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  • 1
    Electronic Resource
    Electronic Resource
    The relationship between prepulse detection and prepulse inhibition of the acoustic startle reflex (2001)
    Oxford, UK : Blackwell Publishing
    Psychophysiology 38 (2001), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Prepulse inhibition (PPI) of the startle reflex is defined as the attenuation of the startle response to a startling stimulus (pulse), when such a stimulus is briefly preceded by a stimulus of subthreshold intensity (prepulse). PPI is thought to be neither learned nor due to conscious response inhibition, as it occurs at stimulus onset asynchronies (SOAs) too short to enable the activation of a volitional response. The present study explored the latter of these assertions by investigating (a) the degree to which human subjects are able to detect prepulses at SOAs of 30, 60 and 120 ms, and (b) whether such detection is related to inhibition. Startle eyeblink reflex and detection were measured in 39 participants subjected to an acoustic startle paradigm. Results revealed a significant trend in prepulse detection according to SOA, with highest detection rates at the 120-ms SOA (75%). However, trials on which detection occurred did not differ from trials without detection on measures of startle inhibition. This suggests that PPI is independent of awareness of the prepulse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1469-8986.3830377
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  • 2
    Electronic Resource
    Electronic Resource
    Cognitive generation of affect in bipolar depression: an fMRI study (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Individuals with bipolar disorder manifest the full spectrum of emotions ranging from depression to mania. In attempting to understand the functional substrates of mood we attempted to identify brain regions associated with the cognitive generation of affect in bipolar depressed patients. We therefore examined ten depressed female subjects with bipolar affective disorder, and ten age-matched and sex-matched healthy comparison subjects using functional magnetic resonance imaging (fMRI) while viewing alternating blocks of captioned pictures designed to evoke negative, positive or no affective change. The activation paradigm involved the presentation of the same visual materials over three experiments alternating (experiment 1) negative and reference; (experiment 2) positive and reference and (experiment 3) positive and negative captioned pictures. The stimuli produced activation in both patients and comparison subjects in brain regions previously implicated in the generation and modulation of affect, in particular the prefrontal and anterior cingulate cortices. The activation in patients, when compared with healthy subjects, involved additional subcortical regions, in particular the amygdala, thalamus, hypothalamus and medial globus pallidus. Patients and comparison subjects displayed differential sensitivity to affective change with negative (experiment 1) and positive (experiment 2) affect induction producing converse patterns of activation. We conclude that bipolar depressed patients perhaps recruit additional subcortical limbic systems for emotional evaluation and this may reflect state-related or trait-related dysfunction. The differential patterns of activation inform us about bipolar depression and have potential diagnostic and therapeutic significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0953-816X.2003.03159.x
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  • 3
    Electronic Resource
    Electronic Resource
    Information processing deficits in withdrawing alcoholics (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction biology 6 (2001), S. 0 
    Details
    ISSN: 1369-1600
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Prepulse inhibition (PPI) of the acoustic startle response (a reduction in response to an intense, startling stimulus (the pulse) if preceded by 30–50 ms by a weaker, non-startling stimulus) is an established model to index information processing deficits in thought-disordered schizophrenic patients. The present study aimed to investigate the influence of alcohol withdrawal on the PPI effect. Eight withdrawing alcoholic patients underwent testing for PPI of the acoustic startle response (defined as percentage reduction of the response over pulse-alone stimulus; prepulses 15 dB above the background) on three occasions (1, 3 and 7 days following the last drink). The results demonstrated remarkably low levels of PPI on days 1 and 3, with this being very robust in three patients who had a history of delirium tremens; there was a trend towards normalization of PPI on day 7. This study, although preliminary, suggests strongly that there is a deficit in the filtering of sensory information in alcohol-dependent patients undergoing alcohol withdrawal. This was most apparent in those with a history of delirium tremens. Further studies are needed to define the cause and chronicity of these deficits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1080/13556210120056571
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  • 4
    Electronic Resource
    Electronic Resource
    Reduced prepulse inhibition in unaffected siblings of schizophrenia patients (2005)
    Oxford, UK : Blackwell Publishing
    Psychophysiology 42 (2005), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: 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. The difference between siblings and controls in prepulse inhibition with the left or right ear prepulse stimuli was not significant because of a pronounced increase in prepulse inhibition with monaural, relative to binaural, prepulses in the sibling group. High schizotypal ratings were mildly associated with reduced prepulse inhibition. Prepulse inhibition may provide a useful measure in the search for schizophrenia genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1469-8986.2005.00346.x
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  • 5
    Electronic Resource
    Electronic Resource
    Reliability of smooth pursuit, fixation, and saccadic eye movements (2003)
    Oxford, UK : Blackwell Publishing
    Psychophysiology 40 (2003), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1469-8986.00063
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Stability of stratified fluid in porous medium in the presence of suspended particles and variable magnetic field (1991)
    Springer
    Czechoslovak journal of physics 41 (1991), S. 450-458 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract General equations governing the stability of stratified fluid in a stratified porous medium in the presence of suspended particles and variable horizontal magnetic field, separately, have been derived. Assuming stratifications in density, viscosity, suspended particles number density, medium porosity, medium permeability and a magnetic field of exponential form the dispersion relations have been obtained. Systems have been found to be stable for stable stratifications and unstable for unstable stratifications. A system which was unstable in the absence of magnetic field can be completely stabilized by a magnetic field for a certain wave-number range. The behaviour of growth rates with respect to fluid viscosity, medium permeability, suspended particles number density and magnetic field has been examined analytically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01597948
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  • 7
    Electronic Resource
    Electronic Resource
    Hydromagnetic instability of streaming fluids in porous medium (1991)
    Springer
    Czechoslovak journal of physics 41 (1991), S. 459-465 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The instability of the plane interface between two uniform, superposed, electrically conducting and counter-streaming fluids through a porous medium is considered in the presence of a horizontal magnetic field. In the absence of surface tension, perturbations transverse to the direction of streaming are found to be unaffected by the presence of streaming if perturbations in the direction of streaming are ignored. For perturbations in all other directions there exists instability for a certain wavenumber range. The instability of this system is postponed by the presence of magnetic field. The magnetic field and surface tension are able to suppress this Kelvin-Helmholtz instability for small wavelength perturbations and the medium porosity reduces the stability range given in terms of a difference between the streaming velocities and the Alfvén velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01597949
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  • 8
    Electronic Resource
    Electronic Resource
    Thermosolutal convection in a Maxwellian viscoelastic fluid in porous medium (1993)
    Springer
    Czechoslovak journal of physics 43 (1993), S. 31-42 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermosolutal convection in a layer of Maxwellian viscoelastic fluid heated and soluted from below in porous medium is considered. The effects of uniform magnetic field and uniform rotation on the thermosolutal convection are also considered. For stationary convection, the Maxwellian viscoelastic fluid behaves like a Newtonian fluid. The sufficient conditions for the nonexistence of overstability are obtained. The critical Rayleigh number is found to increase with the increase in magnetic field, rotation and stable solute gradient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01589582
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  • 9
    Electronic Resource
    Electronic Resource
    Thermosolutal-convective instability of a composite stellar atmosphere in the presence of a variable magnetic field (1991)
    Springer
    Astrophysics and space science 184 (1991), S. 43-48 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermosolutal-convective instability of a composite stellar atmosphere is considered in the presence of variable horizontal magnetic field and collisional effects. The criteria for monotonic instability are obtained which generalize the criterion derived for thermal-convective instability in the absence of above effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00644865
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  • 10
    Electronic Resource
    Electronic Resource
    Smoking withdrawal, nicotine dependence and prepulse inhibition of the acoustic startle reflex (1999)
    Springer
    Psychopharmacology 141 (1999), S. 11-15 
    Details
    ISSN: 1432-2072
    Keywords: Key words Prepulse inhibition ; Acoustic startle reflex ; Smoking withdrawal ; Nicotine dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study examined the relationship between nicotine dependence as measured by the Fagerstrom Tolerance Questionnaire (FTQ) and prepulse inhibition (PPI) of the acoustic startle reflex measured after overnight smoking withdrawal in a non-clinical population of male smokers with no history of psychiatric disorders or drug/alcohol abuse. It was found that smokers who scored high (〉median) on the FTQ showed significantly less PPI as compared to those scoring low (〈median) on this scale. This finding further supports a role for nicotine in modulation of PPI, as has previously been found in rats and also in human beings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050800
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