Occipital and orbitofrontal hemodynamics during naturally paced reading: An fNIRS study

Cortical cognitive processing during reading captured using functional-near infrared spectroscopy

Neuroimaging studies using functional magnetic resonance imaging (fMRI) have provided unparalleled insights into the fundamental neural mechanisms underlying human cognitive processing, such as high-level linguistic processes during reading. Here, we build upon this prior work to capture sentence reading comprehension outside the MRI scanner using functional near infra-red spectroscopy (fNIRS) in a large sample of participants (n = 82). We observed increased task-related hemodynamic responses in prefrontal and temporal cortical regions during sentence-level reading relative to the control condition (a list of non-words), replicating prior fMRI work on cortical recruitment associated with high-level linguistic processing during reading comprehension. These results lay the groundwork towards developing adaptive systems to support novice readers and language learners by targeting the underlying cognitive processes. This work also contributes to bridging the gap between laboratory findings and more real-world applications in the realm of cognitive neuroscience.

Atypical characteristic changes of surface morphology and structural covariance network in developmental dyslexia

BACKGROUND

Developmental dyslexia (DD) is a neurodevelopmental disorder that is characterized by difficulties with all aspects of information acquisition in the written word, including slow and inaccurate word recognition. The neural basis behind DD has not been fully elucidated.

METHOD

The study included 22 typically developing (TD) children, 16 children with isolated spelling disorder (SpD), and 20 children with DD. The cortical thickness, folding index, and mean curvature of Broca's area, including the triangular part of the left inferior frontal gyrus (IFGtriang) and the opercular part of the left inferior frontal gyrus, were assessed to explore the differences of surface morphology among the TD, SpD, and DD groups. Furthermore, the structural covariance network (SCN) of the triangular part of the left inferior frontal gyrus was analyzed to explore the changes of structural connectivity in the SpD and DD groups.

RESULTS

The DD group showed higher curvature and cortical folding of the left IFGtriang than the TD group and SpD group. In addition, compared with the TD group and the SpD group, the structural connectivity between the left IFGtriang and the left middle-frontal gyrus and the right mid-orbital frontal gyrus was increased in the DD group, and the structural connectivity between the left IFGtriang and the right precuneus and anterior cingulate was decreased in the DD group.

CONCLUSION

DD had atypical structural connectivity in brain regions related to visual attention, memory and which might impact the information input and integration needed for reading and spelling.

Stronger functional connectivity during reading contextually predictable words in slow readers

The effect of word predictability is well-documented in terms of local brain activation, but less is known about the functional connectivity among those regions associated with processing predictable words. Evidence from eye movement studies showed that the effect is much more pronounced in slow than in fast readers, suggesting that speed-impaired readers rely more on sentence context to compensate for their difficulties with visual word recognition. The present study aimed to investigate differences in functional connectivity of fast and slow readers within core regions associated with processing predictable words. We hypothesize a stronger synchronization between higher-order language areas, such as the left middle temporal (MTG) and inferior frontal gyrus (IFG), and the left occipito-temporal cortex (OTC) in slow readers. Our results show that slow readers exhibit more functional correlations among these connections; especially between the left IFG and OTC. We interpret our results in terms of the lexical quality hypothesis which postulates a stronger involvement of semantics on orthographic processing in (speed-)impaired readers.

Lexical Frequency and Sentence Context Influence the Brain's Response to Single Words

Typical adults read remarkably quickly. Such fast reading is facilitated by brain processes that are sensitive to both word frequency and contextual constraints. It is debated as to whether these attributes have additive or interactive effects on language processing in the brain. We investigated this issue by analysing existing magnetoencephalography data from 99 participants reading intact and scrambled sentences. Using a cross-validated model comparison scheme, we found that lexical frequency predicted the word-by-word elicited MEG signal in a widespread cortical network, irrespective of sentential context. In contrast, index (ordinal word position) was more strongly encoded in sentence words, in left front-temporal areas. This confirms that frequency influences word processing independently of predictability, and that contextual constraints affect word-by-word brain responses. With a conservative multiple comparisons correction, only the interaction between lexical frequency and surprisal survived, in anterior temporal and frontal cortex, and not between lexical frequency and entropy, nor between lexical frequency and index. However, interestingly, the uncorrected index × frequency interaction revealed an effect in left frontal and temporal cortex that reversed in time and space for intact compared to scrambled sentences. Finally, we provide evidence to suggest that, in sentences, lexical frequency and predictability may independently influence early (<150 ms) and late stages of word processing, but also interact during late stages of word processing (>150-250 ms), thus helping to converge previous contradictory eye-tracking and electrophysiological literature. Current neurocognitive models of reading would benefit from accounting for these differing effects of lexical frequency and predictability on different stages of word processing.

Prefrontal fNIRS-based clinical data analysis of brain functions in individuals abusing different types of drugs

Background

The activation degree of the orbitofrontal cortex (OFC) functional area in drug abusers is directly related to the craving for drugs and the tolerance to punishment. Currently, among the clinical research on drug rehabilitation, there has been little analysis of the OFC activation in individuals abusing different types of drugs, including heroin, methamphetamine, and mixed drugs. Therefore, it becomes urgently necessary to clinically investigate the abuse of different drugs, so as to explore the effects of different types of drugs on the human brain.

Methods

Based on prefrontal high-density functional near-infrared spectroscopy (fNIRS), this research designs an experiment that includes resting and drug addiction induction. Hemoglobin concentrations of 30 drug users (10 on methamphetamine, 10 on heroin, and 10 on mixed drugs) were collected using fNIRS and analyzed by combining algorithm and statistics.

Results

Linear discriminant analysis (LDA), Support vector machine (SVM) and Machine-learning algorithm was implemented to classify different drug abusers. Oxygenated hemoglobin (HbO2) activations in the OFC of different drug abusers were statistically analyzed, and the differences were confirmed. Innovative findings: in both the Right-OFC and Left-OFC areas, methamphetamine abusers had the highest degree of OFC activation, followed by those abusing mixed drugs, and heroin abusers had the lowest. The same result was obtained when OFC activation was investigated without distinguishing the left and right hemispheres.

Conclusions

The findings confirmed the significant differences among different drug abusers and the patterns of OFC activations, providing a theoretical basis for personalized clinical treatment of drug rehabilitation in the future.

Cloze enough? Hemodynamic effects of predictive processing during natural reading

Evidence accrues that readers form multiple hypotheses about upcoming words. The present study investigated the hemodynamic effects of predictive processing during natural reading by means of combining fMRI and eye movement recordings. In particular, we investigated the neural and behavioral correlates of precision-weighted prediction errors, which are thought to be indicative of subsequent belief updating. Participants silently read sentences in which we manipulated the cloze probability and the semantic congruency of the final word that served as an index for precision and prediction error respectively. With respect to the neural correlates, our findings indicate an enhanced activation within the left inferior frontal and middle temporal gyrus suggesting an effect of precision on prediction update in higher (lexico-)semantic levels. Despite being evident at the neural level, we did not observe any evidence that this mechanism resulted in disproportionate reading times on participants' eye movements. The results speak against discrete predictions, but favor the notion that multiple words are activated in parallel during reading.

Fixation-related NIRS indexes retinotopic occipital processing of parafoveal preview during natural reading

While word frequency and predictability effects have been examined extensively, any evidence on interactive effects as well as parafoveal influences during whole sentence reading remains inconsistent and elusive. Novel neuroimaging methods utilize eye movement data to account for the hemodynamic responses of very short events such as fixations during natural reading. In this study, we used the rapid sampling frequency of near-infrared spectroscopy (NIRS) to investigate neural responses in the occipital and orbitofrontal cortex to word frequency and predictability. We observed increased activation in the right ventral occipital cortex when the fixated word N was of low frequency, which we attribute to an enhanced cost during saccade planning. Importantly, unpredictable (in contrast to predictable) low frequency words increased the activity in the left dorsal occipital cortex at the fixation of the preceding word N-1, presumably due to an upcoming breach of top-down modulated expectation. Opposite to studies that utilized a serial presentation of words (e.g. Hofmann et al., 2014), we did not find such an interaction in the orbitofrontal cortex, implying that top-down timing of cognitive subprocesses is not required during natural reading. We discuss the implications of an interactive parafoveal-on-foveal effect for current models of eye movements.

Functional near-infrared spectroscopy-informed neurofeedback: regional-specific modulation of lateral orbitofrontal activation and cognitive flexibility

Cognitive flexibility and reward processing critically rely on the orbitofrontal cortex (OFC). Dysregulations in these domains and orbitofrontal activation have been reported in major psychiatric disorders. Hemodynamic brain imaging-informed neurofeedback allows regional-specific control over brain activation and thus may represent an innovative intervention to regulate orbitofrontal dysfunctions. Against this background the present proof-of-concept study evaluates the feasibility and behavioral relevance of functional near-infrared spectroscopy (fNIRS)-assisted neurofeedback training of the lateral orbitofrontal cortex (lOFC). In a randomized sham-controlled between-subject design, 60 healthy participants have undergone four subsequent runs of training to enhance the lOFC activation. Training-induced changes in the lOFC, attentional set-shifting performance, and reward experience have served as primary outcomes. Feedback from the target channel significantly increases the regional-specific lOFC activation over the four training runs in comparison with sham neurofeedback. The real-time OFC neurofeedback group demonstrates a trend for faster responses during the set-shifting relative to the sham neurofeedback group. Within the real-time OFC neurofeedback group, stronger training-induced lOFC increases are associated with higher reward experience. The present results demonstrate that fNIRS-informed neurofeedback allows regional-specific regulation of lOFC activation and may have the potential to modulate the associated behavioral domains. As such fNIRS-informed neurofeedback may represent a promising strategy to regulate OFC dysfunctions in psychiatric disorders.

Comparison of Hemodynamic Responses in the Prefrontal Cortex According to Differences in Self-Efficacy

Although self-efficacy has been used extensively in the field of nursing (e.g., as an outcome measure of nursing interventions), its underlying nature is poorly understood. Investigation of the relationship between self-efficacy and brain activation will help explain the fundamental nature of self-efficacy. In this study, we compared prefrontal activation measured with near-infrared spectroscopy (NIRS) across 89 undergraduate students categorized into three groups based on their General Self-Efficacy Scale scores: low self-efficacy ( n = 59), moderate self-efficacy ( n = 17), and high self-efficacy ( n = 13). Changes in the hemoglobin levels of the prefrontal cortex (PFC) during a verbal fluency task were assessed using two-channel NIRS. Significant differences in the oxygenated hemoglobin (oxy-Hb) level of the left PFC (LPFC) were observed via analysis of variance. Post hoc Tukey’s test showed a significant difference only between low self-efficacy and moderate self-efficacy groups. We found a medium between-group effect size in the moderate self-efficacy group versus the low self-efficacy group for the changes in oxy-Hb levels of the LPFC ( d = .78; 95% confidence interval for effect size [0.22, 1.33]). No significant between-group differences were observed with respect to changes in the oxy-Hb in the right PFC. The results indicate less left prefrontal activation in the low self-efficacy group than in the moderate self-efficacy group. These findings provide evidence to support the fundamental nature of self-efficacy.

On Elementary Affective Decisions: To Like Or Not to Like, That Is the Question

Perhaps the most ubiquitous and basic affective decision of daily life is deciding whether we like or dislike something/somebody, or, in terms of psychological emotion theories, whether the object/subject has positive or negative valence. Indeed, people constantly make such liking decisions within a glimpse and, importantly, often without expecting any obvious benefit or knowing the exact reasons for their judgment. In this paper, we review research on such elementary affective decisions (EADs) that entail no direct overt reward with a special focus on Neurocognitive Poetics and discuss methods and models for investigating the neuronal and cognitive-affective bases of EADs to verbal materials with differing degrees of complexity. In line with evolutionary and appraisal theories of (aesthetic) emotions and data from recent neurocognitive studies, the results of a decision tree modeling approach simulating EADs to single words suggest that a main driving force behind EADs is the extent to which such high-dimensional stimuli are associated with the “basic” emotions joy/happiness and disgust.

Functional Near-Infrared Spectroscopy (fNIRS) for Assessing Cerebral Cortex Function During Human Behavior in Natural/Social Situations: A Concise Review

Upon adequate stimulation, real-time maps of cortical hemodynamic responses can be obtained by functional near-infrared spectroscopy (fNIRS), which noninvasively measures changes in oxygenated and deoxygenated hemoglobin after positioning multiple sources and detectors over the human scalp. This review is aimed at giving a concise and simple overview of the basic principles of fNIRS including features, strengths, advantages, limitations, and utility for evaluating human behavior. The transportable/wireless commercially available fNIRS systems have a time resolution of 1 to 10 Hz, a depth sensitivity of about 1.5 cm, and a spatial resolution up to 1 cm. fNIRS has been found suitable for many applications on human beings, either adults or infants/children, in the field of social sciences, neuroimaging basic research, and medicine. Some examples of present and future prospects of fNIRS for assessing cerebral cortex function during human behavior in different situations (in natural and social situations) will be provided. Moreover, the most recent fNIRS studies for investigating interpersonal interactions by adopting the hyperscanning approach, which consists of the measurement of brain activity simultaneously on two or more people, will be reported.

Words in Context: The Effects of Length, Frequency, and Predictability on Brain Responses During Natural Reading

Word length, frequency, and predictability count among the most influential variables during reading. Their effects are well-documented in eye movement studies, but pertinent evidence from neuroimaging primarily stem from single-word presentations. We investigated the effects of these variables during reading of whole sentences with simultaneous eye-tracking and functional magnetic resonance imaging (fixation-related fMRI). Increasing word length was associated with increasing activation in occipital areas linked to visual analysis. Additionally, length elicited a U-shaped modulation (i.e., least activation for medium-length words) within a brain stem region presumably linked to eye movement control. These effects, however, were diminished when accounting for multiple fixation cases. Increasing frequency was associated with decreasing activation within left inferior frontal, superior parietal, and occipito-temporal regions. The function of the latter region—hosting the putative visual word form area—was originally considered as limited to sublexical processing. An exploratory analysis revealed that increasing predictability was associated with decreasing activation within middle temporal and inferior frontal regions previously implicated in memory access and unification. The findings are discussed with regard to their correspondence with findings from single-word presentations and with regard to neurocognitive models of visual word recognition, semantic processing, and eye movement control during reading.

Steady-state BOLD Response to Higher-order Cognition Modulates Low-Frequency Neural Oscillations

Steady-state responses (SSRs) reflect the synchronous neural oscillations evoked by noninvasive and consistently repeated stimuli at the fundamental or harmonic frequencies. The steady-state evoked potentials (SSEPs; the representative form of the SSRs) have been widely used in the cognitive and clinical neurosciences and brain–computer interface research. However, the steady-state evoked potentials have limitations in examining high-frequency neural oscillations and basic cognition. In addition, synchronous neural oscillations in the low frequency range (&lt;1 Hz) and in higher-order cognition have received a little attention. Therefore, we examined the SSRs in the low frequency range using a new index, the steady-state BOLD responses (SSBRs) evoked by semantic stimuli. Our results revealed that the significant SSBRs were induced at the fundamental frequency of stimuli and the first harmonic in task-related regions, suggesting the enhanced variability of neural oscillations entrained by exogenous stimuli. The SSBRs were independent of neurovascular coupling and characterized by sensorimotor bias, an indication of regional-dependent neuroplasticity. Furthermore, the amplitude of SSBRs may predict behavioral performance and show the psychophysiological relevance. Our findings provide valuable insights into the understanding of the SSRs evoked by higher-order cognition and how the SSRs modulate low-frequency neural oscillations.

Neurocognitive poetics: methods and models for investigating the neuronal and cognitive-affective bases of literature reception

A long tradition of research including classical rhetoric, esthetics and poetics theory, formalism and structuralism, as well as current perspectives in (neuro)cognitive poetics has investigated structural and functional aspects of literature reception. Despite a wealth of literature published in specialized journals like Poetics, however, still little is known about how the brain processes and creates literary and poetic texts. Still, such stimulus material might be suited better than other genres for demonstrating the complexities with which our brain constructs the world in and around us, because it unifies thought and language, music and imagery in a clear, manageable way, most often with play, pleasure, and emotion (Schrott and Jacobs, 2011). In this paper, I discuss methods and models for investigating the neuronal and cognitive-affective bases of literary reading together with pertinent results from studies on poetics, text processing, emotion, or neuroaesthetics, and outline current challenges and future perspectives.

On forward inferences of fast and slow readers. An eye movement study

Unimpaired readers process words incredibly fast and hence it was assumed that top-down processing, such as predicting upcoming words, would be too slow to play an appreciable role in reading. This runs counter the major postulate of the predictive coding framework that our brain continually predicts probable upcoming sensory events. This means, it may generate predictions about the probable upcoming word during reading (dubbed forward inferences). Trying to asses these contradictory assumptions, we evaluated the effect of the predictability of words in sentences on eye movement control during silent reading. Participants were a group of fluent (i.e., fast) and a group of speed-impaired (i.e., slow) readers. The findings indicate that fast readers generate forward inferences, whereas speed-impaired readers do so to a reduced extent - indicating a significant role of predictive coding for fluent reading.