Biomedical subjects

Markus Mertens

Publications and source records attributed to Markus Mertens.

6 recordsLinked to original sources

PubMed2006

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.

Adult↗

PubMed2006

Left-sided interictal epileptic activity induces shift of language lateralization in temporal lobe epilepsy: an fMRI study.

PURPOSE: By using speech-activated functional MRI (fMRI), we investigated whether the frequency of left-sided interictal epileptic activity (IED: spikes or sharp waves on the EEG) is associated with atypical speech lateralization. METHODS: We investigated 28 patients (13 men, aged 17-59 years) with left-sided mesial temporal lobe epilepsy (MTLE) and 11 patients with right-sided MTLE as a control population. Only patients with unilateral hippocampal sclerosis with unilateral IED were included. For fMRI of individual patients, we contrasted images sampled during covert word generation with a low-level rest condition. With SPM99, an individual comparison for the contrast "word generation versus resting inactivity" was conducted. To characterize speech lateralization in individual patients, we calculated asymmetry indexes (AIs): the difference between activated left-sided and right-sided voxels was divided by all activated voxels. Analyzing long-term EEG, the first 2 min of each hour were evaluated for the frequency of IED. Univariate associations with AIs were assessed by Pearson's correlation and by t test. When testing the independent associations, multivariate linear regression was performed. RESULTS: The AIs in patients with left-sided MTLE were 0.40 +/- 0.53 on average (range, -0.83 to +1.0), whereas in right-sided MTLE, they were 0.78 +/- 0.15 (p = 0.029). For the further investigations, we included left-sided MTLE patients only. The median frequency of IED was six per hour (range, 0-240). Higher IED frequency was correlated with left-right shift of lateralization of speech fMRI activity (p = 0.002). CONCLUSIONS: Higher left-sided spike frequency in MTLE was associated with a left-right shift of speech representation, suggesting that chronic frequent interictal activity may induce a reorganization of speech lateralization.

Adolescent↗

PubMed2005

Functional MRI predicts memory performance after right mesiotemporal epilepsy surgery.

PURPOSE: Anterior temporal lobe resection (ATR) is a treatment option in drug-resistant epilepsy. An important risk of ATR is loss of memory because mesiotemporal structures contribute substantially to memory function. We investigated whether memory-activated functional MRI (fMRI) can predict postoperative memory loss after anterior temporal lobectomy in right-sided medial temporal lobe epilepsy (MTLE). METHODS: We included 16 patients (10 women) aged 16-54 years. The mean age at epilepsy onset was 12.5 years (range, 1-26 years). The patients' mean Wechsler IQ score was 95.2 (range, 62-125). The activation condition of fMRI consisted of retrieval from long-term memory induced by self-paced performance of an imaginative walk. All but one patient had left-sided speech dominance according to speech-activated fMRI. Outside the scanner, we evaluated the pre- and postoperative visual memory retention by using Rey Visual Design Learning Test. RESULTS: We found a correlation between the preoperative asymmetry index of memory-fMRI and the change between pre- and postsurgical measures of memory retention. Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with a favorable memory outcome after right-sided ATR. CONCLUSIONS: In light of the postoperative results, the theoretical implication of our study is that fMRI based on a simple introspective retrieval task measures memory functions. The main clinical implication of our study is that memory-fMRI might replace the invasive Wada test in MTLE by using a simple fMRI paradigm. Predictive power, however, will be studied in larger patient samples. Other studies are required for left-sided MTLE and neocortical epilepsies to assess the clinical usefulness of memory-fMRI.

Adolescent↗

PubMed2005

Bi-hemispheric engagement in the retrieval of autobiographical episodes.

Functional magnetic resonance imaging (fMRI) was used to study the neural correlates of neutral, stressful, negative and positive autobiographical memories. The brain activity produced by these different kinds of episodic memory did not differ significantly, but a common pattern of activation for different kinds of autobiographical memory was revealed that included (1) largely bilateral portions of the medial and superior temporal lobes, hippocampus and parahippocampus, (2) portions of the ventral, medial, superior and dorsolateral prefrontal cortex, (3) the anterior and posterior cingulate, including the retrosplenial, cortex, (4) the parietal cortex, and (5) portions of the cerebellum. The brain regions that were mainly activated constituted an interactive network of temporal and prefrontal areas associated with structures of the extended limbic system. The main bilateral activations with left-sided preponderance probably reflected reactivation of complex semantic and episodic self-related information representations that included previously experienced contexts. In conclusion, the earlier view of a strict left versus right prefrontal laterality in the retrieval of semantic as opposed to episodic autobiographical memory, may have to be modified by considering contextual variables such as task demands and subject variables. Consequently, autobiographical memory integration should be viewed as based on distributed bi-hemispheric neural networks supporting multi-modal, emotionally coloured components of personal episodes.

Adult↗

PubMed2004

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 Broca's 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.

Adult↗

PubMed2003

Functional organization of the brain with malformations of cortical development.

We examined the localization of cerebral functions in 28 patients with focal epilepsy and malformations of cortical development (MCDs). Polymicrogyria occurred in nine, hemimegalencephaly in four, heterotopia in eight, and focal cortical dysplasia (FCD) in nine cases. We used simple (sensomotor, visual) or complex (language, memory) functional magnetic resonance imaging (fMRI) paradigms. Two thirds of MCDs were activated by simple fMRI paradigms, whereas they less frequently showed activity during complex cognitive fMRI paradigms. During simple paradigms, all disturbances of cortical organization (polymicrogyria, schizencephaly, and mild-type FCD) showed activity, whereas other MCDs (disturbances of earlier steps of cortical development: hemimegalencephaly, Taylor-type FCD, and heterotopia) showed activity in only 44% (p < 0.01). The association between the pathophysiology and morphology of MCDs confirms the recently proposed classification system. Both focal neurological signs (p < 0.05) and focal electroencephalogram slowing (p < 0.05) independently correlated with MCD inactivity, confirming that fMRI showed neuronal functions of MCDs. Conclusively, fMRI visualizes the MCD functions and their relationship to the eloquent cortex, providing useful information before epilepsy surgery. Surgery of cortical organization disturbances should be cautiously performed because these malformations may participate to some degree in brain functions.

Adolescent↗