Neurophysiology and neuroanatomy of reflexive and voluntary saccades in non-human primates

A multitude of cognitive functions can easily be tested by a number of relatively simple saccadic eye movement tasks. This approach has been employed extensively with patient populations to investigate the functional deficits associated with psychiatric disorders. Neurophysiological studies in non-human primates performing the same tasks have begun to provide us with insights into the neural mechanisms underlying many cognitive functions. Here, we review studies that have investigated single neuron activity in the superior colliculus (see glossary), frontal eye field, supplementary eye field, dorsolateral prefrontal cortex, anterior cingulate (see glossary) cortex and lateral intraparietal area associated with the performance of visually guided saccades, anti-saccades and memory-guided saccades in awake behaving monkeys.     

Neurophysiology and neuroanatomy of reflexive and voluntary saccades in non-human primates

A multitude of cognitive functions can easily be tested by a number of relatively simple saccadic eye movement tasks. This approach has been employed extensively with patient populations to investigate the functional deficits associated with psychiatric disorders. Neurophysiological studies in non-human primates performing the same tasks have begun to provide us with insights into the neural mechanisms underlying many cognitive functions. Here, we review studies that have investigated single neuron activity in the superior colliculus (see glossary), frontal eye field, supplementary eye field, dorsolateral prefrontal cortex, anterior cingulate (see glossary) cortex and lateral intraparietal area associated with the performance of visually guided saccades, anti-saccades and memory-guided saccades in awake behaving monkeys.     

Demographic, clinical, and neurocognitive correlates of everyday functional impairment in severe mental illness

Although cognitive deficits often accompany severe mental illness, their implications for everyday functioning remain poorly understood. In this study, an occupational therapist (OT) rated the everyday functioning of 105 adult psychiatric patients. Using demographic, clinical, and cognitive variables, the authors tested alternative models to account for the observed variability in OT ratings. Although age, education, and the presence of schizophrenia each contributed to a model that accounted for 27% of the variation in functional independence, adding terms for auditory divided attention and verbal learning increased the proportion of explained variance to 45% and decreased the beta weights for age and education--but not schizophrenia--to nonsignificant levels. These findings demonstrate the relevance of cognitive performance to everyday functioning in severe mental illness. They are discussed with respect to hypothesized determinants of psychiatric disability.     

Some surprising findings on the involvement of the parietal lobe in human memory

The posterior parietal lobe is known to play some role in a far-flung list of mental processes: linking vision to action (saccadic eye movements, reaching, grasping), attending to visual space, numerical calculation, and mental rotation. Here, we review findings from humans and monkeys that illuminate an untraditional function of this region: memory. Our review draws on neuroimaging findings that have repeatedly identified parietal lobe activations associated with short-term or working memory and episodic memory. We also discuss recent neuropsychological findings showing that individuals with parietal lobe damage exhibit both working memory and long-term memory deficits. These deficits are not ubiquitous; they are only evident under certain retrieval demands. Our review elaborates on these findings and evaluates various theories about the mechanistic role of the posterior parietal lobe in memory. The available data point towards the conclusion that the posterior parietal lobe plays an important role in memory retrieval irrespective of elapsed time. However, the available data do not support simple dichotomies such as recall versus recognition, working versus long-term memory. We conclude by formalizing several open questions that are intended to encourage future research in this rapidly developing area of memory research.     

Neurocognitive Functioning in Posttraumatic Stress Disorder

This paper reviews the literature on performance on standard neuropsychological tests among individuals with posttraumatic stress disorder (PTSD). Of 19 studies, 16 reported impairment of attention or immediate memory (or both); however, most of these studies included PTSD patients with significant psychiatric comorbidity, so that the extent to which the observed deficits are specifically attributable to PTSD remains unclear. Other potential confounds, including medical illness, substance abuse, and motivational factors, further preclude definitive conclusions at present. Results of structural and functional neuroimaging studies of PTSD are also summarized. Two studies have reported correlations between hippocampal volume and cognitive findings in PTSD patients; functional studies have indicated specific findings in limbic regions, although the relationship of these results to neuropsychological performance remains to be explored.     

Effects of antisocial personality, cocaine and opioid dependence, and gender on eye movement control

Substance-dependent patients have been reported to exhibit abnormal smooth pursuit and saccadic eye movements. However, contrasts of the effects of different substances and the effects of comorbid psychiatric symptoms such as antisocial personality have rarely been performed. Separate analyses examined the effects of cocaine dependence, opioid dependence, or antisocial personality disorder. In each analysis, sex was included as an additional grouping factor. The dependent measures were the gain of smooth pursuit eye movement and the delay and accuracy of saccadic eye movement. Analyses of covariance indicated that both cocaine dependence and antisocial personality, but not opiate dependence, were associated with a significant reduction in gain of smooth pursuit eye movement. Cocaine dependence and antisocial personality also slowed the onset of saccadic eye movements, but only in men. No group differences were found in the accuracy of saccadic eye movements. The results suggest that the neurophysiological effects of cocaine dependence and antisocial personality overshadow the effects of heroin. The significance of these findings for visual attention and reading skill has yet to be assessed.     

自主控制眼跳：实验范式、神经机制和应用

自主控制眼跳是眼跳类型之一。自主控制眼跳实验范式为研究各种脑损伤,神经疾病和精神失调提供了一种新的研究手段,为研究眼跳的神经机制以及反应抑制、空间工作记忆等高级认知功能提供了重要的方法。文章介绍了自主控制眼跳的两种实验范式：反向眼跳和记忆导向眼跳,阐述了自主控制眼跳的神经机制及其实验范式的应用,指出自主控制眼跳实验范式为评定精神分裂症等脑功能失调病人的神经功能状态提供了重要的信息,为研究各种脑功能失调和精神疾病提供了重要的研究方法。今后的研究趋势是眼跳研究与神经成像技术和临床观察相结合     

Cognitive control of saccadic eye movements

The saccadic eye movement system provides researchers with a powerful tool with which to explore the cognitive control of behaviour. It is a behavioural system whose limited output can be measured with exceptional precision, and whose input can be controlled and manipulated in subtle ways. A range of cognitive processes (notably those involved in working memory and attention) have been shown to influence saccade parameters. Researchers interested in the relationship between cognitive function and psychiatric disorders have made extensive use of saccadic eye movement tasks to draw inferences as to the cognitive deficits associated with particular psychopathologies. The purpose of this review is to provide researchers with an overview of the research literature documenting cognitive involvement in saccadic tasks in healthy controls. An appreciation of this literature provides a solid background against which to interpret the deficits on saccadic tasks demonstrated in patient populations.     

Cognitive control of saccadic eye movements

The saccadic eye movement system provides researchers with a powerful tool with which to explore the cognitive control of behaviour. It is a behavioural system whose limited output can be measured with exceptional precision, and whose input can be controlled and manipulated in subtle ways. A range of cognitive processes (notably those involved in working memory and attention) have been shown to influence saccade parameters. Researchers interested in the relationship between cognitive function and psychiatric disorders have made extensive use of saccadic eye movement tasks to draw inferences as to the cognitive deficits associated with particular psychopathologies. The purpose of this review is to provide researchers with an overview of the research literature documenting cognitive involvement in saccadic tasks in healthy controls. An appreciation of this literature provides a solid background against which to interpret the deficits on saccadic tasks demonstrated in patient populations.     

An examination of the construct validity of posttraumatic stress disorder with veterans using a revised criterion set

Ongoing concerns exist in the literature regarding the construct of posttraumatic stress disorder (PTSD) and how to best conceptualize and measure this disorder. We compared the traditional DSM-IV PTSD symptom criteria (i.e., symptoms from clusters B, C, and D) to a revised criterion set that omits overlapping mood and other anxiety symptoms on PTSD prevalence, PTSD diagnostic caseness, associated psychiatric comorbidity, functional status, and structural validity using a cross-sectional, multi-site primary care sample of 747 veterans. After removing items theorized to overlap with mood and other anxiety disorders, PTSD prevalence was identical using both criterion sets (i.e., 12%). Overall, there were few statistically significant differences in PTSD caseness, associated psychiatric comorbidity, functional status, and structural validity across the two diagnostic criterion sets. These data provide further support that removing items that overlap with other psychiatric disorders does not significantly impact the prevalence of PTSD, its associated comorbidity and functional impairment, or its structural validity. Although the revised criterion set represents a more parsimonious model, the current study findings generally support the strong construct validity of PTSD. The implications of these study findings for research and clinical practice are discussed.     

BIOFEEDBACK OF EVENT-RELATED SLOW POTENTIALS OF THE BRAIN

A biofeedback paradigm was developed for self-regulation of cortical DC-shifts. Subjects received continuous visual feedback of their actual DC-shift during six sec. intervals. Feedback trial series alternated with transfer test trial series. Several studies demonstrated that subjects are able to achieve cortical self-regulation which is maintained and even improved in transfer test trials. This method is used to investigate the covariation of DC-shifts and performance in reaction time tasks, mental tasks and signal detection by varying DC-shifts systematically. The procedure was also applied to different patient groups to test the functional significance of distinct brain regions and to explore deficits in patient groups.     

Distractor ratio influences patterns of eye movements during visual search

We examined the flexibility of guidance in a conjunctive search task by manipulating the ratios between different types of distractors. Participants were asked to decide whether a target was present or absent among distractors sharing either colour or shape. Results indicated a strong effect of distractor ratio on search performance. Shorter latency to move, faster manual response, and fewer fixations per trial were observed at extreme distractor ratios. The distribution of saccadic endpoints also varied flexibly as a function of distractor ratio. When there were very few same-colour distractors, the saccadic selectivity was biased towards the colour dimension. In contrast, when most of the distractors shared colour with the target, the saccadic selectivity was biased towards the shape dimension. Results are discussed within the framework of the guided search model.     

Exploring Predictors of Outcome in the Psychosis Prodrome: Implications for Early Identification and Intervention

Functional disability is a key component of many psychiatric illnesses, particularly schizophrenia. Impairments in social and role functioning are linked to cognitive deficits, a core feature of psychosis. Retrospective analyses demonstrate that substantial functional decline precedes the onset of psychosis. Recent investigations reveal that individuals at clinical-high-risk (CHR) for psychosis show impairments in social relationships, work/school functioning and daily living skills. CHR youth also demonstrate a pattern of impairment across a range of cognitive domains, including social cognition, which is qualitatively similar to that of individuals with schizophrenia. While many studies have sought to elucidate predictors of clinical deterioration, specifically the development of schizophrenia, in such CHR samples, few have investigated factors relevant to psychosocial outcome. This review integrates recent findings regarding cognitive and social-cognitive predictors of outcome in CHR individuals, and proposes potential directions for future research that will contribute to targeted interventions and improved outcome for at-risk youth.     

A Neuropsychological Normative Database for Lung Transplant Candidates

Psychologists are increasingly asked to make decisions regarding patient candidacy for transplantation. Despite the growing incidence of lung transplantation, normative research regarding cognitive functioning and end-stage obstructive lung disease is lacking. Hence, data are presented on 100 consecutively referred candidates for lung transplantation. The group data suggest essentially normal functioning on most cognitive tests for the majority of transplant candidates. Exceptions were seen on measures of attentional set shifting and short-term visual memory, which were impaired in nearly one fourth of this population. Additionally, one half of the patients displayed deficient performance on the Buschke Selective Reminding Test, with subjects at greater risk for severe rather than mild deficits. Unlike prior research, our group data suggest that there is potential risk of short-term noncontextual verbal memory difficulties because of end-stage pulmonary disease. Personality testing data, e.g., elevations on MMPI-2 scales measuring depression and anxiety, are also discussed.     

Increased saccadic rate during smooth pursuit eye movements in patients at Ultra High Risk for developing a psychosis

Abnormalities in eye tracking are consistently observed in schizophrenia patients and their relatives and have been proposed as an endophenotype of the disease. The aim of this study was to investigate the performance of patients at Ultra High Risk (UHR) for developing psychosis on a task of smooth pursuit eye movement (SPEM). Forty-six UHR patients and twenty-eight age and education matched controls were assessed with a task of SPEM and psychiatric questionnaires. Our results showed that both the corrective and non-corrective saccadic rates during pursuit were higher in the UHR group. There were however no differences in smooth pursuit gain between the two groups. The saccadic rate was related to positive UHR symptoms. Our findings indicate that abnormalities in SPEM are already present in UHR patients, prior to a first psychotic episode. These abnormalities occur only in the saccadic system.     

Decision Making with Uncertain Information: Learning from Women in a High Risk Breast Cancer Clinic

Patients and practitioners may believe that clinically validated laboratory tests provide definitive information. Genetic counselors know this is not always so, and the possibility of inconclusive genetic test results is often discussed in the pretest counseling session. This added discussion topic prolongs the process of genetic counseling, but if there is inadequate patient understanding, patient frustration may be high when receiving a result of uncertain significance, and patients may make decisions about subsequent medical management based on incorrect assumptions. For patients/participants in a research setting, where the clinical validity of testing may be unclear, some patients/participants may still want to use test results to influence their medical management. This paper presents findings from a qualitative study wherein 15 women from the High Risk Breast Cancer Clinic at Utah's Huntsman Cancer Institute discussed how uncertainty regarding results affected their decision making. The women were randomly selected from 3 categories--women with test results of uncertain significance; women without cancer who have a mutation; and women who are members of high-risk families, but for whom no mutation was found. Study findings will be used in future studies to better understand how to improve communication regarding uncertain results, especially in a research environment.     

Odor identification impairments in schizophrenia: relationship with demographic measures, clinical variables, and diagnostic subtypes

Smell identification deficits are consistently found in schizophrenia (SZ), but little is known about the nature and characterization of this deficit or its relationship to the phenomenology of the illness. This study aims to further delineate smell identification errors in SZ by examining the relationship of patient demographic differences with smell-identification performance. Our results showed that a patient's gender and education were related to odor-identification scores, with better performance seen in female patients and in those with greater educational attainment. However, there was no effect related to age, ethnicity, or socioeconomic status on odor identification. A smell identification deficit was also unrelated to clinical characteristics of the patients, including age at first hospitalization, number of psychiatric hospitalizations, and duration of illness. Odor identification also did not differ by SZ subtype, nor between SZ and schizoaffective disorder patients. These findings emphasize that odor identification deficits in SZ are unrelated to clinical illness features, cannot be explained by other confounds related to olfaction in the general population, and may be core features related to the SZ disease process.     

The effect of debriefing on laboratory induced helplessness: An attributional analysis1

Debriefing was assessed as means of reversing helplessness deficits through reattribution. Fifty-five subjects listened to escapable or inescapable tones. One inescapable group, prior to anagrams, was debriefed regarding noise uncontrollability. A second inescapable group was administered anagrams by a different experimenter. While exposure to inescapable noise led to performance deficits, switching experimenters obviated these deficits. Debriefing actually facilitated anagram performance. All inescapable subjects—debriefed or not—attributed their lack of control on the noise task to experimenter interference, casting some doubt on reattribution as an explanation of debriefing's effects. Results were discussed in terms of the reformulated learned helplessness model and the ethical implications of debriefing in learned helplessness research.