The antisaccade task performance deficit and specific CNV abnormalities in patients with stereotyped paraphilia and schizophrenia

Effect of Repetitive Head Impacts on Saccade Performance in Canadian University Football Players

OBJECTIVE

Investigate the effect of cumulative head impacts on saccade latency and errors, measured across two successive football seasons.

DESIGN

Participants were acquired from a sample of convenience-one Canadian university football team. Head impacts were collected during training camp, practices, eight regular season games, and four playoff games in each season. Saccade measurements were collected at five time points-before and after training camp, at midseason, after regular season, and after playoffs.

SETTING

Two seasons following players from a single USports football team during practices and games.

PARTICIPANTS

Players who completed a baseline saccade measurement and a minimum of one follow-up measurement were included in the study. A total of 127 players were monitored across two competitive seasons, including 61 players who participated in both seasons.

INDEPENDENT VARIABLES

Head impact measurements were collected using helmet-mounted sensors.

MAIN OUTCOME MEASURES

Saccade latency and number of errors were measured using high-speed video or electro-oculography.

RESULTS

On average, each head impact increased prosaccade latency by 5.16 × 10 -3 ms (95% confidence interval [CI], 2.26 × 10 -4 -1.00 × 10 -2 , P = 0.03) and antisaccade latency by 5.74 × 10 -3 ms (95% CI, 7.18 × 10 -4 -1.06 × 10 -2 , P = 0.02). These latency increases did not decrease between the two seasons; in fact, prosaccade latencies were 23.20 ms longer (95% CI, 19.40-27.14, P < 0.001) at the second season's baseline measurement than the first. The number of saccade errors was not affected by cumulative head impacts.

CONCLUSIONS

Repetitive head impacts in Canadian university football result in cumulative declines in brain function as measured by saccade performance.

CLINICAL RELEVANCE

Football organizations should consider implementing policies focused on reducing head impacts to improve player safety.

Investigation of electrophysiological precursors of attentional errors in schizophrenia: Toward a better understanding of abnormal proactive control engagement

Impaired cognitive control has been associated with the occurrence of attentional errors in those with schizophrenia. However, the extent of altered proactive or reactive control underlying such errors is still unknown. Twenty-two patients with schizophrenia and 21 healthy matched controls performed a detection task (i.e., the continuous temporal expectancy task). Electrophysiological measures of proactive and reactive control were based on two periods of interest: during the target presentation (the critical window) and four trials before the critical window. Regarding the proactive mode, patients with schizophrenia exhibited a specific decrease in frontal midline theta power during the critical window before a miss compared to a correct detection. In contrast, the contingent negative variation amplitude was altered regardless of the response type, four trials before the critical window. Regarding the reactive mode, a reduced P3 amplitude was revealed later before a miss than a correct detection with differences apparent only two trials before the critical window in patients with schizophrenia, whereas it was observable up to four trials prior in healthy controls. Moreover, only the P3 amplitude reduction in patients with schizophrenia predicted the miss rate and was anti-correlated with the clinical symptoms. Thus, our results revealed a specific impairment of the proactive goal-updating process before an error and an altered implementation of the endogenous proactive mode engagement regardless of the response type. The results also highlighted the strong relationship between the disrupted reactive mode and the increased rate of attentional errors and severity of the clinical symptoms of schizophrenia.

Contingent Negative Variation Blunting and Psychomotor Dysfunction in Schizophrenia: A Systematic Review

The contingent negative variation (CNV) is an event-related potential that provides a neural index of psychomotor processes (eg, attention and motor planning) well known to be dysfunctional in schizophrenia. Although evidence suggests that CNV amplitude is blunted in patients with schizophrenia (SZ) compared to healthy controls (HCs), there is currently no meta-analytic evidence for the size of the effect. Further, it is unknown how CNV blunting compares to closely related measures of psychomotor dysfunction, such as reaction time slowing. We used random-effects models to calculate the pooled effect size (ES) across 30 studies investigating CNV amplitude differences between patients and HCs (NSZ = 685, NHC = 714). Effect sizes for reaction time slowing across the studies were also quantified. Potential moderators, including sample characteristics and aspects of the CNV measurement, were examined. There was robust blunting of CNV activity in patients compared to HCs (ES = -0.79). The magnitude of this effect did not differ from reaction time slowing. Notably, CNV blunting in patients was significantly greater at central sites (ES = -0.87) compared to frontal sites (ES = -0.48). No other assessed methodological characteristics significantly moderated the magnitude of CNV differences. There is a large effect for CNV blunting in SZ that appears robust to potential confounds or methodological moderators. In addition, reduced CNV activity was statistically comparable to that of reaction time slowing. Blunting was the largest at central electrodes, which has been implicated in motor preparation. These findings speak to the complexity of psychomotor dysfunction in SZ and suggest significant promise for a biomarker.

The association between slow cortical potentials preceding antisaccades and disturbances of consciousness in persons with paraphilic sexual behaviour

Saccade characteristics and slow potentials in antisaccade tasks were studied in 37 people with disorders of sexual interest, depending on the disturbances of self-consciousness. The study found a decreased level of frontal cortex activation in subjects with disorders of self-consciousness; in subjects without disturbances of self-consciousness a high level of frontal cortex activation was observed. The findings demonstrate the important role of the frontal cortex in providing self-consciousness.

Behavioural and computational varieties of response inhibition in eye movements

Response inhibition is the ability to override a planned or an already initiated response. It is the hallmark of executive control as its deficits favour impulsive behaviours, which may be detrimental to an individual's life. This article reviews behavioural and computational guises of response inhibition. It focuses only on inhibition of oculomotor responses. It first reviews behavioural paradigms of response inhibition in eye movement research, namely the countermanding and antisaccade paradigms, both proven to be useful tools for the study of response inhibition in cognitive neuroscience and psychopathology. Then, it briefly reviews the neural mechanisms of response inhibition in these two behavioural paradigms. Computational models that embody a hypothesis and/or a theory of mechanisms underlying performance in both behavioural paradigms as well as provide a critical analysis of strengths and weaknesses of these models are discussed. All models assume the race of decision processes. The decision process in each paradigm that wins the race depends on different mechanisms. It has been shown that response latency is a stochastic process and has been proven to be an important measure of the cognitive control processes involved in response stopping in healthy and patient groups. Then, the inhibitory deficits in different brain diseases are reviewed, including schizophrenia and obsessive-compulsive disorder. Finally, new directions are suggested to improve the performance of models of response inhibition by drawing inspiration from successes of models in other domains.This article is part of the themed issue 'Movement suppression: brain mechanisms for stopping and stillness'.

The Study of the Antisaccade Performance and Contingent Negative Variation Characteristics in First-Episode and Chronic Schizophrenia Patients

The study tested whether the antisaccade (AS) performance and Contingent Negative Variation (CNV) measures differed between the first-episode and chronic patients to provide the evidence of PFC progressive functional deterioration. Subjects included 15 first-episode and 20 chronic schizophrenic patients (with the duration of illness more than 5 years), and 21 control subjects. The first-episode and chronic patients had significantly elevated error percent (p < .05, effect size 1.10 and p < .001, effect size 1.25), increased AS latencies (p < .01, effect size 1.18 and p < .001, effect size 1.69), and increased latencies variability (p < .01, effect size 1.52 and p < .001, effect size 1.37) compared to controls. Chronic patients had marginally significant increase of the response latency (p = .086, effect size .78) and latency variability (p < .099, effect size .63) compared to first-episode ones. Results of CNV analysis revealed that chronic patients only exhibited robustly declined frontal CNV amplitude at Fz (p < .05, effect size .70), F3 (p < .05, effect size .88), and F4 (p < .05, effect size .71) sites compared to controls. The obtained results might be related to specific changes in prefrontal cortex function over the course of schizophrenia.

Electrophysiological Endophenotypes for Schizophrenia

Endophenotypes are quantitative, heritable traits that may help to elucidate the pathophysiologic mechanisms underlying complex disease syndromes, such as schizophrenia. They can be assessed at numerous levels of analysis; here, we review electrophysiological endophenotypes that have shown promise in helping us understand schizophrenia from a more mechanistic point of view. For each endophenotype, we describe typical experimental procedures, reliability, heritability, and reported gene and neurobiological associations. We discuss recent findings regarding the genetic architecture of specific electrophysiological endophenotypes, as well as converging evidence from EEG studies implicating disrupted balance of glutamatergic signaling and GABAergic inhibition in the pathophysiology of schizophrenia. We conclude that refining the measurement of electrophysiological endophenotypes, expanding genetic association studies, and integrating data sets are important next steps for understanding the mechanisms that connect identified genetic risk loci for schizophrenia to the disease phenotype.