Numerical and non-numerical ordinality processing in children with and without developmental dyscalculia: Evidence from fMRI

Ordinality is – beyond numerical magnitude (i.e., quantity) – an important characteristic of the number system. There is converging empirical evidence that (intra)parietal brain regions mediate number magnitude processing. Furthermore, recent findings suggest that the human intraparietal sulcus (IPS) supports magnitude and ordinality in a domain-general way. However, the latter findings are derived from adult studies and with respect to children (i.e., developing brain systems) both the neural correlates of ordinality processing and the precise role of the IPS (domain-general vs. domain-specific) in ordinality processing are thus far unknown. The present study aims at filling this gap by employing functional magnetic resonance imaging (fMRI) to investigate numerical and non-numerical ordinality knowledge in children with and without developmental dyscalculia. In children (without DD) processing of numerical and non-numerical ordinality alike is supported by (intra)parietal cortex, thus extending the notion of a domain-general (intra)parietal cortex to developing brain systems. Moreover, activation extents in response to numerical ordinality processing differ significantly between children with and without dyscalculia in inferior parietal regions (supramarginal gyrus and IPS).     

Neural correlates of variable working memory load across adult age and skill: dissociative patterns within the fronto-parietal network

We examined neural changes related to variations in working memory load by using an n -back task with three levels and functional magnetic resonance imaging. Younger adults were divided into high- and low-performing groups (Young-High; Young-Low) and compared with older adults. Relative to Young-High, capacity-constraints in working memory were apparent between load 1–2 for the elderly and between load 2–3 for Young-Low. Capacity-constraints in neural activity followed this pattern by showing a monotonically increasing response in parietal cortex and thalamus for Young-High, whereas activity leveled off at 1-back for the elderly and at 2-back for Young-Low. The response in dorsal frontal cortex followed a similar pattern with the addition that the magnitude of activation differed within capacity limitations (Old > Young at 1-back; Young-Low > Young-High at 2-back). These findings indicate that an important determinant of WM capacity is the ability to keep the frontal cortex adequately engaged in relation to current task demands.     

Overt naming fMRI pre- and post-TMS: Two nonfluent aphasia patients, with and without improved naming post-TMS

Two chronic, nonfluent aphasia patients participated in overt naming fMRI scans, pre- and post-a series of repetitive transcranial magnetic stimulation (rTMS) treatments as part of a TMS study to improve naming. Each patient received 10, 1-Hz rTMS treatments to suppress a part of R pars triangularis. P1 was a ‘good responder’ with improved naming and phrase length; P2 was a ‘poor responder’ without improved naming.Pre-TMS (10 years poststroke), P1 had significant activation in R and L sensorimotor cortex, R IFG, and in both L and R SMA during overt naming fMRI (28% pictures named). At 3 mo. post-TMS (42% named), P1 showed continued activation in R and L sensorimotor cortex, R IFG, and in R and L SMA. At 16 mo. post-TMS (58% named), he also showed significant activation in R and L sensorimotor cortex mouth and R IFG. He now showed a significant increase in activation in the L SMA compared to pre-TMS and at 3 mo. post-TMS (p < .02; p < .05, respectively). At 16 mo. there was also greater activation in L than R SMA (p < .08). At 46 mo. post-TMS (42% named), this new LH pattern of activation continued. He improved on the Boston Naming Test from 11 pictures named pre-TMS, to scores ranging from 14 to 18 pictures, post-TMS (2–43 mo. post-TMS). His longest phrase length (Cookie Theft picture) improved from three words pre-TMS, to 5–6 words post-TMS.Pre-TMS (1.5 years poststroke), P2 had significant activation in R IFG (3% pictures named). At 3 and 6 mo. post-TMS, there was no longer significant activation in R IFG, but significant activation was present in R sensorimotor cortex. On all three fMRI scans, P2 had significant activation in both the L and R SMA. There was no new, lasting perilesional LH activation across sessions for this patient. Over time, there was little or no change in his activation. His naming remained only at 1–2 pictures during all three fMRI scans. His BNT score and longest phrase length remained at one word, post-TMS.Lesion site may play a role in each patient’s fMRI activation pattern and response to TMS treatment. P2, the poor responder, had an atypical frontal lesion in the L motor and premotor cortex that extended high, near brain vertex, with deep white matter lesion near L SMA. P2 also had frontal lesion in the posterior middle frontal gyrus, an area important for naming (Duffau et al., 2003); P1 did not. Additionally, P2 had lesion inferior and posterior to Wernicke’s area, in parts of BA 21 and 37, whereas P1 did not.The fMRI data of our patient who had good response following TMS support the notion that restoration of the LH language network is linked in part, to better recovery of naming and phrase length in nonfluent aphasia.     

Superior temporal activation in response to dynamic audio-visual emotional cues

Perception of emotion is critical for successful social interaction, yet the neural mechanisms underlying the perception of dynamic, audio-visual emotional cues are poorly understood. Evidence from language and sensory paradigms suggests that the superior temporal sulcus and gyrus (STS/STG) play a key role in the integration of auditory and visual cues. Emotion perception research has focused on static facial cues; however, dynamic audio-visual (AV) cues mimic real-world social cues more accurately than static and/or unimodal stimuli. Novel dynamic AV stimuli were presented using a block design in two fMRI studies, comparing bimodal stimuli to unimodal conditions, and emotional to neutral stimuli. Results suggest that the bilateral superior temporal region plays distinct roles in the perception of emotion and in the integration of auditory and visual cues. Given the greater ecological validity of the stimuli developed for this study, this paradigm may be helpful in elucidating the deficits in emotion perception experienced by clinical populations.     

Changes in brain activation induced by the training of hypothesis generation skills: an fMRI study

The aim of the present study is to investigate the learning-related changes in brain activation induced by the training of hypothesis generation skills regarding biological phenomena. Eighteen undergraduate participants were scanned twice with functional magnetic resonance imaging (fMRI) before and after training over a period of 2 months. The experimental group underwent eight biological hypothesis generation training programs, but the control group was not given any during the 2-month period. The results showed that the left frontal gyri, the cingulate gyrus, and the cuneus were activated during hypothesis generation. In addition, the brain activation of the trained group increased in the left inferior and the superior frontal gyri, which are related to working memory load and higher-order inferential processes. However, the activation after training decreased in the occipito-parietal route, which is associated with the perception and the analysis processes of visual information. Furthermore, the results have suggested that the dorsolateral prefrontal cortex (DLPFC) region is the critical area in the training of hypothesis generation skills.     

Emotions in word and face processing: Early and late cortical responses

Recent research suggests that emotion effects in word processing resemble those in other stimulus domains such as pictures or faces. The present study aims to provide more direct evidence for this notion by comparing emotion effects in word and face processing in a within-subject design. Event-related brain potentials (ERPs) were recorded as participants made decisions on the lexicality of emotionally positive, negative, and neutral German verbs or pseudowords, and on the integrity of intact happy, angry, and neutral faces or slightly distorted faces. Relative to neutral and negative stimuli both positive verbs and happy faces elicited posterior ERP negativities that were indistinguishable in scalp distribution and resembled the early posterior negativities reported by others. Importantly, these ERP modulations appeared at very different latencies. Therefore, it appears that similar brain systems reflect the decoding of both biological and symbolic emotional signals of positive valence, differing mainly in the speed of meaning access, which is more direct and faster for facial expressions than for words.     

Neurophysiological evidence for categorical perception of color

The aim of this investigation was to examine the time course and the relative contributions of perceptual and post-perceptual processes to categorical perception (CP) of color. A visual oddball task was used with standard and deviant stimuli from same (within-category) or different (between-category) categories, with chromatic separations for within- and between-category stimuli equated in Munsell Hue. CP was found on a behavioral version of the task, with faster RTs and greater accuracy for between- compared to within-category stimuli. On a neurophysiological version of the task, event-related potentials (ERPs) showed earlier latencies for P1 and N1 components at posterior locations to between- relative to within-category deviants, providing novel evidence for early perceptual processes on color CP. Enhanced P2 and P3 waves were also found for between- compared to within-category stimuli, indicating a role for later post-perceptual processes.     

Mechanisms of deficit of visuospatial attention shift in children with developmental coordination disorder: A neurophysiological measure of the endogenous Posner paradigm

The purpose of this study was to investigate and compare the mechanisms of brain activity, as revealed by a combination of the visuospatial attention shifting paradigm and event-related potentials (ERP) in children with developmental coordination disorder (DCD) and typically developing children. Twenty-eight DCD children and 26 typically developing children were recorded with regard to their behavioral performance and ERP measures during a variant of the endogenous Posner paradigm, in which they should react to visual targets preceded by spatial cues or presented uncued. Children with DCD showed longer reaction time and a deficit in inhibitory response capacity when compared to typically developing children. The electrophysiological characteristics also showed distinct modulatory effects upon attentional orienting, anticipatory mechanisms, and cognitive-to-motor transfer in children with DCD: longer cue-P3 and target-N1 latency, smaller target-P3 amplitude, an elongated interval between N2 and the motor response (N2-RT), and small areas on contingent negative variation (CNV). The combined analysis of behavioral performance and ERP data suggested that children with DCD had deficits of slower target identification (N1), less ability in interhemispheric (P3) and cognitive-to-motor transfer speed (N2-RT), as well as a less mature anticipatory and executive process (CNV).     

Cognitive conflict and inhibition in primed dichotic listening

In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable pair, with instructions to ignore the prime and report one syllable from the dichotic pair. When the prime matched one of the syllables in the dichotic pair, response selection was biased towards selecting the unprimed target. The suggested mechanism was that the prime was inhibited to reduce conflict between task-irrelevant prime processing and task-relevant dichotic target processing, and a residual effect of the prime inhibition biased the resolution of the conflict between the two targets. The current experiment repeated the primed dichotic listening task in an event-related fMRI setting. The fMRI data showed that when the task-irrelevant prime matched the task-relevant targets, activations in posterior medial frontal cortex (pMFC) and in right inferior frontal gyrus (IFG) increased, which was considered to represent conflict and inhibition, respectively. Further, matching trials where the unprimed target was selected showed activation in right IFG, while matching trials where the primed target was selected showed activations in pMFC and left IFG, indicating the difference between inhibition-biased selection and unbiased selection.     

Verbal predicates foster conscious recollection but not familiarity of a task-irrelevant perceptual feature – An ERP study

Research on the effects of perceptual manipulations on recognition memory has suggested that (a) recollection is selectively influenced by task-relevant information and (b) familiarity can be considered perceptually specific. The present experiment tested divergent assumptions that (a) perceptual features can influence conscious object recollection via verbal code despite being task-irrelevant and that (b) perceptual features do not influence object familiarity if study is verbal-conceptual. At study, subjects named objects and their presentation colour; this was followed by an old/new object recognition test. Event-related potentials (ERP) showed that a study-test manipulation of colour impacted selectively on the ERP effect associated with recollection, while a size manipulation showed no effect. It is concluded that (a) verbal predicates generated at study are potent episodic memory agents that modulate recollection even if the recovered feature information is task-irrelevant and (b) commonly found perceptual match effects on familiarity critically depend on perceptual processing at study.