Neuropsychologia最新文献

Previous research has established that mind wandering does not necessarily disrupt one's task-switching performance. Here we investigated the effects of mind wandering on electrophysiological signatures, measured using event-related potentials (ERPs), during a switching task. In the current study, a final sample of 22 young adults performed a task-switching paradigm while electroencephalography was continuously recorded; mind wandering was assessed via thought probes at the end of each block. Consistent with previous research, we found no significant disruptive effects of mind wandering on task-switching performance. The ERP results showed that at the posterior electrode sites (P3, Pz, and P4), P3 amplitude was higher for mind-wandering switch trials than on-task switch trials, thus opposing the typical pattern of P3 attenuation during periods of mind wandering relative to on-task episodes. Considering that increased P3 amplitude during higher-order switch trials (e.g., response rule switching) may reflect the implementation of new higher-order task sets/rules, the current findings seem to indicate similar executive control processes underlie mind wandering and task-set switching, providing further evidence in favor of a role for switching in mind wandering.

Morphologically complex words are common across different languages, especially in Chinese, because more than 90% of common modern Chinese words are complex words. Many behavioral studies have suggested the whole-word processing of Chinese complex words, but the neural correlates of whole-word processing remain unclear. Previous electrophysiological studies revealed automatic and early (∼250 ms) access to the orthographic forms of monomorphic words in the ventral occipitotemporal area. In this study, we investigated whether there is also automatic and early orthographic recognition of Chinese complex words (as whole units) by recording event-related potentials (ERPs). A total of 150 two-character words and 150 two-character pseudowords composed of the same 300 characters (morphemes) were pseudorandomly presented to proficient Chinese readers. Participants were required to determine the color of each stimulus in the color decision task and to determine whether each stimulus was a word in the lexical decision task. The two constituent characters of each stimulus were horizontally arranged in Experiment 1 and vertically arranged in Experiment 2. The results revealed a significant early ERP difference between words and pseudowords approximately 250–300 ms after stimulus onset in the parieto-occipital scalp region. The early ERP difference was more prominent in the color decision task than in the lexical decision task, more prominent in Experiment 1 than in Experiment 2, and more prominent in the left parieto-occipital scalp region than in the right. Source analysis results showed that the early ERP difference originated from the left ventral occipitotemporal cortex. These results reflected early and automatic access to whole-word orthographic representations of Chinese complex words in the left ventral occipitotemporal cortex.

Sensory experience shapes brain structure and function, and it is likely to influence the organisation of functional networks of the brain, including those involved in cognitive processing. Here we investigated the influence of early deafness on the organisation of resting-state networks of the brain and its relation to executive processing. We compared resting-state connectivity between deaf and hearing individuals across 18 functional networks and 400 ROIs. Our results showed significant group differences in connectivity between seeds of the auditory network and most large-scale networks of the brain, in particular the somatomotor and salience/ventral attention networks. When we investigated group differences in resting-state fMRI and their link to behavioural performance in executive function tasks (working memory, inhibition and switching), differences between groups were found in the connectivity of association networks of the brain, such as the salience/ventral attention and default-mode networks. These findings indicate that sensory experience influences not only the organisation of sensory networks, but that it also has a measurable impact on the organisation of association networks supporting cognitive processing. Overall, our findings suggest that different developmental pathways and functional organisation can support executive processing in the adult brain.

Humor plays a prominent role in our lives. Thus, understanding the cognitive and neural mechanisms of humor is particularly important. Previous studies that investigated neural substrates of humor used functional MRI and to a lesser extent EEG. In the present study, we conducted intracranial recording in human patients, enabling us to obtain the signal with high temporal precision from within specific brain locations. Our analysis focused on the temporal lobe and the surrounding areas, the temporal lobe was most densely covered in our recording. Thirteen patients watched a fragment of a Charlie Chaplin movie. An independent group of healthy participants rated the same movie fragment, helping us to identify the most funny and the least funny frames of the movie. We compared neural activity occurring during the most funny and least funny frames across frequencies in the range of 1–170 Hz. The most funny compared to least funny parts of the movie were associated with activity modulation in the broadband high-gamma (70−170 Hz; mostly activation) and to a lesser extent gamma band (40−69Hz; activation) and low frequencies (1−12 Hz, delta, theta, alpha bands; mostly deactivation). With regard to regional specificity, we found three types of brain areas: (I) temporal pole, middle and inferior temporal gyrus (both anterior and posterior) in which there was both activation in the high-gamma/gamma bands and deactivation in low frequencies; (II) ventral part of the temporal lobe such as the fusiform gyrus, in which there was mostly deactivation the low frequencies; (III) posterior temporal cortex and its environment, such as the middle occipital and the temporo-parietal junction, in which there was activation in the high-gamma/gamma band. Overall, our results suggest that humor appreciation might be achieved by neural activity across the frequency spectrum.

Biscriptuality is the ability to read and write using two scripts. Despite the increasing number of biscripters, this phenomenon remains poorly understood. Here, we focused on investigating graphomotor processing in French–Arabic biscripters. We chose the French and Arabic alphabets because they have comparable visuospatial complexity and linguistic features, but differ dramatically in their graphomotor characteristics. In a first experiment we describe the graphomotor features of the two alphabets and showed that while Arabic and Latin letters are produced with the same velocity and fluency, Arabic letters require more pen lifts, contain more right-to-left strokes and clockwise curves, and take longer to write than Latin letters. These results suggest that Arabic and Latin letters are produced via different motor patterns. In a second experiment we used functional magnetic resonance imaging to ask whether writing the two scripts relies upon partially distinct or fully overlapping neural networks, and whether the elements of the previously described handwriting network are recruited to the same extent by the two scripts. We found that both scripts engaged the so-called “writing network”, but that within the network, Arabic letters recruited the left superior parietal lobule (SPL) and the left primary motor cortex (M1) more strongly than Latin letters. Both regions have previously been identified as holding scale-invariant representations of letter trajectories. Arabic and Latin letters also activated distinct regions that do not belong to the writing network. Complementary analyses indicate that the differences observed between scripts at the neural level could be driven by the specific graphomotor features of each script. Overall, our results indicate that particular features of the practiced scripts can lead to different motor organization at both the behavioral and brain levels in biscripters.

A simple reaction time (SRT) difference between responses to visual stimuli presented ipsilaterally and contralaterally to the responding hand, known as the Poffenberger effect or the crossed–uncrossed difference (CUD), has been commonly interpreted as a measure of interhemispheric transfer time (IHTT). However, the validity of this interpretation and the measure's reliability have been debated. The present study aimed at obtaining reliable evidence of the influence of spatial attention on the CUD, which would provide an argument against the classical interpretation of CUD. To meet the high statistical power requirements, over 100 thousand SRTs in total were collected from 12 participants. The task had three stimulus presentation conditions differing in the degree of stimulus location uncertainty: blocked (no uncertainty), randomized (full uncertainty), and mixed (25% uncertainty). The results showed robust effects of location uncertainty, proving spatial attention's contribution to the CUD. Further, we observed a strong visual-field asymmetry reflecting the right hemisphere specialization in target detection and spatial reorienting. Lastly, despite exceptional reliability of the component SRT measures, the CUD reliability was still too low to justify using this measure as an index of individual differences.

Damage to the medial temporal lobe (MTL), which is traditionally considered to subserve memory exclusively, has been reported to contribute to impaired face perception. However, it remains unknown how exactly such brain lesions may impact face representations and in particular facial shape and surface information, both of which are crucial for face perception. The present study employed a behavioral-based image reconstruction approach to reveal the pictorial representations of face perception in two amnesic patients: DA, who has an extensive bilateral MTL lesion that extends beyond the MTL in the right hemisphere, and BL, who has damage to the hippocampal dentate gyrus (DG). Both patients and their respective matched controls completed similarity judgments for pairs of faces, from which facial shape and surface features were subsequently derived and synthesized to create images of reconstructed facial appearance. Participants also completed a face oddity judgment task (FOJT) that has previously been shown to be sensitive to MTL cortical damage. While BL exhibited an impaired pattern of performance on the FOJT, DA demonstrated intact performance accuracy. Notably, the recovered pictorial content of faces was comparable between both patients and controls, although there was evidence for atypical face representations in BL particularly with regards to color. Our work provides novel insight into the face representations underlying face perception in two well-studied amnesic patients in the literature and demonstrates the applicability of the image reconstruction approach to individuals with brain damage.

Reared-apart twin studies are a powerful means for identifying the relative contributions of heredity and environment to variation in human physical and behavioural traits. One such characteristic is handedness, for which it has long been noted that approximately 20% of twin pairs are comprised of one right-handed cotwin and one left-handed cotwin. Reared-together twin studies suggest a slightly greater concordance in monozygotic (MZT) than dizygotic (DZT) twins, implying that genetics influences hand preference. We report here two studies of handedness in reared-apart twins. Study 1 synthesizes the available data and estimates that at least N = 560 same-sex reared-apart twin pairs (for which zygosity is known with reasonable confidence) have been identified. Of these, handedness data are available for both members of n = 415 pairs. We observed similar levels of concordance/discordance for reared-apart monozygotic (MZA) and dizygotic (DZA) twins. However, although direction of handedness (right or left) has frequently been examined, strength of handedness (strong or weak) has not. Study 2 examined strength of hand preference and relative hand skill, as well as right- and left-hand speed, information available for participants in the Minnesota Study of Twins Reared Apart (MISTRA). We provide evidence of heritability for right-hand and left-hand speed. We also found hand preference strength was more alike than chance in DZA, but not MZA, twins. Findings are discussed in relation to genetic and environmental influences on human handedness.

Empathy is an intricate ability that entails the subjective feeling and understanding of emotions someone else may be experiencing. Acetaminophen, the active ingredient found in Tylenol, is among the most common pain medications consumed. There is new evidence, however, that suggests this common analgesic may also dampen empathic processes. However, no previous study has investigated the effect acetaminophen may have on pain empathy or mu power during a pain empathy task. Therefore, participants were randomly assigned to either an experimental (acetaminophen) or control (sugar) group in a double-blinded experimental research design aimed to measure mu power, using EEG, and behavioral responses to painful and non-painful images. Participants in the experimental group were administered 1000 mg of acetaminophen, and it was verified that participants were unaware of their group assignment. We found that mu suppression was greater in the acetaminophen group, which was strongest at electrode C3. Additionally, mu power differences between painful and non-painful images were related to trait empathy, and mu power during the painful images were positively correlated with empathy scores. Results from this study suggest that in addition to reducing physical pain, acetaminophen may also change the neural response when perceiving others in pain. The implications of these findings could possibly lead to changes in how we prescribe and administer this common drug.

Aging is associated with changes in cognitive function, including declines in learning, memory, and executive function. Prism adaptation (PA) is a useful paradigm to measure changes in explicit and implicit mechanisms of visuo-motor learning with age, but the neural correlates are not well understood. In the present study, we used PA to investigate visuo-motor learning and error processing in older adults. Twenty older adults (56–85 yrs) and 20 younger adults (18–33 yrs) underwent a goal-oriented reaching task while wearing prism goggles as continuous EEG was recorded to examine neural correlates of error detection. We examined behavioural measures of PA, as well as ERP components previously found associated with the early and late phases of adaptation to visual distortion caused by the prism goggles. Our results indicate important age-related behavioural and neurophysiological differences. Older adults reached more slowly than younger adults but showed the same accuracy throughout the prism exposure. Older adults also displayed larger aftereffects, indicating preserved visuomotor adaptation. EEG results indicated similar initial error processing in older and younger adults, as measured by the feedback error related negativity (FRN). As seen previously in young adults, the P3a and P3b declined over the prism exposure phase in both groups. Older adults displayed reduced P3a amplitude compared to the younger group in the early phase of adaptation, however, suggesting reduced attentional orienting. Finally, the older group exhibited a greater P3b amplitude compared to the younger group in the later phases of adaptation, potentially a marker of enhanced context updating underlying spatial realignment, leading to their larger aftereffect. Implications for age-related learning differences and clinical applications are discussed.