J A Gray

King's College London, London, ENG, United Kingdom

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Publications (172)818.46 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: There is an increasing body of evidence pointing to a neurobiological basis of personality. The purpose of this study was to investigate the biological bases of the major dimensions of Eysenck's and Cloninger's models of personality using a noninvasive magnetic resonance perfusion imaging technique in 30 young, healthy subjects. An unbiased voxel-based analysis was used to identify regions where the regional perfusion demonstrated significant correlation with any of the personality dimensions. Highly significant positive correlations emerged between extraversion and perfusion in the basal ganglia, thalamus, inferior frontal gyrus and cerebellum and between novelty seeking and perfusion in the cerebellum, cuneus and thalamus. Strong negative correlations emerged between psychoticism and perfusion in the basal ganglia and thalamus and between harm avoidance and perfusion in the cerebellar vermis, cuneus and inferior frontal gyrus. These observations suggest that personality traits are strongly associated with resting cerebral perfusion in a variety of cortical and subcortical regions and provide further evidence for the hypothesized neurobiological basis of personality. These results may also have important implications for functional neuroimaging studies, which typically rely on the modulation of cerebral hemodynamics for detection of task-induced activation since personality effects may influence the intersubject variability for both task-related activity and resting cerebral perfusion. This technique also offers a novel approach for the exploration of the neurobiological correlates of human personality.
    NeuroImage 07/2006; 31(2):489-95. · 6.25 Impact Factor
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    ABSTRACT: The amplitude of the startle reflex response is known to be influenced by the concomitant presentation of affect-toned material--if it is positive affect-toned, the reflex is inhibited, and if it is negative affect-toned, the reflex is augmented. Abundant evidence demonstrates the utility of the affect-startle paradigm as a significant tool for measuring both positive and negative emotions. We applied this paradigm to study emotional reactivity in depression, particularly in relation to symptoms of depression, anhedonia, and anxiety. Depressed patients (22) and controls (22) were shown a series of film clips, consisting of two clips with positive valence, two with negative valence, and two with relatively neutral valence. The startle response was measured in reaction to the acoustic startle-eliciting stimuli presented three times binaurally during each clip. Highly depressed and anhedonic patients, relative to controls, showed a reduced mood (self-ratings) and a lack of startle modulation in response to affective film clips whereas patients relatively low on depression/anhedonia displayed a reduced mood only with pleasant clips and a normal pattern of affective startle modulation. Anhedonia and depression were highly positively correlated but neither correlated with anxiety. Anxious patients displayed larger reflexes across all clips and showed a reduced mood modulation with pleasant, but not unpleasant, clips. The large majority of patients was medicated with antidepressants which may have influenced the results. CONCLUSIONS. Reactivity to pleasant stimuli is diminished in patients suffering from low levels of depression and/or anhedonia, but reactivity even to unpleasant stimuli seems compromised at high levels of depression and/or anhedonia. Anxiety is associated with hyperstartle responding.
    Journal of Affective Disorders 12/2004; 83(1):21-31. · 3.76 Impact Factor
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    ABSTRACT: Clozapine-like atypical antipsychotic drugs, such as olanzapine, risperidone and sertindole, bind most strongly to 5-HT(2A) receptors, which may contribute to their antipsychotic effects. Antipsychotic drugs, such as clozapine and haloperidol, have been found to enhance latent inhibition (LI) in humans and rats. LI is a process of learning to ignore irrelevant stimuli that is disrupted in acute, positive-symptom schizophrenia, and can be modelled in animals. The aim of this study was to determine the effects of two selective 5-HT(2A) receptor antagonists, SR 46,349B and ICI 169,369, on LI, as a test of their antipsychotic potential. Doses of the 5-HT(2A) receptor antagonists that were sufficient for receptor blockade were determined in 5-HT behavioural syndrome tests. SR 46,349B and ICI 169,369 were then tested for enhancement of LI and reversal of amphetamine-induced attenuation of LI in a conditioned suppression paradigm. SR 46,349B (0.6-2.4 mg kg(-1) i.p.) and ICI 169,369 (10-40 mg kg(-1) i.p.) antagonised 5-hydroxytryptophan (5-HTP)-induced head twitches and wet dog shakes, which are mediated by 5-HT(2A) receptors, but had no effect on mCPP-induced hypolocomotion, which is mediated by 5-HT(2C) receptors. Neither SR 46,349B (1.2 mg kg(-1) i.p.) nor ICI 169,369 (40 mg kg(-1) i.p) affected 8-hydroxy-2-(di- n-propylamino)tetralin (8-OH-DPAT)-induced forepaw treading, suggesting that they were not in vivo 5-HT(1A) receptor antagonists. SR 46,349B (2.4 mg kg(-1) i.p.) and ICI 169,369 (40 mg kg(-1) i.p.) enhanced LI when given at both the pre-exposure and conditioning stages of the paradigm, but not when given at either pre-exposure or conditioning only. Both drugs also reversed the disruption of LI induced by D-amphetamine (1 mg kg(-1) i.p.). The profile of SR 46,349B and ICI 169,369 in LI differs from that of clozapine and haloperidol in LI, which both enhance LI when given only at the conditioning stage of the paradigm.
    Psychopharmacology 10/2003; 169(3-4):321-31. · 4.06 Impact Factor
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    ABSTRACT: Latent inhibition describes a process of learning to ignore stimuli of no consequence, and is disrupted in acute, positive-symptomatic schizophrenia. Understanding the neural basis of latent inhibition in animals may help to elucidate the neural dysfunction underlying positive schizophrenic symptoms in man. Evidence suggests a crucial role for dopamine transmission in the nucleus accumbens in the control of latent inhibition. The present studies investigated the role of the GABA-ergic efferent from the nucleus accumbens to the ventral pallidum in latent inhibition. The GABA(A) agonist muscimol (4.56 ng/microl), and antagonist picrotoxin (0.2 microg/microl), were infused into the ventral pallidum, and effects on latent inhibition were assessed using a conditioned suppression procedure. Neither drug produced specific effects on latent inhibition when given alone and, in the case of muscimol, failed to reverse the disruption of latent inhibition induced by systemic amphetamine. In addition to significant non-specific drug effects, a positive control experiment revealed that intra-pallidal picrotoxin significantly enhanced locomotion, suggesting that our manipulations of ventral pallidal GABA function were behaviourally effective. We conclude that modulating ventral pallidal GABA transmission does not affect latent inhibition. The implications of this finding for theories of the neural circuitry mediating latent inhibition and for understanding the functional role of ventral pallidal GABA transmission are discussed.
    Neuroscience 02/2003; 122(1):267-75. · 3.12 Impact Factor
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    ABSTRACT: This study used in vivo microdialysis to examine the release of dopamine (DA) in the nucleus accumbens (nAc) during the performance of a previously learned, signalled sucrose reward task, and during conditioning of a neutral tone stimulus to this reward. Behavioural measures (magazine entries) confirmed that stimuli associated with sucrose presentation became secondary rewarding stimuli, and DA release was also monitored during subsequent presentation of these stimuli alone. Perhaps surprisingly, during magazine entry for consumption of sucrose, i.e. in conditions similar to routine training, dialysate DA levels in the nAc did not increase. In contrast, during conditioning of the tone with light-sucrose, dopamine levels increased consistently and significantly. Interestingly, DA levels were somewhat, but significantly, increased when tone alone was presented in a test session, i.e. two hours after conditioning, and even more so when tone was combined with the light previously associated with sucrose. In this latter case the number of magazine entries increased to a level similar to that seen during conditioning. Presentation of light alone resulted in a similar level of magazine entries to tone alone, but no significant increase in DA. In summary, these studies confirm that a neutral stimulus can acquire the behavioural properties of reward when conditioned. The neurochemical data, on the other hand, suggest that increases of DA in nAc are more likely to be related to new associative learning than to established incentive or consumatory processes. The increase in DA release in the test session may be related either to the secondary reinforcing properties acquired by the stimulus, or to the change in contingencies, or to the aversive effects of the omission of reward.
    European Journal of Neuroscience 12/2002; 16(10):1987-93. · 3.75 Impact Factor
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    ABSTRACT: Latent inhibition (LI) is a model of attention, which is a cognitive process that can be modulated by stressors such as chronic intermittent broadband noise, e.g. caused by building work, which is particularly stressful to rats. The aim of this study was to analyse the effect of chronic noise stress, caused by a building project, on LI, and its interaction with SR 46,349B, a 5-HT2A receptor antagonist. Control groups from LI experiments conducted during periods of chronic intermittent noise were compared with control groups from LI experiments conducted in normal quiet conditions. The interaction of SR 46,349B with the effects of chronic noise stress was then tested. Chronic intermittent noise attenuated LI, an effect which was partially reversed by SR 46,349B, 2.4 mg/kg i.p. Attenuation of LI by chronic intermittent noise and reversal of this effect by SR 46,349B support suggestions that stress can modulate attention and that 5-HT2A receptors are involved in mediating the effects of chronic stress.
    Behavioural Pharmacology 11/2002; 13(8):663-667. · 2.30 Impact Factor
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    ABSTRACT: In 'colored-hearing' synesthesia, individuals report color experiences when they hear spoken words. If the synesthetic color experience resembles that of normal color perception, one would predict activation of parts of the visual system specialized for such perception, namely the human 'color center', referred to as either V4 or V8. Using functional magnetic resonance imaging (fMRI), we here locate the region activated by speech in synesthetes to area V4/V8 in the left hemisphere, and demonstrate overlap with V4/V8 activation in normal controls in response to color. No activity was detected in areas V1 or V2, suggesting that activity in primary visual cortex is not necessary for such experience. Control subjects showed no activity in V4/V8 when imagining colors in response to spoken words, despite overtraining on word-color associations similar to those spontaneously reported by synesthetes.
    Nature Neuroscience 05/2002; 5(4):371-5. · 15.25 Impact Factor
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    ABSTRACT: Many theoretical accounts of selective attention and memory retrieval include reference to active inhibitory processes, such as those argued to underlie the negative priming effect. fMRI was used in order to investigate the areas of cortical activation associated with Stroop interference, Stroop facilitation and Stroop negative priming tasks. The most significant activation within the negative priming task was within the inferior parietal lobule, left temporal lobe and frontal lobes. Areas of cortical activation are discussed with reference to theoretical accounts of the negative priming effect.
    Neuroreport 12/2001; 12(16):3619-24. · 1.40 Impact Factor
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    ABSTRACT: Early neuropathology following a prolonged duration of four-vessel occlusion (4 VO) ischemia in the rat was charted using magnetic resonance imaging (MRI). Animals received either 30 minutes of 4 VO (N = 6) or sham operation (N = 6) prior to in vivo assessment. Proton density and T(2) and combined T(2)/diffusion-weighted (T(2)/DW) MRI were performed at 6, 24, and 72 hours postocclusion. T(2)/DW imaging was the most effective sequence for delineating between injured and intact tissues, indicating neuropathology in the dorsolateral striatum at 24 hours and in the CA1/CA2 subfields of the hippocampus at 72 hours following ischemia. Apparent diffusion coefficient values were significantly reduced in the striatum (P = 0.03) and hippocampus (P = 0.005) at 24 and 72 hours, respectively. This is the first report, to our knowledge, of T(2)/DW imaging detecting lesions following 4 VO in accord with the known temporal evolution of ischemic brain damage.
    Journal of Magnetic Resonance Imaging 10/2001; 14(3):207-14. · 2.57 Impact Factor
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    ABSTRACT: The startle response is thought to reflect changes in attentional processes in humans. The startle response shows a number of forms of plasticity, of which prepulse inhibition (PPI) refers to the attenuation of the startle response to a strong sensory stimulus (pulse), when such a pulse is preceded by a stimulus of lower intensity (prepulse). Recent studies have shown that nicotine modulates startle and PPI of the startle reflex in humans and animals. The present study examined individual differences in cognitive benefits obtained from smoking as indexed by startle response and PPI. We investigated, using a within-subjects design, the effects of cigarette smoking via a comparison of baseline and withdrawal measures of startle and PPI in 18 subjects wishing to quit cigarette smoking. The relapse of five of these subjects enabled a between-group comparison of these measures with the successful quitters. Startle and PPI were measured on three separate occasions: before quitting, 24 h after quitting and 1 month after quitting. The presence of a high startle response amplitude while subjects were still engaged in their normal smoking patterns (baseline) and the occurrence of a significant drop of startle amplitude in withdrawal relative to baseline factors were found to be predictive of an individual's ability to quit smoking. Changes in PPI were found to reflect these changes in startle amplitude. The observed response patterns are discussed in terms of individual differences in commitment to quitting and self-dosing to manipulate attentional mechanisms as measured by the acoustic startle response. Furthermore, it is suggested that these specific response profiles may be predictive of the ability to quit smoking.
    Psychopharmacology 08/2001; 156(2-3):360-7. · 4.06 Impact Factor
  • P Postma, V Kumari, M Hines, J A Gray
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    ABSTRACT: 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.
    Psychophysiology 06/2001; 38(3):377-82. · 3.26 Impact Factor
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    ABSTRACT: Despite the many studies highlighting the role of the amygdala in fear perception, few have examined differences between right and left amygdalar responses. Using functional magnetic resonance imaging (fMRI), we examined neural responses in three groups of healthy volunteers (n = 18) to alternating blocks of fearful and neutral faces. Initial observation of extracted time series of both amygdalae to these stimuli indicated more rapid decreases of right than left amygdalar responses to fearful faces, and increasing magnitudes of right amygdalar responses to neutral faces with time. We compared right and left responses statistically by modeling each time series with (1) a stationary fit model (assuming a constant magnitude of amygdalar response to consecutive blocks of fearful faces) and (2) an adaptive model (no assumptions). Areas of significant sustained nonstationarity (time series points with significantly greater adaptive than stationary model fits) were demonstrated for both amygdalae. There was more significant nonstationarity of right than left amygdalar responses to neutral, and left than right amygdalar responses to fearful faces. These findings indicate significant variability over time of both right and left amygdalar responses to fearful and neutral facial expressions and are the first demonstration of specific differences in time courses of right and left amygdalar responses to these stimuli.
    Human Brain Mapping 05/2001; · 6.88 Impact Factor
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    ABSTRACT: The performance of chronic schizophrenic probands (n=21), their first-degree schizotypal (22) and non-schizotypal (19) relatives, and normal controls (24), was measured in two associative learning paradigms, latent inhibition and the Kamin blocking effect. These paradigms assess the effects on learning of initial exposure to other learning contingencies. The normal subjects showed latent inhibition (retarded learning of an association between a burst of white noise and a visually displayed counter increment, if the subject had first been pre-exposed to the white noise without any other consequence) and Kamin blocking (retarded learning of an association between two visual stimuli, if the conditioned stimulus was presented simultaneously with a second, already conditioned stimulus). The schizophrenic probands and both the schizotypal and non-schizotypal relatives were severely impaired in basic associative learning, performing much worse than the normal subjects in the control conditions (i.e. those lacking stimulus pre-exposure of any kind) of both the latent inhibition and the Kamin paradigms and also showed a loss of the normal latent inhibition and Kamin blocking effects. The performance of the three clinically defined groups was statistically indistinguishable. These findings contrast with previous reports of the performance of normal subjects classified as schizotypal by questionnaire, who are not impaired in basic associative learning, and are particularly fast to learn after stimulus pre-exposure. The results question the assumption that high schizotypy, as assessed by questionnaire, is like schizotypy in schizophrenic kin. The severe impairment in basic associative learning in schizophrenic patients and their kin warrants further investigation.
    Schizophrenia Research 04/2001; 48(2-3):273-89. · 4.59 Impact Factor
  • T Perry, H Hodges, J A Gray
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    ABSTRACT: Use of the selective immunotoxin; 192 IgG-saporin, is helping to elucidate the role of the cholinergic system in cognition by overcoming the problems of interpretation associated with the use of non-specific lesioning agents. In separate studies, we have compared the long- and short-term effects of single site and combined saporin lesions of the nucleus basalis magnocellularis and medial septal area, on spatial learning and memory in radial arm and water maze tasks. At 11 months, only rats with combined lesions showed deficits in both radial and water maze tasks, although terminal cholinergic deafferentation was substantial and extensive tissue loss was seen at the injection sites in both single and combined lesions. However, the extensive tissue loss with long-term lesions suggested that behavioural deficits were not solely attributable to cholinergic deafferentation. In contrast, when rats with combined lesions were tested 5 months after lesioning, no deficits were apparent, although there was almost complete loss of choline acetyltransferase- and nerve growth factor receptor-immunoreactivity in the basal forebrain with no tissue damage at the injection sites. This study supports existing literature that selective loss of cholinergic neurons in the basal forebrain does not produce behavioural impairments in standard tasks of learning and memory, but deficits are apparent when damage is non-selective as occurs late after lesioning, confounding interpretation of behavioural data. It further highlights potential problems with this immunotoxin in long-term studies.
    Brain Research Bulletin 02/2001; 54(1):29-48. · 2.94 Impact Factor
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    ABSTRACT: Anxiety states induced experimentally or occurring naturally potentiate the startle reflex elicited by sudden sensory stimuli in both animals and human beings. The authors investigated whether patients with obsessive-compulsive disorder (OCD) show exaggerated startle reactions to acoustic probes, especially during negative-affect-toned stimuli, compared with healthy subjects. Ten patients with OCD and 10 age- and sex-matched comparison subjects were shown a series of film clips. Two of the film clips had positive valence, two had negative valence, and two had relatively neutral valence. The subjects' eyeblink startle response was measured in reaction to startle-eliciting stimuli presented three times binaurally during each film clip. Patients with OCD produced larger startle reflexes and shorter latencies to onset of startle response than the comparison subjects over the entire session. Patients with OCD were excessively responsive to startle-eliciting stimuli. This effect may be associated with the development or maintenance of OCD.
    American Journal of Psychiatry 02/2001; 158(1):134-6. · 14.72 Impact Factor
  • NeuroImage 01/2001; 13(6):718-718. · 6.25 Impact Factor
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    ABSTRACT: There is a well-described projection from the retrohippocampus (subiculum and entorhinal cortex) to the nucleus accumbens that is involved in the control of psychomotor behaviour, and is implicated in the aetiology of schizophrenia. Cortical abnormalities are widely reported in the brains of schizophrenic patients, but it is unclear whether they are the cause or consequence of those changes in subcortical systems that are treated with neuroleptic drugs. We have, therefore, conducted a series of microdialysis experiments in anaesthetized rats to determine whether infusion of the excitotoxin, N-methyl-D-aspartate, into the retrohippocampus increases mesolimbic dopamine release. We found a clear and reproducible increase in extracellular dopamine in the nucleus accumbens following N-methyl-D-aspartate (2.5 microg), that was abolished when we sectioned the fimbria-fornix. Furthermore, inhibition of gamma-aminobutyric acid receptors following retrohippocampus administration of bicuculline (4 microg), also increased dopamine in the nucleus accumbens. The dopamine response to bicuculline was accompanied by an increase in dopamine metabolism, was long lasting, and also reduced by fornix section.The response to both N-methyl-D-aspartate and bicuculline depends on the integrity of the projection from the retrohippocampus to the nucleus accumbens. The results provide an underlying mechanism whereby a primary insult in the temporal cortex, caused by excessive N-methyl-D-aspartate receptor stimulation, can produce a hyperdopaminergic state. In addition, an increase in subiculo-accumbens activity evoked by bicuculline may also explain why patients with limbic epilepsy can develop a psychosis.
    European Journal of Pharmacology 11/2000; 407(1-2):131-8. · 2.59 Impact Factor
  • NeuroImage 05/2000; 11(5). · 6.25 Impact Factor
  • Biological Psychiatry 04/2000; 41(1):131-131. · 9.25 Impact Factor
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    ABSTRACT: Late fetal CA1 hippocampal grafts and stem cell grafts from the conditionally immortal MHP36 clonal line derived from the H-2Kb-tsA58 transgenic mouse neuroepithelium both improved spatial deficits in rats with ischaemic CA1 damage induced by four-vessel occlusion (4VO). However, the distribution of fetal and MHP36 grafts differed. Fetal cells lodged in clumps around the implant sites and along the corpus callosum, whilst MHP36 grafts infiltrated the area of CA1 ischaemic damage, achieving apparent architectural reconstruction of the hippocampus. The migration of MHP36 cells is damage-dependent. Few cells were found in intact brain; after 15 min of 4VO cells repopulated only the discrete area of CA1 cell loss, whereas with more extensive damage after 30 min occlusion cells migrated to all hippocampal fields and to cortex. A higher proportion of grafted MHP36 cells differentiated into neurons in the host CA1 field than grafts of striatal or cortical expanded cell populations. Cortical population grafts were as effective as MHP36 grafts in improving water maze learning, whereas striatal or ventral mesencephalic cells were ineffective, indicating a degree of stem cell specificity. The efficacy of MHP36 cells extends to primates. In marmosets with profound impairments in conditional discrimination tasks after lesions of the CA1 field, MHP36 cells improved performance as effectively as fetal grafts and migrated evenly through the CA1 field, in contrast to clustered fetal cells. These findings suggest that MHP36 stem cell grafts are as effective as fetal grafts in functional repair of hippocampal damage, and that their preference for areas of cell loss and adoption of appropriate morphologies is consistent with a point-to-point repair mechanism.
    Novartis Foundation symposium 02/2000; 231:53-65; discussion 65-9.

Publication Stats

8k Citations
818.46 Total Impact Points


  • 2000–2006
    • King's College London
      • • Department of Neuroimaging
      • • Department of Psychology
      • • Institute of Psychiatry
      London, ENG, United Kingdom
    • Eli Lilly
      Indianapolis, Indiana, United States
    • University of Leicester
      • School of Psychology
      Leicester, ENG, United Kingdom
  • 2002–2003
    • Merck
      Whitehouse Station, New Jersey, United States
  • 1997–2002
    • Goldsmiths, University of London
      • Department of Psychology
      London, ENG, United Kingdom
    • Cardiff University
      • School of Psychology
      Cardiff, WLS, United Kingdom
  • 1984–2002
    • Imperial College London
      • Department of Chemistry
      Londinium, England, United Kingdom
  • 1998
    • The Peninsula College of Medicine and Dentistry
      Plymouth, England, United Kingdom
  • 1984–1998
    • University of London
      Londinium, England, United Kingdom
  • 1996
    • University of Alberta
      • Department of Pharmacology
      Edmonton, Alberta, Canada
  • 1993
    • University of Tuebingen
      • Group of Biological Psychology
      Tübingen, Baden-Wuerttemberg, Germany
  • 1989
    • University College London
      Londinium, England, United Kingdom
    • UK Department of Health
      Londinium, England, United Kingdom
  • 1973–1989
    • University of Oxford
      • Department of Experimental Psychology
      Oxford, ENG, United Kingdom
  • 1987
    • Trent University
      • Department of Psychology
      Peterborough, Ontario, Canada
  • 1981
    • Tel Aviv University
      • Department of Psychology
      Tell Afif, Tel Aviv, Israel
  • 1980
    • University of Cambridge
      Cambridge, England, United Kingdom