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Biomedical subjects

Neil Roberts

Publications and source records attributed to Neil Roberts.

At least 19 recordsLinked to original sources
PubMed2006

Retrieving autobiographical memories of painful events activates the anterior cingulate cortex and inferior frontal gyrus.

UNLABELLED: Patients will often reflect on the meaning of a painful episode, as, for example, when completing questionnaire measures of subjective pain experience or in clinical interviews. Neuroimaging studies of the human cortical and subcortical physical pain response have identified a neural network consistently referred to as the "pain matrix." We used functional magnetic resonance imaging to investigate whether the pain matrix could be activated through the retrieval of memories relating to previously painful events, in the absence of any direct peripheral noxious input. Fourteen pain-free participants were explicitly instructed to recall autobiographical memories of painful episodes in response to pain-related words and non-painful episodes in response to equally salient but non-pain words. Memories triggered by pain-related words produced significantly greater activation of left caudal anterior cingulate cortex (BA32'), and left inferior frontal gyrus (BA44, extending to BA47/45) more than memories triggered by equally salient but non-pain words. We suggest that these activations demonstrate a semantic retrieval process for pain-related memories, which may provide a means of cognitively reappraising the memory of the painful episode, thus allowing the person to elaborate on the circumstances surrounding the event, without physically re-experiencing it. PERSPECTIVE: The present study reveals a putative neural mechanism for the retrieval of autobiographical memories of previously painful events, which may provide a means of cognitively reappraising a painful episode, without physically re-experiencing it. This finding has implications for understanding disease mechanisms of chronic pain and their impact on subsequent treatment.

Accidents, Traffic↗
PubMed2006

The neural system that mediates familiarity memory.

In recognition memory tests, feelings of familiarity for stimuli vary in strength. Increasing levels of felt familiarity should modulate activity in brain structures that mediate familiarity memory. We used this expectation to identify the neural system that underlies scene familiarity memory. Normal subjects studied pictures of scenes and 2 days later while undergoing event-related functional magnetic resonance imaging (fMRI) rated old and new pictures as novel, slightly familiar, moderately familiar, very familiar, or recollected, although they were specifically instructed not to try and recollect. Familiarity strength was, therefore, judged as absent (misses) or present at three levels of increasing strength. A parametric analysis showed that, as perceived strength of familiarity increased activity in the perirhinal cortex, insula and left superior temporal cortex declined linearly whereas activity in the left dorsomedial thalamus, left ventrolateral and anteromedial frontal cortex, posterior cingulate cortex, and left parietal neocortex increased linearly. Hippocampal activity was not modulated linearly or quadratically by changes in familiarity strength. Recollection activated the hippocampus, and left anterior and inferolateral frontal and parietal cortices more than strong familiarity. In contrast, no brain region that was unaffected by recollection (relative to misses and correct rejections) was modulated by variations in familiarity strength. The implications of these findings for the functional and neural bases of familiarity and recollection are considered.

Adult↗
PubMed2006

Two-center prospective randomized controlled trial of Blake versus Portex drains after cardiac surgery.

OBJECTIVE: To compare the efficacy of two drain types after cardiac surgery in a randomized controlled trial, with primary outcome measure being depth of pericardial effusion 3 to 5 days after drain removal. METHODS: A prospective randomized controlled trial was conducted at two university hospitals. A total of 199 patients undergoing first-time cardiac procedures were randomized at surgery to receive either small-bore flexible Blake drains (19F) or larger Portex drains (28F). Drains were removed according to the study protocol and patients underwent echocardiography 3 to 5 days after drain removal to measure residual pericardial effusion. RESULTS: Ninety patients received Blake drains and 109 patients received Portex drains. There were no statistically significant differences in preoperative variables between the groups. There was no difference in the number of drains inserted per patient between groups (Blake 2.1 +/- 0.4 vs Portex 2.0 +/- 0.5). Mean difference in size of pericardial effusion between groups was 1.96 mm (95% confidence interval -0.02, 3.95 mm), which did not exceed the predefined non-inferiority margin of 10 mm. There was no significant difference in the mean maximal hourly drainage rate between groups (Blake 94.7 mL vs Portex 123.1 mL; P = .070) or in the total drainage rates (Blake 541 mL vs Portex 679 mL; P = .066). Although the Blake group had a higher percentage of patients with detectable effusion (46.3% vs 27.4%; P = .011) than the Portex group, there was no difference in need for late drainage of pericardial effusions (1.1% vs 1.9%) or insertion of further chest drains (8.8% vs 7.2%). CONCLUSION: The performance of small-bore Blake drains is not inferior to that of standard Portex drains after cardiac surgery.

Aged↗
PubMed2005

Role for human posterior parietal cortex in visual processing of aversive objects in peripersonal space.

The posterior parietal cortex of both human and non-human primates is known to play a crucial role in the early integration of visual information with somatosensory, proprioceptive and vestibular signals. However, it is not known whether in humans this region is further capable of discriminating if a stimulus poses a threat to the body. In this functional magnetic resonance imaging (fMRI) study, we tested the hypothesis that the posterior parietal cortex of humans is capable of modulating its response to the visual processing of noxious threat representation in the absence of tactile input. During fMRI, participants watched while we "stimulated" a visible rubber hand, placed over their real hand with either a sharp (painful) or a blunt (nonpainful) probe. We found that superior and inferior parietal regions (BA5/7 and BA40) increased their activity in response to observing a painful versus nonpainful stimulus. However, this effect was only evident when the rubber hand was in a spatially congruent (vs. incongruent) position with respect to the participants' own hand. In addition, areas involved in motivational-affective coding such as mid-cingulate (BA24) and anterior insula also showed such relevance-dependent modulation, whereas premotor areas known to receive multisensory information about limb position did not. We suggest these results reveal a human anatomical-functional homologue to monkey inferior parietal areas that respond to aversive stimuli by producing nocifensive muscle and limb movements.

Adult↗
PubMed2005

Structural and functional asymmetry of lateral Heschl's gyrus reflects pitch perception preference.

The relative pitch of harmonic complex sounds, such as instrumental sounds, may be perceived by decoding either the fundamental pitch (f0) or the spectral pitch (fSP) of the stimuli. We classified a large cohort of 420 subjects including symphony orchestra musicians to be either f0 or fSP listeners, depending on the dominant perceptual mode. In a subgroup of 87 subjects, MRI (magnetic resonance imaging) and magnetoencephalography studies demonstrated a strong neural basis for both types of pitch perception irrespective of musical aptitude. Compared with f0 listeners, fSP listeners possessed a pronounced rightward, rather than leftward, asymmetry of gray matter volume and P50m activity within the pitch-sensitive lateral Heschl's gyrus. Our data link relative hemispheric lateralization with perceptual stimulus properties, whereas the absolute size of the Heschl's gyrus depends on musical aptitude.

Acoustic Stimulation↗
PubMed2005

Voxel-based morphometry and stereology provide convergent evidence of the importance of medial prefrontal cortex for fluid intelligence in healthy adults.

We investigated whether a relationship exists between frontal lobe volume and fluid intelligence as measured by both Cattell's Culture Fair test and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Performance scale, but not with crystallized intelligence as measured by the WAIS-R Verbal scale, in healthy adults, using two well-established image analysis techniques applied to high-resolution MR brain images. Firstly, using voxel-based morphometry (VBM), we investigated whether a significant relationship exists between gray matter concentration and fluid intelligence on a voxel-by-voxel basis. Secondly, we applied the Cavalieri method of modern design stereology in combination with point counting to investigate possible relationships between macroscopic volumes of relevant brain regions defined as dorsolateral, dorsomedial, orbitolateral, and orbitomedial prefrontal cortex on the basis of neuroanatomical landmarks, and fluid intelligence. We also examined the effect on these relationships of normalizing regional brain volumes to intracranial volume. VBM analysis revealed a positive correlation between gray matter concentration in the medial region of prefrontal cortex and Culture Fair scores (corrected for multiple comparisons), and also WAIS-R Performance Intelligence sum of scaled scores (SSS) (uncorrected for multiple comparisons before controlling for age, and this converges with the stereological finding of the positive correlation between volume of dorsomedial prefrontal cortex normalized to intracranial volume and Culture Fair scores after controlling for age. WAIS-R Verbal Intelligence SSS showed no correlations. We interpret our findings, from independent analyses of both VBM and stereology, as evidence of the importance of medial prefrontal cortex in supporting fluid intelligence.

Adult↗
PubMed2005

Sparing of the familiarity component of recognition memory in a patient with hippocampal pathology.

Subject KN has a persistent anterograde amnesia as a result of brain injury following meningitis in 1993. MRI scans reveal a bilateral decrease in the volume of his hippocampal region (dentate gyrus, CA1-4, subicular cortices) of approximately 45% in both the right and left hemispheres, although the volume of his perirhinal cortex appears normal. Aside from some changes to his occipital lobe and bilateral shrinkage of the amygdala, the rest of his brain appears normal on recent quantitative MRI scans. A striking feature of his memory loss is his ability to perform at normal levels on some tests of recognition, despite his consistent deficit on tests of recall. Two tests designed specifically to distinguish performance of two putative divisions of recognition memory (the Remember/Know procedure and the use of receiver operating characteristics to distinguish familiarity and recollection), provide evidence for a selective sparing of the familiarity component of recognition. The dissociation within recognition memory supports dual-process models of recognition, and also supports proposals that anatomically linked regions within the medial temporal lobe make qualitatively different contributions to recognition.

Adult↗
PubMed2005

Automatic analysis of cerebral asymmetry: an exploratory study of the relationship between brain torque and planum temporale asymmetry.

Leftward occipital and rightward frontal lobe asymmetry (brain torque) and leftward planum temporale asymmetry have been consistently reported in postmortem and in vivo neuroimaging studies of the human brain. Here automatic image analysis techniques are applied to quantify global and local asymmetries, and investigate the relationship between brain torque and planum temporale asymmetries on T1-weighted magnetic resonance (MR) images of 30 right-handed young healthy subjects (15 male, 15 female). Previously described automatic cerebral hemisphere extraction and 3D interhemispheric reflection-based methods for studying brain asymmetry are applied with a new technique, LowD (Low Dimension), which enables automatic quantification of brain torque. LowD integrates extracted left and right cerebral hemispheres in columns orthogonal to the midsagittal plane (2D column maps), and subsequently integrates slices along the brain's anterior-posterior axis (1D slice profiles). A torque index defined as the magnitude of occipital and frontal lobe asymmetry is computed allowing exploratory investigation of relationships between this global asymmetry and local asymmetries found in the planum temporale. LowD detected significant torque in the 30 subjects with occipital and frontal components found to be highly correlated (P<0.02). Significant leftward planum temporale asymmetry was detected (P<0.05), and the torque index correlated with planum temporale asymmetry (P<0.001). However, torque and total brain volume were not correlated. Therefore, although components of cerebral asymmetry may be related, their magnitude is not influenced by total hemisphere volume. LowD provides increased sensitivity for detection and quantification of brain torque on an individual subject basis, and future studies will apply these techniques to investigate the relationship between cerebral asymmetry and functional laterality.

Adult↗
PubMed2005

A combined clinical, neuropsychological, and neuroanatomical study of adults with high functioning autism.

INTRODUCTION: Three hypotheses concerning associations between neuroanatomical abnormalities, neuropsychological impairments, and the behavioural manifestations of autism were investigated. The primary hypothesis was that the social interaction impairments diagnostic of autism are associated with deficits of socioemotional perception and abnormalities of the amygdala. One subsidiary hypothesis was that the learning and language impairments that occur in less able individuals with autism are associated with impaired memory, and with abnormalities of hippocampal regions. A second subsidiary hypothesis was that the repetitive behaviour diagnostic of autism is associated with executive deficits and with abnormalities of the prefrontal cortex. Associations between the neuroanatomical regions investigated were also examined. METHODS: Ten adult males with high functioning autism (HFA) were compared with 10 healthy controls matched for age, sex, verbal and nonverbal ability. Hypothesis-driven structural MRI and neuropsychological tests were used to collect neuroanatomical and neuropsychological data on all subjects. A version of the Wing Autism Diagnostic Interview Checklist was used to collect clinical data on the HFA subjects. RESULTS: Strong convergent evidence in support of the amygdala hypothesis was obtained, and preliminary support for the hippocampal/parahippocampal hypothesis. No clear evidence was obtained in support of the prefrontal hypothesis. Patterns of associations amongst volume measures within and between medial temporal and prefrontal regions suggest stronger within-region and weaker between-region associations in the HFA group compared with controls. CONCLUSIONS: These findings are discussed in terms of a model of autism in which selective abnormalities of the amygdala and hippocampus (in all cases) and of the parahippocampal gyrus (in lower functioning cases) are implicated, and in which a disruption of coordinated limbic and prefrontal activity may be critical.

Journal Article↗
PubMed2005

Structural, functional, and perceptual differences in Heschl's gyrus and musical instrument preference.

The musical pitch of harmonic complex sounds, such as instrumental sounds, is perceived primarily by decoding either the fundamental pitch (keynote) or spectral aspects of the stimuli, for example, single harmonics. We divided 334 professional musicians, including symphony orchestra musicians, 75 amateur musicians, and 54 nonmusicians, into either fundamental pitch listeners or spectral pitch listeners. We observed a strong correlation between pitch perception preference and asymmetry of brain structure and function in the pitch-sensitive lateral areas of Heschl's gyrus (HG), irrespective of musical ability. In particular, fundamental pitch listeners exhibited both larger gray matter volume measured using magnetic resonance imaging (MRI) and enhanced P50m activity measured using magnetoencephalography (MEG) in the left lateral HG, which is sensitive to rapid temporal processing. Their chosen instruments were percussive or high-pitched instruments that produce short, sharp, or impulsive tones (e.g., drums, guitar, piano, trumpet, or flute). By contrast, spectral pitch listeners exhibited a dominant right lateral HG, which is known to be sensitive to slower temporal and spectral processing. Their chosen instruments were lower-pitched melodic instruments that produce rather sustained tones with characteristic changes in timbre (e.g., bassoon, saxophone, french horn, violoncello, or organ). Singers also belonged to the spectral pitch listeners. Furthermore, the absolute size of the neural HG substrate depended strongly on musical ability. Overall, it is likely that both magnitude and asymmetry of lateral HG, and the related perceptual mode, may have an impact on preference for particular musical instruments and on musical performance.

Acoustic Stimulation↗
PubMed2004

Comparison of standard and optimized voxel-based morphometry for analysis of brain changes associated with temporal lobe epilepsy.

We compared statistical parametric maps (SPMs) of group-wise regional gray matter differences between temporal lobe epilepsy (TLE) patients with unilateral hippocampal atrophy (HA) determined by manual volumetric analysis relative to a healthy control population using standard and optimized voxel-based morphometry (VBM). We also investigated the impact of customized neuroanatomical templates on SPMs. Standard and optimized VBM analyses of gray matter concentration (GMC) and gray matter volume (GMV) correctly identified HA, regardless of the template used for normalization. The distribution of hippocampal and extrahippocampal abnormalities differed according to the technique (standard v optimized; GMC v GMV), but was not dependent on template type (default v customized) within each technique. In particular, hippocampal GMC reduction was confined to subregions of hippocampus, whereas GMV reduction was observed in the hippocampal head, body, and tail. Unlike standard and optimized GMC reduction, symmetrical GMV reduction was observed in bilateral thalamus, lenticular nuclei, cerebellum, and ipsilateral entorhinal cortex, perirhinal cortex, and fusiform gyrus in both left and right HA patients. These results show that group-wise SPMs of GMC (i.e., regional distribution of gray matter) and GMV (i.e., volume per se) reduction can identify focal atrophy that has been quantified with manual region of interest techniques, although effects are attenuated in analyses of GMC. Unlike SPMs of GMC, analyses of GMV revealed similar extrahippocampal abnormalities as previous region-of-interest volumetric and histopathological studies of intractable TLE. We suggest that in studies of neurological disorders, optimized VBM analyses of GMV may reveal subtle neuroanatomical changes that are not identified in analyses of GMC.

Adolescent↗
PubMed2004

Recalling spatial information as a component of recently and remotely acquired episodic or semantic memories: an fMRI study.

Activations produced by the recall of episodic and semantic memories differing in spatial content and age were examined. Recall of recent episodic memories with differing spatial content activated the medial temporal lobes and the retrosplenial-posterior cingulate cortex-precuneus complex more than recall of recent semantic memories with similarly differing spatial content. Some of these differences related to the amount of spatial information recalled because spatially richer recent memories, regardless of whether they were episodic or semantic, activated the right posterior parahippocampal cortex, precuneus, and posterior parietal cortex more. This spatial effect was found to be independent of memory age for semantic memories, although some episodic-semantic memory differences, including one in the left hippocampus, were not age independent. Episodic-semantic memory recall activation differences are therefore probably a function of the amount recalled, memory age, and what is recalled, particularly with respect to spatial information.

Adult↗
PubMed2004

Dissociation between recall and recognition memory performance in an amnesic patient with hippocampal damage following carbon monoxide poisoning.

Some patients with relatively selective hippocampal damage have shown proportionate recall and recognition deficits. Moreover, familiarity as well as recollection have been found to be impaired in some of these patients. In contrast, other patients with apparently similar damage presented with relatively preserved recognition despite having severely impaired recall, and some of these patients have been shown to have preserved familiarity. We report here the case of an amnesic patient who suffered bilateral hippocampal damage and temporoparietal atrophy after carbon monoxide poisoning. On tests matched for difficulty, his recall performance was more severely impaired than his recognition memory, for verbal as well as for visual materials. Moreover, he performed within the range of healthy matched subjects on nine recognition tests out of ten. In a task using the process dissociation procedure, the patient's familiarity was preserved although his recollection was impaired. These findings indicate that recall and recognition memory can be dissociated in amnesic patients with hippocampal lesions even when temporoparietal cortical atrophy is also present.

Aged↗
PubMed2004

Experience with mobile inhaled nitric oxide during transport of neonates and children with respiratory insufficiency to an extracorporeal membrane oxygenation center.

OBJECTIVE: To share our experience with the use of inhaled nitric oxide (iNO) during the transport of ventilated neonates and children to an extracorporeal membrane oxygenation (ECMO) center and to discuss the efficacy and safety of iNO use in this situation. DATA SOURCES: Case note review of 55 consecutive patients transported while receiving iNO to Glenfield Hospital, Leicester, UK, for consideration of ECMO. STUDY SELECTION: Retrospective case note review. DATA EXTRACTION: The clinical condition of each patient recorded at arrival of the transport team at the referring hospital, during transport, and at arrival at Glenfield Hospital. Preclinical and postclinical conditions were compared using the paired Student's t-test. DATA SYNTHESIS: Overall data showed a significant improvement in transcutaneous oximetry measurements (Spo(2): 84.8% preclinical, 90.6% postclinical; p = .006) and Pao(2) (59 torr [7.87 kPa] preclinical, 84 torr [11.23 kPa] postclinical; p = .001) during transport in our patient group. Based on limited safety data, no untoward events or toxic metabolites were observed with iNO therapy during transport. CONCLUSIONS: iNO does appear to improve oxygenation during transfer of patients for ECMO in our series. Based on limited safety data, iNO appears safe to use in transport.

Administration, Inhalation↗
PubMed2004

Vicarious responses to pain in anterior cingulate cortex: is empathy a multisensory issue?

Results obtained with functional magnetic resonance imaging show that both feeling a moderately painful pinprick stimulus to the fingertips and witnessing another person's hand undergo similar stimulation are associated with common activity in a pain-related area in the right dorsal anterior cingulate cortex (ACC). Common activity in response to noxious tactile and visual stimulation was restricted to the right inferior Brodmann's area 24b. These results suggest a shared neural substrate for felt and seen pain for aversive ecological events happening to strangers and in the absence of overt symbolic cues. In contrast to ACC 24b, the primary somatosensory cortex showed significant activations in response to both noxious and innocuous tactile, but not visual, stimuli. The different response patterns in the two areas are consistent with the ACC's role in coding the motivational-affective dimension of pain, which is associated with the preparation of behavioral responses to aversive events.

Adult↗
PubMed2003

Sex-dependent effects of schizophrenia: an MRI study of gyral folding, and cortical and white matter volume.

Alterations, sometimes sex-dependent, in volumes and gyral structure of areas of cerebral cortex have been reported in schizophrenia. Such changes imply an anomaly of connectivity. The gyrification, percentage of tissue volume attributed to white matter, cortical volume and white matter volume were measured from magnetic resonance images in males and females with (n = 61) and without (n = 42) schizophrenia. The frontal, temporal and an amalgam of occipital and parietal lobes were examined in both hemispheres. There was no effect of schizophrenia on the gyrification of the brain. For the volume of occipito-parietal white matter, females with schizophrenia had bilaterally lower volumes, while males with schizophrenia had greater volumes than controls. It is concluded that the changes in connectivity underlying the pathogenesis of schizophrenia are sex-specific and expressed in occipito-parietal white matter.

Adult↗
PubMed2003

Application of a new image analysis technique to study brain asymmetry in schizophrenia.

The hypothesis that normal brain torque (i.e. rightward frontal and leftward occipital asymmetry) is anomalous in schizophrenia (Crow, 1997. Trends in Neuroscience, 20, 339-343) was tested by application of a novel image analysis technique on three-dimensional magnetic resonance images obtained in 26 adult patients with chronic schizophrenia (18 males, 8 females) and 24 controls (14 males, 10 females). Right and left cerebral hemisphere tissue was extracted via non-linear co-registration with a mask image, and maps were computed of inter-hemispheric differences in tissue volume in an array of columns of voxels orthogonal to the mid-plane (2D), and profiles of coronal slice volumes (1D). Furthermore, integration of two-dimensional column maps gave approximate lobar asymmetries, and occipital and frontal asymmetries were combined to give a volumetric measure of brain torque. Significant brain torque was revealed in male and female control and patient groups, and did not correlate with brain size. Frontal and occipital asymmetries were significantly correlated in all groups. Both frontal and occipital components of torque were significantly increased in males than females. Patients tended to have reduced torque, particularly the leftward occipital component. Furthermore, 3/26 patients (but no controls) had reversed torque (leftward frontal and rightward occipital asymmetry). Contrary to Crow's hypothesis, brain torque was not significantly reduced in patients with schizophrenia relative to controls, although reversal of torque was found in three cases. Future studies with larger sample sizes should consider sexual dimorphism and specific symptoms in relation to asymmetry.

Brain↗