Claus Lamm

Subjects deciding whether two objects presented at angular disparity are identical or mirror versions of each other usually show response times that linearly increase with the angle between objects. This phenomenon has been termed mental rotation. While there is widespread agreement that parietal cortex plays a dominant role in mental rotation, reports concerning the involvement of motor areas are less consistent. From a theoretical point of view, activation in motor areas suggests that mental rotation relies upon visuo-motor rather than visuo-spatial processing alone. However, the type of information that is processed by motor areas during mental rotation remains unclear. In this study we used event-related fMRI to assess whether activation in parietal and dorsolateral premotor areas (dPM) during mental rotation is distinctively related to processing spatial orientation information. Using a newly developed task paradigm we explicitly separated the processing steps (encoding, mental rotation proper and object matching) required by mental rotation tasks and additionally modulated the amount of spatial orientation information that had to be processed. Our results show that activation in dPM during mental rotation is not strongly modulated by the processing of spatial orientation information, and that activation in dPM areas is strongest during mental rotation proper. The latter finding suggests that dPM is involved in more generalized processes such as visuo-spatial attention and movement anticipation. We propose that solving mental rotation tasks is heavily dependent upon visuo-motor processes and evokes neural processing that may be considered as an implicit simulation of actual object rotation.

Alexithymia, a deficit in emotional self-awareness, and deficits in empathy, which encompasses the awareness of other's emotions, are related constructs that are both associated with a range of psychopathological disorders. Neuroimaging studies suggest that there is overlap between the neural bases of alexithymia and empathy, but no systematic comparison has been conducted so far. The aim of this structural magnetic resonance imaging study was to disentangle the overlap and differences between the morphological profiles of the cognitive and affective dimensions of alexithymia and empathy, and to find out to what extent these differ between women and men. High-resolution T1 anatomical images were obtained from 125 healthy right-handers (18-42years), 70 women and 55 men. By means of voxel-based morphometry, region of interest (ROI) analyses were performed on gray matter volumes of several anatomically defined a-priori regions previously linked to alexithymia and empathy. Partial c...

The current study investigated whether or not the physical aspect of stimulus size has an effect on neuronal correlates of feedback processing. A time estimation task was administered applying three different feedback stimulus categories: small, middle, and large size stimuli. Apart from early visual ERPs such as P1 and N1 components, later feedback processing stages were also affected by the size of feedback stimuli. In particular, small size stimuli compared to middle and large size ones led to diminished amplitudes in both FRN and P300 components, despite intact discrimination between negative and positive outcomes in these two ERPs. In contrast, time estimation performance was not influenced by feedback size. The current results indicate that small size feedback stimuli were perceived as less salient and hence were processed less deeply than the others. This suggests that future feedback studies could manipulate feedback salience simply by presenting differently sized feedback stimuli, at least when the focus lies on FRN and P300 amplitude variation.

Recent neuroscience theories suggest that different kinds of self-regulation may share a common psychobiological mechanism. However, empirical evidence for a domain general self-regulation mechanism is scarce. The aim of this study was to investigate whether focused anodal transcranial direct current stimulation (tDCS), facilitating the activity of the dorsolateral prefrontal cortex (dlPFC), acts on a domain general self-regulation mechanism and thus modulates both affective and appetitive self-regulation. Twenty smokers participated in this within-subject sham controlled study. Effects of anodal left, anodal right and sham tDCS over the dlPFC on affective picture appraisal and nicotine craving-cue appraisal were assessed. Anodal right tDCS over the dlPFC reduced negative affect in emotion appraisal, but neither modulated regulation of positive emotion appraisal nor of craving appraisal. Anodal left stimulation did not induce any significant effects. The results of our study show th...

Previous results point towards a lateralization of dorsolateral prefrontal cortex (DLPFC) function in risky decision making. While the right hemisphere seems involved in inhibitory cognitive control of affective impulses, the left DLPFC is crucial in the deliberative processing of information relevant for the decision. However, a lack of empirical evidence precludes definitive conclusions. The aim of our study was to determine whether anodal transcranial direct current stimulation (tDCS) over the right DLPFC with cathodal tDCS over the lDLPFC (anodal right/cathodal left) or vice versa (anodal left/cathodal right) differentially modulates risk-taking in a task [the Columbia Card Task (CCT)] specifically engaging affect-charged (Hot CCT) vs. deliberative (Cold CCT) decision making. The facilitating effect of the anodal stimulation on neuronal activity was emphasized by the use of a small anode and a big cathode. To investigate the role of individual differences in risk-taking, partici...

Using slow-cortical potentials (SCPs), Vitouch et al. demonstrated that subjects with low ability to solve a complex visuo-spatial imagery task show higher activity in occipital, parietal and frontal cortex during task processing than subjects with high ability. This finding has been interpreted in the sense of the so-called "neural efficiency" hypothesis, which assumes that the central nervous system of individuals with higher intellectual abilities is functioning in a more efficient way than the one of individuals with lower abilities. Using a higher spatial resolution of SCP recordings, and by employing the source localization method of LORETA (low-resolution electromagnetic tomography), we investigated this hypothesis by performing an extended replication of Vitouch et al.'s study. SCPs during processing of a visuo-spatial imagery task were recorded in pre-selected subjects with either high or low abilities in solving the imagery task. Topographic and LORETA analys...

Philosophers and social and developmental psychologists have long debated the nature of empathy (eg, Batson et al., 1991; Eisenberg & Miller, 1987; Thompson, 2001) and whether the capacity to share and understand other people's emotions sets humans apart from other species (eg, de Waal, 2005). Here, we consider empathy as a construct to account for a sense of similarity in feelings experienced by the self and the other without confusion between the two individuals (Decety & Jackson, 2004; Decety & Lamm, 2006). The ...

Impaired awareness of memory deficits has been recognized as a common phenomenon in Alzheimer's disease (AD) and research is now increasingly focusing on awareness in groups at risk for future dementia. This study aimed to determine whether levels of awareness differ among healthy elderly people and patients with subjective cognitive decline (SCD), amnestic and non-amnestic subtypes of mild cognitive impairment (aMCI, naMCI), Alzheimer's disease (AD) and Parkinson's disease (PD), to explore correlates of awareness and to establish frequencies of memory over- and underestimation within each diagnostic group. 756 consecutive outpatients of a memory clinic and 211 healthy controls underwent thorough neuropsychological testing. Impairment of awareness was measured as the difference between subjective memory appraisals (16-item questionnaire on current memory-related problems in everyday life) and objective memory performance (15-item delayed recall task). Subgroups of over- and underestimators were classified using percentile ranks of controls. At group level, awareness significantly decreased along the naMCI→aMCI→AD continuum, with naMCI patients showing a tendency towards overestimation of memory dysfunction. PD patients showed accurate self-appraisals as long as memory function was largely unaffected. However, there was a considerable between-group overlap in awareness scores. Furthermore, different correlates of awareness were observed depending on the diagnostic group. In general, unawareness seems to be associated with decreased cognitive performance in various domains (especially memory), higher age and lower levels of depression and self-reported functional impairment. Impaired awareness is an important symptom in aMCI. Yet, given the considerable variability in awareness scores, longitudinal studies are required to evaluate their predictive power.