study, we investigated the profile of cardiorespiratory activity during the experience of fear, anger, sadness and happiness. ECG and respiratory activity was recorded in 43 healthy volunteers during the recall and experiential reliving of one or two potent emotional autobiographical episodes and a neutral episode.

Preferring one taste over another without recognizing either.

Stimuli can be discriminated without being consciously perceived and can be preferred without being remembered. Here we report a subject with a previously unknown dissociation of abilities: a strong behavioral preference for the taste of sugar over saline, despite a complete failure of recognition. The pattern of brain damage responsible for the dissociation suggests that reliable behavioral choice among tastes can occur in the absence of the gustatory cortex necessary for taste recognition.

Investment behavior and the negative side of emotion.

Can dysfunction in neural systems subserving emotion lead, under certain circumstances, to more advantageous decisions? To answer this question, we investigated how normal participants, patients with stable focal lesions in brain regions related to emotion (target patients), and patients with stable focal lesions in brain regions unrelated to emotion (control patients) made 20 rounds of investment decisions. Target patients made more advantageous decisions and ultimately earned more money from their investments than the normal participants and control patients. When normal participants and control patients either won or lost money on an investment round, they adopted a conservative strategy and became more reluctant to invest on the subsequent round; these results suggest that they were more affected than target patients by the outcomes of decisions made in the previous rounds.

A mechanism for impaired fear recognition after amygdala damage.

Ten years ago, we reported that SM, a patient with rare bilateral amygdala damage, showed an intriguing impairment in her ability to recognize fear from facial expressions. Since then, the importance of the amygdala in processing information about facial emotions has been borne out by a number of lesion and functional imaging studies. Yet the mechanism by which amygdala damage compromises fear recognition has not been identified.

A neural basis for collecting behaviour in humans.

Collecting behaviour is commonplace in the normal population, but there has been little investigation of its neural basis in humans. The observation that collecting behaviour can assume pathological proportions in patients with certain patterns of brain damage led us to hypothesize that dysfunction in a system encompassing mesial prefrontal cortices accounts for abnormal collecting and may guide normal collecting. We tested the hypothesis in 86 subjects with focal lesions of the telencephalon, by relating the neuroanatomical placement of the lesions to the presence of repetitive and indiscriminate acquisition behaviour and impaired discard behaviour.

Dissociable neural systems for recognizing emotions.

This study tested the hypothesis that the recognition of emotions would draw upon anatomically separable brain regions, depending on whether the stimuli were static or explicitly conveyed information regarding actions. We investigated the hypothesis in a rare subject with extensive bilateral brain lesions, patient B., by administering tasks that assessed recognition and naming of emotions from visual and verbal stimuli, some of which depicted actions and some of which did not.

Neuroanatomical correlates of brainstem coma.

The brainstem tegmentum, including the reticular formation, contains distinct nuclei, each of which has a set of chemical, physiological and anatomical features. Damage to the brainstem tegmentum is known to cause coma, the most radical disturbance of consciousness. However, it has remained unclear which nuclei within the tegmentum are crucial for the maintenance of consciousness in humans.

Differential distribution of calbindin D28k and parvalbumin among functionally distinctive sets of structures in the macaque brainstem.

In a study of brainstem in the cynomolgus monkey, we found that the distribution of calbindin D28K (CB) and parvalbumin (PV) is nonoverlapping among functionally distinct sets of brainstem structures. Nuclei involved in representation and regulation of the organism's internal state contain CB, whereas those involved in the representation of the external environment and the representation or execution of externally directed actions contain only PV. Moreover, our findings indicate that different nuclei known as components of the ascending reticular activating system (ARAS) contain either CB or PV or both, suggesting that this system in primates operates with both CB and PV.

Role of the amygdala in decision-making.

The somatic marker hypothesis proposes that both the amygdala and the orbitofrontal cortex are parts of a neural circuit critical for judgment and decision-making. Although both structures couple exteroceptive sensory information with interoceptive information concerning somatic/emotional states, they do so at different levels, thus making different contributions to the process. We define "primary inducers" as stimuli that unconditionally, or through learning (e.

Neural correlates of conceptual knowledge for actions.

The neural correlates of conceptual knowledge for actions are not well understood. To begin to address this knowledge gap, we tested the hypothesis that the retrieval of conceptual knowledge for actions depends on neural systems located in higher-order association cortices of left premotor/prefrontal, parietal, and posterior middle temporal regions. The investigation used the lesion method and involved 90 subjects with damage to various regions of the left or right hemisphere.