Biomedical subjects

Philip J Corr

Publications and source records attributed to Philip J Corr.

15 recordsLinked to original sources

PubMed2006

The role of theory in the psychophysiology of personality: from Ivan Pavlov to Jeffrey Gray.

Psychophysiological approaches to personality have made significant progress in recent years, partly as a spin-off of technological innovation (e.g., functional neuroimaging) and partly as a result of an emerging theoretical consensus regarding the structure and biology of basic processes. In this field, Jeffrey Gray's influential psychophysiological theory of personality - now widely known as Reinforcement Sensitivity Theory (RST) - owes much to Pavlov, who devoted a large proportion of his later life to personality differences and their implications for psychiatry. In this article, we trace the influence of Pavlov on Hans Eysenck's and Jeffrey Gray's work, and then provide a brief description of RST in order to highlight some of the central problems - as well as some tentative solutions - in the psychophysiology of personality. Specifically, the importance of theory in personality research is stressed by the contrast of Gray's theoretically driven model with less fertile atheoretical (i.e., exploratory-inductive) approaches. The fecundity of RST, which has been in continual development over a period of thirty years, is discussed in the light of Karl Popper's views on the nature of science, especially the formulation of the 'problem situation', which sets up the theoretical and operational conditions under which hypotheses may be challenged and tested to destruction. In this respect, we see the truth of Lewin's [Lewin, K., 1951. Field theory in social science: selected theoretical papers. In: Cartwright, D., (Ed.). Harper & Row, New York] famous phrase, "There is nothing so practical as a good theory".

Animals↗

PubMed2006

Reactions to threat and personality: psychometric differentiation of intensity and direction dimensions of human defensive behaviour.

Gray and McNaughton [Gray JA, McNaughton N. The neuropsychology of anxiety. Oxford: Oxford University Press; 2000] predict that fear is associated with orientation away from threat whereas anxiety is associated with orientation towards threat; this first dimension of 'defensive direction' is independent of a second dimension of 'defensive intensity'. Defensive reactions were measured using a threat scenario questionnaire developed by Blanchard et al. [Blanchard DC, Hynd AL, Minke KA, Minemoto T, Blanchard RJ. Human defensive behaviours to threat scenarios show parallels to fear- and anxiety-related defence patterns of non-human mammals. Neurosci Biobehav Rev 2001;25:761-70] who found that responses paralleled the defensive reactions of rodents faced with real threats. In a sample of 141 participants we replicated Blanchard et al.'s findings as well as confirming the Gray and McNaughton hypotheses. As predicted, trait anxiety was associated with a tendency to orientate towards threat. In addition, the personality trait of psychoticism (tough-mindedness) was related to defensive intensity with low scorers on psychoticism being more sensitive to threat in general and high scorers being more threat insensitive. A well-established personality measure of general punishment sensitivity, namely the Carver and White [Carver CS, White TL. Behavioural inhibition, behavioural activation, and affective responses to impending reward and punishment: the BIS/BAS scales. J Pers Soc Psychol 1994;67:319-33] BIS scale, was positively correlated with both defensive intensity and direction. These data indicate that the threat scenario questionnaire has some validity as a measure of human reactions to threat.

Adolescent↗

PubMed2006

Schizotypy and creativity in visual artists.

'Every work of art is an uncommitted crime' Adorno (1951). Cited in Julius (2002). Given the putative relationship between creativity and schizotypy/psychoticism, the current study set out to investigate differences in scores on a range of personality and creativity measures between visual artists and non-artists. Results found that the visual artists group scored higher on measures of positive-schizotypy, disorganized-schizotypy, asocial-schizotypy, neuroticism, openness and divergent thinking (uniqueness) than did the non-artist group and lower on agreeableness. These findings lend support to other studies reporting higher schizotypy scores in artistic and creative cohorts, although provide some of the first evidence of higher unusual experiences and impulsive nonconformity scores on the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) in visual artists. The relationship between creativity and schizotypy is discussed in terms of unusual ideas and a propensity to endorse socially undesirable responses.

Adult↗

PubMed2005

Saccadic eye movements, schizotypy, and the role of neuroticism.

We investigated the relationships of anti- and prosaccades with psychometric schizotypy. One aim was to estimate the role of negative emotionality and general psychopathology (i.e. neuroticism) in this relationship. 115 non-clinical volunteers underwent infrared oculographic assessment of antisaccades and prosaccades. Schizotypy was assessed with the Personality Syndrome Questionnaire (PSQ-80), the Rust Inventory of Schizotypal Cognitions (RISC), and Eysenck Personality Questionnaire-Revised (EPQ-R) Psychoticism. Higher positive schizotypy scores predicted increased antisaccade errors (RISC) and greater prosaccade spatial error (PSQ-80 Unreality). Greater thought disorder (PSQ-80 Activity) predicted shorter prosaccade latencies. EPQ-R Neuroticism was substantially correlated with schizotypy but was not related to saccadic measures and did not account for their relationship with schizotypy. We conclude that saccadic performance patterns in schizotypy are not due to negative emotionality or general psychopathology, but specific to schizophrenia spectrum signs and symptoms.

Adolescent↗

PubMed2005

Social exclusion and the hierarchical defense system: comment on MacDonald and Leary (2005).

G. MacDonald and M. R. Leary hypothesized that physical pain and social exclusion share many affective features in common. In this comment, the author discusses the implications of J. A. Gray and N. McNaughton's (2000) hierarchical defense system model, which MacDonald and Leary used in the development of their theoretical claims. Issues are discussed that require, at least, clarification; but more substantive problems need closer consideration of hierarchically organized defense. It is argued that research findings may be better understood (a) by systems of interacting neural modules, which lead to state dissociations between affective states, and (b) by general modulatory influences on the entire defense system that lead to trait associations (i.e., personality) between physical pain and emotional distress.

Affect↗

PubMed2005

Prepulse inhibition of the acoustic startle reflex and oculomotor control.

Prepulse inhibition and the suppression of reflexive saccades on the antisaccade task are thought to tap inhibitory function. Reports of a lack of association between these measures suggest that they reflect different facets of inhibition. This study aimed to reexamine this relationship in a large sample and investigate the association of prepulse inhibition with oculomotor tasks that require inhibition of a reflexive saccade with lower concurrent processing demands than antisaccades, namely the oculomotor delayed response and fixation with distractors tasks. One hundred and seven healthy volunteers took part. Prepulse inhibition was uncorrelated with oculomotor performance. The error rate was highest for antisaccades, intermediate for the delayed response task, and lowest for fixation with distractors, and was correlated across tasks. These findings provide no evidence of a relationship between prepulse inhibition and oculomotor inhibition. Failure in suppressing reflexive saccades toward a peripheral target may represent a common inhibitory component underlying these oculomotor tasks.

Acoustic Stimulation↗

PubMed2004

Prepulse-elicited startle in prepulse inhibition.

BACKGROUND: Prepulse inhibition (PPI) has become a major experimental paradigm in the study of psychiatric disorders. In this study, a potential confound in measurement and interpretation of PPI, namely startle reactions to so-called "nonstartling" prepulses, was examined. METHODS: Prepulses of 80, 85, and 90 dB(A) were presented on their own or followed by a pulse of 115 dB(A) (lead interval: 120 msec). RESULTS: Even at only 80 dB(A), prepulses presented alone elicited a response in about 50% of trials; and, except in the first stage of the experiment, responses became more frequent as prepulse intensity increased. Importantly, PPI at 80 and 85 dB(A) was negatively correlated with response probability to prepulses presented alone. CONCLUSIONS: Prepulses reliably activate the very startle system that they are thought to inhibit, and a high level of responsiveness to prepulses is associated with relatively lower levels of PPI. These findings might hold important implications for clinical and psychopharmacologic studies of PPI, and we suggest that the extent and influence of prepulse-elicited startles should be routinely examined.

Adolescent↗

PubMed2004

Reinforcement sensitivity theory and personality.

A fully fledged neuroscience of personality is beginning to emerge, shaped and guided in large measure by the seminal work of Jeffrey A. Gray over a period of 40 years. In this Festschrift, I trace the theoretical development of Gray's approach--now known as Reinforcement Sensitivity Theory (RST)--out of the Eysenckian tradition to its most recent articulation. Experimental attempts to test RST are reviewed and the theoretical problems raised by this literature discussed. Also presented are data relating to a recent clarification of RST, viz. the joint subsystems hypothesis, which postulates a fundamental interdependence of appetitive and aversive systems in the typical human laboratory. The value of Gray's general approach to building behavioural theories on the bases of both the conceptual nervous system and the real nervous system is validated in personality, which has long been thought a philosophical mystery rather than a standard problem to be tackled by scientific method.

Animals↗

PubMed2004

A two-dimensional neuropsychology of defense: fear/anxiety and defensive distance.

We present in this paper a picture of the neural systems controlling defense that updates and simplifies Gray's "Neuropsychology of Anxiety". It is based on two behavioural dimensions: 'defensive distance' as defined by the Blanchards and 'defensive direction'. Defensive direction is a categorical dimension with avoidance of threat corresponding to fear and approach to threat corresponding to anxiety. These two psychological dimensions are mapped to underlying neural dimensions. Defensive distance is mapped to neural level, with the shortest defensive distances involving the lowest neural level (periaqueductal grey) and the largest defensive distances the highest neural level (prefrontal cortex). Defensive direction is mapped to separate parallel streams that run across these levels. A significant departure from prior models is the proposal that both fear and anxiety are represented at all levels. The theory is presented in a simplified form that does not incorporate the interactions that must occur between non-adjacent levels of the system. It also requires expansion to include the dimension of escapability of threat. Our current development and these proposed future extensions do not change the core concepts originally proposed by Gray and, we argue, demonstrate their enduring value.

Amygdala↗

PubMed2004

Volumetric neural correlates of antisaccade eye movements in first-episode psychosis.

OBJECTIVE: The authors investigated the structural brain correlates of antisaccade performance. METHOD: Magnetic resonance imaging was used to measure the volumes of the prefrontal, premotor, sensorimotor, and occipitoparietal cortices as well as the caudate, thalamus, cerebellar vermis, and cerebrum in 20 first-episode psychosis patients and 18 healthy comparison subjects. Antisaccades were recorded by using infrared oculography. RESULTS: Groups significantly differed in terms of antisaccade error rate and amplitude gain and tended to differ in terms of latency but not brain region volumes. Premotor cortex volume predicted antisaccade error rate among comparison subjects. In the patient group, caudate volume was related to latency and amplitude gain. Negative symptoms, independent of structural volumes, predicted error rate. CONCLUSIONS: These findings point to altered structure-function relationships in first-episode psychosis.

Adult↗

PubMed2003

Effects of procyclidine on eye movements in schizophrenia.

Smooth pursuit eye movement (SPEM) and antisaccade deficits are observed in the schizophrenia spectrum and have been used to study the pathophysiology as well as the genetic basis of this condition. The neurotransmitter acetylcholine has been implicated in a number of cognitive processes thought to underlie SPEM and antisaccade performance. This study investigates effects on eye movements of procyclidine, an anticholinergic drug often administered to schizophrenic patients. A total of 13 patients completed a double-blind placebo-controlled crossover design, receiving 15 mg procyclidine and placebo. Seven participants received procyclidine first and placebo second, six participants were tested in the reverse order. SPEM and antisaccade (as well as fixation and prosaccade) eye movements were recorded using infrared oculography. Results showed that procyclidine overall, relative to placebo, mildly worsened SPEM performance, as indicated by nonsignificantly reduced gain (p=0.08) and increased frequency of intrusive anticipatory saccades during pursuit (p=0.06). A significant interaction of group and order of administration indicated that procyclidine increased the rate of antisaccade reflexive errors only when administered first; the opposite pattern was observed when placebo was administered first, likely due to the operation of practice effects at second assessment. These findings indicate that acute administration of a clinically relevant dose of procyclidine leads to mild impairments in eye movement performance in schizophrenic patients, suggesting the need to consider this compound in oculomotor studies in schizophrenia. The action of this anticholinergic drug on oculomotor performance is consistent with the hypothesized role of the cholinergic system in the cognitive mechanisms of attention and working memory, processes thought to underlie SPEM and antisaccade performance. Effects of order of administration and practice on the antisaccade task suggest that these factors need to be taken into consideration in future pharmacological studies.

Adult↗

PubMed2003

Reliability of smooth pursuit, fixation, and saccadic eye movements.

The present study investigated the reliability and susceptibility to practice effects of oculomotor tasks. Smooth pursuit, fixation, antisaccade, and prosaccade tasks were administered to 31 healthy participants to assess internal consistency (Cronbach's alpha) and within-session practice effects. Twenty-one of these participants were retested after an average interval of 57.86 days to assess temporal stability and between-session practice effects. Internal consistencies were high for most measures, with few within-session performance changes. Test-retest reliabilities of most measures were good. Between-session practice effects were most consistently observed on the antisaccade task, indicated by reduced error rate and improved spatial accuracy at retest. Magnitude of improvement on these measures was related to performance, indicating that poor performers benefited most from repeated assessment. These findings support the trait nature of oculomotor function and point to the need to take into consideration between-session practice effects on the antisaccade task in longitudinal studies.

Adult↗

PubMed2002

Procedural learning in schizophrenia: a functional magnetic resonance imaging investigation.

Procedural learning (PL) is a type of rule-based learning in which performance facilitation occurs with practice on task without the need for conscious awareness. Schizophrenic patients have often (though not invariably) been found to show impaired PL. We performed functional magnetic resonance imaging (fMRI) during a blocked, periodic sequence-learning task with groups of: (i) healthy subjects, and (ii) schizophrenic patients on conventional antipsychotics. Healthy subjects showed significant PL, but patients did not. In healthy subjects, PL was associated with increased activation in the striatum, thalamus, cerebellum, precuneus, medial frontal lobe, and cingulate gyrus. The power of activation in the thalamus, striatum, precuneus, cingulate gyrus and BA 6 was related to the magnitude of PL in these subjects. No regions, except the anterior inferior gyrus, were significantly activated in patients. The caudate nucleus, thalamus, precuneus, and sensorimotor regions were activated significantly differently between the two groups. The findings demonstrate the involvement of the striatum, cerebellum, thalamus, cingulate gyrus, precuneus, and sensorimotor regions in PL. Further fMRI studies of PL in normal subjects treated with conventional antipsychotics, drug naïve patients, and patients given atypical antipsychotics would help to clarify the roles of schizophrenic disease processes and antipsychotic medication in impaired PL and associated brain abnormalities in schizophrenia.

Adult↗

PubMed2002

Relationship between brain structure and saccadic eye movements in healthy humans.

This study used structural magnetic resonance imaging (MRI) to investigate associations between brain structure and saccadic eye movements. Seventeen healthy subjects underwent structural MRI and infra-red oculographic assessment of a reflexive saccade task. Volumes of prefrontal, premotor, and occipitoparietal cortex, caudate, thalamus, and cerebellar vermis were used as predictors in multiple regression with prosaccade gain as a dependent variable, controlling for whole-brain volume. Using voxel-based morphometry (VBM), gain was entered into correlational analysis with grey matter density. Regression analysis indicated that vermis volumes predicted prosaccade gain. VBM replicated this finding: gain was correlated with grey matter in the left cerebellar hemisphere and vermis. These findings agree with previous studies on the role of the cerebellar vermis in saccadic gain and support the validity of structural neuroimaging methods in elucidating the neural correlates of saccadic eye movements.

Adult↗

PubMedDate not supplied

Smooth pursuit and antisaccade eye movements in siblings discordant for schizophrenia.

Smooth pursuit eye movement (SPEM) and antisaccade deficits have been proposed as endophenotypes in the search for schizophrenia genes. We assessed these measures in 24 schizophrenia patients, 24 of their healthy siblings, and 24 healthy controls closely matched to the siblings. Between-group differences were assessed using a random effects regression model taking into account the relatedness between patients and siblings. Patients showed reduced SPEM gain, increased frequency of saccades during pursuit, increased antisaccade error rate, and reduced antisaccade gain compared to controls. Siblings performed intermediate, i.e. between patients and controls, on most measures, but were particularly characterised by reduced antisaccade gain. SPEM gain at one target velocity was significantly correlated between patients and siblings, highlighting the necessity of taking into account within-family correlations in the statistical analysis of between-group differences. It is concluded that subtle SPEM and antisaccade deficits are observed in clinically unaffected siblings of schizophrenia patients; these deficits may be useful markers of genetic liability to schizophrenia.

Adult↗