Multicenter analysis of glucocerebrosidase mutations in Parkinson's disease

BACKGROUND

Recent studies indicate an increased frequency of mutations in the gene encoding glucocerebrosidase (GBA), a deficiency of which causes Gaucher's disease, among patients with Parkinson's disease. We aimed to ascertain the frequency of GBA mutations in an ethnically diverse group of patients with Parkinson's disease.

METHODS

Sixteen centers participated in our international, collaborative study: five from the Americas, six from Europe, two from Israel, and three from Asia. Each center genotyped a standard DNA panel to permit comparison of the genotyping results across centers. Genotypes and phenotypic data from a total of 5691 patients with Parkinson's disease (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews) were analyzed, with multivariate logistic-regression models and the Mantel-Haenszel procedure used to estimate odds ratios across centers.

RESULTS

All 16 centers could detect two GBA mutations, L444P and N370S. Among Ashkenazi Jewish subjects, either mutation was found in 15% of patients and 3% of controls, and among non-Ashkenazi Jewish subjects, either mutation was found in 3% of patients and less than 1% of controls. GBA was fully sequenced for 1883 non-Ashkenazi Jewish patients, and mutations were identified in 7%, showing that limited mutation screening can miss half the mutant alleles. The odds ratio for any GBA mutation in patients versus controls was 5.43 across centers. As compared with patients who did not carry a GBA mutation, those with a GBA mutation presented earlier with the disease, were more likely to have affected relatives, and were more likely to have atypical clinical manifestations.

CONCLUSIONS

Data collected from 16 centers demonstrate that there is a strong association between GBA mutations and Parkinson's disease.

Charcot-Marie-Tooth type 4B is caused by mutations in the gene encoding myotubularin-related protein-2

A gene mutated in Charcot-Marie-Tooth disease type 4B (CMT4B), an autosomal recessive demyelinating neuropathy with myelin outfoldings, has been mapped on chromosome 11q22. Using a positional-cloning strategy, we identified in unrelated CMT4B patients mutations occurring in the gene MTMR2, encoding myotubularin-related protein-2, a dual specificity phosphatase (DSP).

The nicotinic receptor beta 2 subunit is mutant in nocturnal frontal lobe epilepsy

Clustered attacks of epileptic episodes originating from the frontal lobe during sleep are the main symptoms of autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE, MIM 600513). Despite the clinical homogeneity, three forms of ADNFLE have been associated with chromosomes 20 (ENFL1; ref. 1), 15 (ENFL2; ref. 2) and 1 (ENFL3; ref. 3). Mutations of the gene encoding the neuronal nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4 ) have been found in ADNFLE-ENFL1 families, but these mutations account for only a small proportion of ADNFLE cases. The newly identified locus associated with ENFL3 harbours several candidate genes, including CHRNB2 (ref. 8), whose gene product, the beta 2 nicotinic acetylcholine receptor (nAChR) subunit, co-assembles with the alpha 4 nAChR subunit to form the active receptor.

Cationic lipids improve antisense oligonucleotide uptake and prevent degradation in cultured cells and in human serum

The power of antisense phosphodiester oligonucleotides (aODN) as regulatory molecules of gene expression is strongly limited by their low cellular uptake and very rapid nuclease-mediated degradation. This study deals with the effect of artificial cationic lipids on ODN cellular uptake and degradation in cell cultures and in human serum. At the ODN levels normally used in antisense-mediated gene regulation experiments, a cationic lipid, DOTAP, enhances the rate of ODN uptake more than 25 fold, but at lower ODN levels the effect of DOTAP is absent. These findings are consistent with a mechanism of ODN internalization by receptor-mediated saturable endocytosis that is bypassed by DOTAP. ODN degradation by nucleases is markedly prevented by DOTAP both in cultured cells and in human serum. Other cationic lipids, namely DOTMA and DOGS, exhibit very similar behaviour. The relatively slight cellular toxicity revealed by cationic lipids contribute to render these molecules very suitable for aODN vehiculation.

Essential head tremor is associated with cerebellar vermis atrophy: a volumetric and voxel-based morphometry MR imaging study

BACKGROUND AND PURPOSE

Our aim was to investigate the presence of brain gray matter (GM) abnormalities in patients with different forms of essential tremor (ET).

MATERIALS AND METHODS

We used optimized voxel-based morphometry (VBM) and manually traced single region-of-interest analysis in 50 patients with familial ET and in 32 healthy subjects. Thirty patients with ET had tremor of the arms (a-ET), whereas the remaining 20 patients had both arm and head tremor (h-ET).

RESULTS

VBM showed marked atrophy of the cerebellar vermis in the patients with h-ET with respect to healthy subjects (P(corrected) < .001). Patients with a-ET showed a trend toward a vermal GM volume loss that did not reach a significant difference with respect to healthy controls (P(uncorrected) < .01). The region-of-interest analysis showed a reduction of the cerebellar volume (CV) in the h-ET group (98.2 +/- 13.6 mm(3)) compared with healthy controls (110.5 +/- 15.5 mm(3), P < .012) as well as in the entire vermal area (790.3 +/- 94.5 mm(2), 898.6 +/- 170.6 mm(2), P < .04 in h-ET and control groups, respectively).

CONCLUSIONS

Atrophy of the cerebellar vermis detected in patients with h-ET strongly supports the evidence for the involvement of the cerebellum in the pathophysiology of ET. The lack of a significant CV loss observed in patients with a-ET suggests that a-ET and h-ET might represent distinct subtypes of the same disease.

Machine learning on brain MRI data for differential diagnosis of Parkinson's disease and Progressive Supranuclear Palsy

BACKGROUND

Supervised machine learning has been proposed as a revolutionary approach for identifying sensitive medical image biomarkers (or combination of them) allowing for automatic diagnosis of individual subjects. The aim of this work was to assess the feasibility of a supervised machine learning algorithm for the assisted diagnosis of patients with clinically diagnosed Parkinson's disease (PD) and Progressive Supranuclear Palsy (PSP).

METHOD

Morphological T1-weighted Magnetic Resonance Images (MRIs) of PD patients (28), PSP patients (28) and healthy control subjects (28) were used by a supervised machine learning algorithm based on the combination of Principal Components Analysis as feature extraction technique and on Support Vector Machines as classification algorithm. The algorithm was able to obtain voxel-based morphological biomarkers of PD and PSP.

RESULTS

The algorithm allowed individual diagnosis of PD versus controls, PSP versus controls and PSP versus PD with an Accuracy, Specificity and Sensitivity>90%. Voxels influencing classification between PD and PSP patients involved midbrain, pons, corpus callosum and thalamus, four critical regions known to be strongly involved in the pathophysiological mechanisms of PSP.

COMPARISON WITH EXISTING METHODS

Classification accuracy of individual PSP patients was consistent with previous manual morphological metrics and with other supervised machine learning application to MRI data, whereas accuracy in the detection of individual PD patients was significantly higher with our classification method.

CONCLUSIONS

The algorithm provides excellent discrimination of PD patients from PSP patients at an individual level, thus encouraging the application of computer-based diagnosis in clinical practice.

Prolactin secretion in man: a useful tool to evaluate the activity of drugs on central 5-hydroxytryptaminergic neurones. Studies with fenfluramine

Acute oral administration of various doses of fenfluramine, a 5-HT releaser, induced a dose-related increase of PRL secretion in nine healthy volunteers. Fenfluramine reached the maximum effect on PRL secretion at 4 h after its administration. This effect was already significant at 2 h and lasted till 8 h. Metergoline, a 5-HT receptor blocker, when administered alone, decreased serum PRL levels in six healthy subjects. The pretreatment with this drug significantly antagonized the PRL-releasing action of fenfluramine (60 mg) suggesting that the effect of fenfluramine on PRL release may be mediated through a 5-HT mechanism in the brain. These findings suggest the possibility that serum PRL levels in humans may represent a useful tool to evaluate, in vivo, the activity of drugs possessing putative 5-hydroxytryptaminergic properties.

Posttranscriptional regulation of gene expression in learning by the neuronal ELAV-like mRNA-stabilizing proteins

The view that memory is encoded by variations in the strength of synapses implies that long-term biochemical changes take place within subcellular microdomains of neurons. These changes are thought ultimately to be an effect of transcriptional regulation of specific genes. Localized changes, however, cannot be fully explained by a purely transcriptional control of gene expression. The neuron-specific ELAV-like HuB, HuC, and HuD RNA-binding proteins act posttranscriptionally by binding to adenine- and uridine-rich elements (AREs) in the 3' untranslated region of a set of target mRNAs, and by increasing mRNA cytoplasmic stability and/or rate of translation. Here we show that neuronal ELAV-like genes undergo a sustained up-regulation in hippocampal pyramidal cells only of mice and rats that have learned a spatial discrimination paradigm. This learning-specific increase of ELAV-like proteins was localized within cytoplasmic compartments of the somata and proximal dendrites and was associated with the cytoskeleton. This increase was also accompanied by enhanced expression of the GAP-43 gene, known to be regulated mainly posttranscriptionally and whose mRNA is demonstrated here to be an in vivo ELAV-like target. Antisense-mediated knockdown of HuC impaired spatial learning performance in mice and induced a concomitant down-regulation of GAP-43 expression. Neuronal ELAV-like proteins could exert learning-induced posttranscriptional control of an array of target genes uniquely suited to subserve substrates of memory storage.

Brain atrophy and lesion load in a large population of patients with multiple sclerosis

OBJECTIVE

To measure white matter (WM) and gray matter (GM) atrophy and lesion load in a large population of patients with multiple sclerosis (MS) using a fully automated, operator-independent, multiparametric segmentation method.

METHODS

The study population consisted of 597 patients with MS and 104 control subjects. The MRI parameters were abnormal WM fraction (AWM-f), global WM-f (gWM-f), and GM fraction (GM-f).

RESULTS

Significant differences between patients with MS and control subjects included higher AWM-f and reduced gWM-f and GM-f. MRI data showed significant differences between patients with relapsing-remitting and secondary progressive forms of MS. Significant correlations between MRI parameters and between MRI and clinical data were found.

CONCLUSIONS

Patients with multiple sclerosis have significant atrophy of both white matter (WM) and gray matter (GM); secondary progressive patients have significantly more atrophy of both WM and GM than do relapsing-remitting patients and a significantly higher lesion load (abnormal WM fraction); lesion load is related to both WM and even more to GM atrophy; lesion load and WM and GM atrophy are significantly related to Expanded Disability Status Scale score and age at onset (suggesting that the younger the age at disease onset, the worse the lesion load and brain atrophy); and GM atrophy is the most significant MRI variable in determining the final disability.

Defining a neuron: neuronal ELAV proteins

Neuronal cells strongly depend on the control exerted by RNA-binding proteins (RBPs) on gene expression for the establishment and maintenance of their phenotype. Neuronal ELAV (nELAV) proteins are RBPs able to influence virtually every aspect of the postsynthesis fate of bound mRNAs, from polyadenylation, alternative splicing and nuclear export to cytoplasmic localization, stability and translation. They enhance gene expression through the last two, best documented activities, increasing mRNA half-life and promoting protein synthesis by a still-unknown molecular mechanism. Developmentally, nELAV proteins have been shown to act as inducers of the transition between neural stem/progenitor cells and differentiation-committed cells, also assisting these neuroblasts in the completion of their maturation program. In brain physiology, they are also the first RBPs demonstrated to have a pivotal role in memory, where they probably control mRNA availability for translation in subcellular domains, thereby providing a biochemical means for selective increase in synaptic strength.

Cerebellar atrophy in essential tremor using an automated segmentation method

BACKGROUND AND PURPOSE

Essential tremor (ET) is a slowly progressive disorder characterized by postural and kinetic tremors most commonly affecting the forearms and hands. Several lines of evidence from physiologic and neuroimaging studies point toward a major role of the cerebellum in this disease. Recently, voxel-based morphometry (VBM) has been proposed to quantify cerebellar atrophy in ET. However, VBM was not originally designed to study subcortical structures, and the complicated anatomy of the cerebellum may hamper the automatic processing of VBM. The aim of this study was to determine the efficacy and utility of using automated subcortical segmentation to identify atrophy of the cerebellum and other subcortical structures in patients with ET.

MATERIALS AND METHODS

We used a recently developed automated volumetric method (FreeSurfer) to quantify subcortical atrophy in ET by comparing results obtained with this method with those provided by previous evidence. The study included T1-weighted MR images of 46 patients with ET grouped into those having arm ET (n = 27, a-ET) or head ET (n = 19, h-ET) and 28 healthy controls.

RESULTS

Results revealed the expected reduction of cerebellar volume in patients with h-ET with respect to healthy controls after controlling for intracranial volume. No significant difference was detected in any other subcortical area.

CONCLUSIONS

Volumetric data obtained with automated segmentation of subcortical and cerebellar structures approximate data from a previous study based on VBM. The current findings extend the literature by providing initial validation for using fully automated segmentation to derive cerebellar volumetric information from patients with ET.

GABA(B) receptor 1 polymorphism (G1465A) is associated with temporal lobe epilepsy

BACKGROUND

Dysfunction of gamma-aminobutyric acid (GABA) (B) receptors has been implicated in the pathogenesis of temporal lobe epilepsy (TLE).

OBJECTIVE

To evaluate the genetic contribution of cloned human GABA(B) receptors to TLE.

METHODS

The authors genotyped 141 patients (78 women and 63 men; mean age = 49.1 +/- 18.0 years) with nonlesional TLE and 372 age- and sex-matched normal individuals for the known polymorphism G1465A in the human GABA(B) receptor 1 [GABA(B[1])] gene.

RESULTS

There was a highly significant overrepresentation of the G1465A heterozygote in patients with TLE compared with controls. The A/G genotype was found in 17% of the 141 patients with TLE and in only 0.5% of the 372 controls (p < 0.0001). The authors also found that patients carrying the A allele had a significantly higher risk (p = 0.003, OR = 6.47, 95% CI = 2.02 to 20.76) of developing drug-resistant TLE. Furthermore, the age at onset of seizures tended to be lower in patients with A/G genotype, but the difference was not significant.

CONCLUSIONS

The results of this study indicate that the GABA(B[1]) polymorphism (G1465A) confers a highly increased susceptibility to TLE. Moreover, it seems to influence the severity of this common epileptic disorder.

Transverse sinus stenoses persist after normalization of the CSF pressure in IIH

BACKGROUND

Bilateral transverse sinus (TS) stenosis has been found in more than 90% of patients with idiopathic intracranial hypertension (IIH).

OBJECTIVE

To evaluate whether TS stenosis changed after normalization of CSF pressure in patients with IIH during medical treatment.

METHODS

Fourteen consecutive patients with IIH with bilateral TS stenosis on cerebral MR venography (MRV) during the medical treatment were studied. Patients were followed for over a 6-year period. During the follow-up, patients underwent repeated lumbar punctures (LPs) and cerebral MRV. MRV was always performed before each LP.

RESULTS

TS stenosis persisted in all the patients during the follow-up. In 9 of 14 (64%) patients with IIH, CSF pressure normalized during medical treatment.

CONCLUSIONS

Transverse sinus (TS) stenoses, as revealed by MR venography, persist in patients with idiopathic intracranial hypertension after normalization of CSF pressure, suggesting the lack of a direct relationship between the caliber of TS and CSF pressure.

Cognitive dysfunction in patients with relapsing-remitting multiple sclerosis

Cognitive dysfunction is considered one of the clinical markers of multiple sclerosis (MS). However, in the literature there are inconsistent reports on the prevalence of cognitive dysfunction, and separate data for the relapsing-remitting (RR) type of the disease are not always presented. In this study, we submitted 461 RRMS patients to a battery of neuropsychological tests to investigate their impairment in various cognitive domains. As a consequence of the exclusion criteria, the sample is not fully representative of the entire population of RRMS patients. In this selected sample, when only the eight scores of a core battery (Mental Deterioration Battery) were considered (with respective cutoffs), it emerged that 31% of the patients were affected by some degree of cognitive deficit. In particular, 15% had mild, 11.2% moderate and 4.8% had severe impairment. Information processing speed was the most frequently impaired area, followed by memory. When two other tests (SDMT and MCST) were added and cognitive domains were considered, it emerged that 39.3% of the patients were impaired in two or more domains. When four subgroups were obtained by means of cluster analysis and then compared, it emerged that information processing speed and memory deficits differentiated the still cognitively unimpaired from the mildly impaired MS patients. Significant associations were found between cognitive and clinical characteristics. However, due to the large sample size, clinically irrelevant relationships may also have emerged. Even with the limitations imposed by the sample selection and the possible underestimation of the prevalence and severity of cognitive dysfunction, these results seem to provide further evidence that information processing speed deficit may be an early and important marker of cognitive impairment in MS patients.

A conserved AU-rich element in the 3' untranslated region of bcl-2 mRNA is endowed with a destabilizing function that is involved in bcl-2 down-regulation during apoptosis

The control of mRNA stability is becoming recognized as a crucial point of gene expression regulation. A common element responsible for mRNA decay modulation is the adenine- and uracil-rich element that is found in the 3' untranslated region of numerous mRNAs subjected to fast expression changes in response to various stimuli. Previously we identified a post-transcriptional regulation level for the antiapoptotic bcl-2 gene, which could be involved in t(14;18) lymphoma-associated bcl-2 overexpression. Here we demonstrate that bcl-2 mRNA is endowed with an adenine- and uracil-rich element (ARE) characterized by high evolutionary conservation not only among all chordates examined, but even between chordates and the nematode Caenorhabditis elegans (ced-9 gene). As for other well-established destabilizing AREs, the insertion of the bcl-2 ARE downstream from stable beta-globin mRNA causes an enhanced decay of the beta-globin transcript, which proves its functional role. This possibility is corroborated by the fact that the pathway leading to the modulating activity of bcl-2 ARE is influenced by PKC, since the addition of DAG and TPA markedly attenuated the bcl-2 ARE destabilizing potential. Conversely, it is noteworthy that when C(2)-ceramide is added to the culture medium as the apoptotic agent, the beta-globin transcript harboring the bcl-2 ARE undergoes a dramatic increase in decay. This observation clearly indicates that the destabilizing function of bcl-2 ARE is enhanced by apoptotic stimuli and suggests that this element could be involved in a post-transcriptional mechanism of bcl-2 down-regulation during apoptosis. The half-life of the mRNA of bcl-2 in Jurkat cells is prolonged by PKC stimulation and shortened by C(2)-ceramide addition, strongly supporting the view that bcl-2 mRNA stability plays a physiological role in modulating bcl-2 expression, particularly in its down-regulation during apoptosis. Thus, this element becomes a new candidate for mediating those bcl-2 gene expression changes-from apoptosis-associated down-regulation to tumor-associated overexpression-observed thus far that profoundly influence single cell fate and tissue homeostasis.

Randomized trial comparing two different high doses of methylprednisolone in MS: a clinical and MRI study

OBJECTIVE

To assess the efficacy of two different high doses of intravenous methylprednisolone (IVMP) for the treatment of relapses in MS.

BACKGROUND

IVMP is the treatment of choice for MS relapses, but it is unknown whether its effects are dose related.

METHODS

We conducted a double-blind, randomized study. Follow-up included serial clinical and MRI recordings at baseline and at 7, 15, 30, and 60 days after the beginning of treatment. Outcome measures were the number of brain and cervical spinal cord MRI contrast-enhancing lesions, and the Expanded Disability Status Scale score.

RESULTS

Both treatment regimens improved clinical scores and reduced the number of MRI enhancing lesions during the follow-up period. The higher dose of IVMP was significantly more effective than the lower dose in reducing the number of MRI contrast-enhanced lesions at 30 and 60 days, mainly by decreasing the rate of new lesion formation.

CONCLUSIONS

The higher dosage of IVMP has a more powerful and prolonged action in maintaining blood-brain barrier integrity after a clinical relapse.

Genetic counselling in ALS: facts, uncertainties and clinical suggestions

The clinical approach to patients with amyotrophic lateral sclerosis (ALS) has been largely modified by the identification of novel genes, the detection of gene mutations in apparently sporadic patients, and the discovery of the strict genetic and clinical relation between ALS and frontotemporal dementia (FTD). As a consequence, clinicians are increasingly facing the dilemma on how to handle genetic counselling and testing both for ALS patients and their relatives. On the basis of existing literature on genetics of ALS and of other late-onset life-threatening disorders, we propose clinical suggestions to enable neurologists to provide optimal clinical and genetic counselling to patients and families. Genetic testing should be offered to ALS patients who have a first-degree or second-degree relative with ALS, FTD or both, and should be discussed with, but not offered to, all other ALS patients, with special emphasis on its major uncertainties. Presently, genetic testing should not be proposed to asymptomatic at-risk subjects, unless they request it or are enrolled in research programmes. Genetic counselling in ALS should take into account the uncertainties about the pathogenicity and penetrance of some genetic mutations; the possible presence of mutations of different genes in the same individual; the poor genotypic/phenotypic correlation in most ALS genes; and the phenotypic pleiotropy of some genes. Though psychological, social and ethical implications of genetic testing are still relatively unexplored in ALS, we recommend multidisciplinary counselling that addresses all relevant issues, including disclosure of tests results to family members and the risk for genetic discrimination.

Dopamine D2 receptor gene polymorphism and the risk of levodopa-induced dyskinesias in PD

OBJECTIVE

To investigate whether polymorphisms in the genes for dopamine receptors D1 and D2 are associated with the risk of developing peak-dose dyskinesias in PD.

BACKGROUND

Peak-dose dyskinesias are the most common side effects of levodopa therapy for PD. The identified predictors may only partially account for the risk of developing peak-dose dyskinesias because a substantial proportion of patients never develop peak-dose dyskinesias. Genetic factors could play a role in determining the occurrence of peak-dose dyskinesias.

METHODS

A case-control study of 136 subjects with sporadic PD and 224 population control subjects. We studied three polymorphisms involving the dopamine receptor D1 gene and one intronic short tandem repeat polymorphism of the dopamine receptor D2 gene.

RESULTS

The polymorphisms of the dopamine receptor D1 gene were not associated with the risk of developing PD or peak-dose dyskinesias. The 15 allele of the polymorphism of the dopamine receptor D2 gene was more frequent in parkinsonian subjects than in control subjects. More important, the frequency of both the 13 allele and the 14 allele of the dopamine receptor D2 gene polymorphism was higher in nondyskinetic than in the dyskinetic PD subjects. The risk reduction of developing peak-dose dyskinesias for PD subjects carrying at least 1 of the 13 or 14 alleles was 72% with respect to the PD subjects who did not carry these alleles.

CONCLUSIONS

Certain alleles of the short tandem repeat polymorphism of the dopamine receptor D2 gene reduce the risk of developing peak-dose dyskinesias and could contribute to varying susceptibility to develop peak-dose dyskinesias during levodopa therapy.

Autosomal recessive hereditary motor and sensory neuropathy with focally folded myelin sheaths: clinical, electrophysiologic, and genetic aspects of a large family

We describe 10 patients from a large family with early onset motor and sensory neuropathy. Six were still living at the time of the study. In all cases, early motor milestones had been achieved. Mean age at onset of symptoms was 34 months; these included progressive distal and proximal muscle weakness of lower limbs. Pes equinovarus developed in all patients during childhood. Slight facial weakness was present in four patients, and one of them also had bilateral facial synkinesia. Intellectual function was normal in all cases. There was no evidence of thickened peripheral nerves. All three adult patients (mean age, 27 years) were seriously handicapped and wheelchair-bound. Death occurred in the fourth to fifth decade of life and the duration of the illness varied from 27 to 39 years. Motor nerve conduction velocities ranged from 15 to 17 m/sec in the upper limbs of the youngest patients, and were undetectable in the adult patients. Sensitive action potentials were almost always absent. In all patients, auditory evoked potentials showed abnormally delayed interpeak I-III latencies. The most prominent pathologic finding was a highly unusual myelin abnormality consisting of irregular redundant loops and folding of the myelin sheath. The genealogic study gave strong evidence of autosomal-recessive inheritance. The molecular analysis failed to demonstrate either duplication in the chromosome 17p11.2-12, point mutations in the four exons of the PMP-22 (17p11.2) and the six exons of the Po (1q21-q25) genes, or linkage to chromosome 8q13-21.1.

Increased functional connectivity within mesocortical networks in open people

Openness is a personality trait reflecting absorption in sensory experience, preference for novelty, and creativity, and is thus considered a driving force of human evolution. At the brain level, a relation between openness and dopaminergic circuits has been proposed, although evidence to support this hypothesis is lacking. Recent behavioral research has also found that people with mania, a psychopathological condition linked to dopaminergic dysfunctions, may display high levels of openness. However, whether openness is related to dopaminergic circuits has not been determined thus far. We addressed this issue via three functional magnetic resonance imaging (fMRI) experiments in n=46 healthy volunteers. In the first experiment participants lied at rest in the scanner while in the other two experiments they performed active tasks that included the presentation of pleasant odors and pictures of food. Individual differences in openness and other personality traits were assessed via the NEO-PI-R questionnaire (NEO-Personality Inventory-Revised), a widely employed measure of the five-factor model personality traits. Correlation between fMRI and personality data was analyzed via state-of-art methods assessing resting-state and task-related functional connectivity within specific brain networks. Openness was positively associated with the functional connectivity between the right substantia nigra/ventral tegmental area, the major source of dopaminergic inputs in the brain, and the ipsilateral dorsolateral prefrontal cortex (DLPFC), a key region in encoding, maintaining, and updating information that is relevant for adaptive behaviors. Of note, the same connectivity pattern was consistently found across all of the three fMRI experiments. Given the critical role of dopaminergic signal in gating information in DLPFC, the increased functional connectivity within mesocortical networks in open people may explain why these individuals display a wide "mental permeability" to salient stimuli and an increased absorption in sensory experience.

Spatial learning induced changes in expression of the ryanodine type II receptor in the rat hippocampus

Calcium signaling critical to neural functions is mediated through Ca(2+) channels localized on both the plasma membrane and intracellular organelles such as endoplasmic reticulum. Whereas Ca(2+) influx occurs via the voltage- or/and ligand-sensitive Ca(2+) channels, Ca(2+) release from intracellular stores that amplifies further the Ca(2+) signal is thought to be involved in more profound and lasting changes in neurons. The ryanodine receptor, one of the two major intracellular Ca(2+) channels, has been an important target for studying Ca(2+) signaling in brain functions, including learning and memory, due to its characteristic Ca(2+)-induced Ca(2+) release. In this study, we report regional and cellular distributions of the type-2 ryanodine receptor (RyR2) mRNA in the rat brain, and effects of spatial learning on RyR2 gene expression at mRNA and protein levels in the rat hippocampus. Using in situ hybridization, reverse transcription polymerase chain reaction, and ribonuclease protection assays, significant increases in RyR2 mRNA were found in the hippocampus of rats trained in an intensive water maze task. With immunoprecipitation and immunoblotting, protein levels of RyR2 were also demonstrated to be increased in the microsomal fractions prepared from hippocampi of trained rats. These results suggest that RyR2, and hence the RyR2-mediated Ca(2+) signals, may be involved in memory processing after spatial learning. The increases in RyR2 mRNA and protein at 12 and 24 h after training could contribute to more permanent changes such as structural modifications during long-term memory storage. Zhao, W., Meiri, N., Xu, H., Cavallaro, S., Quattrone, A., Zhang, L., Alkon, D. A. Spatial learning induced changes in expression of the ryanodine type II receptor in the rat hippocampus.

MRI evidence of mesial temporal sclerosis in sporadic "benign" temporal lobe epilepsy

OBJECTIVE

To determine whether there is MRI-detectable mesial temporal sclerosis (MTS) in patients with sporadic benign temporal lobe epilepsy (BTLE).

METHODS

Brain MRIs were obtained from 101 consecutive, unrelated patients (51 women; mean age 37.3 +/- 17.5 years; range 10 to 83 years) with BTLE, who reported rarely or never having had seizures at the time of long-term (> 2 years) follow-up. The mean age at seizure onset was 22.3 +/- 17.4 years; the mean duration of epilepsy was 16.4 +/- 14.1 years. MRI diagnosis of MTS was based on the occurrence of hippocampal formation atrophy on T1 slices, an increased mesial temporal signal intensity alteration on fluid-attenuated inversion-recovery (FLAIR) or T2 images, or both.

RESULTS

Thirty-nine of 101 patients (38.6%) had MRI evidence of unilateral MTS (19/39 left MTS, 20/39 right MTS), which correlated with the epileptiform activity. Hyperintense FLAIR and T2 signal with or without atrophy was observed in 24 of 39 individuals. There was no difference between patients with or without MRI-detected MTS in age at onset and duration of epilepsy. Family history of epilepsy or febrile convulsions (FCs) was more frequent in patients with MRI-detected MTS (36%) as compared with patients with normal MRI (22.7%), but the difference was not significant. Antecedent FCs were more frequent (p = 0.03) in patients with MRI-detected MTS (9/39; 23%) vs those with normal MRI (5/62; 8%).

CONCLUSIONS

MRI-detected mesial temporal sclerosis is often encountered in patients with sporadic benign temporal lobe epilepsy.