The neural basis of cognitive control: Response selection and inhibition

The functional neuroanatomy of tasks that recruit different forms of response selection and inhibition has to our knowledge, never been directly addressed in a single fMRI study using similar stimulus–response paradigms where differences between scanning time and sequence, stimuli, and experimenter instructions were minimized. Twelve right-handed participants were scanned on two standard cognitive control tasks, a stimulus–response incompatibility task, and a response inhibition task. A compound trial design allowed comparison of preparing to inhibit an upcoming automatic response to wholly inhibiting an automatic response. Furthermore, inhibiting an automatic response to perform an alternative task-relevant response was compared to wholly inhibiting an automatic response. No differences were found in prefrontal activity when preparing to inhibit an automatic response was compared to wholly inhibiting an automatic response, suggesting a mostly common network. The left inferior frontal gyrus was found to be commonly recruited during both tasks when controlled responses were required, likely due to its role in response selection. In contrast, the right inferior frontal gyrus was found to be more involved when task demands were stronger for response inhibition. Our results are largely consistent with models of cognitive control that postulate that separate psychological constructs, such as response selection and inhibition, are related processes largely served by a common prefrontal network. This prefrontal network is recruited to a greater or lesser extent depending on specific task demands.     

A developmental study of the influence of task characteristics on motor overflow

Motor overflow refers to involuntary movement or muscle activity that may coincide with voluntary movement. This study examined factors influencing motor overflow in 17 children (8-11 years), and 17 adults (18-35 years). Participants performed a finger pressing task by exerting either 33% or 66% of their maximal force output using their dominant or non-dominant hand. Attention was manipulated by tactile stimulation to one or both hands. Overflow relative to the target force was greater in children compared to adults, and at the lower target force for both groups, but was not influenced by attentional stimulation. Childhood overflow was greater when the left-hand performed the task. Although an immature motor system may underlie an inability to suppress involuntary movement, childhood overflow may provide motor stabilization.     

The neural evidence for simulation is weaker than I think you think it is

Simulation theory accounts of mind-reading propose that the observer generates a mental state that matches the state of the target and then uses this state as the basis for an attribution of a similar state to the target. The key proposal is thus that mechanisms that are primarily used online, when a person experiences a kind of mental state, are then co-opted to run Simulations of similar states in another person. Here I consider the neuroscientific evidence for this view. I argue that there is substantial evidence for co-opted mechanisms, leading from one individual’s mental state to a matching state in an observer, but there is no evidence that the output of these co-opted mechanisms serve as the basis for mental state attributions. There is also substantial evidence for attribution mechanisms that serve as the basis for mental state attributions, but there is no evidence that these mechanisms receive their input from co-opted mechanisms.     

A Sex Difference on a Novel Spatial Working Memory Task in Humans

Neurophysiological and behavioral evidence suggests that the prefrontal cortex (PFC) may be sexually differentiated in nonhuman primates. The present study examined whether there are sex differences in working memory in humans that might reflect sexual differentiation of human PFC. Male and female undergraduates were administered a novel multitrial spatial working memory task (SPWM) and a verbal working memory task. In three experiments, females committed significantly fewer working memory errors and took significantly less time to reach criterion than males on the SPWM task. The female advantage was not accounted for by differences in general intellectual ability, attention, perceptual speed, incidental memory, or speed of verbal access. In Study 3, a sex difference was also observed on a measure of verbal working memory. The findings suggest that some prefrontal functions may be sexually differentiated in humans.     

Your own actions influence how you perceive other people: A misattribution of action appraisals

The attribution of personal traits to other persons depends on the actions the observer performs at the same time (Bach & Tipper, 2007). Here, we show that the effect reflects a misattribution of appraisals of the observers’ own actions to the actions of others. We exploited spatial compatibility effects to manipulate how fluently—how fast and how accurately—participants identified two individuals performing sporty or academic actions. The traits attributed to each person in a subsequent rating task depended on the fluency of participants’ responses in a specific manner. An individual more fluently identified while performing the academic action appeared more academic and less sporty. An individual more fluently identified while performing the sporty action appeared sportier. Thus, social perception is—at least partially—embodied. The ease of our own responses can be misattributed to the actions of others, affecting which personal traits are attributed to them.     

Broad-Perspective Perceptual Disorder of the Right Hemisphere

Traditional accounts of right-posterior brain injury describe a syndrome of low-level perceptual sequelae producing marked acute dependency and transient safety concerns. The syndrome is also held to spare cognition and to carry a generally favorable long-term prognosis. The present paper reviews publications and anecdotal data that challenge this picture. Recent theoretical expositions and empirical studies stipulate three major cognitive functions of the right posterior association cortex: processing novel input, guiding reactions to emergencies, and anticipating consequences. Appearing benign after acute recovery, the impairment of these processes produces vocational, social and marital dysfunctions that increase as a function of chronicity, ultimately becoming more broadly disabling than focal injuries in other cortical loci. The unique symptom picture and serious implications suggest that the long-term syndrome should be labeled (Broad-Perspective Perceptual Disorder) and incorporated in future clinical taxonomies, underscoring the need for extraordinary long-term assistance and specialized therapeutics. Procedures for assessment and differential diagnosis are outlined.     

When the self represents the other: a new cognitive neuroscience view on psychological identification

There is converging evidence from developmental and cognitive psychology, as well as from neuroscience, to suggest that the self is both special and social, and that self-other interaction is the driving force behind self-development. We review experimental findings which demonstrate that human infants are motivated for social interactions and suggest that the development of an awareness of other minds is rooted in the implicit notion that others are like the self. We then marshall evidence from functional neuroimaging explorations of the neurophysiological substrate of shared representations between the self and others, using various ecological paradigms such as mentally representing one's own actions versus others' actions, watching the actions executed by others, imitating the others' actions versus being imitated by others. We suggest that within this shared neural network the inferior parietal cortex and the prefrontal cortex in the right hemisphere play a special role in the essential ability to distinguish the self from others, and in the way the self represents the other. Interestingly, the right hemisphere develops its functions earlier than the left.     

Layer and regional effects of environmental enrichment on the pyramidal neuron morphology of the rat

The environmental enrichment (EE) paradigm is widely used to study experience-dependent brain plasticity. Several studies have investigated functional and anatomical EE effects. However, as EE effects are different according to cerebral region, cortical layer, dendritic field and morphological index considered, a univocal characterization of neuronal morphological changes following rearing in enriched environments is lacking.Aim of the present study was to characterize in the rat the effects of EE on the neuronal morphology of frontal and parietal cortical regions, the main target areas of the stimulation provided by the paradigm. Male Wistar rats were housed in an enriched environment for 3.5 months from the 21st postnatal day. For the morphological analysis, biotinylated dextran amine (BDA)-labeled pyramidal neurons were selected from frontal (M1–M2) and parietal (S1–S2) cortical layers III and V. Apical and basal dendritic branching and spines were analyzed using the Sholl method.Results showed that EE increased branching and spines in both layers of frontal cortex, but had a greater effect on apical arborization. In parietal cortex, EE significantly affected branching and spines in layer III but not layer V neurons, in which only a tendency to be influenced by the rearing conditions was observed in basal arborization.It is hypothesized that these multifaceted morphological EE effects are connected to the heavy involvement of a sensory-motor circuit engaged in the guidance of voluntary action and in motor learning activated by EE stimulation.