The relationship between self-awareness of attentional status, behavioral performance and oscillatory brain rhythms

High-level cognitive factors, including self-awareness, are believed to play an important role in human visual perception. The principal aim of this study was to determine whether oscillatory brain rhythms play a role in the neural processes involved in self-monitoring attentional status. To do so we measured cortical activity using magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) while participants were asked to self-monitor their internal status, only initiating the presentation of a stimulus when they perceived their attentional focus to be maximal. We employed a hierarchical Bayesian method that uses fMRI results as soft-constrained spatial information to solve the MEG inverse problem, allowing us to estimate cortical currents in the order of millimeters and milliseconds. Our results show that, during self-monitoring of internal status, there was a sustained decrease in power within the 7-13 Hz (alpha) range in the rostral cingulate motor area (rCMA) on the human medial wall, beginning approximately 430 msec after the trial start (p < 0.05, FDR corrected). We also show that gamma-band power (41-47 Hz) within this area was positively correlated with task performance from 40-640 msec after the trial start (r = 0.71, p < 0.05). We conclude: (1) the rCMA is involved in processes governing self-monitoring of internal status; and (2) the qualitative differences between alpha and gamma activity are reflective of their different roles in self-monitoring internal states. We suggest that alpha suppression may reflect a strengthening of top-down interareal connections, while a positive correlation between gamma activity and task performance indicates that gamma may play an important role in guiding visuomotor behavior. © 2013 Yamagishi et al.

A quantitative study of the pathological changes in ten patients with multiple system atrophy (MSA)

The densities of the glial cytoplasmic inclusions (GCI), neuronal inclusions (NI), and abnormal neurons were studied in the frontal cortex, hippocampus, cerebellum, basal ganglia and areas of the pons and medulla in 10 cases of multiple system atrophy (MSA). GCI density was greater in the substantia nigra and globus pallidus compared with the frontal cortex and hippocampus. Abnormal neurons were most abundant in the frontal cortex, substantia nigra, and inferior olivary nucleus. NI and abnormal neuron densities were positively correlated in the globus pallidus but negatively correlated in the hippocampus. The NI and GCI were only positively correlated in the pons. GCI in the pons and inferior olivary nucleus, NI in the substantia nigra, and abnormal neurons in the frontal cortex varied significantly between cases. The MSA cases did not cluster according to disease subtype. The data suggest that: 1) the greatest densities of pathological changes occur in the substantia nigra and globus pallidus, 2) density of the GCI is unrelated to that of the NI, and 3) there is overlapping pathology between the various subtypes of MSA.

The histogenesis of lymphoid organs in Tilapia mossambica and antibody responses in adults and fry

The thymic anlagen appears in Tilapia mossambica at 2 days post hatching and becomes lymphoid at 5 days. Lymphoid cells were first seen in the pronephros at 14 days and in the spleen at approximately five weeks of age. Differentiation into red and white pulp regions was seen by 10 weeks of age. Light and electron microscopic studies of adult lymphoid organ revealed increases in size and lymphoid cell numbers. Adult thymus develops a clearer corticomedullary differentiation of thymic corpuscles in the medulla and in the splenic red and white pulp became more distinct. Melanomacrophage centres were seen in spleen and pronephros. Adult fish gave primary and secondary antibody responses following challenge with sheep red bloods cells (SRBC), Escherichia coli (E. coli) and human gamma globulin (HGG). Plaque forming cell and immunocytoadherence assays revealed that head kidney and spleen were major sites for antibody production and development of antigen reactive cells. Proliferative activity in these organs was revealed using autoradiography and scintillation counting. Increased levels of pyroninophilia were also seen following antigenic challenge. Pilot studies on adults revealed that they were capable of rejecting first and second set allografts and leucocytes from spleen and head kidney proliferated in mixed leucocyte cultures. Antibody responses to SRBC, E. coli and HGG develop at about 10-12 weeks of age. Fry given either a single injection of SRBC at 10 weeks or two injections of the same antigen at 10 weeks and 12 days later, failed to respond to a further challenge with SRBC 56 days after the first injection (A time when animals would normally respond positively to this antigen). Injection of E. coli at the same times resulted in a prolonged antibody response.

The functional anatomy of the McCollough contingent colour after-effect

We report two functional magnetic resonance imaging (fMRI) experiments which reveal a cortical network activated when perceiving coloured grids, and experiencing the McCollough effect (ME). Our results show that perception of red-black and green-black grids activate the right fusiform gyrus (area V4) plus the left and right lingual gyri, right striate cortex (V1) and left insula. The ME activated the left anterior fusiform gyrus as well as the ventrolateral prefrontal cortex, and in common with colour perception, the left insula. These data confirm the critical role of the fusiform gyrus in actual and illusory colour perception as well as revealing localized frontal cortical activation associated with the ME, which would suggest that a 'top-down' mechanism is implicated in this illusion.

Changing faces

News & Comment. Many influential models of prefrontal cortex function suggest that activity within this area is often associated with additional activity in posterior regions of the cortex that support perception. The purpose of this cortical ‘coupling’ is to ensure that a perceptual representation is generated and then maintained within the working memory system. Areas in the right ventrolateral prefrontal cortex (vlPFC) and the fusiform gyrus have been implicated as associate areas involved in face processing. In an interesting case study by Vignal, Chauvel and Halgren the functional relationship between these two areas was tested1. In order to confirm the epileptogenic foci prior to resective surgery in a 30-year-old male patient, depth electrodes were implanted into sites around prefrontal, anterior temporal and premotor cortices. While the patient was looking at a blank screen, 50-Hz electrical stimulation of two probes implanted into the right anterior frontal gyrus resulted in the patient’s reporting the perception of a series of colourful faces. These facial hallucinations were described as being ‘…like passing slides, one after the after, linked together’. When asked to look at an actual face during stimulation at the same sites the patient reported transformation of that face (such as appearing without spectacles or with a hat). These findings were related to activity of a cortical network involving the vlPFC and the fusiform gyrus. This paper thus suggests a role in face processing for the vlPFC, evoking working memory processes to maintain facial representations.

Having a word with yourself:neural correlates of self-criticism and self-reassurance

Self-criticism is strongly correlated with a range of psychopathologies, such as depression, eating disorders and anxiety. In contrast, self-reassurance is inversely associated with such psychopathologies. Despite the importance of self-judgements and evaluations, little is known about the neurophysiology of these internal processes. The current study therefore used a novel fMRI task to investigate the neuronal correlates of self-criticism and self-reassurance. Participants were presented statements describing two types of scenario, with the instruction to either imagine being self-critical or self-reassuring in that situation. One scenario type focused on a personal setback, mistake or failure, which would elicit negative emotions, whilst the second was of a matched neutral event. Self-criticism was associated with activity in lateral prefrontal cortex (PFC) regions and dorsal anterior cingulate (dAC), therefore linking self-critical thinking to error processing and resolution, and also behavioural inhibition. Self-reassurance was associated with left temporal pole and insula activation, suggesting that efforts to be self-reassuring engage similar regions to expressing compassion and empathy towards others. Additionally, we found a dorsal/ventral PFC divide between an individual's tendency to be self-critical or self-reassuring. Using multiple regression analyses, dorsolateral PFC activity was positively correlated with high levels of self-criticism (assessed via self-report measure), suggesting greater error processing and behavioural inhibition in such individuals. Ventrolateral PFC activity was positively correlated with high self-reassurance. Our findings may have implications for the neural basis of a range of mood disorders that are characterised by a preoccupation with personal mistakes and failures, and a self-critical response to such events.

Familial and disease specific abnormalities in the neural correlates of the Stroop Task in Bipolar Disorder

Patients with Bipolar Disorder (BD) perform poorly on tasks of selective attention and inhibitory control. Although similar behavioural deficits have been noted in their relatives, it is yet unclear whether they reflect dysfunction in the same neural circuits. We used functional magnetic resonance imaging and the Stroop Colour Word Task to compare task related neural activity between 39 euthymic BD patients, 39 of their first-degree relatives (25 with no Axis I disorders and 14 with Major Depressive Disorder) and 48 healthy controls. Compared to controls, all individuals with familial predisposition to BD, irrespective of diagnosis, showed similar reductions in neural responsiveness in regions involved in selective attention within the posterior and inferior parietal lobules. In contrast, hypoactivation within fronto-striatal regions, implicated in inhibitory control, was observed only in BD patients and MDD relatives. Although striatal deficits were comparable between BD patients and their MDD relatives, right ventrolateral prefrontal dysfunction was uniquely associated with BD. Our findings suggest that while reduced parietal engagement relates to genetic risk, fronto-striatal dysfunction reflects processes underpinning disease expression for mood disorders. © 2011 Elsevier Inc.

The impact of the Val158Met catechol-O-methyltransferase genotype on neural correlates of sad facial affect processing in patients with bipolar disorder and their relatives

Background - The Met allele of the catechol-O-methyltransferase (COMT) valine-to-methionine (Val158Met) polymorphism is known to affect dopamine-dependent affective regulation within amygdala-prefrontal cortical (PFC) networks. It is also thought to increase the risk of a number of disorders characterized by affective morbidity including bipolar disorder (BD), major depressive disorder (MDD) and anxiety disorders. The disease risk conferred is small, suggesting that this polymorphism represents a modifier locus. Therefore our aim was to investigate how the COMT Val158Met may contribute to phenotypic variation in clinical diagnosis using sad facial affect processing as a probe for its neural action. Method - We employed functional magnetic resonance imaging to measure activation in the amygdala, ventromedial PFC (vmPFC) and ventrolateral PFC (vlPFC) during sad facial affect processing in family members with BD (n=40), MDD and anxiety disorders (n=22) or no psychiatric diagnosis (n=25) and 50 healthy controls. Results - Irrespective of clinical phenotype, the Val158 allele was associated with greater amygdala activation and the Met allele with greater signal change in the vmPFC and vlPFC. Signal changes in the amygdala and vmPFC were not associated with disease expression. However, in the right vlPFC the Met158 allele was associated with greater activation in all family members with affective morbidity compared with relatives without a psychiatric diagnosis and healthy controls. Conclusions - Our results suggest that the COMT Val158Met polymorphism has a pleiotropic effect within the neural networks subserving emotional processing. Furthermore the Met158 allele further reduces cortical efficiency in the vlPFC in individuals with affective morbidity. © 2010 Cambridge University Press.

Pilot investigation of the changes in cortical activation during facial affect recognition with lamotrigine monotherapy in bipolar disorder

Background: Bipolar disorder is associated with dysfunction in prefrontal and limbic areas implicated in emotional processing. Aims: To explore whether lamotrigine monotherapy may exert its action by improving the function of the neural network involved in emotional processing. Method: We used functional magnetic resonance imaging to examine changes in brain activation during a sad facial affect recognition task in 12 stable patients with bipolar disorder when medication-free compared with healthy controls and after 12 weeks of lamotrigine monotherapy. Results: At baseline, compared with controls, patients with bipolar disorder showed overactivity in temporal regions and underactivity in the dorsal medial and right ventrolateral prefrontal cortex, and the dorsal cingulate gyrus. Following lamotrigine monotherapy, patients demonstrated reduced temporal and increased prefrontal activation. Conclusions: This preliminary evidence suggests that lamotrigine may enhance the function of the neural circuitry involved in affect recognition.

Investigating the human mirror neuron system by means of cortical synchronization during the imitation of biological movements

The human mirror neuron system (MNS) has recently been a major topic of research in cognitive neuroscience. As a very basic reflection of the MNS, human observers are faster at imitating a biological as compared with a non-biological movement. However, it is unclear which cortical areas and their interactions (synchronization) are responsible for this behavioural advantage. We investigated the time course of long-range synchronization within cortical networks during an imitation task in 10 healthy participants by means of whole-head magnetoencephalography (MEG). Extending previous work, we conclude that left ventrolateral premotor, bilateral temporal and parietal areas mediate the observed behavioural advantage of biological movements in close interaction with the basal ganglia and other motor areas (cerebellum, sensorimotor cortex). Besides left ventrolateral premotor cortex, we identified the right temporal pole and the posterior parietal cortex as important junctions for the integration of information from different sources in imitation tasks that are controlled for movement (biological vs. non-biological) and that involve a certain amount of spatial orienting of attention. Finally, we also found the basal ganglia to participate at an early stage in the processing of biological movement, possibly by selecting suitable motor programs that match the stimulus.

The special case of self-perspective inhibition in mental, but not non-mental, representation

The ventrolateral prefrontal cortex (vlPFC) has been implicated in studies of both executive and social functions. Recent meta-analyses suggest that vlPFC plays an important but little understood role in Theory of Mind (ToM). Converging neuropsychological and functional Magnetic Resonance Imaging (fMRI) evidence suggests that this may reflect inhibition of self-perspective. The present study adapted an extensively published ToM localizer to evaluate the role of vlPFC in inhibition of self-perspective. The classic false belief, false photograph vignettes that comprise the localizer were modified to generate high and low salience of self-perspective. Using a factorial design, the present study identified a behavioural and neural cost associated with having a highly salient self-perspective that was incongruent with the representational content. Importantly, vlPFC only differentiated between high versus low salience of self-perspective when representing mental state content. No difference was identified for non-mental representation. This result suggests that different control processes are required to represent competing mental and non-mental content.

Representation, control, or reasoning? Distinct functions for theory of mind within the medial prefrontal cortex

The medial pFC (mPFC) is frequently reported to play a central role in Theory of Mind (ToM). However, the contribution of this large cortical region in ToM is not well understood. Combining a novel behavioral task with fMRI, we sought to demonstrate functional divisions between dorsal and rostral mPFC. All conditions of the task required the representation of mental states (beliefs and desires). The level of demands on cognitive control (high vs. low) and the nature of the demands on reasoning (deductive vs. abductive) were varied orthogonally between conditions. Activation in dorsal mPFC was modulated by the need for control, whereas rostral mPFC was modulated by reasoning demands. These findings fit with previously suggested domain-general functions for different parts of mPFC and suggest that these functions are recruited selectively in the service of ToM.

Multiple roles for executive control in belief-desire reasoning:distinct neural networks are recruited for self perspective inhibition and complexity of reasoning

Belief-desire reasoning is a core component of 'Theory of Mind' (ToM), which can be used to explain and predict the behaviour of agents. Neuroimaging studies reliably identify a network of brain regions comprising a 'standard' network for ToM, including temporoparietal junction and medial prefrontal cortex. Whilst considerable experimental evidence suggests that executive control (EC) may support a functioning ToM, co-ordination of neural systems for ToM and EC is poorly understood. We report here use of a novel task in which psychologically relevant ToM parameters (true versus false belief; approach versus avoidance desire) were manipulated orthogonally. The valence of these parameters not only modulated brain activity in the 'standard' ToM network but also in EC regions. Varying the valence of both beliefs and desires recruits anterior cingulate cortex, suggesting a shared inhibitory component associated with negatively valenced mental state concepts. Varying the valence of beliefs additionally draws on ventrolateral prefrontal cortex, reflecting the need to inhibit self perspective. These data provide the first evidence that separate functional and neural systems for EC may be recruited in the service of different aspects of ToM.

Mus Musculus Neural Crest Development: Is Pax3 Regulating the Expression of Endothelin Receptor B?

The vertebrate Neural Crest (NC) is formed during early embryonic development at the neurulation stage. This group of multi potent cells gives rise to a variety of derivatives such as the skin's pigmented cells (Melanocytes), the peripheral nervous system with its associated components, and the endocrine cells of the adrenal medulla amongst others. There are several molecular mechanisms that underlie the development and migration of NC derived cells. For example, during melanocyte differentiation and migration the Endothelin Receptor B and its ligand Endothelin 3 (EdnrB/Edn3), the kit/ Steel factor and the FGF receptor I FGF pathways amongst others play important roles. Additionally, several transcription factors such as Pax3, SoxlO and Mitfalso intervene during the NC cells differentiation processes. In this work, the possible regulatory interaction of Pax3 and EdnrB was assessed by in situ hybridization methods with EdnrB, SoxlO and Dct riboprobes in Pax3 homozygous embryos. To further characterize this interaction, genetic crosses between Pax3 heterozygous mutants and EdnrB heterozygous animals were established. Coat pigmentation was used as an indicator of genetic interaction on the progeny. Experimental results indicated that Pax3 does not directly regulate the expression of EdnrB during neural crest development but interact to produce normal coat color. I propose two possible models to explain the epistatic relationship of Pax3 and EdnrB during normal melanocyte development.

Caracterização citoarquitetônica e por imunoistoquímica para tirosina-hidroxilase da substância negra, área tegmentar ventral e zona retrorubral do Sagui (Callithrix jacchus)

It is known that the catecholamine group is constituted by dopamine, noradrenaline and adrenaline, in which the synthesis is regulated by an enzyme named tyrosine hydroxylase. Thus, 3-hydroxytyramine/dopamine (DA) is a precursor of the noradrenaline and adrenaline synthesis and acts as a neurotransmitter in the central nervous system. The three main nuclei, named the retrorubral field (A8 group), the substantia nigra pars compacta (A9 group) and the ventral tegmental area (A10 group), are arranged in the die-mesencephalic portion and are involved in three complexes circuitries - the mesostriatal, mesolimbic and mesocortical pathways. These pathways are related to behavioral manifestations, motricity, learning, reward and pathologies such as Parkinson’s Disease and Schizophrenia. Thus, the aim of this study was to perform de morphological analysis of the A8, A9 and A10 nuclei of the common marmoset (Callithrix jacchus). The marmoset is a neotropical primate, whose morphological and functional characteristics supports the suitability of use of this animal in biomedical research. Coronal sections of the marmoset brain were submitted to cytoarchitectonic characterization and TH-immunohistochemistry. Based on the morphology of the neurons, it was possible to subdivide the A10 group in seven regions: interfascicular nucleus, raphe rostral linear nucleus and raphe caudal linear nucleus, in the middle line; paranigral and parainterfascicular nucleus, in the middle zone; rostral portion of the ventral tegmental area nucleus and parabrachial pigmented nucleus, located in the dorsolateral portion of the mesencephalic tegmentum. A9 group was divided into four regions: substantia nigra compacta dorsal and ventral tiers; substantia nigra compacta lateral and medial clusters. No subdivisions were founded into A8 group. These results revealed that A8, A9 and A10 are phylogenetically conserved between species, but it’s necessary to expand the studies about this compartmentalization, investigating its occurrence in other primate species or investigating its functional relevance.