Reconsidering the emergence of social complexity in early Saharan pastoral societies, 5000 - 2500 B.C.

Debates on the subject of cultural complexity and its material manifestations are situated at the centre of research on prehistoric pastoralism in North Africa. Employing already published databases, this article integrates raw data from archaeological sites across the Sahara with ethnography to generate a framework of analysis in which changes in material culture can be interpreted. It attempts to establish a relationship between the analysis of human and cattle remains in order to study (a) the relations between modes of interment of animals and of humans, and social changes, and (b) the processes responsible for the appearance of a symbolism of power in the mid- and late Holocene funerary rituals.

Cross-talk of instructed and applied arbitrary visuomotor mappings.

Humans are able to perform any voluntary motor response to any environmental stimulus. This cornerstone of the flexibility of human behaviour has been investigated under the label of arbitrary visuomotor mapping. The focus of research has been the question as to how these mappings are executed once the subjects have been instructed appropriately.

Impaired self-initiated task preparation during task switching in Parkinson's disease.

Patients with Parkinson's disease (PD) typically show reduced performance in clinical tests involving cognitive control processes, presumably due to reduced availability of dopamine in striatofrontal neuronal circuits. Although task switching paradigms are considered as an ideal experimental measure of cognitive control, previous studies on task switching in PD have yielded ambiguous results, indicating that performance deficits depend on the specific task requirements. Among these, the aspect of self-initiated as opposed to externally triggered task preparation seems to play an important role, as evidenced by recent research.

Voluntary selection of task sets revealed by functional magnetic resonance imaging.

In everyday life, we have to selectively adapt our behavior to different situations and tasks. In cognitive psychology, such adaptive behavior can be investigated with the task-switching paradigm. However, in contrast to everyday life, in experiments participants are unequivocally told which task to perform.

Methane emissions from terrestrial plants under aerobic conditions.

Methane is an important greenhouse gas and its atmospheric concentration has almost tripled since pre-industrial times. It plays a central role in atmospheric oxidation chemistry and affects stratospheric ozone and water vapour levels. Most of the methane from natural sources in Earth's atmosphere is thought to originate from biological processes in anoxic environments.

Methodological and empirical issues when dissociating cue-related from task-related processes in the explicit task-cuing procedure.

In the explicit cuing version of the task-switching paradigm, each individual task is indicated by a unique task cue. Consequently, a task switch is accompanied by a cue switch. Recently, it has been proposed that priming of cue encoding contributes to the empirically observed switch costs.

When hearing turns into playing: movement induction by auditory stimuli in pianists.

In this study, pianists were tested for learned associations between actions (movements on the piano) and their perceivable sensory effects (piano tones). Actions were examined that required the playing of two-tone sequences (intervals) in a four-choice paradigm. In Experiment 1, the intervals to be played were denoted by visual note stimuli.

Who comes first? The role of the prefrontal and parietal cortex in cognitive control.

Cognitive control processes enable us to adjust our behavior to changing environmental demands. Although neuropsychological studies suggest that the critical cortical region for cognitive control is the prefrontal cortex, neuro-imaging studies have emphasized the interplay of prefrontal and parietal cortices. This raises the fundamental question about the different contributions of prefrontal and parietal areas in cognitive control.

Imitation: is cognitive neuroscience solving the correspondence problem?

Imitation poses a unique problem: how does the imitator know what pattern of motor activation will make their action look like that of the model? Specialist theories suggest that this correspondence problem has a unique solution; there are functional and neurological mechanisms dedicated to controlling imitation. Generalist theories propose that the problem is solved by general mechanisms of associative learning and action control. Recent research in cognitive neuroscience, stimulated by the discovery of mirror neurons, supports generalist solutions.

The role of the inferior frontal junction area in cognitive control.

Cognitive control processes refer to our ability to coordinate thoughts and actions in accordance with internal goals. In the fronto-lateral cortex such processes have been primarily related to mid-dorsolateral prefrontal cortex (mid-DLPFC). However, recent brain-imaging and meta-analytic studies suggest that a region located more posterior in the fronto-lateral cortex plays a pivotal role in cognitive control as well.

Goal-directed imitation in patients with Ideomotor Apraxia.

The present study compared imitation performance in patients with ideomotor apraxia (IMA), eight right hemispheric-damaged patients, and eight control participants without neurological damage in three experiments. Experiment 1 confirmed in the Goldenberg test that IMA patients were particularly impaired in hand gestures and combined finger and hand gestures, but not in the imitation of finger gestures, compared to the other two groups. Experiment 2, however, demonstrated that finger selection is not per se preserved in imitative behaviour in patients with IMA.

Involvement of the inferior frontal junction in cognitive control: meta-analyses of switching and Stroop studies.

There is growing evidence that a specific region in the posterior frontolateral cortex is involved intimately in cognitive control processes. This region, located in the vicinity of the junction of the inferior frontal sulcus and the inferior precentral sulcus, was termed the inferior frontal junction (IFJ). The IFJ was shown to be involved in the updating of task representations and to be activated commonly in a within-subject investigation of a task-switching paradigm, the Stroop task, and a verbal n-back task.

Internally generated and directly cued task sets: an investigation with fMRI.

It is widely acknowledged that the prefrontal cortex (PFC) plays a major role for goal-directed behaviour. In this context it is usually necessary to coordinate environmental information and internally represented intentions. Such goal-directed "endogenous control processes" can be investigated with the task-switching paradigm in which participants are required to alternate between different tasks.

Advance preparation and stimulus-induced interference in cued task switching: further insights from BOLD fMRI.

To switch from one cognitive task to another is thought to rely on additional control effort being indicated by performance costs relative to repeating the same task. This switch cost can be reduced by advance task preparation. In the present experiment the nature of advance preparation was investigated by comparing a situation where an explicit task cue was presented 2000 ms in advance of the target stimulus (CTI-2000) with a situation where cue and target were presented in close succession (CTI-100).

The inhibition of imitative and overlearned responses: a functional double dissociation.

Neuropsychological research has established that the inhibition of dominant response tendencies is a function of the prefrontal cortex. These inhibitory mechanisms are tested using tasks like the Stroop task, in which the prepotency of the dominant response is based on a learned relationship of stimulus and response. However, it has also been reported that patients with prefrontal lesions may have problems inhibiting imitative responses.

Cognitive control in the posterior frontolateral cortex: evidence from common activations in task coordination, interference control, and working memory.

Cognitive control has often been associated with activations of middorsolateral prefrontal cortex. However, recent evidence highlights the importance of a more posterior frontolateral region around the junction of the inferior frontal sulcus and the inferior precentral sulcus (the inferior frontal junction area, IFJ). In the present experiment, we investigated the involvement of the IFJ in a task-switching paradigm, a manual Stroop task, and a verbal n-back task in a within-session within-group design.

Selection for cognitive control: a functional magnetic resonance imaging study on the selection of task-relevant information.

The complex environment we live in makes it necessary to distinguish relevant from irrelevant information constantly and reliably. The aim of the present study was to investigate the neural substrate underlying the selection of task-relevant information. We devised a new paradigm in which participants had to switch between two different tasks that were instructed by task cues.

Decomposing components of task preparation with functional magnetic resonance imaging.

It is widely acknowledged that the prefrontal cortex plays a major role in cognitive control processes. One important experimental paradigm for investigating such higher order cognitive control is the task-switching paradigm. This paradigm investigates the ability to switch flexibly between different task situations.

Action-effect coupling in pianists.

Recent theories have stressed the role of effect anticipation in action control. Such a mechanism requires the prior acquisition of integrated action-effect associations. The strength of such associations should directly depend on the amount of learning, and therefore be most pronounced in motor experts.

Event-related analysis for event types of fixed order and restricted spacing by temporal quantification of trial-averaged fMRI time courses.

Purpose: To develop a method for event-related fMRI that allows rapidly presented event sequences to be analyzed, without requiring transitions of different event-types to be counterbalanced.

Materials And Methods: A cued task switching procedure was investigated with an experimental trial comprising a visual task cue that indicated how to process a subsequent visual target stimulus. Cue and target were either presented quasi-simultaneously, separated by a 100 msec cue-target-interval (CTI100), or the target presentation was delayed by 2000 msec (CTI2000).

When the same response has different meanings: recoding the response meaning in the lateral prefrontal cortex.

The ability to adapt our behavioral repertoire to different situations and tasks is crucial for our behavioral control. Since the same motor behavior can have different meanings in different task situations, we often have to change the meaning of our responses when we get into a different task context. In a functional MRI experiment we manipulated this response recoding process.

Equivalence of cognitive processes in brain imaging and behavioral studies: evidence from task switching.

A growing number of studies on the higher-order cognitive functions of the human brain use brain-imaging techniques, such as functional magnetic resonance imaging (fMRI). For the validity and generality of fMRI results, it is important that the relevant cognitive processes are equivalent to those functioning in typical settings used in behavioral research. This equivalence could be, for example, endangered by different spatial frames of reference when lying in the scanner.

Imitative response tendencies in patients with frontal brain lesions.

It is widely accepted that patients with frontal lesions have problems inhibiting automatic response tendencies. Whereas inhibition deficits of overlearned responses have been extensively investigated using interference tasks like the Stroop task (J. R.

The role of the frontal cortex in task preparation.

The ability to prepare a task is crucial for the voluntary control of our actions. It enables us to react flexibly and rapidly to a changing environment. In the present event-related functional magnetic resonance imaging study we investigated task preparation with a task-cueing paradigm.