Jo Grothe

Emotional context modulates subsequent memory effect

Emotions have been shown to modulate memory processes. However, the neuronal substrate underlying these modulatory effects is largely unknown. Using event-related functional magnetic resonance imaging (fMRI), we investigated whether the context of emotional encoding modulates brain activation predictive for subsequent recall of emotionally neutral material. While inferior frontal activation predicted recall in general, our data show that in a positive encoding context, recall was predicted by activation of right anterior parahippocampal and extrastriate visual brain areas, whereas in a negative encoding context, recall was predicted by activation of the amygdala. Thus, we could demonstrate that successful episodic encoding is differentially modulated by emotional context. These results contribute to the understanding of the interaction of emotion and cognition and moreover are of general relevance for studies of episodic memory.

The Sound of Concepts: Four Markers for a Link between Auditory and Conceptual Brain Systems

Traditionally, concepts are conceived as abstract mental entities distinct from perceptual or motor brain systems. However, recent results let assume modality-specific representations of concepts. The ultimate test for grounding concepts in perception requires the fulfillment of the following four markers: conceptual processing during (1) an implicit task should activate (2) a perceptual region (3) rapidly and (4) selectively. Here, we show using functional magnetic resonance imaging and recordings of event-related potentials, that acoustic conceptual features recruit auditory brain areas even when implicitly presented through visual words. Fulfilling the four markers, the findings of our study unequivocally link the auditory and conceptual brain systems: recognition of words denoting objects, for which acoustic features are highly relevant (e.g.,“telephone”), ignited cell assemblies in posterior superior and middle temporal gyri (pSTG/MTG) within 150 ms that were also activated by sound perception. Importantly, activity within a cluster of pSTG/MTG increased selectively as a function of acoustic, but not of visual and action-related feature relevance. The implicitness of the conceptual task, the selective modulation of left pSTG/MTG activity by acoustic feature relevance, the early onset of this activity at 150 ms and its anatomical overlap with perceptual sound processing are four markers for a modality-specific representation of auditory conceptual features in left pSTG/MTG. Our results therefore provide the first direct evidence for a link between perceptual and conceptual acoustic processing. They demonstrate that access to concepts involves a partial reinstatement of brain activity during the perception of objects.

Human anterior cingulate cortex is activated by negative feedback: evidence from event-related potentials in a guessing task

It has been controversially discussed whether the error-related negativity (ERN) or error negativity (N(e)), an electrophysiological index of anterior cingulate activation, reflects response conflict or response evaluation subserving error monitoring processes. We investigated event-related potentials (ERPs) in a guessing task which did not induce response conflict. Subjects had to guess which of the four aces of a French card play would be presented next and received feedback at random. We observed a negative ERP deflection in trials following negative feedback which was identified as ERN/N(e). Dipole analysis of scalp potentials indicated sources in the anterior cingulate and left inferior prefrontal cortex. The observation of the ERN/N(e) following negative feedback during guessing suggests that this ERP component mirrors response evaluation processes comparing expected and actual response outcome rather than response conflict.

The neural correlates of driving.

We studied 12 healthy subjects with fMRI while they performed a driving simulation task. In the active condition they steered the car themselves (driving), in the passive condition a person from outside the scanner was steering the car (passive driving). Common activations in both conditions were found in occipital and parietal regions bilaterally. Activity specifically associated with driving was found only in the sensorimotor cortex and the cerebellum. Compared to passive driving, activity during driving was reduced in numerous brain regions including MT/MST. It is concluded that simulated driving requires mainly perceptual–motor integration and that the limited cognitive capacity model of driving has to be revised.

Side Effects of Transcranial Magnetic Stimulation Biased Task Performance in a Cognitive Neuroscience Study

Summary:Transcranial magnetic stimulation (TMS) is increasingly used as a research tool for functional brain mapping in cognitive neuroscience. Despite being mostly tolerable, side effects of TMS could influence task performance in behavioural TMS studies. In order to test this issue, healthy subjects assessed the discomfort caused by the stimulation during a verbal working memory task. We investigated the relation between subjective disturbance and task performance. Subjects were stimulated during the delay period of a delayed-match-to-sample task above cortical areas that had been identified before to be involved in working memory. Task performance and subjective disturbance due to side effects were monitored. The subjects’ grade of discomfort correlated with the error rates: the higher the discomfort, the more errors were made. Conclusively, TMS side effects may bias task performance in cognitive neuroscience studies and may thereby lead to misinterpretation of results. We emphasize the importance of controlling side effects of the stimulation as a source of biasing effects in TMS studies.

Speaking in Multiple Languages: Neural Correlates of Language Proficiency in Multilingual Word Production.

The human brain has the fascinating ability to represent and to process several languages. Although the first and further languages activate partially different brain networks, the linguistic factors underlying these differences in language processing have to be further specified. We investigated the neural correlates of language proficiency in a homogeneous sample of multilingual native Ladin speakers from a mountain valley in South Tyrol, Italy, who speak Italian as second language at a high level, and English at an intermediate level. In a constrained word production task under functional magnetic resonance imaging (fMRI), participants had to name pictures of objects in Ladin, Italian and English in separate blocks. Overall, multilingual word production activated a common set of brain areas dedicated to known subcomponents of picture naming. In comparison to English, the fluently spoken languages Ladin and Italian were associated with enhanced right prefrontal activity. In addition, the MR signal in right prefrontal cortex correlated with naming accuracy as a measure of language proficiency. Our results demonstrate the significance of right prefrontal areas for language proficiency. Based on the role of these areas for cognitive control, our findings suggest that right prefrontal cortex supports language proficiency by effectively supervising word retrieval.

The Brain Positioning Software

In the assessment and analysis of neuroimaging data often the automated reference to a brain atlas is required. We describe a little software tool, the brain positioning software (BPS), that relies on computerized brain atlases (in Talairach coordinates, by default) and has interfaces to the SPM data analysis software (freely available on http://www.fil.ion.ucl.ac.uk/spm/distrib.html). BPS allows the transformation in two directions: It can project and visualize areas of atlas regions in SPM. When called from SPM, it shows the name of the region under the current cursor position. The default version of the BPS tool uses the Talairach atlas made available on the “Talairach Daemon” website (http://ric.uthscsa.edu/projects/). Other atlases can also be used. For fast performance, the atlas database is converted and label descriptions are managed in a hash-table. The BPS can be downloaded from our website on http://www.informatik.uni-ulm.de/ni/staff/FSommer/BPS.html.