The Influence of Maternal Schizotypy on the perception of Facial Emotional Expressions during Infancy: an Event-Related Potential Study.

Parenting directly affects the developmental and clinical outcomes of children. How parental personality relates to perceptual and cognitive mechanisms during early development is not clear. For parents with traits of the personality dimension schizotypy, would their infant display brain responses similar to those on the schizophrenia-spectrum? This study investigates whether maternal personality influences early social-cognitive awareness during the first 6 postnatal months. Schizotypy is a dimension of personality within the general population. If deficits contribute to the development of schizophrenia-spectrum disorders by influencing the development of symptom-like characteristics, they may be observable in neurotypical individuals with schizotypal characteristics. Parents and their infants were shown standardised positive and negative faces and event-related potential responses were assessed. It was hypothesised that the infants of schizotypic mothers would display differential Negative-central event-related potentials for the happy and fearful expressions when compared to infants of non-schizotypic mothers. Results support prior literature; indicating 6-month-old infants allocate more attentional resources to fearful when contrasted to happy faces. The adult cohort displays this same ability. In addition, schizotypic mothers displayed comparable amplitudes for both expressions in comparison to the control mothers who exhibited larger amplitudes towards the fearful compared to the happy expression. Infants of schizotypic mothers did not show a greater sensitivity to facial expressions at 6-months, but schizotypic mothers showed a generalised response towards facial expressions compared to the typical P600 response illustrated by the control mothers. The present study suggests that development in the higher cognitive domains, such as the allocation of attention to novel stimuli, are not affected at 6 months of age by maternal personality related to schizotypy when examined at the group level. Implications for personality development, maternal-infant interactions and cognitive neuroscience methodologies are discussed.

The Effects of Previous Error and Success in Alzheimer's Disease and Mild Cognitive Impairment.

This work investigated in Alzheimer's disease dementia (AD), whether the probability of making an error on a task (or a correct response) was influenced by the outcome of the previous trials. We used the antisaccade task (AST) as a model task given the emerging consensus that it provides a promising sensitive and early biological test of cognitive impairment in AD. It can be employed equally well in healthy young and old adults, and in clinical populations. This study examined eye-movements in a sample of 202 participants (42 with dementia due to AD; 65 with mild cognitive impairment (MCI); 95 control participants). The findings revealed an overall increase in the frequency of AST errors in AD and MCI compared to the control group, as predicted. The errors on the current trial increased in proportion to the number of consecutive errors on the previous trials. Interestingly, the probability of errors was reduced on the trials that followed a previously corrected error, compared to the trials where the error remained uncorrected, revealing a level of adaptive control in participants with MCI or AD dementia. There was an earlier peak in the AST distribution of the saccadic reaction times for the inhibitory errors in comparison to the correct saccades. These findings revealed that the inhibitory errors of the past have a negative effect on the future performance of healthy adults as well as people with a neurodegenerative cognitive impairment.

The perception of real and illusory motion in schizophrenia.

An illusion of rapid movement is normally perceived when an attentional cue (such as a peripheral flash) preceeds the onset of a line. The movement is perceived as receding away from the cue. This study investigated how this illusion was perceived by people with schizophrenia. Nineteen participants with schizophrenia and 26 healthy matched controls were presented with a series of real, illusory, no motion or combined real and illusory motion stimuli at various target speeds. Detection thresholds were measured to determine the reliability of motion perception. The participants with schizophrenia were not distinguished from the control group in the perception of real motion. However, the motion detection curves for the schizophrenia group revealed a reduction in the perceptual effect of illusory motion in comparison to controls. The findings revealed that people with schizophrenia may be less easily deceived by illusory motion in comparison to healthy participants.

The effects of illusory line motion on incongruent saccades: implications for saccadic eye movements and visual attention.

A complex neural problem must be solved before a voluntary eye movement is triggered away from a stimulus (antisaccade). The location code activated by a stimulus must be internally translated into an appropriate signal to direct the eyes into the opposite visual field, while the reflexive tendency to look directly at the stimulus must be suppressed. No doubt these extra processes contribute to the ubiquitous slowing of antisaccades. However, there is no consensus on the cognitive mechanisms that contribute to the antisaccade programme. Visual attention is closely associated with the generation of saccadic eye movements and it has been shown that attention will track an illusion of line motion. A series of experiments combined this illusion with a saccadic eye movement that was congruent (i.e. directed towards), or incongruent with (i.e. direct away from), a peripheral target. Experiment 1 showed that congruent saccades had faster reaction times than incongruent saccades. In contrast, Experiments 2 and 3 demonstrated that, with illusory line motion, incongruent saccades now had faster reaction times than congruent saccades. These findings demonstrate that an illusory phenomenon can accelerate the processing of an incongruent relative to a congruent saccade.

Melanic moth frequencies in Yorkshire, an old English industrial hot spot.

A survey has been carried out in Leeds, England, in the west Yorkshire industrial heartland, and in neighboring York, surrounded by agriculture, of melanic frequency in the moth species Biston betularia, Odontoptera bidentata, and Apamea crenata. All show a decline in melanics in the postindustrial environment, the first over almost the full range from nearly 100% to less that 10%, the others to smaller extents. Changes in several species over as great a magnitude and as wide an area must result from selection. The results are compared with others along a transect through northern England. The onset of response is progressively later from west to east. The rate of decline is lower at the extremes of the transect to west and east than it is in the center. We still do not have a clear picture of the causes of the changes. One major factor is likely to be selective predation, which is shown to be critically dependent on predation rate. As a consequence, differences in settling behavior between the species could account for different responses even if the species are attacked by the same predators.

Differential effects of olanzapine and risperidone on cognition in schizophrenia? A saccadic eye movement study.

Recent studies suggest that novel antipsychotics have positive effects on certain cognitive functions in schizophrenia. The present study investigated this claim by means of saccadic paradigms, which provide a selective index of cognitive function. Thirty-three first-episode schizophrenic patients were randomly assigned to either olanzapine or risperidone treatment and compared with healthy control subjects for three saccadic paradigms. The influence of symptom profile, extrapyramidal symptoms, age, education, gender, hospitalization, and medication dose on cognitive performance was also investigated. Although the two patient groups did not differ from each other in task performance, both patient groups showed substantial problems in inhibitory control of saccades. A high level of education appeared to be protective for this impairment.

Cognition and the inhibitory control of saccades in schizophrenia and Parkinson's disease.

Historically, various lines of evidence have converged on the view that the brain expends much of its neural resources on inhibiting its own activity in a critical step towards the cognitive control of behaviour. The loss of inhibitory control is widely reported in neurological and psychiatric disorders; however, the consequences of reduced inhibition in terms of wider cognitive effects on cognitive control operations such as planning, abstract thought, working memory and the ability to appreciate the perspective of others ('theory of mind') has been widely overlooked. The antisaccade paradigm examines the conflict between a prepotent stimulus that produces a powerful urge to fixate the target, and the overriding goal to 'look' in the opposite direction. In this chapter we illustrate how this paradigm is increasingly used to explore the relationship of inhibitory control and cognition in Parkinson's disease, schizophrenia and healthy participants. Evidence is presented that is consistent with the theory of cognitive inhibition as a distinct process that can be dissociated from working memory. We conclude that the inhibitory control of saccadic eye movement should be studied in the wider context of cognitive operations.

Short and long term effects of antipsychotic medication on smooth pursuit eye tracking in schizophrenia.

RATIONALE: Smooth pursuit abnormalities have been observed in antipsychotic naive first-episode patients, suggesting that they are intrinsic to the illness. However, it is not clear whether these abnormalities are as severe as those observed in more chronic patients. In addition, although research suggests that there are no short-term effects of conventional antipsychotic medication, the effects of long-term antipsychotic medication on smooth pursuit eye movements are relatively unknown. OBJECTIVES: To determine the short and long term effects of antipsychotic medication on the smooth pursuit performance of first-episode and chronic patients with schizophrenia. METHODS: We compared the smooth pursuit performance of antipsychotic-treated and untreated first-episode and chronic schizophrenic patients with healthy controls using a comprehensive range of performance measures. This included velocity gain, the number, type and size of intrusive and corrective saccades, and the average time between the change in direction of the target and the change in direction of the eye movement, a measure of subjects' ability to predict target movement. RESULTS: Chronic schizophrenic patients had significantly reduced velocity gain, took longer to respond to the change in target direction and made more catch-up saccades than both first-episode schizophrenic patients and controls. First-episode patients were impaired relative to controls only on the measure of velocity gain. There were no differences between antipsychotic-naive and treated first-episode patients. Antipsychotic-free chronic patients were significantly less impaired on velocity gain than matched continuously treated chronic patients. These results were not influenced by group differences in age and symptom severity. CONCLUSIONS: These results show that: 1) the main index of smooth pursuit, velocity gain, is impaired early in the course of schizophrenia; 2) whereas velocity gain is unaffected by short-term (weeks) medication, it is worsened by chronic (years) treatment; 3) other indices of smooth pursuit, catch-up saccades and ability to predict target movement, are adversely influenced by illness chronicity rather than medication.

Saccadic hypometria in drug-naive and drug-treated schizophrenic patients: a working memory deficit?

In certain conditions patients with schizophrenia make markedly smaller (hypometric) saccades than controls. This hypometria has been thought to reflect dopaminergic blockade as a result of antipsychotic medication. We tested this hypothesis by comparing the performance of an antipsychotic-naïve group and an antipsychotic-treated group of first-episode schizophrenic patients on a predictive saccade paradigm. We explored the possibility that hypometria reflects a spatial working memory deficit by correlating performance on neuropsychological tests of mnemonic function with saccadic accuracy. Both the drug-naïve and treated schizophrenic patients made hypometric saccades when compared with a group of matched controls. Primary saccade amplitude also correlated significantly with performance on some of the neuropsychological tests. These results are discussed in terms of the roles of cortical dopamine and working memory deficits in schizophrenic patients.

Dyslexia and the centre-of-gravity effect.

When human observers are presented with a double target display, a saccadic eye movement is triggered to an intermediate position close to the 'centre-of-gravity' of the configuration. This study examined the saccadic eye movements of dyslexic and normal readers in response to displays of single and double targets. Eye movement analyses revealed no differences in the spatial position of saccadic eye movements of dyslexic and normal readers in response to single targets presented at 5 degrees or 10 degrees. However, when presented with two targets simultaneously at 5 degrees AND 10 degrees, in contrast to normal readers who generated saccades to an intermediate position between the two targets (towards the 'centre-of gravity'), dyslexics generated saccades that landed close to the near target eccentricity. These findings suggest that dyslexia is associated with a deficit in the processing of global spatial information for the control of saccadic eye movements.

Parsing cognition in schizophrenia using saccadic eye movements: a selective overview.

Eye movements provide a behavioural measure of sensorimotor processing and higher cognitive functions of the brain. With the development of novel paradigms that can be used for the study of various cognitive operations, saccadic eye movements in particular, have become increasingly popular. Patients with schizophrenia have neurocognitive impairments that can be readily investigated with these paradigms. From animal, human lesion and neuroimaging studies, the cerebral centres underlying saccadic eye movements have been identified. The areas of the prefrontal cortex include the dorsolateral prefrontal cortex, the frontal eye fields, the supplementary eye fields, and the anterior cingulate cortex. Pathology of saccadic eye movements, therefore, provides information on the functional status of the underlying neural circuitry in brain disorders such as schizophrenia. In this paper, we evaluate: (i) methodological considerations that are central to the design and application of saccadic paradigms; (ii) brain activation that is associated with saccadic paradigms; (iii) recent findings in healthy subjects and schizophrenic patients; (iv) saccadic abnormalities in other psychiatric and neurological disorders and in individuals at risk for developing schizophrenia.

Smooth pursuit eye tracking over a structured background in first-episode schizophrenic patients.

Whilst most laboratory smooth pursuit tasks are performed in the dark, in everyday life pursuit commonly occurs over a structured background. This background provides a powerful stimulus to the optokinetic reflex (OKR), inducing a background "drag" on pursuit eye movements. An inability to inhibit the influence of the OKR may be a contributing factor to the dysfunctional pursuit performance observed in many schizophrenic patients. Smooth pursuit performance was measured in 23 first-episode schizophrenic patients and 23 healthy controls matched for age and estimated IQ, both in the dark and over a structured background (a random checkerboard of black and white squares). Velocity gain was measured, as well as the number and size of corrective saccades (catch-up saccades) and intrusive saccades (anticipatory saccades and square wave jerks). Overall, schizophrenic patients had lower velocity gain and made more catch-up saccades than controls. The effect of the background was to lower velocity gain and increase the number of catch-up saccades to the same extent in schizophrenic patients and controls. There were no significant interactions between group and background effect. These results suggest that, although their overall level of performance was worse, the schizophrenic patients were as able as controls to inhibit the effect of the OKR. Since lesion studies show that inhibition of the OKR requires intact inferior parietal regions in man (Lawden et al., 1995), one hypothesis is that the parietal component of smooth pursuit may be intact in schizophrenia.

Deficits of smooth pursuit initiation in patients with degenerative cerebellar lesions.

It is well known that cerebellar dysfunction can lead to an impairment of eye velocity during sustained pursuit tracking of continuously moving visual target. We have now studied the initiation of smooth pursuit eye movements towards predictable and randomized visual step-ramp stimuli in six patients with degenerative cerebellar lesions and six age-matched healthy controls using the magnetic scleral search-coil technique. In comparison with the control subjects, the cerebellar patients showed a significant delay of pursuit onset, and their initial eye acceleration was significantly decreased. These cerebellar deficits of pursuit initiation were similarly found in response to both randomized and predictable step-ramps, suggesting that predictive input does not compensate for cerebellar deficits in the initiation period of smooth pursuit. When we compared initial saccades during smooth tracking of foveofugal and foveopetal step-ramps, the absolute position error of these saccades did not significantly differ between patients and controls. In fact, none of the patients showed any bias of the saccadic position error that was related to the direction or velocity of the ongoing target motion. This work presents further evidence that the effect of cerebellar degeneration is not limited to the impaired velocity gain of steady-state smooth pursuit. Instead, it prolongs the processing time required to initiate smooth pursuit and impairs the initial eye acceleration. These two deficits were not associated with an abnormal assessment of target velocity and they were not modified by predictive control mechanisms, suggesting that cerebellar deficits of smooth initiation are not primarily caused by abnormal information on target motion being relayed to the cerebellum.

Saccadic eye movements in families multiply affected with schizophrenia: the Maudsley Family Study.

OBJECTIVE: Family studies have shown that abnormalities of smooth pursuit eye movement are increased in the adult relatives of schizophrenic probands as well as in the probands themselves. More recently, an inability of schizophrenic subjects to inhibit reflexive saccades reliably has been shown. This study aimed to test the hypothesis that the latter dysfunction is part of the extended schizophrenia phenotype. METHOD: With the use of infrared oculography, measurements of reflexive saccades and antisaccades were undertaken in 29 probands with schizophrenia, 50 of their nonpsychotic first-degree relatives, and 38 unrelated healthy volunteers. RESULTS: Probands, relatives, and healthy subjects showed no overall differences in the generation of reflexive saccades. However, in the antisaccade task, probands showed more saccadic distractibility when they were required to inhibit reflexive saccades. Analysis of corrective saccades showed that this was not due to failed comprehension or motivation. Relatives of the probands with high saccadic distractibility showed a higher distractibility rate than relatives of the probands with normal distractibility. Across all subjects, females showed a higher rate of distractibility errors than males. CONCLUSIONS: The ability to suppress reflexive saccades is an objective neurocognitive measure that is impaired in schizophrenic patients and in a proportion of their biological relatives. This antisaccade abnormality may be a vulnerability marker in a subset of schizophrenic patients and their families.

Smooth pursuit and saccadic abnormalities in first-episode schizophrenia.

BACKGROUND: Previous studies of oculomotor dysfunction in schizophrenia have tended to concentrate on abnormalities of smooth pursuit eye tracking in chronic medicated patients. We report the results of a study of smooth pursuit, reflexive and antisaccade performance in drug naive and antipsychotic treated first-episode schizophrenic patients. METHODS: Smooth pursuit and saccadic eye movements were recorded in 36 first-episode schizophrenic patients and 36 controls matched for age and estimated IQ. The schizophrenic patients were divided into drug-naive (N = 17) and antipsychotic treated groups (N = 19). RESULTS: Smooth pursuit velocity gain was significantly lower than controls only in the drug-naive patients. The treated patients did not differ significantly from either the controls or the untreated group. In an antisaccade paradigm both treated and drug-naive schizophrenic patients demonstrated an increased number of errors, but only drug-naive patients also demonstrated an increased latency in initiating correct antisaccades. CONCLUSIONS: These impairments are unlikely to be due to a generalized deficit in oculomotor function in the schizophrenic groups, as there were no differences between the groups in saccadic metrics on a reflexive saccade task. The results show that both smooth pursuit and saccadic abnormalities are present at the onset of schizophrenia and are integral to the disorder.

Abnormalities of predictive saccades in Parkinson's disease.

Saccades of patients with mild Parkinson's disease (PD) are said to be abnormal in the absence of a concurrently visible target or when they are part of a rapid sequence of eye movements. We tested this hypothesis using a predictive saccade paradigm in which target visibility is withdrawn for a period. Three rates of target alternation were used (0.25 Hz, 0.5 Hz and 1.0 Hz). Withdrawal of target visibility brought out the extremes of primary saccade gain for both the controls and the patients with PD, most undershoot being displayed at the lowest frequency, whereas the gain was greatest at the highest frequency, actually overshooting the target location. These results demonstrate that the spatial error of parkinsonian saccades does not invariably take the form of hypometria when part of a rapid sequence of eye movements.

Transient motion of visual texture delays saccadic eye movements.

Neurophysiological research has established that a transient stimulus, spatially located outside the receptive field of visual cells, can activate some cells and inhibit firing in others. However, the significance of this phenomenon for behavioural responses in man is unclear. This study investigated the effect of a transient peripheral event on the initiation of saccadic eye movements to a luminance increment. In Experiment 1 human saccadic eye movements to targets that varied in luminance were compared on 'shift' trials, in which the saccadic target was timed to coincide with a step displacement of a vertical grating in the background, and on 'no-shift' trials, when the background remained stationary. The results showed a significant delay in mean saccadic latencies on 'shift trials' compared to 'no-shift' trials. Saccadic latencies were reduced in both conditions with increasing target intensity. Measurement of visual sensitivity showed a small non-significant increase in thresholds in the background 'shift' condition. A second experiment manipulated visuo-temporal information by varying both target duration and intensity. This experiment revealed significant effects of target duration and signal intensity on saccadic latency; and a 3-way interaction showing that saccades suffered the greatest delay in the background 'shift' condition at the lowest duration and intensity targets. These results show that the peripheral motion of visual texture delays the programming of saccadic eye movements and there is a particularly marked effect for targets of low signal strength.

Abnormal saccadic distractibility in patients with schizophrenia: a 99mTc-HMPAO SPET study.

Recent research has shown that some patients with schizophrenia have a severe impairment in the suppression of reflexive saccadic eye movements in the ANTI-saccade task. This saccadic distractibility has previously been found in patients with lesions of dorsolateral prefrontal cortex, implicating an abnormality of prefrontal cortex. The objective of the present study was to determine the contribution of these and other areas to the ANTI-saccadic abnormality in schizophrenia by functional neuroimaging. Using 99mtechnetium-HMPAO high resolution multidetector single-photon emission tomography, regional cerebral blood flow (rCBF) during performance of the ANTI-saccade eye-movement task was compared, by statistical parametric mapping, in ten male schizophrenic patients on stable antipsychotic medication who had a high distractibility error rate on the task, and eight similar patients who had normal distractibility error rates. Compared with the normal error group, the patients with high error rates showed significantly decreased rCBF bilaterally, in the anterior cingulate, insula, and in left striatum. These same patients also had increased perseverative errors on the Wisconsin Card Sort Test.

Saccadic abnormalities in psychotic patients. I. Neuroleptic-free psychotic patients.

Most of the previous research reporting abnormalities of rapid re-fixation eye movements (saccades) in patients with schizophrenia has used patients receiving neuroleptic medication. In this study non-neuroleptically medicated schizophrenics were compared with other psychiatric patients using a variety of saccadic paradigms to determine the specificity of saccadic dysfunction. The patient groups consisted of schizophrenics (N = 18), bipolar affectives (N = 18), anxiety neurotics (N = 10) and normal controls (N = 31), none of whom had received neuroleptic medication for the preceding 6 months. Four behavioural paradigms, reflexive, predictive, remembered and ANTI were used to elicit saccades. The primary abnormality in the schizophrenic group was a significantly increased rate of distractibility in the ANTI (saccades made towards the target rather than in an opposite direction) and REM (saccades made prior to the imperative cue) paradigms. The major neuropsychological variable predictive of these errors was Wisconsin card sort perseverative errors. These data, in conjunction with findings from previous neurological research, would seem to provide converging evidence towards dysfunction of prefrontal cortex in schizophrenia.