The covariation of independent and dependant variables in neurofeedback: A proposal framework to identify cognitive processes and brain activity variables

This methodological article proposes a framework for analysing the relationship between cognitive processes and brain activity using variables measured by neurofeedback (NF) carried out by functional Magnetic Resonance Imagery (fMRI NF). Cognitive processes and brain activity variables can be analysed as either the dependant variable or the independent variable. Firstly, we propose two traditional approaches, defined in the article as the “neuropsychological” approach (NP) and the “psychophysiology” approach (PP), to extract dependent and independent variables in NF protocols. Secondly, we suggest that NF can be inspired by the style of inquiry used in neurophenomenology. fMRI NF allows participants to experiment with his or her own cognitive processes and their effects on brain region of interest (ROI) activations simultaneously. Thus, we suggest that fMRI NF could be improved by implementing “the elicitation interview method”, which allows the investigator to gather relevant verbatim from participants’ introspection on subjective experiences.     

The relationship between puberty and social emotion processing

The social brain undergoes developmental change during adolescence, and pubertal hormones are hypothesized to contribute to this development. We used fMRI to explore how pubertal indicators (salivary concentrations of testosterone, oestradiol and DHEA; pubertal stage; menarcheal status) relate to brain activity during a social emotion task. Forty‐two females aged 11.1 to 13.7 years underwent fMRI scanning while reading scenarios pertaining either to social emotions, which require the representation of another person’s mental states, or to basic emotions, which do not. Pubertal stage and menarcheal status were used to assign girls to early or late puberty groups. Across the entire sample, the contrast between social versus basic emotion resulted in activity within the social brain network, including dorsomedial prefrontal cortex (DMPFC), the posterior superior temporal sulcus, and the anterior temporal cortex (ATC) in both hemispheres. Increased hormone levels (independent of age) were associated with higher left ATC activity during social emotion processing. More advanced age (independent of hormone levels) was associated with lower DMPFC activity during social emotion processing. Our results suggest functionally dissociable effects of pubertal hormones and age on the adolescent social brain.     

Cerebral white matter abnormalities and lifetime cognitive change: a 67-year follow-up of the Scottish Mental Survey of 1932

Cerebral white matter abnormalities relate to cognitive functioning in elders. We examine whether this association is (a) independent of mental ability in youth and (b) related to general and/or specific mental abilities. We retested 83 participants of the Scottish Mental Survey of 1932 on a battery of mental tests. Their brains were scanned by magnetic resonance imaging. Three independent ratings (Fazekas) were made of periventricular, and subcortical and deep white matter abnormalities. Structural equation models showed that, irrespective of brain location, white matter abnormalities contributed about 14% of cognitive function variance in old age. Some of this effect might be due to hypertension. This contribution is independent of mental function in early life and is associated with general cognitive ability.     

Creativity and Brain-Functioning in Product Development Engineers: A Canonical Correlation Analysis

This study used canonical correlation analysis to explore the relation among scores on the Torrance test of figural and verbal creativity and demographic, psychological and physiological measures in Swedish product-development engineers. The first canonical variate included figural and verbal flexibility and originality as dependent measures and (a) higher scores on the brain integration scale, (b) faster speed of processing in an event-related potential task, (c) faster conflict-resolution during the Stroop task, (d) higher moral reasoning, and (e) higher manageability and lower comprehensibility as independent measures. Flexibility and originality reflect the ability to see old situations in new ways leading to unique responses. Greater mental adaptability was associated with greater brain integration and speed of processing along with higher moral reasoning and feeling of being in control. Future research could investigate effects of interventions that optimize brain integration on creative output across professions.     

Brain Function Associated with Cooccurring Trauma and Depression Symptoms in College Students

The goal of this pilot study was to determine if functional brain differences are present among individuals with high and low cooccurring trauma and depression symptoms. This pilot study examined how the P300 latency component of event-related potentials (ERPs), measured using electroencephalography (EEG) while participants performed a go/no-go task, might be associated with cooccurring self-report of trauma and depression symptoms in a sample of college students (N = 38). Alpha-corrected independent sample t tests revealed statistically significant differences in ERP P300 peak latencies between those in the high cooccurring trauma and depression symptoms group (n = 12) and those in the low group (n = 26) for all 3 midline electrode sites (Fz, Cz, and Pz). This pilot study provides preliminary evidence of differential brain functioning in individuals experiencing cooccurring trauma and depression symptoms. Accordingly, these findings support future research examining brain functioning in cooccurring symptoms.     

Investigating the modality specificity of response selection using a temporal flanker task

The neurocognitive architecture for response selection is uncertain. Some theorists suggest that it is mediated by an amodal central mechanism, whereas others propose a set of independent control mechanisms. In a functional neuroimaging experiment, we investigated the nature of response selection by examining how its underlying brain mechanisms are affected by stimulus modality. To do this, we used a modified flanker task, in which the target and flanker (distractor) stimuli differed in time rather than space, making it accessible for both visual and auditory stimuli. As in the traditional flanker task, larger reaction times were observed for incongruent than congruent trials (i.e., a congruency effect) for both modalities. Congruency affected brain activation for both modalities in prefrontal cortex, parietal cortex, and the putamen. Modality-dependent activation was found in additional prefrontal and parietal regions for the visual modality and in left inferior prefrontal cortex for the auditory modality. Modality-dependent activity specifically related to response congruency was also found in sensory cortical regions. These data suggest that modality affects the brain regions throughout the cortex mediating response selection even for conceptually identical stimuli and tasks. They are consistent with the hypothesis that (at least partially) independent brain networks mediate response selection and that input modality may be a powerful factor for organizing neural activity to support task performance.     

A new method for detecting causality in fMRI data of cognitive processing

One of the most important achievements in understanding the brain is that the emergence of complex behavior is guided by the activity of brain networks. To fully apply this theoretical approach fully, a method is needed to extract both the location and time course of the activities from the currently employed techniques. The spatial resolution of fMRI received great attention, and various non-conventional methods of analysis have previously been proposed for the above-named purpose. Here, we briefly outline a new approach to data analysis, in order to extract both spatial and temporal activities from fMRI recordings, as well as the pattern of causality between areas. This paper presents a completely data-driven analysis method that applies both independent components analysis (ICA) and the Granger causality test (GCT), performed in two separate steps. First, ICA is used to extract the independent functional activities. Subsequently the GCT is applied to the independent component (IC) most correlated with the stimuli, to indicate its causal relation with other ICs. We therefore propose this method as a promising data-driven tool for the detection of cognitive causal relationships in neuroimaging data.     

The biological bases of unfairness: Neuroimaging evidence for the distinctiveness of procedural and distributive justice

A classic debate in the organizational justice literature concerns the question of whether procedural justice and distributive justice are independent constructs. We investigate this question by using fMRI methods to examine brain activation patterns associated with procedural and distributive unfairness. We observed a clear dissociation of activation between these two forms of justice, and only a minimal amount of shared activation in the hypothesized regions. Specifically, unfair procedures evoked greater activation in parts of the brain related to social cognition, such as the ventrolateral prefrontal cortex (VLPFC) and the superior temporal sulcus (STS), whereas unfair outcomes evoked greater activation in more emotional areas of the brain, such as the anterior cingulate cortex (ACC), anterior insula (AI) and the dorsolateral prefrontal cortex (DLPFC). We interpret the findings as supporting the notion that the two forms of justice reflect distinct constructs, while recognizing that, as forms of justice, they are closely related nomologically.     

Interleaving brain systems for episodic and recognition memory

Conflicting models persist over the nature of long-term memory. Crucial issues are whether episodic memory and recognition memory reflect the same underlying processes, and the extent to which various brain structures work as a single unit to support these processes. New findings that have resulted from improved resolution of functional brain imaging, together with recent studies of amnesia and developments in animal testing, reinforce the view that recognition memory comprises at least two independent processes: one recollective and the other using familiarity detection. Only recollective recognition appears to depend on episodic memory. Attempts to map brain areas supporting these two putative components of recognition memory indicate that they depend on separate, but interlinked, structures.     

Brain rCBF and performance in visual imagery tasks: Common and distinct processes

The present study was designed to discover whether variations in normalised regional cerebral blood flow (rCBF) in different brain areas predict variations in performance of different imagery tasks. Positron emission tomography (PET) was used to assess brain activity as 16 participants performed four imagery tasks. These tasks were designed so that performance was particularly sensitive to the participant's ability to form images with high resolution, to generate images from distinct segments, to parse imaged forms into parts while inspecting them, or to transform (rotate) images. Response times and error rates were recorded. Multiple regression analyses revealed that variations in most brain areas predicted variations in performance of only one task, thus demonstrating that the four tasks tap largely independent imagery processes. However, we also found that some underlying processes were recruited by more than one task, particularly those implemented in the occipito‐parietal sulcus, the medial frontal cortex, and Area 18.     

Optimal response biases and the slope of ROC curves as a function of signal intensity,signal probability,and relative payoff

Rats performed in a two-lever analogue of the yes-no psychophysical procedure. The signal consisted of of an increment in the intensity of a random noise. Correct responses were reinforced with single bursts of brain stimulation; incorrect responses produced brief periods of time-out. Receiver-operating-characteristic curves were generated at each of several signal intensities by varying either the signal probability (0.1–0.9) or the relative number of brain stimulations for correct responses (1:3–3:1). The index d’ (or d’_e) increased with the signal intensity and was independent of response bias. When the signal probability was varied, the animals optimized the number of correct trials. and hence the number of brain stimulations obtained at each level of detection. They approximated this optimum more closely as the signal intensity was reduced. When the ratio of brain stimulations was varied, the animals compromised between optimizing the number of correct trials and optimizing the number of brain stimulations obtained. The slopes of the ROC curves plotted on normal-normal coordinates frequently departed from unity, but did not change systematically with either the signal intensity or the method by which they were generated.     

Auditory evoked responses recorded from 16-month-old human infants to words they did and did not know

Auditory evoked responses (AERs) were recorded from the frontal, temporal, and parietal scalp regions of nine male and nine female 16-month-old infants while they listened to a series of words. The brain responses reliably discriminated between words the infants were thought to understand versus those that they did not appear to know as judged by their parents and two independent raters. Findings from this study indicated that the brain wave patterns could discriminate known from unknown words. Sex differences in the patterns of lateralized hemispheric responses to the known and unknown words were also noted. These data indicate that auditory evoked responses may be used to detect differences in word meanings in young infants.     

The conscious access hypothesis: origins and recent evidence

Consciousness might help to mobilize and integrate brain functions that are otherwise separate and independent. Evidence for this 'conscious access hypothesis' was described almost two decades ago, in a framework called global workspace theory. The theory had little impact at first, for three reasons: because consciousness was controversial; the evidence, though extensive, was indirect; and integrative theory was unfashionable. Recent neuroimaging evidence appears broadly to support the hypothesis, which has implications for perception, learning, working memory, voluntary control, attention and self systems in the brain.     

An ERP investigation on the temporal dynamics of emotional prosody and emotional semantics in pseudo- and lexical-sentence context

Previous evidence supports differential event-related brain potential (ERP) responses for emotional prosodic processing and integrative emotional prosodic/semantic processing. While latter process elicits a negativity similar to the well-known N400 component, transitions in emotional prosodic processing elicit a positivity. To further substantiate this evidence, the current investigation utilized lexical-sentences and sentences without lexical content (pseudo-sentences) spoken in six basic emotions by a female and a male speaker. Results indicate that emotional prosodic expectancy violations elicit a right-lateralized positive-going ERP component independent of basic emotional prosodies and speaker voice. In addition, expectancy violations of integrative emotional prosody/semantics elicit a negativity with a whole-head distribution. The current results nicely complement previous evidence, and extend the results by showing the respective effects for a wider range of emotional prosodies independent of lexical content and speaker voice.     

Cognitive and affective development in adolescence

Questions about the nature of normative and atypical development in adolescence have taken on special significance in the last few years, as scientists have begun to recast old portraits of adolescent behavior in the light of new knowledge about brain development. Adolescence is often a period of especially heightened vulnerability as a consequence of potential disjunctions between developing brain, behavioral and cognitive systems that mature along different timetables and under the control of both common and independent biological processes. Taken together, these developments reinforce the emerging understanding of adolescence as a critical or sensitive period for a reorganization of regulatory systems, a reorganization that is fraught with both risks and opportunities.     

Histidine-decarboxylase knockout mice show deficient nonreinforced episodic object memory, improved negatively reinforced water-maze performance, and increased neo- and ventro-striatal dopamine turnover

The brain's histaminergic system has been implicated in hippocampal synaptic plasticity, learning, and memory, as well as brain reward and reinforcement. Our past pharmacological and lesion studies indicated that the brain's histamine system exerts inhibitory effects on the brain's reinforcement respective reward system reciprocal to mesolimbic dopamine systems, thereby modulating learning and memory performance. Given the close functional relationship between brain reinforcement and memory processes, the total disruption of brain histamine synthesis via genetic disruption of its synthesizing enzyme, histidine decarboxylase (HDC), in the mouse might have differential effects on learning dependent on the task-inherent reinforcement contingencies. Here, we investigated the effects of an HDC gene disruption in the mouse in a nonreinforced object exploration task and a negatively reinforced water-maze task as well as on neo- and ventro-striatal dopamine systems known to be involved in brain reward and reinforcement. Histidine decarboxylase knockout (HDC-KO) mice had higher dihydrophenylacetic acid concentrations and a higher dihydrophenylacetic acid/dopamine ratio in the neostriatum. In the ventral striatum, dihydrophenylacetic acid/dopamine and 3-methoxytyramine/dopamine ratios were higher in HDC-KO mice. Furthermore, the HDC-KO mice showed improved water-maze performance during both hidden and cued platform tasks, but deficient object discrimination based on temporal relationships. Our data imply that disruption of brain histamine synthesis can have both memory promoting and suppressive effects via distinct and independent mechanisms and further indicate that these opposed effects are related to the task-inherent reinforcement contingencies.     

DISSOCIATION OF STORAGE AND REHEARSAL IN VERBAL WORKING MEMORY:

Abstract— Current cognitive models of verbal working memory include two components a phonological store and a rehearsal mechanism that refreshes the contents of this store We present research using positron emission tomography (PET) to provide further evidence for this functional division In Experiment I, subjects performed a variant of Sternberg's (1966) item recognition task Experiment 2 used a continuous memory task with control conditions designed to separate the brain regions underlying storage and rehearsal The results show that independent brain regions mediate storage and rehearsal In Experiment 3, a dual-task procedure supported the assumption that these memory tasks elicited a rehearsal strategy     

State dependent modification of auditory brain stem potentials

It is well known, amplitudes and latencies of auditory brain stem potentials are almost independent of viligance state. Contrary to that, simple cognitive requirements effect amplitude changes (enhancement of variance, amplitude reduction) in a part 2/3) of the subjects.     

On the interplay between familiarity and emotional expression in face perception

Traditional models of face perception (e.g. Bruce and Young 1986) stress independent routes for processing identity and emotional expression. We investigated the interplay between familiarity and emotional expression by systematically varying both factors. In contrast to earlier studies which used binary forced-choice decisions, participants had to judge the familiarity of the presented face and the emotional hedonic valence and emotional arousal of its expressed emotion (angry, happy or neutral), using rating scales. The results demonstrated symmetric, strong interactions between familiarity and expressed emotion. Thus, this study supports more recent models of face perception (Haxby et al. 2000) that were mostly based on brain imaging data. These data together with our behavioural results emphasize the interaction of emotional expression and personal identity and support approaches that propose a relative segregation of these processes, rather than completely independent coding (Calder and Young 2005).     

The temporal organization of functional brain connectivity is abnormal in schizophrenia but does not correlate with symptomatology

Previous work employing graph theory and nonlinear analysis has found increased spatial and temporal disorder, respectively, of functional brain connectivity in schizophrenia. We present a new method combining graph theory and nonlinear techniques that measures the temporal disorder of functional brain connections. Multichannel electroencephalographic data were windowed and functional networks were reconstructed using the minimum spanning trees of correlation matrices. Using a method based on Shannon entropy, we found elevated connection entropy in gamma activity of patients with schizophrenia; however, gamma connection entropy remained elevated in patients with schizophrenia even after a reduction in symptoms due to treatment with antipsychotics. Our results are consistent with several possibilities: (1) aberrant functional connectivity is epiphenomenal to schizophrenia, (2) aberrant functional connectivity is a central feature but antipsychotics reduce symptoms by an independent mechanism, or (3) connection entropy is not an appropriately sensitive measure of brain abnormalities in schizophrenia.