Transcranial direct current stimulation of the frontal eye fields during pro- and antisaccade tasks

Transcranial direct current stimulation (tDCS) has been successfully applied to cortical areas such as the motor cortex and visual cortex. In the present study, we examined whether tDCS can reach and selectively modulate the excitability of the frontal eye field (FEF). In order to assess potential effects of tDCS, we measured saccade latency, landing point, and its variability in a simple prosaccade task and in an antisaccade task. In the prosaccade task, we found that anodal tDCS shortened the latency of saccades to a contralateral visual cue. However, cathodal tDCS did not show a significant modulation of saccade latency. In the antisaccade task, on the other hand, we found that the latency for ipisilateral antisaccades was prolonged during the stimulation, whereas anodal stimulation did not modulate the latency of antisaccades. In addition, anodal tDCS reduced the erroneous saccades toward the contralateral visual cue. These results in the antisaccade task suggest that tDCS modulates the function of FEF to suppress reflexive saccades to the contralateral visual cue. Both in the prosaccade and antisaccade tasks, we did not find any effect of tDCS on saccade landing point or its variability. Our present study is the first to show effects of tDCS over FEF and opens the possibility of applying tDCS for studying the functions of FEF in oculomotor and attentional performance

Original Articles Brain stimulation and inhibitory control

a b s t r a c t Inhibitory control mechanisms are important in a range of behaviours to prevent execution of motor acts which, having been planned, are no longer necessary or appropriate. Examples of this can be seen in a range of sports, such as cricket and baseball, where the choice between execution and inhibition of a bat swing must be made in a very brief time window. Deficits in inhibitory control have been associated with problems in behavioural regulation in impulsive violence as well as a range of clinical disorders. The roles of various areas, including the frontal eye fields (FEF), the pre-supplementary motor area (pre-SMA) and the inferior frontal gyrus, in inhibitory control have been investigated using an inhibitory control task and both transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). Typically effects on response inhibition but no effects on response generation have been seen. The contributions of these areas to performance seem to differ with, for example, pre-SMA being involved when the task is relatively novel whereas this is not the case for FEF. The findings from brain stimulation studies offer both insight into which areas are necessary for effective inhibitory control and recent extension of findings for the role of the inferior frontal gyrus illustrate how the specific functions by which these areas contribute may be further clarified. Future work, including making use of the temporal specificity of TMS and combination of TMS/tDCS with other neuroimaging techniques, may further clarify the nature and functions played by the network of areas involved in inhibitory control

Original Articles Brain stimulation and inhibitory control

a b s t r a c t Inhibitory control mechanisms are important in a range of behaviours to prevent execution of motor acts which, having been planned, are no longer necessary or appropriate. Examples of this can be seen in a range of sports, such as cricket and baseball, where the choice between execution and inhibition of a bat swing must be made in a very brief time window. Deficits in inhibitory control have been associated with problems in behavioural regulation in impulsive violence as well as a range of clinical disorders. The roles of various areas, including the frontal eye fields (FEF), the pre-supplementary motor area (pre-SMA) and the inferior frontal gyrus, in inhibitory control have been investigated using an inhibitory control task and both transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). Typically effects on response inhibition but no effects on response generation have been seen. The contributions of these areas to performance seem to differ with, for example, pre-SMA being involved when the task is relatively novel whereas this is not the case for FEF. The findings from brain stimulation studies offer both insight into which areas are necessary for effective inhibitory control and recent extension of findings for the role of the inferior frontal gyrus illustrate how the specific functions by which these areas contribute may be further clarified. Future work, including making use of the temporal specificity of TMS and combination of TMS/tDCS with other neuroimaging techniques, may further clarify the nature and functions played by the network of areas involved in inhibitory control

Increased positive and disorganised schizotypy in synaesthetes who experience colour from letters and tones.

Synaesthesia is a condition in which one property of a stimulus induces a conscious experience of an additional attribute. For example, in grapheme-colour synaesthesia, a visually presented grapheme results in synaesthetic experiences of colour. These experiences occur in approximately 4% of the population (Simner et al., 2006) and the authenticity of the condition is well established (Cohen Kadosh and Henik, 2007). Despite this, our understanding of the neuropsychiatric profiles of synaesthetes remains limited and surprisingly few studies have addressed whether synaesthesia is linked to more widespread abnormalities in perception that extend beyond the synaesthetic experience itself. There is, however, growing evidence to suggest that synaesthesia may be linked to a broader phenotype. For example, synaesthetes who experience colour show early processing differences to stimuli which do not evoke synaesthesia (Barnett et al., 2008); and the presence of synaesthesia has been linked with other phenotypic manifestations including out-of-body experiences (Terhune, 2009), creativity (Ward et al., 2008), mental imagery (Barnett and Newell, 2008), and mitempfindung (Burrack et al., 2006). Here, we examined the relationship between synaesthesia involving colour and the abnormal perceptions observed in schizophrenia by assessing levels of schizotypy in synaesthetes and non-synaesthetes. We report that synaesthesia for colour is associated with greater levels of positive and disorganised schizotypy (Fig. 1A), suggesting widespread perceptual differences in synaesthesia that extend beyond the synaesthetic concurrent

Better Cognitive Performance Is Associated With the Combination of High Trait Mindfulness and Low Trait Anxiety

There are several ways in which cognitive and neurophysiological parameters have been consistently used to explain the variability in cognitive ability between people. However, little has been done to explore how such cognitive abilities are influenced by differences in personality traits. Dispositional mindfulness and anxiety are two inversely linked traits that have been independently attributed to a range of cognitive functions. The current study investigated these two traits in combination along with measures of the attentional network, cognitive inhibition, and visual working memory (VWM) capacity. A total of 392 prospective participants were screened to select two experimental groups each of 30 healthy young adults, with one having high mindfulness and low anxiety (HMLA) and the second having low mindfulness and high anxiety (LMHA). The groups performed an attentional network task, a color Stroop task, and a change detection test of VWM capacity. Results showed that the HMLA group was more accurate than the LMHA group on the Stroop and change detection tasks. Additionally, the HMLA group was more sensitive in detecting changes and had a higher WMC than the LMHA group. This research adds to the literature that has investigated mindfulness and anxiety independently with a comprehensive investigation of the effects of these two traits in conjunction on executive function

Special issue "Culture and Cognition". Cognitive Neuroscience

There is increasing interest in the nature and both environmental and cognitive origins of culturally associated differences in a range of behaviors. This special issue of Cognitive Neuroscience presents six empirical papers investigating diverse categories of potential culturally related effects as well as a review article, all of which provide timely updates of the current state of knowledge in this area