Uta Wolfensteller

Function and Structure of the Right Inferior Frontal Cortex Predict Individual Differences in Response Inhibition: A Model-Based Approach

The ability to suppress ones impulses and actions constitutes a fundamental mechanism of cognitive control, thought to be subserved by the right inferior frontal cortex (rIFC). The neural bases of more selective inhibitory control when selecting between two actions have thus far remained articulated with less precision. Selective inhibition can be explored in detail by extracting parameters from response time (RT) distributions as derived from performance in the Simon task. Individual differences in RT distribution parameters not only can be used to probe the efficiency and temporal dynamics of selective response inhibition, but also allow a more detailed analysis of functional neuroimaging data. Such model-based analyses, which capitalize on individual differences, have demonstrated that selective response inhibition is subserved by the rIFC. The aim of the present study was to specify the relationship between model parameters of response inhibition and their functional and structural underpinnings in the brain. Functional magnetic resonance imaging (fMRI) data were obtained from healthy participants while performing a Simon task in which irrelevant information can activate incorrect responses that should be selectively inhibited in favor of selecting the correct response. In addition, structural data on the density of coherency of white matter tracts were obtained using diffusion tensor imaging (DTI). The analyses aimed at quantifying the extent to which RT distribution measures of response inhibition are associated with individual differences in both rIFC function and structure. The results revealed a strong correlation between the model parameters and both fMRI and DTI characteristics of the rIFC. In general, our results reveal that individual differences in inhibition are accompanied by differences in both brain function and structure.

Motion Class Dependency in Observers' Motor Areas Revealed by Functional Magnetic Resonance Imaging

Human and animal data suggest that the mere observation of biological motion activates those premotor areas that also underlie the initiation of the same motion. However, data also indicate that the human premotor cortex (PM), in contrast to the monkey PM, responds not only to the observation of goal-directed (transitive) motion but also to intransitive motion. The present study used functional magnetic resonance imaging to test this hypothesis directly. Participants were presented cycles of intransitive motion specified as belonging to the distal (fingers and mouth), proximal (knee, ankle, elbow, and wrist), or axial (trunk and shoulder) motion class. Attention to motion was behaviorally tested by a forced-choice task on motion acceleration and deceleration. Results revealed extended PM activation for each motion condition. However, direct contrasts showed that the most significant activations were elicited in ventrolateral PM by distal motion, in dorsolateral PM by proximal motion, and medial PM (supplementary motor area) by axial motion. Findings confirm observed intransitive motions to engage premotor areas along a gross-scaled somatotopy.

Understanding non-biological dynamics with your own premotor system

The human premotor cortex (PM) appears to subserve a variety of cognitive and motor functions, including the prediction of non-biological dynamics. In the present study we directly tested the correspondence of premotor correlates of predicting different non-biological dynamics and imagining different actions by means of functional magnetic resonance imaging. Prediction tasks on either spatial, object or rhythmic dynamics were expected to draw on premotor areas involved in motor imagery tasks for arm, hand and mouth movements, respectively. Firstly, the results confirmed comparable dorsal-to-ventral distributions of property effects (in prediction) and movement effects (in motor imagery) in PM. Secondly, even more direct correspondences were observed for mouth movement imagery and rhythm prediction in inferior ventral PM and for arm movement imagery and spatial prediction in dorsal PM. Hand movement imagery and object prediction led to activations in closely adjacent areas in left superior ventral PM. Together, the present findings support the notion that to-be-predicted stimulus dynamics and motor effectors are coupled in lateral PM according to a pragmatic default. Beyond that, the results add further support to the notion that the human PM is involved in the prediction of many if not all kinds of dynamics.

“What” Becoming “Where”: Functional Magnetic Resonance Imaging Evidence for Pragmatic Relevance Driving Premotor Cortex

Previous studies using the serial prediction task (SPT) have shown that attending to the locations of objects activates the dorsal part of premotor cortex more than attending to the sizes of objects. The opposite holds for the ventral part of the premotor cortex. The present study used functional magnetic resonance imaging to investigate whether the learning of arbitrary stimulus-response mappings influences this functional dissociation. One experimental group learned to assign stimuli to response buttons based on stimulus size; another group did so based on stimulus location. More specifically, one-half of the participants in both experimental groups learned to assign stimuli to finger movements of their right hand, whereas the other half assigned stimuli to finger movements of their left hand. During scanning, all participants performed both size SPT and location SPT. Thus, we investigated the effects of the attended stimulus property (size or location), the motor effector assigned to it (fingers of left or right hand), and the spatial arrangement of the targets (the same in all groups). As expected, without motor training, the dorsal premotor cortex was less activated during size SPT compared with location SPT. The opposite held for ventral premotor cortex. With motor training, however, this differential activity pattern vanished. Activity in dorsal premotor cortex reflected neither the attended stimulus property nor the motor effector assigned to it. Instead, its activity may be related to the spatial properties of the response targets once some object property, such as size, takes on the “pragmatic relevance” of a spatially directed response.

When the choice is ours: Context and agency modulate the neural bases of decision-making

The option to choose between several courses of action is often associated with the feeling of being in control. Yet, in certain situations, one may prefer to decline such agency and instead leave the choice to others. In the present functional magnetic resonance imaging (fMRI) study, we provide evidence that the neural processes involved in decision-making are modulated not only by who controls our choice options (agency), but also by whether we have a say in who is in control (context). The fMRI results are noteworthy in that they reveal specific contributions of the anterior frontomedian cortex (viz. BA 10) and the rostral cingulate zone (RCZ) in decision-making processes. The RCZ is engaged when conditions clearly present us with the most choice options. BA 10 is engaged in particular when the choice is completely ours, as well as when it is completely up to others to choose for us which in turn gives rise to an attribution of control to oneself or someone else, respectively. After all, it does not only matter whether we have any options to choose from, but also who decides on that.

Bending the rules: Strategic behavioral differences are reflected in the brain

The implementation of higher-order conditional motor behavior was investigated in the present fMRI study with the objective of answering three questions: (a) what happens in situations where one stimulus dimension alone does not sufficiently determine the correct response?; (b) does the implementation of second-order stimulus–response (S–R) rules on the basis of matching (congruent) or nonmatching (incongruent) S–R associations differ from the implementation of congruent and incongruent first-order S–R rules?; and (c) is the cerebral implementation of second-order rules influenced by interindividual behavioral differences arising from the use of different strategies? The findings indicate that several cortical areas were more strongly engaged for second-order rules. More specifically, rule integration based on a rule match led to enhanced activation in posterior parietal cortex, whereas rule integration based on a rule mismatch was associated with enhanced activation in dorsal premotor cortex and left rostrolateral prefrontal cortex. Interindividual strategy differences were revealed by strikingly different behavioral data patterns: One subgroup of participants displayed strong congruency effects for second-order rules, whereas another subgroup displayed nonsignificant or even reversed congruency effects. Importantly, these strategy differences strongly modulated the cerebral implementation of second-order rules based on a rule mismatch. Together, the present findings reveal differential brain activation patterns for higher-order S–R rules depending on rule congruency and interindividual strategy differences. Moreover, they emphasize the necessity of taking interindividual behavioral differences into account when investigating the cerebral implementation of cognitive processes even in rather simple and well-controlled experimental paradigms.

How are actions physically implemented

This chapter focuses on the interdisciplinary discussion between cognitive psychologists and neuroscientists on how actions, the results of decision processes, are implemented. After surveying the approaches used in action implementation research, we analyze the contributions of these different approaches in more detail. Topics covered include expertise research in sports science, knowledge structures, neuroscientific research on motor imagery and decision making, computational models in motor control, robotics, and brain-machine interfaces. This forms the basis for discussing central issues for interdisciplinary research on action implementation from different viewpoints. In essence, most findings show the need to abandon serial frameworks of information processing suggesting a step-by-step pattern from perception, evaluation, and selection to execution. Instead, an outlook on new approaches is given, opening a route for future research in this field.

Juggling with the brain — thought and action in the human motor system

Empirical findings from various research fields indicate that cognitive and motor processes are far less dissimilar than previously thought. The present chapter takes a neuroscientific perspective and offers evidence for similarities between cognition and action focusing on three key players of the classical motor system: the primary motor cortex, the cerebellum, and the premotor cortex. Briefly, although movement execution is apparently supported in part by the same cerebral resources engaged in cognitive processes, the three brain regions reviewed here are differentially engaged in more or less action-bound cognitive processes.