Neurophysiological correlates of excitement in schizophrenia.

Objective: The excitement cluster (excitement, hostility, uncooperativeness and impulsivity) may contribute to the risk of violent behaviour, treatment non-adherence, likelihood of discharge and substance use in psychosis. Evidence suggests involvement of frontal executive mechanisms that may show sex differences in their association with symptom severity. The current study tests the association between excitement and the frontal N200 and P300 components of the auditory event-related potential in schizophrenia as a function of sex.

N100 and P300 amplitude to Go and No-Go variants of the auditory oddball in siblings discordant for schizophrenia.

Background: P300 amplitude reduction is reliably seen in schizophrenia. Inconsistent reports of isolated frontal and/or parietal deficits in unaffected family members may be clarified using a task that places greater load on frontal function.

Method: Go and No-Go versions of the auditory oddball task were performed by eighteen schizophrenia patients, age-matched unaffected siblings and healthy controls matched closely to unaffected siblings on age, sex, education, socioeconomic-status, handedness and ethnicity.

A behavioural and functional neuroimaging investigation into the effects of nicotine on sensorimotor gating in healthy subjects and persons with schizophrenia.

Rationale: Schizophrenia patients display an excessive rate of smoking compared to the general population. Nicotine increases acoustic prepulse inhibition (PPI) in animals as well as healthy humans, suggesting that smoking may provide a way of restoring deficient sensorimotor gating in schizophrenia. No previous study has examined the neural mechanisms of the effect of nicotine on PPI in humans.

Reduced prepulse inhibition in unaffected siblings of schizophrenia patients.

We investigated whether prepulse inhibition of the startle response is reduced in siblings of schizophrenia patients compared to age- and sex-matched healthy controls. Nineteen unaffected biological siblings and 19 controls were assessed on prepulse inhibition by monaural and binaural acoustic prepulse stimuli, with the startle stimuli always presented binaurally. There was significantly less prepulse inhibition in siblings, compared to controls, with binaural prepulse stimuli, as also seen previously in schizophrenia patients.

Structural brain correlates of prepulse inhibition of the acoustic startle response in healthy humans.

Neural regions modulating prepulse inhibition (PPI) of the startle response, an operational measure of sensorimotor gating, are well established from animal studies using surgical and pharmacological procedures. The limbic and cortico-pallido-striato-thalamic circuitry is thought to be responsible for modulation of PPI in the rat. The involvement of this circuitry in human PPI is suggested by observations of deficient PPI in a number of neuropsychiatric disorders characterized by abnormalities at some level in this circuitry and recent functional neuroimaging studies in humans.

Lack of association between prepulse inhibition and antisaccadic deficits in chronic schizophrenia: implications for identification of schizophrenia endophenotypes.

Individuals with schizophrenia, compared to healthy individuals, are known to exhibit deficient prepulse inhibition (PPI) of the startle response as well as reduced performance on the antisaccade task. There is evidence for genetic transmission of both PPI and antisaccadic abnormalities in schizophrenia. It has been suggested that PPI and antisaccade measures identify separate endophenotypes, on the basis of a lack of relationship between PPI and antisaccade deficits in patients with schizotypal personality disorder.

Association between violent behaviour and impaired prepulse inhibition of the startle response in antisocial personality disorder and schizophrenia.

Violent behaviour has a strong association with antisocial personality disorder (APD) and schizophrenia. Although developments in the understanding of socio-environmental factors associated with violence should not be ignored, advances in prevention and treatment of violent behaviour would benefit by improved understanding of its neurobiological and cognitive basis. The authors, therefore, investigated prepulse inhibition (PPI) of the startle response in APD and schizophrenia in relation to a history of serious violence.

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.

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.

Cognitive effects of nicotine in humans: an fMRI study.

To elucidate the neural correlates of cognitive effects of nicotine, we examined behavioral performance and blood oxygenation level-dependent regional brain activity, using functional magnetic resonance imaging, during a parametric "n-back" task in healthy nonsmoking males after the administration of nicotine (12 microg/kg body weight) or saline. Nicotine, compared to placebo, improved accuracy (P = 0.008) in all active conditions (2%-11%), and had a load-specific effect on latency (P = 0.

Effects of acute procyclidine administration on prepulse inhibition of the startle response in schizophrenia: a double-blind, placebo-controlled study.

Prepulse inhibition (PPI) of the startle response refers to a reduction in response to a strong stimulus (pulse) if this is preceded shortly by a weak non-startling stimulus (prepulse). Consistent with theories of deficiencies in early stages of information processing, PPI is found to be reduced in patients with schizophrenia. Atypical antipsychotics are found to be more effective than typical antipsychotics in improving PPI in this population.