Depression represents one of the most common comorbidities in patients with epilepsy. However, the mechanisms of depression in epilepsy patients are poorly understood. Establishment of animal models of this comorbidity is critical for both understanding the mechanisms of the condition, and for preclinical development of effective therapies. The current study examined whether a commonly used animal model of temporal lobe epilepsy (TLE) is characterized by behavioral and biochemical alterations involved in depression. Male Wistar rats were subjected to LiCl and pilocarpine status epilepticus (SE). The development of chronic epileptic state was confirmed by the presence of spontaneous seizures and by enhanced brain excitability. Post-SE animals exhibited increase in immobility time under conditions of forced swim test (FST) which was indicative of despair-like state, and loss of taste preference in saccharin solution consumption test which pointed to the symptomatic equivalence of anhedonia. Biochemical studies revealed compromised serotonergic transmission in the raphe-hippocampal serotonergic pathway: decrease of serotonin (5-HT) concentration and turnover in the hippocampus, measured by high performance liquid chromatography, and decrease of 5-HT release from the hippocampus in response to raphe stimulation, measured by fast cyclic voltammetry. Administration of fluoxetine (FLX, 20 mg/kg/day for 10 days) to naïve animals significantly shortened immobility time under conditions of FST, and inhibited 5-HT turnover in the hippocampus. In post-SE rats FLX treatment led to a further decrease of hippocampal 5-HT turnover; however, performance in FST was not improved. At the same time, FLX reversed SE-induced increase in brain excitability. In summary, our studies provide initial evidence that post-SE model of TLE might serve as a model of the comorbidity of epilepsy and depression. The finding that behavioral equivalents of depression were resistant to an antidepressant medication suggested that depression in epilepsy might have distinct underlying mechanisms beyond alterations in serotonergic pathways.
Comorbidity; depression; epilepsy; hippocampus; serotonin
Children with autism exhibit a host of motor disorders including poor coordination, poor tool use, and delayed learning of complex motor skills like riding a tricycle. Theory suggests that one of the crucial steps in motor learning is the ability to form internal models: to predict the sensory consequences of motor commands and learn from errors to improve performance on the next attempt. The cerebellum appears to be an important site for acquisition of internal models, and indeed the development of the cerebellum is abnormal in autism. Here, we examined autistic children on a range of tasks that required a change in the motor output in response to a change in the environment. We first considered a prism adaptation task in which the visual map of the environment was shifted. The children were asked to throw balls to visual targets with and without the prism goggles. We next considered a reaching task that required moving the handle of a novel tool (a robotic arm). The tool either imposed forces on the hand or displaced the cursor associated with the handle position. In all tasks, the children with autism adapted their motor output by forming a predictive internal model, as exhibited through after-effects. Surprisingly, the rates of acquisition and washout were indistinguishable from normally developing children. Therefore, the mechanisms of acquisition and adaptation of internal models in self-generated movements appeared normal in autism. Sparing of adaptation suggests that alternative mechanisms contribute to impaired motor skill development in autism. Furthermore, the findings may have therapeutic implications, highlighting a reliable mechanism by which children with autism can most effectively alter their behavior.
reach adaptation; prism adaptation; motor control; autism
Transplanted neural stem/precursor cells possess peculiar therapeutic plasticity and can simultaneously instruct several therapeutic mechanisms in addition to cell replacement. Here, we interrogated the therapeutic plasticity of neural stem/precursor cells after their focal implantation in the severely contused spinal cord. We injected syngeneic neural stem/precursor cells at the proximal and distal ends of the contused mouse spinal cord and analysed locomotor functions and relevant secondary pathological events in the mice, cell fate of transplanted neural stem/precursor cells, and gene expression and inflammatory cell infiltration at the injured site. We used two different doses of neural stem/precursor cells and two treatment schedules, either subacute (7 days) or early chronic (21 days) neural stem/precursor cell transplantation after the induction of experimental thoracic severe spinal cord injury. Only the subacute transplant of neural stem/precursor cells enhanced the recovery of locomotor functions of mice with spinal cord injury. Transplanted neural stem/precursor cells survived undifferentiated at the level of the peri-lesion environment and established contacts with endogenous phagocytes via cellular–junctional coupling. This was associated with significant modulation of the expression levels of important inflammatory cell transcripts in vivo. Transplanted neural stem/precursor cells skewed the inflammatory cell infiltrate at the injured site by reducing the proportion of ‘classically-activated’ (M1-like) macrophages, while promoting the healing of the injured cord. We here identify a precise window of opportunity for the treatment of complex spinal cord injuries with therapeutically plastic somatic stem cells, and suggest that neural stem/precursor cells have the ability to re-programme the local inflammatory cell microenvironment from a ‘hostile’ to an ‘instructive’ role, thus facilitating the healing or regeneration past the lesion.
neural stem cells; spinal cord injury; cell transplantation; macrophages; immune regulation; tissue healing
Lesch–Nyhan disease (LND) is caused by deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). Affected individuals exhibit over-production of uric acid, along with a characteristic neurobehavioural syndrome that includes mental retardation, recurrent self-injurious behaviour and motor disability. Prior studies involving relatively small numbers of patients have provided different conclusions on the nature of the motor disorder. The current study includes the results of a multi-centre international prospective study of the motor disorder in the largest cohort of patients studied to date. A total of 44 patients ranging from 2 to 38 years presented a characteristic motor syndrome that involved severe action dystonia superimposed on baseline hypotonia. Although some patients also displayed other extrapyramidal or pyramidal signs, these were always less prominent than dystonia. These results are compared with a comprehensive review of 122 prior reports that included a total of 254 patients. Explanations for the differing observations available in the literature are provided, along with a summary of how the motor disorder of LND relates to current understanding of its pathophysiology involving the basal ganglia.
cerebral palsy; choreoathetosis; dystonia; neurogenetics
Pathological gambling is an impulse control disorder reported in association with dopamine agonists used to treat Parkinson’s disease. Although impulse control disorders are conceptualized as lying within the spectrum of addictions, little neurobiological evidence exists to support this belief. Functional imaging studies have consistently demonstrated abnormalities of dopaminergic function in patients with drug addictions, but to date no study has specifically evaluated dopaminergic function in Parkinson’s disease patients with impulse control disorders. We describe results of a [11C] raclopride positron emission tomography (PET) study comparing dopaminergic function during gambling in Parkinson’s disease patients, with and without pathological gambling, following dopamine agonists. Patients with pathological gambling demonstrated greater decreases in binding potential in the ventral striatum during gambling (13.9%) than control patients (8.1%), likely reflecting greater dopaminergic release. Ventral striatal bindings at baseline during control task were also lower in patients with pathological gambling. Although prior imaging studies suggest that abnormality in dopaminergic binding and dopamine release may be markers of vulnerability to addiction, this study presents the first evidence of these phenomena in pathological gambling. The emergence of pathological gambling in a number of Parkinson’s disease patients may provide a model into the pathophysiology of this disorder.
PMID: 19346328 CAMSID: cams2369
Parkinson’s disease; dopamine; impulse control disorders; pathological gambling; PET; functional imaging
To identify the disease-causing gene responsible for an autosomal dominantly inherited Charcot–Marie–Tooth neuropathy subtype in a family excluded for mutations in the common Charcot–Marie–Tooth genes, we used array-based sequence capture to simultaneously analyse the disease-linked protein coding exome at chromosome 14q32. A missense mutation in fibulin-5, encoding a widely expressed constituent of the extracellular matrix that has an essential role in elastic fibre assembly and has been shown to cause cutis laxa, was detected as the only novel non-synonymous sequence variant within the disease interval. Screening of 112 index probands with unclassified Charcot–Marie–Tooth neuropathies detected two further fibulin-5 missense mutations in two families with Charcot–Marie–Tooth disease and hyperextensible skin. Since fibulin-5 mutations have been described in patients with age-related macular degeneration, an additional 300 probands with exudative age-related macular degeneration were included in this study. Two further fibulin-5 missense mutations were identified in six patients. A mild to severe peripheral neuropathy was detected in the majority of patients with age-related macular degeneration carrying mutations in fibulin-5. This study identifies fibulin-5 as a gene involved in Charcot–Marie–Tooth neuropathies and reveals heterozygous fibulin-5 mutations in 2% of our patients with age-related macular degeneration. Furthermore, it adumbrates a new syndrome by linking concurrent pathologic alterations affecting peripheral nerves, eyes and skin to mutations in the fibulin-5 gene.
age-related macular degeneration; CMT; cutis laxa; fibulin-5; neuropathy
The definition of the clinicopathological entity of amyotrophic lateral sclerosis evolved over half a century. Although the definitive term amyotrophic lateral sclerosis that acknowledged both upper and lower motor neuron involvement was attributed to Jean-Martin Charcot in 1874, his initial case was published nearly a decade earlier; and it is accepted that, from at least the 1830s, several others (including Charles Bell, François-Amilcar Aran and Jean Cruveilhier) had already recognized a progressive lower motor neuron-only syndrome within a broader, clinically-defined group of disorders, termed progressive muscular atrophy. Although William Gowers first grouped the three phenotypes of amyotrophic lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy together as part of the same syndrome, the term motor neuron disease, as an over-arching label, was not suggested until nearly a century later by W. Russell Brain. Augustus Jacob Lockhart Clarke (1817–80) is best known for his descriptions of spinal cord anatomy. However, in two detailed case reports from the 1860s, he carried out rigorous post-mortem neuropathological studies of what appear to be classical cases of amyotrophic lateral sclerosis. Furthermore, he recognized the additional involvement of the corticospinal tracts that distinguished this from progressive muscular atrophy. Several aspects of the exquisite clinical histories documented as part of both studies, one by Charles Bland Radcliffe, resonate with contemporary debates concerning the evolution of disease in amyotrophic lateral sclerosis. These ‘past masters’ still have much to teach us.
amyotrophic lateral sclerosis; motor neuron disease; Lockhart Clarke; Radcliffe; Charcot
Experimental prolonged febrile seizures (FS) lead to structural and molecular changes that promote hippocampal hyperexcitability and reduce seizure threshold to further convulsants. However, whether these seizures provoke later-onset epilepsy, as has been suspected in humans, has remained unclear. Previously, intermittent EEGs with behavioural observations for motor seizures failed to demonstrate spontaneous seizures in adult rats subjected to experimental prolonged FS during infancy. Because limbic seizures may be behaviourally subtle, here we determined the presence of spontaneous limbic seizures using chronic video monitoring with concurrent hippocampal and cortical EEGs, in adult rats (starting around 3 months of age) that had sustained experimental FS on postnatal day 10. These subjects were compared with groups that had undergone hyperthermia but in whom seizures had been prevented (hyperthermic controls), as well as with normothermic controls. Only events that fulfilled both EEG and behavioural criteria, i.e. electro-clinical events, were considered spontaneous seizures. EEGs (over 400 recorded hours) were normal in all normothermic and hyperthermic control rats, and none of these animals developed spontaneous seizures. In contrast, prolonged early-life FS evoked spontaneous electro-clinical seizures in 6 out of 17 experimental rats (35.2%). These seizures consisted of sudden freezing (altered consciousness) and typical limbic automatisms that were coupled with polyspike/sharp-wave trains with increasing amplitude and slowing frequency on EEG. In addition, interictal epileptiform discharges were recorded in 15 (88.2%) of the experimental FS group and in none of the controls. The large majority of hippocampally-recorded seizures were heralded by diminished amplitude of cortical EEG, that commenced half a minute prior to the hippocampal ictus and persisted after seizure termination. This suggests a substantial perturbation of normal cortical neuronal activity by these limbic spontaneous seizures. In summary, prolonged experimental FS lead to later-onset limbic (temporal lobe) epilepsy in a significant proportion of rats, and to interictal epileptifom EEG abnormalities in most others, and thus represent a model that may be useful to study the relationship between FS and human temporal lobe epilepsy.
prolonged febrile seizures; temporal lobe epilepsy; video-EEG; rat; prospective study
Normobaric hyperoxia is under investigation as a treatment for acute ischaemic stroke. In experimental models, normobaric hyperoxia reduces cerebral ischaemic injury and improves functional outcome. The mechanisms of neuroprotection are still debated because, (i) inhalation of 100% O2 does not significantly increase total blood O2 content; (ii) it is not known whether normobaric hyperoxia increases O2 delivery to the severely ischaemic cortex because of its short diffusion distance; and (iii) hyperoxia may reduce collateral cerebral blood flow (CBF) to ischaemic penumbra because it can cause vasoconstriction. We addressed these issues using real-time two-dimensional multispectral reflectance imaging and laser speckle flowmetry to simultaneously and non-invasively determine the impact of normobaric hyperoxia on CBF and oxygenation in ischaemic cortex. Ischaemia was induced by distal middle cerebral artery occlusion (dMCAO) in normoxic (30% inhaled O2, arterial pO2 134 ± 9 mmHg), or hyperoxic mice (100% inhaled O2 starting 15 min after dMCAO, arterial pO2 312 ± 10 mmHg). Post-ischaemic normobaric hyperoxia caused an immediate and progressive increase in oxyhaemoglobin (oxyHb) concentration, nearly doubling it in ischaemic core within 60 min. In addition, hyperoxia improved CBF so that the area of cortex with ≤20% residual CBF was decreased by 45% 60 min after dMCAO. Furthermore, hyperoxia reduced the frequency of peri-infarct depolarizations (PIDs) by more than 60%, and diminished their deleterious effects on CBF and metabolic load. Consistent with these findings, infarct size was reduced by 45% in the hyperoxia group 2 days after 75 min transient dMCAO. Our data show that normobaric hyperoxia increases tissue O2 delivery, and that novel mechanisms such as CBF augmentation, and suppression of PIDs may afford neuroprotection during hyperoxia.
neuroprotection; laser speckle flowmetry; multispectral reflectance imaging; middle cerebral artery occlusion; acute stroke
Dystonia is characterised by two main pathophysiological abnormalities: reduced excitability of inhibitory systems at many levels of the sensorimotor system, and increased plasticity of neural connections in sensorimotor circuits at a brainstem and spinal level. A surprising finding in two recent papers has been the fact that abnormalities of inhibition similar to those in organic dystonia are also seen in patients who have psychogenic dystonia. To try to determine the critical feature that might separate organic and psychogenic conditions, we investigated cortical plasticity in a group of 10 patients with psychogenic dystonia and compared the results with those obtained in a matched group of 10 patients with organic dystonia and 10 healthy individuals. We confirmed the presence of abnormal motor cortical inhibition (short interval intracortical inhibition, SICI) in both organic and psychogenic groups. However, we found that plasticity (paired associative stimulation, PAS) was abnormally high only in the organic group, while there was no difference between the plasticity measured in psychogenic patients and healthy controls. We conclude that abnormal plasticity is a hallmark of organic dystonia; furthermore it is not a consequence of reduced inhibition since the latter is seen in psychogenic patients who have normal plasticity.
associative plasticity; organic dystonia; psychogenic dystonia; paired associative stimulation; transcranial magnetic stimulation
Lesions obtained early in the course of multiple sclerosis (MS) have been studied immunocytochemically, and compared with the early stages of the experimental lesion induced in rats by the intraspinal injection of lipopolysaccharide. Large hemispheric or double hemispheric sections were examined from patients who had died in the course of acute or early relapsing multiple sclerosis. In MS patients exhibiting hypoxia-like lesions [Pattern III; Lucchinetti et al. Ann Neurol (2000) 47: 707–17], focal areas in the white matter showed mild oedema, microglial activation and mild axonal injury in the absence of overt demyelination. In such lesions T-cell infiltration was mild and restricted to the perivascular space. Myeloperoxidase and the inducible form of nitric oxide synthase were expressed primarily by microglia, and the activated form of these cells was associated with extracellular deposition of precipitated fibrin. In addition, these lesions showed up-regulation of proteins involved in tissue preconditioning. When active demyelination started, lesions were associated with massive T-cell infiltration and microglia and macrophages expressed all activation markers studied. Similar tissue alterations were found in rats in the pre-demyelinating stage of lesions induced by the focal injection of bacterial lipopolysaccharide into the spinal white matter. We suggest that the areas of microglial activation represent an early stage of tissue injury, which precedes the formation of hypoxia-like demyelinated plaques. The findings indicate that mechanisms associated with innate immunity may play a role in the formation of hypoxia-like demyelinating lesions in MS.
multiple sclerosis; lesion development; microglial activation; fibrin; innate immunity; lipopolysaccharide
Human locomotion must be flexible in order to meet varied environmental demands. Alterations to the gait pattern occur on different time scales, ranging from fast, reactive adjustments to slower, more persistent adaptations. A recent study in humans showed the cerebellum to play a key role for slower walking adaptations in inter-limb coordination during split-belt treadmill walking, but not fast reactive changes. It is not known whether cerebral structures are also important in these processes, though some studies of cats have suggested that they are not. In this study, we used a split-belt treadmill walking task to test whether cerebral damage from stroke impairs either type of flexibility. Results showed that stroke involving cerebral structures did not impair either reactive or adaptive abilities and did not disrupt storage of new inter-limb relationships (i.e. after-effects). This suggests that cerebellar interactions with brainstem, rather than cerebral structures, comprise the critical circuit for this type of inter-limb control. Further, the after-effects from a 15-minute adaptation session could temporarily induce symmetry in subjects who demonstrated baseline asymmetry of spatio-temporal gait parameters. In order to re-establish symmetric walking, the choice of which leg is on the fast belt during split-belt walking must be based on the subject’s initial asymmetry. These findings demonstrate that cerebral stroke survivors are indeed able to adapt inter-limb coordination. This raises the possibility that asymmetric walking patterns post-stroke could be remediated utilizing the split-belt treadmill as a long-term rehabilitation strategy.
stroke; motor; locomotion; movement
Oligodendrocyte loss and demyelination are major pathological hallmarks of multiple sclerosis. In pattern III lesions, inflammation is minor in the early stages, and oligodendrocyte apoptosis prevails, which appears to be mediated at least in part through mitochondrial injury. Here, we demonstrate poly(ADP-ribose) polymerase activation and apoptosis inducing factor nuclear translocation within apoptotic oligodendrocytes in such multiple sclerosis lesions. The same morphological and molecular pathology was observed in an experimental model of primary demyelination, induced by the mitochondrial toxin cuprizone. Inhibition of poly(ADP-ribose) polymerase in this model attenuated oligodendrocyte depletion and decreased demyelination. Poly(ADP-ribose) polymerase inhibition suppressed c-Jun N-terminal kinase and p38 mitogen-activated protein kinase phosphorylation, increased the activation of the cytoprotective phosphatidylinositol-3 kinase-Akt pathway and prevented caspase-independent apoptosis inducing factor-mediated apoptosis. Our data indicate that poly(ADP-ribose) polymerase activation plays a crucial role in the pathogenesis of pattern III multiple sclerosis lesions. Since poly(ADP-ribose) polymerase inhibition was also effective in the inflammatory model of multiple sclerosis, it may target all subtypes of multiple sclerosis, either by preventing oligodendrocyte death or attenuating inflammation.
poly(ADP-ribose) polymerase; multiple sclerosis; cuprizone; demyelination; oligodendrocyte apoptosis; Akt; AIF; JNK
Numerous treatment strategies for spinal cord injury seek to maximize recovery of function and two strategies that show substantial promise are olfactory bulb-derived olfactory ensheathing glia (OEG) transplantation and treadmill step training. In this study we re-examined the issue of the effectiveness of OEG implantation but used objective, quantitative measures of motor performance to test if there is a complementary effect of long-term step training and olfactory bulb-derived OEG implantation. We studied complete mid-thoracic spinal cord transected adult female rats and compared four experimental groups: media-untrained, media-trained, OEG-untrained and OEG-trained. To assess the extent of hindlimb locomotor recovery at 4 and 7 months post-transection we used three quantitative measures of stepping ability: plantar stepping performance until failure, joint movement shape and movement frequency compared to sham controls. OEG transplantation alone significantly increased the number of plantar steps performed at 7 months post-transection, while training alone had no effect at either time point. Only OEG-injected rats plantar placed their hindpaws for more than two steps by the 7-month endpoint of the study. OEG transplantation combined with training resulted in the highest percentage of spinal rats per group that plantar stepped, and was the only group to significantly improve its stepping abilities between the 4- and 7-month evaluations. Additionally, OEG transplantation promoted tissue sparing at the transection site, regeneration of noradrenergic axons and serotonergic axons spanning the injury site. Interestingly, the caudal stump of media- and OEG-injected rats contained a similar density of serotonergic axons and occasional serotonin-labelled interneurons. These data demonstrate that olfactory bulb-derived OEG transplantation improves hindlimb stepping in paraplegic rats and further suggest that task-specific training may enhance this OEG effect.
locomotion; regeneration; spinal cord injury; rehabilitation; olfactory ensheathing glia
Mutations in the receptor expression enhancing protein 1 (REEP1) have recently been reported to cause autosomal dominant hereditary spastic paraplegia (HSP) type SPG31. In a large collaborative effort, we screened a sample of 535 unrelated HSP patients for REEP1 mutations and copy number variations. We identified 13 novel and 2 known REEP1 mutations in 16 familial and sporadic patients by direct sequencing analysis. Twelve out of 16 mutations were small insertions, deletions or splice site mutations. These changes would result in shifts of the open-reading-frame followed by premature termination of translation and haploinsufficiency. Interestingly, we identified two disease associated variations in the 3′-UTR of REEP1 that fell into highly conserved micro RNA binding sites. Copy number variation analysis in a subset of 133 HSP index patients revealed a large duplication of REEP1 that involved exons 2–7 in an Irish family. Clinically most SPG31 patients present with a pure spastic paraplegia; rare complicating features were restricted to symptoms or signs of peripheral nerve involvement. Interestingly, the distribution of age at onset suggested a bimodal pattern with the appearance of initial symptoms of disease either before the age of 20 years or after the age of 30 years. The overall mutation rate in our clinically heterogeneous sample was 3.0%; however, in the sub-sample of pure HSP REEP1 mutations accounted for 8.2% of all patients. These results firmly establish REEP1 as a relatively frequent autosomal dominant HSP gene for which genetic testing is warranted. We also establish haploinsufficiency as the main molecular genetic mechanism in SPG31, which should initiate and guide functional studies on REEP1 with a focus on loss-of-function mechanisms. Our results should be valid as a reference for mutation frequency, spectrum of REEP1 mutations, and clinical phenotypes associated with SPG31.
hereditary spastic paraplegia; SPG31; REEP1; haploinsufficiency; micro RNA
Orbitofrontal Cortex (OFC) structural abnormality in schizophrenia has not been well characterized, probably due to marked anatomical variability and lack of consistent definitions. We previously reported OFC sulcogyral pattern alteration and its associations with social disturbance in schizophrenia, but OFC volume associations with psychopathology and cognition have not been investigated. We compared chronically treated schizophrenia patients with healthy control (HC) subjects, using a novel, reliable parcellation of OFC subregions and their association with cognition, especially the Iowa Gambling Task (IGT), and with schizophrenic psychopathology including thought disorder. Twenty-four patients with schizophrenia and 25 age-matched HC subjects underwent MRI. OFC Regions of Interest (ROI) were manually delineated according to anatomical boundaries: Gyrus Rectus (GR); Middle Orbital Gyrus (MiOG); and Lateral Orbital Gyrus (LOG). The OFC sulcogyral pattern was also classified. Additionally, MiOG probability maps were created and compared between groups in a voxel-wise manner. Both groups underwent cognitive evaluations using the IGT, Wisconsin Card SortingTest, and Trail Making Test (TMT). An 11% bilaterally smaller MiOG volume was observed in schizophrenia, compared with HC (F1,47=17.4, P= 0.0001). GR and LOG did not differ, although GR showed a rightward asymmetry in both groups (F1,47=19.2, P<0.0001). The smaller MiOG volume was independent of the OFC sulcogyral pattern, which differed in schizophrenia and HC (χ2=12.49, P= 0.002). A comparison of MiOG probability maps suggested that the anterior heteromodal region was more affected in the schizophrenia group than the posterior paralimbic region. In the schizophrenia group, a smaller left MiOG was strongly associated with worse `positive formal thought disorder' (r=−0.638, P= 0.001), and a smaller right MiOG with a longer duration of the illness (r=−0.618, P= 0.002). While schizophrenics showed poorer performance than HC in the IGT, performance was not correlated with OFC volume. However, within the HC group, the larger the right hemisphere MiOG volume, the better the performance in the IGT (r=0.541, P= 0.005), and the larger the left hemisphere volume, the faster the switching attention performance for the TMT, Trails B (r=−0.608, P= 0.003). The present study, applying a new anatomical parcellation method, demonstrated a subregion-specific OFC grey matter volume deficit in patients with schizophrenia, which was independent of OFC sulcogyral pattern. This volume deficit was associated with a longer duration of illness and greater formal thought disorder. In HC the finding of a quantitative association between OFC volume and IGT performance constitutes, to our knowledge, the first report of this association.
schizophrenia; orbitofrontal region; thought disorder; decision making; Iowa gambling task
We analysed the influence of mesial temporal lobe epilepsy on the thickness of the corpus callosum (CC) in a large sample of well-characterized patients (n = 96) and healthy controls (n = 28). In particular, we investigated whether callosal structures are differentially affected depending on the affected hemisphere and age of epilepsy onset. Overall, we observed that epilepsy is associated with a decreased thickness in posterior callosal regions. Patients with an early onset, especially patients with left onset, additionally exhibited a smaller callosal thickness in more anterior and midbody regions. These findings may reflect non-specific as well as specific effects of temporal lobe epilepsy on CC development and interhemispheric connectivity.
corpus callosum; temporal lobe epilepsy; MRI
Orbitofrontal alteration in schizophrenia has not been well characterized, likely due to marked anatomical variability. To investigate the presence of such alterations, we evaluated the sulcogyral pattern of this ‘H-shaped’ sulcus. Fifty patients with schizophrenia (100 hemispheres) and 50 age- and gender-matched control subjects (100 hemispheres) were evaluated using 3D high-spatial resolution MRI. Based on a previous study by Chiavaras and Petrides (2000), the sulcogyral pattern of the ‘H-shaped’ sulcus, which forms the boundaries of major orbitofrontal gyri, was classified into three types (Type I, II and III, in order of frequency) within each hemisphere. Chi-square analysis was performed to compare the sulcogyral pattern, and categorical regression was applied to investigate clinical/cognitive associations. The control data replicated the orbitofrontal sulcogyral pattern reported by Chiavaras and Petrides (P = 0.90–0.95), where the distribution was significantly different between the left and right hemisphere (Type I: right>left, Type II, III: left>right, χ2 = 6.41, P = 0.041). For schizophrenics, the distribution differed significantly from controls (χ2 = 11.90, P = 0.003), especially in the right hemisphere (χ2 = 13.67, P = 0.001). Moreover, the asymmetry observed in controls was not present in schizophrenia (χ2 = 0.13, P = 0.94). Specifically, the most frequent Type I expression was decreased and the rarest Type III expression was increased in schizophrenia, relative to controls. Furthermore, patients with Type III expression in any hemisphere evinced poorer socioeconomic status, poorer cognitive function, more severe symptoms and impulsivity, compared to patients without Type III expression. In contrast, patients with Type I in any hemisphere showed better cognitive function and milder symptoms compared to patients without Type I. Structurally, patients with Type III had significantly smaller intra-cranial contents (ICC) volumes than did patients without Type III (t40 = 2.29, P = 0.027). The present study provides evidence of altered distribution of orbitofrontal sulcogyral pattern in schizophrenia, possibly reflecting a neurodevelopmental aberration in schizophrenia. Such altered sulcogyral pattern is unlikely to be due to secondary effects of the illness such as medication. Moreover, the structural association between Type III and small ICC volume, observed in the patient group, may suggest that Type III expression could be part of a systematic neurodevelopmental alteration, given that the small ICC volume could reflect early reduction of cranial growth driven by brain growth. The observed contrasting association of Type III expression with poorer outcome, and that of Type I expression with better outcome, further suggests clinical heterogeneity, and possible differences in treatment responsiveness in schizophrenia.
schizophrenia; sulcus; orbitofrontal cortex; magnetic resonance imaging; neurodevelopment
Neuronal oscillations span a wide range of spatial and temporal scales that extend beyond traditional clinical EEG. Recent research suggests that high-frequency oscillations (HFO), in the ripple (80–250Hz) and fast ripple (250–1000Hz) frequency range, may be signatures of epileptogenic brain and involved in the generation of seizures. However, most research investigating HFO in humans comes from microwire recordings, whose relationship to standard clinical intracranial EEG (iEEG) has not been explored. In this study iEEG recordings (DC − 9000Hz) were obtained from human medial temporal lobe using custom depth electrodes containing both microwires and clinical macroelectrodes. Ripple and fast-ripple HFO recorded from both microwires and clinical macroelectrodes were increased in seizure generating brain regions compared to control regions. The distribution of HFO frequencies recorded from the macroelectrodes was concentrated in the ripple frequency range, compared to a broad distribution of HFO frequencies recorded from microwires. The average frequency of ripple HFO recorded from macroelectrodes was lower than that recorded from microwires (143.3 ± 49.3 Hz versus 116.3 ± 38.4, Wilcoxon rank sum P<0.0001). Fast-ripple HFO were most often recorded on a single microwire, supporting the hypothesis that fast-ripple HFO are primarily generated by highly localized, sub-millimeter scale neuronal assemblies that are most effectively sampled by microwire electrodes. Future research will address the clinical utility of these recordings for localizing epileptogenic networks and understanding seizure generation.
high-frequency oscillations; ripple; fast ripple; intracranial EEG; epilepsy
Neurodegenerative disorders are pathologically characterized by the deposition of abnormal proteins in the brain. It is likely that future treatment trials will target the underlying protein biochemistry and it is therefore increasingly important to be able to distinguish between different pathologies during life. The aim of this study was to determine whether rates of brain atrophy differ in neurodegenerative dementias that vary by pathological diagnoses and characteristic protein biochemistry. Fifty-six autopsied subjects were identified with a clinical diagnosis of dementia and two serial head MRI. Subjects were subdivided based on pathological diagnoses into Alzheimer's disease (AD), dementia with Lewy bodies (DLB), mixed AD/DLB, frontotemporal lobar degeneration with ubiquitin-only-immunoreactive changes (FTLD-U), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP). Twenty-five controls were matched by age, gender, and scan interval, to the study cohort. The boundary-shift integral was used to calculate change over time in whole brain (BBSI) and ventricular volume (VBSI). All BSI results were annualized by adjusting for scan interval. The rates of whole brain atrophy and ventricular expansion were significantly increased compared to controls in the AD, mixed AD/DLB, FTLD-U, CBD and PSP groups. However, atrophy rates in the DLB group were not significantly different from control rates of atrophy. The largest rates of atrophy were observed in the CBD group which had a BBSI of 2.3% and VBSI of 16.2%. The CBD group had significantly greater rates of BBSI and VBSI than the DLB, mixed AD/DLB, AD and PSP groups, with a similar trend observed when compared to the FTLD-U group. The FTLD-U group showed the next largest rates with a BBSI of 1.7% and VBSI of 9.6% which were both significantly greater than the DLB group. There was no significant difference in the rates of atrophy between the AD, mixed AD/DLB and PSP groups, which all showed similar rates of atrophy; BBSI of 1.1, 1.3 and 1.0% and VBSI of 8.3, 7.2 and 10.9% respectively. Rates of atrophy therefore differ according to the pathological diagnoses and underlying protein biochemistry. While rates are unlikely to be useful in differentiating AD from cases with mixed AD/DLB pathology, they demonstrate important pathophysiological differences between DLB and those with mixed AD/DLB and AD pathology, and between those with CBD and PSP pathology.
magnetic resonance imaging; Alzheimer's disease; dementia with Lewy bodies; frontotemporal lobar degeneration; progressive supranuclear palsy
Mild cognitive impairment (MCI), particularly the amnestic subtype (aMCI), is considered as a transitional stage between normal aging and a diagnosis of clinically probable Alzheimer's disease (AD). The aMCI construct is particularly useful as it provides an opportunity to assess a clinical stage which in most subjects represents prodromal AD. The aim of this study was to assess the progression of cerebral atrophy over multiple serial MRI during the period from aMCI to conversion to AD. Thirty-three subjects were selected that fulfilled clinical criteria for aMCI and had three serial MRI scans: the first scan approximately three years before conversion to AD, the second scan approximately one year before conversion, and the third scan at the time of conversion from aMCI to AD. A group of 33 healthy controls were age and gender-matched to the study cohort. Voxel-based morphometry (VBM) was used to assess patterns of grey matter atrophy in the aMCI subjects at each time-point compared to the control group. Customized templates and prior probability maps were used to avoid normalization and segmentation bias. The pattern of grey matter loss in the aMCI subject scans that were three years before conversion was focused primarily on the medial temporal lobes, including the amygdala, anterior hippocampus and entorhinal cortex, with some additional involvement of the fusiform gyrus, compared to controls. The extent and magnitude of the cerebral atrophy further progressed by the time the subjects were one year before conversion. At this point atrophy in the temporal lobes spread to include the middle temporal gyrus, and extended into more posterior regions of the temporal lobe to include the entire extent of the hippocampus. The parietal lobe also started to become involved. By the time the subjects had converted to a clinical diagnosis of AD the pattern of grey matter atrophy had become still more widespread with more severe involvement of the medial temporal lobes and the temporoparietal association cortices and, for the first time, substantial involvement of the frontal lobes. This pattern of progression fits well with the Braak and Braak neurofibrillary pathological staging scheme in AD. It suggests that the earliest changes occur in the anterior medial temporal lobe and fusiform gyrus, and that these changes occur at least three years before conversion to AD. These results also suggest that 3-dimensional patterns of grey matter atrophy may help to predict the time to conversion in subjects with aMCI.
Alzheimer's disease; mild cognitive impairment; longitudinal; magnetic resonance imaging; voxel-based morphometry
Acute administration of neuropeptide Y (NPY) modulates alcohol intake in genetic and chemical models of high intake, while leaving intake unaffected during ‘normal’ or baseline conditions. In non-selected, normal rat lines, alcohol consumption can be increased by prolonged exposure to alcohol, and it is unclear what effect a constitutive increase in NPY function will have on alcohol intake. The purpose of the present study was to examine the effects on alcohol intake of an inducible, constitutive overexpression of NPY, one of the most abundant neuropeptides in the central nervous system. A liquid diet was used in combination with repeated alcohol deprivation sessions to increase alcohol intake in normal Wistar rats. We then examined the effect of NPY overexpression in the amygdala on excessive alcohol intake produced by prolonged exposure to alcohol and alcohol deprivation. Repeated withdrawal increased alcohol consumption in a 24-h continuous access two-bottle choice model. Both the number of withdrawals as well as the length of the withdrawal periods affected alcohol consumption with an increased intake resulting from multiple withdrawals and the alcohol deprivation effect being enhanced by longer periods of abstinence. The increase in intake following repeated abstinence was blunted by intra-amygdala administration of a Sindbis viral vector containing NPY cDNA. Amygdala NPY overexpression also was demonstrated to be anxiolytic in the open field test. Repeated withdrawal in combination with a history of alcohol consumption significantly elevated alcohol intake, and the amygdala may mediate the transition to high-drinking states in this model.
alcoholism; animal model; neuropeptide Y; viral vector; amygdala
Apraxia of speech (AOS) is a motor speech disorder characterized by slow speaking rate, abnormal prosody and distorted sound substitutions, additions, repetitions and prolongations, sometimes accompanied by groping and trial-and error articulatory movements. Although AOS is frequently subsumed under the heading of aphasia, and indeed most often co-occurs with aphasia, it can be the predominant or even the sole manifestation of a degenerative neurologic disease. In this study we determined whether the clinical classifications of aphasia and AOS correlated with pathological diagnoses and specific biochemical and anatomical structural abnormalities. Seventeen cases with initial diagnoses of a degenerative aphasia or AOS were reclassified independently by two speech-language pathologists — blinded to pathologic and biochemical findings - into one of five operationally defined categories of aphasia and AOS. Pathological diagnoses in the 17 cases were progressive supranuclear palsy in six, corticobasal degeneration in five, frontotemporal lobar degeneration with ubiquitin-only-immunoreactive changes in five, and Pick’s disease in one. Voxel-based morphometry and SPECT were completed, blinded to the clinical diagnoses, and clinico-imaging and clinico-pathological associations were then sought. Interjudge clinical classification reliability was 87% (κ =0.8) for all evaluations. Eleven cases had evidence of AOS, of which all (100%) had a pathological diagnosis characterized by underlying tau biochemistry, while five of the other six cases without AOS did not have tau biochemistry (p=0.001). A majority of the 17 cases had more than one yearly evaluation, demonstrating the evolution of the speech and language syndromes, as well as motor signs. Voxel-based morphometry revealed the premotor and supplemental motor cortices to be the main cortical regions associated with AOS, while the anterior peri-sylvian region was associated with non-fluent aphasia. Refining the classification of the degenerative aphasias and AOS may be necessary to improve our understanding of the relationships among behavioral, pathological, and imaging correlations.
Premotor cortex; supplementary motor cortex; progressive supranuclear palsy; apraxia of speech; aphasia
Alzheimer’s disease poses a looming crisis for the health care system as well as society in general. The low efficacy of current treatments for those already affected with this disease has prompted the suggestion that interventions might be more successful if they were applied before the development of significant pathology, that is, when individuals are clinically asymptomatic. Currently, the field requires a sensitive and specific diagnostic tool for identifying those individuals destined to develop this disease. As a first step, we present here an analysis of cross-sectional data for 95 asymptomatic offspring (50–75 years of age) of autopsy-confirmed late-onset familial Alzheimer’s disease cases and 90 age-matched controls, studied with functional magnetic resonance imaging (fMRI) to investigate brain activation patterns. Analysis of activation in response to a paired-associates memory paradigm found significantly different patterns in these groups. At-risk individuals showed more intense and extensive activation in the frontal and temporal lobes including the hippocampus during memory encoding, an increase unrelated to the APOE ε4 allele. They also showed decreased activation particularly in the cingulum and thalamus during both the encoding and recall phases of the task. These results demonstrate that asymptomatic individuals, at genetic risk for development of late-onset Alzheimer’s disease by virtue of familial clustering, show functional activation patterns distinct from those without such risk more than a decade before their parent’s onset age. While longitudinal study is needed to determine whether these patterns, or a subset of them, are predictive of disease onset, these findings suggest that functional neuro-imaging holds promise as a method of identifying pre-clinical Alzheimer’s disease.
fMRI; familial Alzheimer’s disease; pre-clinical changes
There is comparatively little information about premorbid maturational brain abnormalities in schizophrenia. We investigated whether a history of childhood enuresis, a well-established marker of neurodevelopmental delay, is associated with schizophrenia and with measures of brain abnormalities also associated with schizophrenia. A DSM-IV based history of enuresis, volumetric brain MRI scans, and neuropsychological testing were obtained in patients with schizophrenia, their non-psychotic siblings, and non-psychiatric controls. The subjects were 211 patients (79.6% male), 234 of their siblings (43.2% male), and 355 controls (39.2% male). Frequency of enuresis was compared across groups and correlated with cognitive measures. Total and regional brain volumes were determined using VBM on matched subsets of probands (n=82) with or without enuresis (n=16, n=66, respectively) and controls (n=102) with or without enuresis (n=11, n=91, respectively). Patients with schizophrenia had higher rates of childhood enuresis (21%) compared with siblings (11%; χ2=6.42, p=0.01) or controls (7%; χ2=23.65, p<0.0001) and relative risk for enuresis was increased in siblings (λS=2.62). Patients with enuresis performed worse on two frontal lobe cognitive tests [Letter Fluency (t=1.97, p=0.05, df=200) and Category Fluency (t=2.15, p=0.03, df=200)] as compared with non-enuretic patients. VBM analysis revealed gray matter volume reductions in several frontal regions (right BA 9, right BA 10, and bilateral BA 45), and right superior parietal cortex (BA 7) in patients with a history of enuresis as compared with non-enuretic patients (all t>3.57, all p<0.001). The high frequency of childhood enuresis associated with schizophrenia, and abnormalities in prefrontal function and structure in patients with a childhood history of enuresis suggest that childhood enuresis may be a premorbid marker for neurodevelopmental abnormalities related to schizophrenia. These findings add to the evidence implicating prefrontal dysmaturation in this disorder, potentially related to genetic risk factors.
Schizophrenia; Enuresis; Development; Neuroimaging; Frontal lobes