Martina Piefke

Mirror Neuron and Theory of Mind Mechanisms Involved in Face-to-Face Interactions: A Functional Magnetic Resonance Imaging Approach to Empathy

Empathy allows emotional psychological inference about other persons mental states and feelings in social contexts. We aimed at specifying the common and differential neural mechanisms of self- and other-related attribution of emotional states using event-related functional magnetic resonance imaging. Subjects viewed faces expressing emotions with direct or averted gaze and either focused on their own emotional response to each face (self-task) or evaluated the emotional state expressed by the face (other-task). The common network activated by both tasks included the left lateral orbito-frontal and medial prefrontal cortices (MPFC), bilateral inferior frontal cortices, superior temporal sulci and temporal poles, as well as the right cerebellum. In a subset of these regions, neural activity was significantly correlated with empathic abilities. The self- (relative to the other-) task differentially activated the MPFC, the posterior cingulate cortex (PCC)/precuneus, and the temporo-parietal junction bilaterally. Empathy-related processing of emotional facial expressions recruited brain areas involved in mirror neuron and theory-of-mind (ToM) mechanisms. The differential engagement of the MPFC, the PCC/precuneus, and temporo-parietal regions in the self-task indicates that these structures act as key players in the evaluation of ones own emotional state during empathic face-to-face interaction. Activation of mirror neurons in a task relying on empathic abilities without explicit task-related motor components supports the view that mirror neurons are not only involved in motor cognition but also in emotional interpersonal cognition. An interplay between ToM and mirror neuron mechanisms may hold for the maintenance of a self-other distinction during empathic interpersonal face-to-face interactions.

Gender differences in the functional neuroanatomy of emotional episodic autobiographical memory

Autobiographical memory is based on interactions between episodic memory contents, associated emotions, and a sense of self‐continuity along the time axis of ones life. The functional neuroanatomy subserving autobiographical memory is known to include prefrontal, medial and lateral temporal, as well as retrosplenial brain areas; however, whether gender differences exist in neural correlates of autobiographical memory remains to be clarified. We reanalyzed data from a previous functional magnetic resonance imaging (fMRI) experiment to investigate gender‐related differences in the neural bases of autobiographical memories with differential remoteness and emotional valence. On the behavioral level, there were no significant gender differences in memory performance or emotional intensity of memories. Activations common to males and females during autobiographical memory retrieval were observed in a bilateral network of brain areas comprising medial and lateral temporal regions, including hippocampal and parahippocampal structures, posterior cingulate, as well as prefrontal cortex. In males (relative to females), all types of autobiographical memories investigated were associated with differential activation of the left parahippocampal gyrus. By contrast, right dorsolateral prefrontal cortex was activated differentially by females. In addition, the right insula was activated differentially in females during remote and negative memory retrieval. The data show gender‐related differential neural activations within the network subserving autobiographical memory in both genders. We suggest that the differential activations may reflect gender‐specific cognitive strategies during access to autobiographical memories that do not necessarily affect the behavioral level of memory performance and emotionality. Hum Brain Mapping 24:313–324, 2005.

Posttraumatic stress disorder and fMRI activation patterns of traumatic memory in patients with borderline personality disorder.

BACKGROUND Early traumatization and additional posttraumatic stress disorder are frequent in patients with borderline personality disorder (BPD). The purpose of this study was to investigate neural correlates of traumatic memory in BPD with and without posttraumatic stress disorder (PTSD) using functional magnetic resonance imaging (fMRI). METHODS We studied 12 traumatized female patients BPD, 6 of them with and 6 without PTSD. According to an autobiographical interview key words (cues) were defined for traumatic and for negative but nontraumatic episodes. In a block-designed fMRI task patients recalled these episodes. Contrasts between trauma condition and nontrauma condition were analyzed. RESULTS Analyses for all subjects revealed activation of orbitofrontal cortex areas in both hemispheres, anterior temporal lobes, and occipital areas. In the subgroup without PTSD, activation of orbitofrontal cortex on both sides and Brocas area predominated. In the subgroup with additional PTSD, we observed right more than left activation of anterior temporal lobes, mesiotemporal areas, amygdala, posterior cingulate gyrus, occipital areas, and cerebellum. CONCLUSIONS Dependent on absence or presence of additional PTSD different neural networks seem to be involved in the traumatic memory of patients with BPD.

Functional MRI correlates of the recall of unresolved life events in borderline personality disorder

BACKGROUND Patients with borderline personality disorder (BPD) frequently report unresolved life events but it is still poorly understood, how these experiences are represented in the brain. Using functional magnetic resonance imaging (fMRI), the present study aimed at investigating the neural correlates of the recall of unresolved life events in patients with BPD and healthy controls. METHOD Twenty female BPD patients and 21 healthy control subjects underwent fMRI. During measurement subjects recalled unresolved and resolved negative life events. Individual cue words were used to stimulate autobiographical memory. After scanning, subjects rated their emotional states during the recall of both types of memories. RESULTS When contrasting unresolved and resolved life events, patients showed significant bilateral activation of frontotemporal areas including the insula, amygdala, and the anterior cingulate cortex, the left posterior cingulate cortex, right occipital cortex, the bilateral cerebellum and the midbrain. In healthy subjects, no differential brain activation was related to these conditions. The 2 x 2 factorial analysis (DeltaBPD - Deltacontrols) revealed similar results with bilateral activation of the frontal cortex including parts of the insula and of the orbitofrontal cortex, temporal activation including the amygdala, activation of the right occipital cortex, and parts of the cerebellum. Patients but not controls reported higher levels of anxiety and helplessness during the unresolved versus resolved memory condition. CONCLUSIONS The activation of both, the amygdala and prefrontal areas, might reflect an increased effortful but insufficient attempt to control intensive emotions during the recall of unresolved life events in patients with BPD.

Recollections of one's own past: the effects of aging and gender on the neural mechanisms of episodic autobiographical memory.

Episodic autobiographical recollection is the most complex form of human memory. It relies on interactions between episodic memory, associated emotions, and a sense of self-continuity along the time axis of one’s personal life history. Evidence exists that autobiographical memory performance as well as its underlying brain mechanisms are influenced by genetic, physiological, psychological, situational, and social-cultural factors. In particular, age (normal cognitive aging as well as age of memories, as defined by the time interval elapsed since information encoding) and gender affect both the performance level and the neural substrates of autobiographical recollection. In this review, studies concerned with aging and gender effects on autobiographical memory are discussed with reference to other age- and gender-related influences on human cognition, as well as clinical data on demented patients. Both age and gender act upon the functional hemispheric lateralization of autobiographical recollection and the prefrontal, hippocampal and parahippocampal engagement in information processing. On the performance level, re-collective qualities such as episodic detail and emotional intensity of autobiographical memories are modulated by both factors. Although the effects of aging and gender on human brain function are built upon different genetic and physiological mechanisms, they influence at least in part the same neurofunctional and behavioral dimensions of autobiographical recollection. Interestingly, age- and gender-related specificities in the neural mechanisms of autobiographical recollection need not be reflected on the performance level.

Basic parameters of spontaneous speech as a sensitive method for measuring change during the course of aphasia

BACKGROUND Spontaneous speech of aphasic persons is often scored on rating scales assessing aphasic symptoms. Rating scales have the advantage of an easy and fast scoring system, but might lack sensitivity. Quantitative analysis of either aphasic symptoms or basic parameters provides a useful alternative. Basic parameters are essential units of language like word categories or syntactic completeness and can be identified in both impaired and unimpaired adult and child language. AIMS To examine whether basic parameters of spontaneous speech are more sensitive to change during the course of recovery from aphasia than conventional spontaneous speech rating scales. METHODS & PROCEDURES Spontaneous speech samples of 28 aphasic participants were analysed using a quantitative computer-assisted method as well as conventional spontaneous speech rating scales before and after 7 weeks of intensive language treatment. The analysis focused on the following basic parameters: percentage words, percentage open class words, syntactic completeness, complexity, and mean length of utterances. The participants were also tested with the Aachen Aphasia Test before and after treatment. OUTCOME & RESULTS Significant change in at least one basic parameter was observed in 20 participants, while only four participants showed significant change in one of the spontaneous speech rating scales. CONCLUSIONS In comparison with conventional spontaneous speech rating scales, the basic parameters proved to be more sensitive to change. For the time being, however, some limitations remain with regard to the specificity of the basic parameters. Thus, additional data are needed to provide further support of the clinical significance of the measured changes.

Modulatory effects of levodopa on cognitive control in young but not in older subjects: A pharmacological fmri study

Older individuals show decline of prefrontal cortex (PFC) functions which may be related to altered dopaminergic neurotransmission. We investigated the effects of aging and dopaminergic stimulation in 15 young and 13 older healthy subjects on the neural correlates of interference control using fMRI. In a double-blind, placebo-controlled within-subject design, subjects were measured after levodopa (100 mg) or placebo administration. In each session, subjects performed a visual–spatial interference task based on a Stroop/Simon-like paradigm. Across age groups, interference (incongruent relative to congruent trials) was associated with activations in the presupplementary motor area, ACC, and intraparietal cortex. Increased interference was found behaviorally in older volunteers. Differential activation in left dorsolateral PFC in young subjects and bilateral PFC activity in older subjects was observed to be associated with interference control. Performance deteriorated under levodopa only in young subjects. This was accompanied by an increase of neural activity in ACC (p < .05; small-volume correction for multiple comparisons). Worsening of performance under levodopa in young subjects and the associated effect on ACC may indicate that overstimulation of the dopaminergic system compromises interference control. This supports the inverted-U-shaped model of neurotransmitter action.

Neurofunctional modulation of brain regions by distinct forms of motor cognition and movement features

Extrastriate, parietal, and frontal brain regions are differentially involved in distinct kinds of body movements and motor cognition. Using functional magnetic resonance imaging, we investigated the neural mechanisms underlying the observation and mental imagery of meaningful face and limb movements with or without objects. The supplementary motor area was differentially recruited by the mental imagery of movements while there were differential responses of the extrastriate body area (EBA) during the observation conditions. Contrary to most previous reports, the EBA responded to face movements, albeit to a lesser degree than to limb movements. The medial wall of the intraparietal sulcus and adjacent intraparietal cortex was selectively recruited by the processing of meaningful upper limb movements, irrespective of whether these were object‐related or not. Besides reach and grasp movements, the intraparietal sulcus may thus be involved in limb gesture processing, that is, in an important aspect of human social communication. We conclude that subregions of a frontal–parietal network differentially interact during the cognitive processing of body movements according to the specific motor‐related task at hand and the particular movement features involved. Hum Brain Mapp, 2009.

The neurofunctional mechanisms of traumatic and non-traumatic memory in patients with acute PTSD following accident trauma

Neurofunctional alterations in acute posttraumatic stress disorder (PTSD) and changes thereof during the course of the disease are not well investigated. We used functional magnetic resonance imaging to assess the functional neuroanatomy of emotional memory in surgical patients with acute PTSD. Traumatic (relative to non-traumatic) memories increased neural activity in the amygdala, hippocampus, lateral temporal, retrosplenial, and anterior cingulate cortices. These regions are all implicated in memory and emotion. A comparison of findings with data on chronic PTSD suggests that brain circuits affected by the acute disorder are extended and unstable while chronic disease is characterized by circumscribed and stable neurofunctional abnormalities.

Aging-related changes of neural mechanisms underlying visual-spatial working memory

Capacities of the prefrontal cortex (PFC) such as working memory (WM) are known to decline with increasing age. However, it is unclear which neurofunctional mechanisms may underlie this aging-related cognitive decline. The finding that PFC activity tends to be less lateralized in older subjects has led to the assumption of a hemispheric asymmetry reduction in the PFC associated with aging (HAROLD). Using functional magnetic resonance imaging (fMRI), we here investigated aging-related neurofunctional alterations during the performance of a visual-spatial WM task with differential levels of difficulty. Older volunteers activated dorsolateral PFC regions bilaterally while young subjects recruited these areas only in the left hemisphere. These data corroborate the hemispheric asymmetry reduction in the PFC associated with aging (HAROLD) account. However, we also observed functional reorganizations in parieto-occipital areas, and with increasing WM demands, an aging-related reversed hemispheric asymmetry of prefrontal activations. Importantly, neither PFC nor parieto-occipital reorganizations prevented older participants from showing worse WM performance than young volunteers. We conclude that frontal-parietal functional reorganizations may reflect compensational mechanisms related to aging, but do not obviate diminished visual-spatial WM performance in older people.