Cortex

It is still a matter of scientific debate whether the line bisection bias frequently observed in patients with spatial neglect is due to attentional underawareness of the left end of the line, attentional hyperattention towards the right end, or a logarithmically compressed perception of the line. To address this question, neglect patients who showed a line bisection bias were administered additional tasks involving horizontal lines (e.g., number line estimation tasks). Their performance was compared to neglect patients not showing a line bisection bias, patients with right hemisphere damage without neglect, and healthy controls. Results indicated that patients with a line bisection bias tended to overestimate lefthand segments when they had to dissect lines into three or four equal parts. This is congruent with both the notions of an underawareness of lefthand segments as well as a logarithmic compression of the line. However, when these patients had to imagine the lines as bounded fraction number lines ranging from 0-1, the results were mixed. When the number lines ranged from 0-10, these patients showed rightward overestimation biases for the numbers 4 and 5. Additionally, all patient groups, but not healthy controls, tended to place number 1 too far to the left and number 9 too far to the right, suggesting a general bias towards endpoints. In sum, this seems more congruent with attentional accounts than a perceptual one. Spatial-numerical associations could be ruled out, as all participants showed a verbal number bisection bias towards smaller numbers (i.e., the left of the mental number line). Therefore, these findings seem to indicate that the line bisection bias is most likely due to underawareness of the left end rather than hyperattention towards the right or a logarithmic perception of the line.

Visual imagery refers to the mental generation of visual representations of stimuli, while visual working memory involves retaining visual information for a short period without external input. Due to the conceptual overlap between these two constructs, successful performance on visual working memory tasks may rely on the use of visual imagery to rehearse items during the retention interval. Consequently, individuals with aphantasia, who lack voluntary visual imagery, may experience difficulties with such tasks. However, prior research has suggested that some individuals with aphantasia might employ non-visual strategies to compensate for this deficit. In two experiments, we examined visual working memory performance in aphantasic and control participants across a range of stimulus types. In Experiment 1, participants completed a change localization task using color squares and complex fractals; in Experiment 2, stimuli included real words, phonologically valid pseudowords, and phonologically invalid pseudowords. Across both experiments, aphantasic participants demonstrated significantly impaired visual working memory compared to controls. Notably, their performance was equally impaired for stimuli that were easily verbalizable (i.e., colors and words) and those that were not (i.e., fractals and pseudowords). Furthermore, individual differences in visual imagery ability, as measured by the Vividness of Visual Imagery Questionnaire (VVIQ), significantly predicted working memory performance across all stimulus types. These findings provide direct evidence for the critical role of visual imagery in supporting visual working memory.

Visuospatial neglect (VSN) after right-hemisphere stroke causes reduced engagement with left-sided stimuli, but how VSN affects automatic processes, i.e. the registration of regularities and regularity violations is still equivocal. This study investigated these processes using event-related potential components C1, C2/N1, and the visual mismatch negativity (vMMN), and how they differ in VSN compared to stroke and healthy controls, and their changes with time and rehabilitation. We applied a passive oddball paradigm, where diamond patterns periodically disappeared (OFF events) and reappeared (ON events) on the lower left and right sides, creating two simultaneous but independent sequences with standard and deviant events. The study included a VSN group (N=17, M=53.88{+/-}0.28 yrs); stroke patients (N=16, M = 56.81 {+/-} 13.26 yrs); and healthy participants (N=17, M=53.89{+/-}10.79 yrs). The VSN group underwent measurements three times: pre- and post-rehabilitation, and at a 4-month follow-up. Our results show that the C1 component emerged reliably in healthy participants and as a tendency in stroke controls, but not in VSN at any measurement point. The C2/N1 component emerged for all events without group differences. VSN patients showed no reliable vMMN, while it emerged in stroke patients for left-sided OFF events. Healthy controls showed vMMN in every condition. Our results suggest that both stroke and VSN impair the automatic detection of regularity violations, but VSN does so in a more substantial way, and this deficit does not improve with time or rehabilitation. Furthermore, the missing C1 component in VSN may indicate an early-stage deficiency even in visual processing.

Clinical research has documented a heterogeneous effect of neurodegenerative disorders on creativity. Some disorders are associated with impaired creative performance, while others may preserve, or even enhance, it. However, the underlying cognitive mechanisms that give rise to the heterogeneous behavioural manifestations remain poorly understood. From a theory-driven approach, we conducted a neuropsychological investigation to examine how frontotemporal lobar degeneration (FTLD), and Alzheimer's Disease (AD) differentially affected the cognitive mechanisms underlying creative thought (semantic cognition, episodic memory, executive control functions). In parallel, we assessed participants' verbal creative idea generation performance using the ideational fluency task (also known as the Alternate Uses Task). We analysed data from 24 individuals with FTLD [clinical consensus diagnosis corticobasal syndrome (CBS: n=20) or progressive supranuclear palsy (PSP: n=4)], 24 individuals with clinical consensus diagnosis AD, and 24 healthy individuals. We reached four major conclusions. First, while both disease groups exhibited deficits in controlled semantic retrieval and executive control functions, only participants with AD exhibited degradation in semantic representations and episodic memory. Second, both disease groups generated fewer responses in both typical and creative conditions across objects that were context-free - i.e., associated with multiple contexts (e.g., brick) and context-bound -i.e., associated with a dominant context (e.g., table knife). Third, when given a context-free object prompt, the ability to generate novel responses appeared to be preserved in participants with FTLD, which contrasted with an impaired ability when prompted to give creative uses for the context-bound object. Fourth, participants with AD produced similar levels of response novelty for both context-free and context-bound objects. From a clinical-cognitive neuroscience perspective, this study demonstrates that distinct cognitive profiles resulting from different neurodegenerative conditions yield differential effects on creative thought. As the first study to show that the contextual information of semantic stimuli can mediate the novelty of verbal responses, we suggest that future research should carefully examine how this factor influences creative task performance.

For years, dissociation studies on neurological single cases with brain lesions were the dominant method to infer fundamental cognitive functions in neuropsychology. In contrast, the association between deficits was considered to be of less epistemological value and even misleading. Still, principal component analysis (PCA) - an associational method for dimensionality reduction - recently became popular for the identification of fundamental functions. The current study evaluated the ability of PCA and factor analysis (FA) to overcome the association problem in behavioural data of neurological patients and to identify the fundamental variables underlying a battery of measures. Synthetic data were simulated to resemble neuropsychological data with typical dissociation patterns and, thereby, typical patterns of dependence between variables. In most experiments, PCA and FA succeeded to measure the underlying target variables with high up to almost perfect precision. However, this success was fragile and relied on the success of factor rotation, which failed its intended purpose when no test scores existed that primarily measured each underlying target variable. Further, commonly used strategies to estimate the number of meaningful factors appear to underfactor neuropsychological data, thereby consistently underestimating the dimensionality of the data. Finally, simulations suggested a high potential of PCA to denoise data, with factor rotation providing an additional filter function. This can be invaluable in neuropsychology, where measures are often inherently noisy, and PCA can be superior to common compound measures, such as the arithmetic mean, in the measurement of variables with high reliability. In summary, PCA and FA appear to be powerful tools in neuropsychology that are well capable to infer fundamental cognitive functions with high precision, but the typical structure of neuropsychological data and limited informative value of associations in neuropsychology place clear limitations and a risk of a complete failure on the methods.

Inhibition of return (IOR) refers to the slowing of response times (RTs) for stimuli repeated at previously inspected locations, as compared with novel ones. However, the exact processing stage(s) at which IOR occurs, and its nature across different response modalities, remain debated. We tested predictions on these issues originating from the FORTIOR model (fronto-parietal organization of response times in IOR; Seidel Malkinson & Bartolomeo, 2018), and from evidence accumulation models. We reanalysed RT data from a target-target IOR paradigm (Bourgeois et al.,2013a, 2013b) by using a LATER-like evidence accumulation model (Carpenter & Williams, 1995), to test the predictions of FORTIOR, and specifically whether IOR could occur at sensory/attentional stages of processing, or at stages of decision and action selection. We considered the following conditions: manual or saccadic response modality, before or after TMS perturbation over four cortical regions. Results showed that the Gaussian noise parameter best explained both manual and saccadic IOR, suggesting that in both response modalities IOR may result from slower accumulation of evidence for repeated locations. Additionally, across stimulated regions, TMS affected only manual RTs, lowering them equally in the conditions with repeated targets (Return) and non-repeated targets (Non-return). Accordingly, the modelling results show that TMS stimulation did not significantly alter the pattern between model parameters, with the Gaussian noise parameter remaining the parameter best explaining the Return - Non-return RT difference. Moreover, TMS over the right intra-parietal sulcus (IPS) perturbed IOR by shortening the Return RT. When directly testing this effect by modelling the TMS impact in the Return condition, the Bayesian information criterion of the Gaussian noise parameter was the smallest, but this effect did not reach significance. These results support the hypothesis that target-target IOR is a predominantly sensory/attentional phenomenon, and may be modulated by activity in fronto-parietal networks.

Many individuals with limb apraxia after left-hemisphere stroke exhibit a lack of awareness of their tool-related action errors, i.e., unawareness of apraxia (UA; also called anosognosia of apraxia). Little is known about the prevalence of UA, the relationship between UA and apraxia severity, or its underlying mechanisms. Here, we assessed both the causes and consequences of UA. Based on a mechanistic model, we hypothesized that UA may arise because of deficits in representations signaling how tool-related movements should look and feel--a component of action knowledge--and that degradation of this knowledge impedes the detection of mismatches between planned and actual tool-related actions. We further predicted that a consequence of UA is a reduction in error-correction attempts. Fifty-six individuals with chronic LCVA gestured to show how to use tools. Immediately after the gesture production task, participants were asked if they made any errors. All participants also completed an action knowledge task to measure the integrity of tool-related movement goals. Individuals were denoted as exhibiting UA if they performed below a normative cutoff for apraxia yet reported making no errors. Our sample included 21 individuals with apraxia; of these, nearly half (48%) exhibited UA. These two groups made a comparable number of gesture errors and were of equivalent stroke severity, yet individuals with UA had significantly more impaired action knowledge. Additionally, individuals with UA were less likely to attempt to correct their errors compared to individuals who were aware of their apraxia. These data support the hypothesis that action knowledge (how tool actions look and feel) serves a key role in error detection and awareness of apraxia and may contribute to the difficulties with everyday tasks experienced by many people with apraxia.

To address suggestions that human brain responses to autonomous system errors may be used as brain-based measures of trust in automation, the present study asked participants to monitor the performance of either a virtual human or an autonomous system partner performing a novel, complex, real-world image classification task. We predicted visual feedback of partner errors would elicit the feedback-related negativity and P3 ERP components, and that these components would differ between the human and system groups. Behavioral results showed that while participants calibrated their trust in their partner according to our intended manipulation of error rates, no group differences were found. The ERP data, however, revealed FRN and P3 effects for both groups, modulated by accuracy and error rate. An unexpected finding was that the P3 topography differed between groups, as while the P3 for the human group was widespread, the P3 for the system group was limited to posterior electrodes with the P3a being completely absent. These results demonstrate the potential for EEG-based measures of real-time trust in automation to be used in applied scenarios with benefits beyond traditional methods. Further, we found that a distinct neural processing of autonomous system errors compared to human errors may exist, necessitating further research in this emerging field.

During stop-signal task performance, little is known how the quality of visual information of the go stimuli may indirectly affect the interplay between the go and stop processes. In this study, we assessed how perceptual degradation of the visual go stimuli affect response inhibition. Twenty-six healthy individuals (mean age 33.34 {+/-} 9.61) completed a modified 12-minute stop-signal task, where V and Y letters were used as visual go stimuli. The stimuli were subjected to four levels of perceptual degradation using Gaussian smoothing, to parametrically manipulate stop difficulty across low, intermediate-1, intermediate-2 and high difficulty conditions. On 33% of trials, the stop-signal (50ms audio tone) followed a go stimulus after a stop-signal delay, which was individually adjusted for each participant. As predicted, we found that with increased level of stop difficulty (little perceptual degradation), reaction times on go trials and the proportion of successful behavioural inhibitions on stop trials (P(i)) decreased in normal healthy adults. Contrary to our predictions, there was no effect of increased stop difficulty on the number of correct responses on go trials and reaction times on stop trials. Overall, manipulation of the completion time of the go process via perceptual degradation has been partially successful, whereby increased stop difficulty differentially affected P(i) and SSRT. These findings have implications for the relationship between the go and stop processes and the horse-race model, which may be limited in explaining the role of various cortico-basal ganglia loops in modulation of response inhibition. HighlightsO_LIManipulation of the completion time of the go process is partially successful C_LIO_LIPerceptual degradation differentially affects stop-signal performance C_LIO_LIIncreased stop difficulty (easy go) results in lower P(i) C_LIO_LIIncreased stop difficulty (easy go) has no effect on SSRT C_LIO_LIHorse-race model does not fully explain basal ganglia involvement in inhibition C_LI

Imagining actions is a covert and multidimensional skill difficult to quantify. Comprehensive assessments rarely combine measures of imagery generation, maintenance, and manipulation. We developed and validated a combination of tests to assess these processes of movement imagery, online. 180 healthy individuals completed the MIQ-RS questionnaire (generation), the Imagined Finger Sequence Task (iFST; maintenance), and the Hand Laterality Judgement Task (HLJT; manipulation). MIQ-RS showed a bifactorial structure (visual and kinesthetic modalities) according to confirmatory factor analysis, and its reliability (internal consistency) was good. In the iFST, internal validity analyses via generalized mixed models showed a clear effect of sequence complexity, stronger for execution than imagery. Reliability, estimated via signal-to-noise ratios (SNRs) using hierarchical Bayesian models, was also adequate (SNR [≥] 1.6). In the HLJT, expected effects of rotation angle, hand view, and their interaction, consistent with biomechanical constraints, were also found. Reliability was also adequate (SNR [≥] 1.75). Criterion validity across tests, assessed using Bayesian Spearmans correlations, showed that correlations were generally absent (BF01 [≥] 3), and when present, of small magnitude (r [≤] 0.27). Test-retest reliability (123 participants reassessed 6-8 days after), computed via Intraclass Correlation Coefficients (ICCs), was generally adequate (ICCs [≥] 0.67). We conclude that the online versions of these tests showed adequate structural/internal validity and (test-retest) reliability. However, weak criterion validity suggests individuals with high ability to generate movement imagery may not necessarily have high ability to maintain and/or manipulate movement imagery, underscoring the need for comprehensive assessment of this capacity.

While language impairment is the defining symptom of aphasia, the co-occurrence of non-language cognitive deficits and their importance in predicting rehabilitation and recovery outcomes is well documented. Despite this, people with aphasia (PWA) are rarely tested on assessments of higher order cognitive functions, making it difficult for studies to associate these functions with a consistent lesion correlate. Contrary to classic models of speech and language, cumulative evidence shows that Brocas area and surrounding regions in the left inferior frontal cortex (LIFC) are involved in, but not specific to, speech production - suggesting that these regions may be involved in higher-level cognitive functions that support language production. A better understanding of language processing in the context of other domain general cognitive functions is essential for improving aphasia treatments. This study aimed to explore the brain-behaviour relationships between tests of individual cognitive skill and language abilities in people with post-stroke aphasia, with a focus on language production deficits and their associated lesion correlates. We predicted our analysis would reveal a latent (non-language specific) cognitive component, that would be driven by damage to LIFC. We analysed the behavioural and neural correlates of an extensive battery of language and non-language cognitive tests in a sample of thirty-six adults with long-term speech production deficits from post-stroke aphasia. All participants were anomic, with relatively intact speech comprehension and no apraxia of speech. The behavioural variables were analysed using Principal Component Analysis and their neural correlates were estimated using Voxel-Based Correlational Morphology. A significant number of anomic adults showed impaired performance on tests of non-language specific cognitive function. The variance underlying behavioural performance was best captured by four orthogonal components, two higher-order cognitive components (executive functions and verbal working memory) and two linguistic processing components (phonology and semantics). Brain-behaviour relationships revealed separable neural correlates for each component in line with previous studies and an executive functions correlate in the left inferior frontal cortex (LIFC). Our findings suggest that in adults with chronic post-stroke language production deficits (anomia), higher-level cognitive functions explain more of the variance in language function than classical models of the condition imply. Additionally, lesions to the LIFC, including Brocas area, were associated with executive (dys)function, independent of language abilities, suggesting that lesions to this area are associated with non-language specific higher-level cognitive functions that support speech production. These findings support contemporary models of speech production that place language processing within the context of domain-general perception, action and conceptual knowledge.

The present study tested the validity of inferring verbal-analytic motor processing from EEG left-temporal alpha activity. Participants (n = 20) reached for and transport a jar under three conditions: one control condition and two self-talk conditions aimed at eliciting either task-unrelated verbal processing or task-related conscious control, while 32-channel EEG and kinematics were recorded. Compared to the control condition, both self-talk conditions elicited greater self-reported levels of verbal processing, but only the task-related self-talk condition was accompanied by greater left temporal activity (i.e., EEG alpha power decreased) during movement production. However, this increase was not localised to the left temporal region but was rather evident over all scalp regions examined, suggesting an interpretation more consistent with diminished neural efficiency. No effects for left temporal-frontal (T7-Fz) connectivity were detected across conditions. Our results failed to endorse left-temporal EEG alpha activity as valid index of verbal-analytic processing during motor tasks.

Spatialization in working memory refers to the spatial coding of non-spatial information along a mental horizontal line when encoding verbal material. This phenomenon is thought to support working memory by facilitating order encoding. Although it has been observed for both visually and auditorily presented stimuli, no direct comparison has yet examined whether these modalities rely on similar neural mechanisms. In this study, we investigated whether spatialization in visual and auditory modalities involves shared or distinct patterns of activity within the working-memory network. Forty-nine participants performed both a visual and an auditory working memory SPoARC task of the same verbal material, allowing to study the cortical patterns associated with distinct serial positions at both encoding and recognition across sensory modalities. Whole-brain analyses revealed similar frontoparietal networks across conditions. In addition, a representational similarity analysis (RSA) was conducted to assess the similarity of neural patterns between early and late serial positions in a sequence and across sensory modalities. This multivoxel pattern analysis revealed modality-dependent patterns distinguishing early and late positions in the inferior frontal gyrus. Additional modality-specific effects were observed in the anterior intraparietal sulcus in the visual modality and in the posterior hippocampus in the auditory modality. Drawing on the framework proposed by Bottini & Doeller (2020), we propose that order decoding in the IPS might reflect a low-dimensional spatial coding of order (e.g., along a horizontal axis), whereas order decoding in the hippocampus might reflect higher-dimensional spatial representations or temporal representations.

AimCerebral Visual Impairment (CVI), an underdiagnosed cause of childhood visual impairment, presents heterogeneous symptoms involving varying degrees of dorsal and ventral stream dysfunction. We investigated whether impaired reach-to-grasp integration occurs in CVI as a potential marker of dorsal stream dysfunction. MethodPeople with CVI (children aged 7-17, n = 16; adults aged 18-25, n = 6) and control participants (children, n = 14; adults, n = 10) reached with their left hand to grasp plastic blocks with and without a blindfold. Reach-to-grasp timing and hand shaping measures were assessed using frame-by-frame video analysis. ResultsEven when they could see the block, people with CVI displayed prolonged grasp relative to reach durations, more static hand shaping during the reach, and increased reliance on non-visual hand shaping strategies after block contact to secure final grasp. The three measures were incorporated into a single composite Reach-to-Grasp Integration (RGI) score that distinguished people with CVI from controls. InterpretationTemporal, sensory, and functional dissociation of the reach and grasp occurs in CVI, consistent with dorsal stream dysfunction, and is captured by the RGI score. The RGI score could form the basis for CVI behavioural screening tools beyond standard visual assessments. What this paper addsO_LIPeople with CVI display impaired visually-guided integration of the reach and grasp, consistent with dorsal stream dysfunction. C_LIO_LIPeople with CVI use static preplanned hand shapes during visually-guided reaching. C_LIO_LIPeople with CVI rely on non-visual hand shaping strategies after target contact to facilitate grasping. C_LIO_LIThe composite Reach-to-Grasp Integration (RGI) score distinguishes CVI from control children and adults. C_LI

IntroductionGlioma patients with tumors near critical language regions present significant clinical challenges. Surgeons often lack the tools to understand how each unique surgical approach may impact linguistic ability, leading to subjective decisions and unpredictable outcomes. ObjectiveWe aim to develop an approach that uses data-driven preoperative brain mapping to quantitatively predict the impact of planned resections on long-term language function. MethodsThis study included 79 consecutive patients undergoing resection of language-eloquent gliomas. Patients underwent preoperative navigated transcranial magnetic stimulation (nTMS) language mapping to identify language-positive sites ("TMS points") and their associated white matter tracts ("TMS tracts") as well as formal language evaluations pre and postoperatively. The resection of regions identified by preoperative mapping was correlated with persistent postoperative language deficits (PLDs). ResultsThe resection of TMS points did not predict PLDs. However, a TMS point subgroup defined by white matter connectivity significantly predicted PLDs (OR=8.74, p<.01) and exhibited a canonical group-level anatomical distribution of cortical language sites. TMS-derived tracts recapitulated normative group-level patterns of white matter connectivity defined by the Human Connectome Project (HCP). Subcortical resection of TMS tracts predicted PLDs independently of cortical resection (OR=60, p<.001). The resected TMS tract segments in patients with PLDs co-localized with normative, language-associated subcortical pathways, in contrast to the resected TMS tract segments in non-aphasic patients (p<.05). Accordingly, resecting patient- specific co-localizations between TMS tracts and normative tracts in native space predicted PLDs with an accuracy of 94% (OR=134, p<.001). Co-localization between individualized and normative tracts precisely predicted the linguistic performance of a patient intraoperatively in response to direct electrophysiological stimulation of subcortical brain. ConclusionThis study outlines a data-driven brain mapping approach that provides surgical insight by preoperatively predicting the impact of individual glioma resection on long-term language function. Key PointsO_LIWhite matter connectivity determines the long-term functionality of cortical language sites mapped by TMS. C_LIO_LILong-term deficits in language processing result from resecting individualized subcortical regions within language-associated white matter tracts. C_LIO_LINon-invasive TMS language mapping combined with routine preoperative imaging can predict language outcomes of individual surgical approaches with an accuracy of 94%. C_LI

Lesion and imaging studies have shown that the left inferior frontal gyrus (IFG) is involved in selective semantic retrieval of information from the temporal lobes. However, causal, i.e., interventional, evidence is sparse. In the present study we addressed this question by testing whether transcranial direct current stimulation (tDCS) over the left IFG in a group of individuals with primary progressive aphasia may improve semantic fluency, a task that relies to selective semantic retrieval. Semantic fluency improved significantly more in the tDCS vs. sham condition immediately post-treatment and improvement lasted up to 2 months. We further addressed the question of who will benefit most from such an intervention by testing possible demographic, clinical and functional connectivity variables that may predict the behavioral tDCS effect. We found that patients with stronger baseline functional connectivity between the subareas of the left IFG opercularis and triangularis, and between the middle temporal pole and superior temporal gyrus. were the most likely to benefit from tDCS over the left IFG. We thus provided causal evidence that the left IFG is the neural substrate of selective semantic retrieval and tDCS over the left IFG may improve semantic fluency in individuals with stronger baseline functional connectivity.

The influence of non-visual information on visual awareness judgments has recently gained substantial interest. Using single-pulse Transcranial Magnetic Stimulation (TMS), we investigate the potential contribution of evidence from the motor system to judgment of visual awareness. We hypothesized that TMS-induced activity in the primary motor cortex (M1) would increase reported visual awareness as compared to the control condition. Additionally, we investigated whether TMS-induced motor-evoked potential could measure accumulated evidence for stimulus perception. Following stimulus presentation and TMS, participants first rated their visual awareness verbally using the Perceptual Awareness Scale, after which they responded manually to a Gabor orientation identification task. Delivering TMS to M1 resulted in higher average awareness ratings as compared to the control condition, in both correct and incorrect identification task response trials, when the hand with which participants responded was contralateral to the stimulated hemisphere (TMS-response-congruent trials). This effect was accompanied by longer Perceptual Awareness Scale response times, irrespective of the congruence between TMS and identification response. Moreover, longer identification response times were observed in TMS-response-congruent trials in the M1 condition as compared to the control condition. Additionally, the amplitudes of motor-evoked potentials were related to the awareness ratings when response congruence was taken into account. We argue that motor-evoked potential can serve as an indirect measure of evidence accumulated for stimulus perception and that longer Perceptual Awareness Scale response times and higher amplitudes of motor-evoked potentials in the M1 condition reflect integration of additional evidence with visual awareness judgment. In conclusion, we advocate that motor activity influences perceptual awareness judgments.

This study focuses on the approbation of the Keen Eye method for diagnosing visual neglect. A total of 102 patients with right hemisphere damage participated in the study, 38 of whom were diagnosed with neglect. The primary goal was to assess the effectiveness of Keen Eye in comparison with traditional paper-based tests. Keen Eye is based on a dual-task paradigm, integrating target identification and visual stimulus localization tasks, with stimuli presented in different areas of the screen. The results demonstrated the high diagnostic accuracy of the method, enabling the detection of covert forms of neglect. The study showed that the method allows for the assessment of both horizontal and vertical neglect severity and the identification of patients with neglect combined with non-lateralized attention deficits. The method exhibited high criterion and construct convergent validity and holds significant potential for clinical application.

BackgroundAudiovisual integration is essential for daily functions such as speech comprehension. It relies on a temporal constraint whereby events from different sensory modalities are perceptually bound within a limited temporal window, the audiovisual temporal binding window, defining the range of stimulus onset asynchronies perceived as synchronous. While correlational neuroimaging studies (fMRI, EEG) have implicated a distributed network in audiovisual integration, the causal neural underpinnings of the temporal binding window remain largely unknown. ObjectiveTo identify cortical regions causally supporting audiovisual simultaneity judgment. Methods: Direct electrical stimulation (DES) was prospectively applied to 62 cortical sites during awake brain surgery in 39 patients. Patients performed an audiovisual simultaneity judgment task with varying stimuli onset asynchronies alongside standard sensory-motor, language, and visuospatial tasks. Montreal Neurological Institute coordinates were obtained for all stimulated areas. ResultsDES selectively impaired audiovisual simultaneity judgments while sparing other standard tasks, in 7 highly focal, right-hemispheric cortical sites (<1 cm2). Three sites were situated around the intraparietal sulcus, and four near the supplementary motor area. Stimulation of left-hemisphere sites produced non-selective impairments, also affecting language-related tasks. ConclusionsThese findings provide causal evidence for a right-lateralized frontoparietal network, involving focal regions near the intraparietal sulcus and supplementary motor area, in audiovisual temporal integration. Given the established roles of these regions in attentional and decisional processes, this study refines their contribution to the temporal binding window network and underscores the clinical importance of preserving this network during awake brain surgery.

Recent work suggests that pointing based assessments may underestimate or mischaracterize perceptual and cognitive abilities in minimally verbal autism (mvASD). Extending this line of work, we address the classic global local question by testing whether mvASD children access global visual structure and whether it is consistently expressed in behavior using Kanizsa illusory contours (KIC) and circular colinear contours (CC). Typically developing (TD) and mvASD children viewed KIC and CC stimuli on a touchscreen while spontaneous eye gaze and pointing were recorded. Participants also completed a goal directed drag and drop matching task that required selecting the solid shape corresponding to the global KIC configuration. In spontaneous responses, mvASD children were more drawn to local elements (e.g., individual inducers, the CC frame, single Gabors) and showed less centralized responding than TD peers. Notably, CC pointing was often anchored to one half of the contour regardless of contour screen location, suggesting object centered global selection. Also, in the drag and drop task, approx. 90% of mvASD participants performed above chance in at least one condition and half performed at ceiling, demonstrating accurate global matching. These findings suggest that global structure is available in mvASD but may be underweighted in spontaneous response selection under ambiguity, consistent with the Affordance Competition Hypothesis and ambiguity resolution accounts. Lay SummaryAutism research often asks whether autistic people can see the wood for the trees--integrate parts into a coherent whole. This is difficult to test in minimally verbal autism because many standard tasks rely on a single pointing response that may not reflect what a child actually perceives. In our study, children viewed visual illusions in which a clear shape seems to appear even though it is not actually drawn, for example, a triangle you see because several Pac Man shapes are arranged in just the right way, while we measured both where they looked and where they touched the screen. Minimally verbal autistic children were often more drawn to the smaller parts than typically developing peers, yet when a simple drag and drop game required an explicit choice of the overall shape, most selected the correct global shape. Together, the findings suggest that global structure can be available in mvASD, but its expression in spontaneous behavior may be more context dependent under uncertainty, highlighting the value of using more than one way to measure ability.