Neurolinguistic Studies of Reading in Chinese.

Using the Chinese writing system, which is unique with respect to the composition of each character in terms of its graphic shape, as an example, this chapter addresses the neurobiological underpinnings of reading and writing and how these brain circuits are used in different languages.

Assessment of psychiatric disorders among sex offenders: Prevalence and associations with criminal history.

BACKGROUND: Much of the research on the prevalence of psychiatric disorders among sex offenders has been conducted in the USA or Europe. Less is known about it in other regions, particularly in Asia. AIMS: The objective of this study is to determine the prevalence of psychiatric disorders among sex offenders in Taiwan and their associations with offender characteristics and criminal history. METHODS: Participants were randomly selected from men serving sentences in Taiwan's prison for serious sex offenders. Consenting men were assessed using the structured clinical interviews for DSM-IV-TR Axis I and II disorders. Demographics and criminal history were also recorded. RESULTS: Over two-thirds of the 68 participants met criteria for one or more lifetime Axis I disorders, and nearly 60% met criteria for one or more Axis II disorder. The higher the number of Axis I and cluster B personality disorders, the higher was the total number of convictions. CONCLUSIONS: Our study adds to the literature that suggests that psychiatric assessment is likely to have an important role in the management and treatment of sex offenders. The finding that multiple disorders are common in this group and associated with more convictions for sex offences suggests that failure to include psychiatric assessment in planning the management of sex offenders may increase the risk of recidivism.

Brain stimulation improves cognitive control by modulating medial-frontal activity and preSMA-vmPFC functional connectivity.

Previous research has demonstrated that brain stimulation can improve inhibitory control. However, the neural mechanisms underlying such artificially induced improvement remain unclear. In this study, by coupling anodal transcranial direct current stimulation (atDCS) with functional MRI, we found that atDCS over preSMA effectively improved stopping speed, which was associated with increased BOLD response in the preSMA and ventromedial prefrontal cortex (vmPFC). Furthermore, such atDCS-induced BOLD increase in vmPFC was positively correlated with participants' improvement in stopping efficiency, and the functional connectivity between preSMA and vmPFC increased during successful stop. These results suggest that the rapid behavioral improvement from preSMA brain stimulation involves modulated medial-frontal activity and preSMA-vmPFC functional connectivity.

Far-space neglect in conjunction but not feature search following transcranial magnetic stimulation over right posterior parietal cortex.

Near- and far-space coding in the human brain is a dynamic process. Areas in dorsal, as well as ventral visual association cortex, including right posterior parietal cortex (rPPC), right frontal eye field (rFEF), and right ventral occipital cortex (rVO), have been shown to be important in visuospatial processing, but the involvement of these areas when the information is in near or far space remains unclear. There is a need for investigations of these representations to help explain the pathophysiology of hemispatial neglect, and the role of near and far space is crucial to this. We used a conjunction visual search task using an elliptical array to investigate the effects of transcranial magnetic stimulation delivered over rFEF, rPPC, and rVO on the processing of targets in near and far space and at a range of horizontal eccentricities. As in previous studies, we found that rVO was involved in far-space search, and rFEF was involved regardless of the distance to the array. It was found that rPPC was involved in search only in far space, with a neglect-like effect when the target was located in the most eccentric locations. No effects were seen for any site for a feature search task. As the search arrays had higher predictability with respect to target location than is often the case, these data may form a basis for clarifying both the role of PPC in visual search and its contribution to neglect, as well as the importance of near and far space in these.

Unleashing potential: transcranial direct current stimulation over the right posterior parietal cortex improves change detection in low-performing individuals.

The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.

Right temporoparietal junction and attentional reorienting.

The interaction between goal-directed and stimulus-driven attentional control allows humans to rapidly reorient to relevant objects outside the focus of attention--a phenomenon termed contingent reorienting. Neuroimaging studies have observed activation of the ventral and dorsal attentional networks, but specific involvement of each network remains unclear. The present study aimed to determine whether both networks are critical to the processes of top-down contingent reorienting. To this end, we combined the contingent attentional capture paradigm with the use of transcranial magnetic stimulation (TMS) to interfere with temporoparietal junction (TPJ; ventral network) and frontal eye field (dorsal network) activity. The results showed that only right TPJ (rTPJ) TMS modulated contingent orienting. Furthermore, this modulation was highly dependent on visual fields: rTPJ TMS increased contingent capture in the left visual field and decreased the effect in the right visual field. These results demonstrate a critical involvement of the ventral network in attentional reorienting and reveal the spatial selectivity within such network.

The location probability effects of saccade reaction times are modulated in the frontal eye fields but not in the supplementary eye field.

The visual system constantly utilizes regularities that are embedded in the environment and by doing so reduces the computational burden of processing visual information. Recent findings have demonstrated that probabilistic information can override attentional effects, such as the cost of making an eye movement away from a visual target (antisaccade cost). The neural substrates of such probability effects have been associated with activity in the superior colliculus (SC). Given the immense reciprocal connections to SC, it is plausible that this modulation originates from higher oculomotor regions, such as the frontal eye field (FEF) and the supplementary eye field (SEF). To test this possibility, the present study employed theta burst transcranial magnetic stimulation (TMS) to selectively interfere with FEF and SEF activity. We found that TMS disrupted the effect of location probability when TMS was applied over FEF. This was not observed in the SEF TMS condition. Together, these 2 experiments suggest that the FEF plays a critical role not only in initiating saccades but also in modulating the effects of location probability on saccade production.

Modulating inhibitory control with direct current stimulation of the superior medial frontal cortex.

The executive control of voluntary action involves not only choosing from a range of possible actions but also the inhibition of responses as circumstances demand. Recent studies have demonstrated that many clinical populations, such as people with attention-deficit hyperactivity disorder, exhibit difficulties in inhibitory control. One prefrontal area that has been particularly associated with inhibitory control is the pre-supplementary motor area (Pre-SMA). Here we applied non-invasive transcranial direct current stimulation (tDCS) over Pre-SMA to test its role in this behavior. tDCS allows for current to be applied in two directions to selectively excite or suppress the neural activity of Pre-SMA. Our results showed that anodal tDCS improved efficiency of inhibitory control. Conversely, cathodal tDCS showed a tendency towards impaired inhibitory control. To our knowledge, this is the first demonstration of non-invasive intervention tDCS altering subjects' inhibitory control. These results further our understanding of the neural bases of inhibitory control and suggest a possible therapeutic intervention method for clinical populations.

Trial type probability modulates the cost of antisaccades.

The antisaccade task, where eye movements are made away from a target, has been used to investigate the flexibility of cognitive control of behavior. Antisaccades usually have longer saccade latencies than prosaccades, the so-called antisaccade cost. Recent studies have shown that this antisaccade cost can be modulated by event probability. This may mean that the antisaccade cost can be reduced, or even reversed, if the probability of surrounding events favors the execution of antisaccades. The probabilities of prosaccades and antisaccades were systematically manipulated by changing the proportion of a certain type of trial in an interleaved pro/antisaccades task. We aimed to disentangle the intertwined relationship between trial type probabilities and the antisaccade cost with the ultimate goal of elucidating how probabilities of trial types modulate human flexible behaviors, as well as the characteristics of such modulation effects. To this end, we examined whether implicit trial type probability can influence saccade latencies and also manipulated the difficulty of cue discriminability to see how effects of trial type probability would change when the demand on visual perceptual analysis was high or low. A mixed-effects model was applied to the analysis to dissect the factors contributing to the modulation effects of trial type probabilities. Our results suggest that the trial type probability is one robust determinant of antisaccade cost. These findings highlight the importance of implicit probability in the flexibility of cognitive control of behavior.

Predictability of saccadic behaviors is modified by transcranial magnetic stimulation over human posterior parietal cortex.

Predictability in the visual environment provides a powerful cue for efficient processing of scenes and objects. Recently, studies have suggested that the directionality and magnitude of saccade curvature can be informative as to how the visual system processes predictive information. The present study investigated the role of the right posterior parietal cortex (rPPC) in shaping saccade curvatures in the context of predictive and non-predictive visual cues. We used an orienting paradigm that incorporated manipulation of target location predictability and delivered transcranial magnetic stimulation (TMS) over rPPC. Participants were presented with either an informative or uninformative cue to upcoming target locations. Our results showed that rPPC TMS generally increased saccade latency and saccade error rates. Intriguingly, rPPC TMS increased curvatures away from the distractor only when the target location was unpredictable and decreased saccadic errors towards the distractor. These effects on curvature and accuracy were not present when the target location was predictable. These results dissociate the strong contingency between saccade latency and saccade curvature and also indicate that rPPC plays an important role in allocating and suppressing attention to distractors when the target demands visual disambiguation. Furthermore, the present study suggests that, like the frontal eye fields, rPPC is critically involved in determining saccade curvature and the generation of saccadic behaviors under conditions of differing target predictability.

Big time is not always long: numerical magnitude automatically affects time reproduction.

To reproduce the duration of an event precisely, one needs to represent the temporal information without being influenced by other magnitude attributes (e.g., size) of the event. In the present study, however, task-irrelevant numerical magnitude automatically affected participants' reproduction of the duration of a stimulus. In Experiment 1, participants made key-press responses to reproduce the duration of numbers. Reproduced durations were shorter for small numbers (e.g., 1) than for large numbers (e.g., 9). In contrast, in Experiment 2, participants' reproductions of a standard duration were longer when their key-press response was accompanied by visual presentation of a small number than when it was accompanied by presentation of a large number. These results clearly demonstrate that number-time interference extends beyond simple mapping between stimulus categories and response alternatives. The findings support the notion that either a common magnitude representation or closely connected magnitude representations underlie numerical and temporal processing.

Dynamic allocation of attention to metrical and grouping accents in rhythmic sequences.

Most people find it easy to perform rhythmic movements in synchrony with music, which reflects their ability to perceive the temporal periodicity and to allocate attention in time accordingly. Musicians and non-musicians were tested in a click localization paradigm in order to investigate how grouping and metrical accents in metrical rhythms influence attention allocation, and to reveal the effect of musical expertise on such processing. We performed two experiments in which the participants were required to listen to isochronous metrical rhythms containing superimposed clicks and then to localize the click on graphical and ruler-like representations with and without grouping structure information, respectively. Both experiments revealed metrical and grouping influences on click localization. Musical expertise improved the precision of click localization, especially when the click coincided with a metrically strong beat. Critically, although all participants located the click accurately at the beginning of an intensity group, only musicians located it precisely when it coincided with a strong beat at the end of the group. Removal of the visual cue of grouping structures enhanced these effects in musicians and reduced them in non-musicians. These results indicate that musical expertise not only enhances attention to metrical accents but also heightens sensitivity to perceptual grouping.

Inhibitory control and the frontal eye fields.

Inhibitory control mechanisms are important in a range of behaviors to prevent execution of motor acts which, having been planned, are no longer necessary. Ready examples of this can be seen in a range of sports, such as cricket and baseball, where the choice between execution or inhibition of a bat swing must be made in a brief time interval. The role of the FEFs, an area typically described in relation to eye movement functions but also involved in visual processes, was investigated in an inhibitory control task using transcranial magnetic stimulation (TMS). A stop signal task with manual responses was used, providing measures of impulsivity and inhibitory control. TMS over FEF had no effect on response generation (impulsivity, indexed by go signal RT) but disrupted inhibitory control (indexed by stop signal RT). This is the first demonstration of a role for FEF in this type of task in normal subjects in a task which did not require eye movements and complements previous TMS findings of roles for pre-SMA and inferior frontal gyrus (IFG) in inhibitory control.

Antisaccade cost is modulated by contextual experience of location probability.

It is well known that pro- and antisaccades may deploy different cognitive processes. However, the specific reason why antisaccades have longer latencies than prosaccades is still under debate. In three experiments, we studied the factors contributing to the antisaccade cost by taking attentional orienting and target location probabilities into account. In experiment 1, using a new antisaccade paradigm, we directly tested Olk and Kingstone's hypothesis, which attributes longer antisaccade latency to the time it takes to reorient from the visual target to the opposite saccadic target. By eliminating the reorienting component in our paradigm, we found no significant difference between the latencies of the two saccade types. In experiment 2, we varied the proportion of prosaccades made to certain locations and found that latencies in the high location-probability (75%) condition were faster than those in the low location-probability condition. Moreover, antisaccade latencies were significantly longer when location probability was high. This pattern can be explained by the notion of competing pathways for pro- and antisaccades in findings of others. In experiment 3, we further explored the degrees of modulation of location probability by decreasing the magnitude of high probability from 75 to 65%. We again observed a pattern similar to that seen in experiment 2 but with smaller modulation effects. Together, these experiments indicate that the reorienting process is a critical factor in producing the antisaccade cost. Furthermore, the antisaccade cost can be modulated by probabilistic contextual information such as location probabilities.

Control of prepotent responses by the superior medial frontal cortex.

The inhibitory control of prepotent action is vital for appropriate behaviour. An example of the importance of such control can be seen in the inhibition of aggressive behavior, deficits in which may have broader consequences for society. Many studies have related lesions or the under-development of the prefrontal cortex to inefficiency of inhibitory control. Here we used transcranial magnetic stimulation and a stop-signal task, which occasionally requires the inhibition of a prepotent motor response, to investigate the role of pre-supplementary motor area (Pre-SMA) in inhibitory control. While no effects were seen on the ability to generate responses, TMS delivered over the Pre-SMA disrupted the ability to respond to a stop signal. These results are the first to establish a casual link between Pre-SMA and inhibitory control in normal subjects. The understanding of the underlying mechanisms of inhibitory control may lead to clearer understanding of the neural basis of inappropriate behaviour.

Preference for Object Relative Clauses in Chinese Sentence Comprehension: Evidence From Online Self-Paced Reading Time.

Most prior studies have reported that subject-extracted relative clauses (SRCs) are easier to process than object-extracted relative clauses (ORCs). However, whether such an SRC preference is universal across different languages remains an open question. Several reports from Chinese have provided conflicting results; thus, in the present study, we conducted two self-paced reading experiments to examine the comprehension of Chinese relative clauses. The results demonstrated a clear ORC preference that Chinese ORCs were easier to comprehend than Chinese SRCs. These findings were most compatible with the prediction of the integration cost account, which claims that the processing difference between SRCs and ORCs arises at the point of dependency formation. The ORC preference in Chinese poses a challenge to the universality of the SRC preference assumed by the structural distance hypothesis and highlights the values of cross-linguistic research.

Flexible spatial mapping of different notations of numbers in Chinese readers.

The spatial component of numerical and ordinal information has been explored in previous research. However, how such mapping emerges and how it is affected by the learning experience are issues still under debate. In the current study, we examined the orientation of the mental number line for different numerical notations (e.g., "1", "---", "[symbol: see text]") in Chinese readers. Our data demonstrated that Arabic numbers are mentally aligned horizontally with a left-to-right directionality, while Chinese number words are aligned vertically with a top-to-bottom directionality. These findings indicate that different notations of the same concept have flexible mappings within space, which is plausibly shaped by the dominant context in which the numerical notations appear.

Time pressure leads to inhibitory control deficits in impulsive violent offenders.

Impulsive violent criminal behavior is often ascribed to problems with behavioral control. Such behavior could be a consequence of stronger pre-potent responses or a failure of inhibitory control. A countermanding task which allows dissociation of these two processes was used to examine whether impulsive violent offenders were found to exhibit impaired inhibitory control. An experiment with a time restriction on responding was performed to effectively limit the ability of the subjects to strategically control their error rate. The results showed that the performance of the impulsive violent offenders was only impaired in the time pressure condition. These findings suggest that impulsive violent behavior may be linked to abnormal modulation of the frontal cortical areas, areas thought to be involved in response inhibition by negative feedback or emotional responses, rather than frontal dysfunction per se.

Is There a Processing Preference for Object Relative Clauses in Chinese? Evidence From ERPs.

A consistent finding across head-initial languages, such as English, is that subject relative clauses (SRCs) are easier to comprehend than object relative clauses (ORCs). However, several studies in Mandarin Chinese, a head-final language, revealed the opposite pattern, which might be modulated by working memory (WM) as suggested by recent results from self-paced reading performance. In the present study, event-related potentials (ERPs) were recorded when participants with high and low WM spans (measured by forward digit span and operation span tests) read Chinese ORCs and SRCs. The results revealed an N400-P600 complex elicited by ORCs on the relativizer, whose magnitude was modulated by the WM span. On the other hand, a P600 effect was elicited by SRCs on the head noun, whose magnitude was not affected by the WM span. These findings paint a complex picture of relative clause processing in Chinese such that opposing factors involving structural ambiguities and integration of filler-gap dependencies influence processing dynamics in Chinese relative clauses.

Temporal dynamics of the consistency effect in reading Chinese: an event-related potentials study.

This study aimed to explore the temporal dynamics of the consistency effect in reading Chinese phonograms. High-consistency and low-consistency characters were used in the homophone judgment task, and the event-related potentials were recorded. The data showed that low-consistency characters elicited greater N170 amplitude in the temporal-occipital region and greater P200 amplitude in the frontal region than high-consistency characters, whereas high-consistency characters showed greater amplitude of the N400 negativity than low-consistency characters. These findings can be interpreted as indicating that low-consistency characters produce a greater activation for the initial analysis of the orthographical and phonological representations, whereas high-consistency characters involve a greater lexical competition in the later stage.