Neocortical maturation during adolescence: change in neuronal soma dimension

During adolescence, cognitive abilities increase robustly. To search for possible related structural alterations of the cerebral cortex, we measured neuronal soma dimension (NSD = width times height), cortical thickness and neuronal densities in different types of neocortex in post-mortem brains of five 12-16 and five 17-24 year-olds (each 2F, 3M). Using a generalized mixed model analysis, mean normalized NSD comparing the age groups shows layer-specific change for layer 2 (p < .0001) and age-related differences between categorized type of cortex: primary/primary association cortex (BA 1, 3, 4, and 44) shows a generalized increase; higher-order regions (BA 9, 21, 39, and 45) also show increase in layers 2 and 5 but decrease in layers 3, 4, and 6 while limbic/orbital cortex (BA 23, 24, and 47) undergoes minor decrease (BA 1, 3, 4, and 44 vs. BA 9, 21, 39, and 45: p = .036 and BA 1, 3, 4, and 44 vs. BA 23, 24, and 47: p = .004). These data imply the operation of cortical layer- and type-specific processes of growth and regression adding new evidence that the human brain matures during adolescence not only functionally but also structurally.     

Dual language use in sign-speech bimodal bilinguals: fNIRS brain-imaging evidence

The brain basis of bilinguals’ ability to use two languages at the same time has been a hotly debated topic. On the one hand, behavioral research has suggested that bilingual dual language use involves complex and highly principled linguistic processes. On the other hand, brain-imaging research has revealed that bilingual language switching involves neural activations in brain areas dedicated to general executive functions not specific to language processing, such as general task maintenance. Here we address the involvement of language-specific versus cognitive-general brain mechanisms for bilingual language processing. We study a unique population, bimodal bilinguals proficient in signed and spoken languages, and we use an innovative brain-imaging technology, functional Near-Infrared Spectroscopy (fNIRS; Hitachi ETG-4000). Like fMRI, the fNIRS technology measures hemodynamic change, but it is also advanced in permitting movement for unconstrained speech and sign production. Participant groups included (i) hearing ASL–English bilinguals, (ii) ASL monolinguals, and (iii) English monolinguals. Imaging tasks included picture naming in “Monolingual mode” (using one language at a time) and in “Bilingual mode” (using both languages either simultaneously or in rapid alternation). Behavioral results revealed that accuracy was similar among groups and conditions. By contrast, neuroimaging results revealed that bilinguals in Bilingual mode showed greater signal intensity within posterior temporal regions (“Wernicke’s area”) than in Monolingual mode. Significance: Bilinguals’ ability to use two languages effortlessly and without confusion involves the use of language-specific posterior temporal brain regions. This research with both fNIRS and bimodal bilinguals sheds new light on the extent and variability of brain tissue that underlies language processing, and addresses the tantalizing questions of how language modality, sign and speech, impact language representation in the 7brain.     

Influence of handedness and bilateral eye movements on creativity

We investigated the effects of increased inter-hemispheric interaction (IHI) on five creativity dimensions (appropriateness, detail, categorical distinctiveness, fluency, and originality) of the Alternate Uses Task. Two methods were used to indicate degree of IHI. Trait IHI was indicated by individual differences in handedness, mixed-handers showing greater IHI than strong-handers. State IHI was directly manipulated by central (control group) and bilateral viewing conditions of a 30 s eye movement task (EM). Results indicate significantly higher creativity for mixed-handers, as compared to strong-handers, for all five sub-scores separately and linearly combined. Bilateral EM increased originality and categorical distinctiveness (i.e., flexibility) of strong-handers, but had no effect on mixed-handers. Strong-handers in the bilateral EM group were not different from mixed-handers. Additionally, the bilateral EM effect on strong-handers had different durations for originality (up to 7–9 min) and categorical distinctiveness (up to 3 min). The results suggest that greater IHI can facilitate creativity of strong-handers, but that the characteristically higher IHI of mixed-handers was unaffected by the bilateral EM manipulation.     

Neural mechanisms of social influence

The present investigation explores the neural mechanisms underlying the impact of social influence on preferences. We socially tagged symbols as valued or not – by exposing participants to the preferences of their peers – and assessed subsequent brain activity during an incidental processing task in which participants viewed popular, unpopular, and novel symbols. The medial prefrontal cortex (mPFC) differentiated between symbols that were and were not socially tagged – a possible index of normative influence – while aspects of the striatum (the caudate) differentiated between popular and unpopular symbols – a possible index of informational influence. These results suggest that integrating activity in these two brain regions may differentiate objects that have become valued as a result of social influence from those valued for non-social reasons.     

An experimental investigation of the automatic/voluntary dissociation in limb apraxia

The ability of apraxic patients to perform gestures in everyday life is a controversial issue. In this paper, we aimed to evaluate the automatic/voluntary dissociation (AVD) in four patients affected by clinically relevant limb apraxia. For this purpose, we sampled different kinds of gestures belonging to patients' motor repertoire and then assessed their production in a testing session. Our experimental procedure consisted of two steps: in the first phase, we recorded gestures produced by patients in two natural conditions; in the second phase, we assessed production of correctly produced tool-actions, and of spontaneous non tool-actions and meaningless conversational (cohesive and beats) gestures under different modalities. AVD was observed for all types of gestures, albeit to different degree in single patients. The present findings demonstrate that the context provides strong bottom-up cues for the retrieval of motor patterns, while artificial testing conditions impose an additional cognitive load.     

Neural evidence for the interplay between language, gesture, and action: a review

Co-speech gestures embody a form of manual action that is tightly coupled to the language system. As such, the co-occurrence of speech and co-speech gestures is an excellent example of the interplay between language and action. There are, however, other ways in which language and action can be thought of as closely related. In this paper we will give an overview of studies in cognitive neuroscience that examine the neural underpinnings of links between language and action. Topics include neurocognitive studies of motor representations of speech sounds, action-related language, sign language and co-speech gestures. It will be concluded that there is strong evidence on the interaction between speech and gestures in the brain. This interaction however shares general properties with other domains in which there is interplay between language and action.     

Etiologic Subtypes of Attention-Deficit/Hyperactivity Disorder: Brain Imaging, Molecular Genetic and Environmental Factors and the Dopamine Hypothesis

Multiple theories of Attention-Deficit/Hyper- activity Disorder (ADHD) have been proposed, but one that has stood the test of time is the dopamine deficit theory. We review the narrow literature from recent brain imaging and molecular genetic studies that has improved our understanding of the role of dopamine in manifestation of symptoms of ADHD, performance deficits on neuropsychological tasks, and response to stimulant medication that constitutes the most common treatment of this disorder. First, we consider evidence of the presence of dopamine deficits based on the recent literature that (1) confirms abnormalities in dopamine-modulated frontal-striatal circuits, reflected by size (smaller-than-average components) and function (hypoactivation); (2) clarifies the agonist effects of stimulant medication on dopaminergic mechanisms at the synaptic and circuit level of analysis; and (3) challenges the most-widely accepted ADHD-related neural abnormality in the dopamine system (higher-than-normal dopamine transporter [DAT] density). Second, we discuss possible genetic etiologies of dopamine deficits based on recent molecular genetic literature, including (1) multiple replications that confirm the association of ADHD with candidate genes related to the dopamine receptor D4 (DRD4) and the DAT; (2) replication of differences in performance of neuropsychological tasks as a function of the DRD4 genotype; and (3) multiple genome-wide linkage scans that demonstrate the limitations of this method when applied to complex disorders but implicate additional genes that may contribute to the genetic basis of ADHD. Third, we review possible environmental etiologies of dopamine deficits based on recent studies of (1) toxic substances that may affect the dopamine system in early development and contribute substantially to the etiology of ADHD; (2) fetal adaptations in dopamine systems in response to stress that may alter early development with lasting effects, as proposed by the developmental origins of health and disease hypothesis; and (3) gene-environment interactions that may moderate selective damage or adaptation of dopamine neurons. Based on these reviews, we identify critical issues about etiologic subtypes of ADHD that may involve dopamine, discuss methods that could be used to address these issues, and review old and new theories that may direct research in this area in the future.     

Composition of brain oscillations and their functions in the maintenance of auditory,visual and audio–visual speech percepts: an exploratory study

In the present exploratory study based on 7 subjects, we examined the composition of magnetoencephalographic (MEG) brain oscillations induced by the presentation of an auditory, visual, and audio-visual stimulus (a talking face) using an oddball paradigm. The composition of brain oscillations were assessed here by analyzing the probability-classification of short-term MEG spectral patterns. The probability index for particular brain oscillations being elicited was dependent on the type and the modality of the sensory percept. The maintenance of the integrated audio-visual percept was accompanied by the unique composition of distributed brain oscillations typical of auditory and visual modality, and the contribution of brain oscillations characteristic for visual modality was dominant. Oscillations around 20 Hz were characteristic for the maintenance of integrated audio-visual percept. Identifying the actual composition of brain oscillations allowed us (1) to distinguish two subjectively/consciously identical mental percepts, and (2) to characterize the types of brain functions involved in the maintenance of the multi-sensory percept.     

辛苦所得与意外所得的非理性消费偏差：基于IAT检测和ERP证据

不同来源的财富因其在人们心理的权重差异会导致对其消费态度与方式的不同。前人运用一系列行为实验已发现意外所得更容易消费、辛苦所得则不容易消费。基于心理账户和内隐社会认知等理论, 运用IAT和ERP考察财富的意外所得与辛苦所得在人们心理引起的内在消费偏差, 进而对内隐消费态度和脑加工机制进行间接检测。IAT研究结果表明, 意外所得与容易消费的联结更加紧密, 辛苦所得与不易消费的联结更加紧密, 从内隐层面验证了前人的行为研究结论; ERP研究结果发现辛苦所得与意外所得这两个不同收入来源可能建立了不同脑加工机制, 且在P3和LPC成分得到反映, P3成分可能是反映辛苦所得组偏好难消费型消费方式的ERP成分, LPC反映了意外所得收入条件下个体偏好易消费型消费方式的特点。     

Moving Beyond Computational Cognitivism: Understanding Intentionality,Intersubjectivity and Ecology of Mind

The emergence of the Cognitive Sciences, in the middle of the 20th Century, was initially based on an abstract model of the mind: the computer metaphor. The human mind was understood in analogy to the digital computer, as a rule-based, symbol processor. As a consequence, the human being was envisioned as logically-rationally guided, radically disembodied and isolated from culture. Over the last few decades, several disciplines, such as Biology, Mathematics, Philosophy, Psychology and Neuroscience, have begun to address the study of intentionality, intersubjectivity and natural cognition. Searching for a better understanding of these complex issues, a number of approaches have been developed with the promise of capturing the specific qualities of human cognition, radically omitted from a computationalist view of mind. Nevertheless, since these research programs are rather recent, concrete methodological designs and empirical approaches in the form of experimentally testable hypotheses are still scarce. This special issue brings together several perspectives in order to propose alternative research approaches in the topics of Intentionality, Intersubjectivity and Ecology of Mind. We believe it is necessary to discuss and advance towards explicit empirical frames in the form of actual experiments, specific predictions and formal models. The essays presented here constitute an attempt to move in this direction, with the specific aim of reconsidering the study of some forgotten properties of brain and mind.