Functional MRI study of gender effects in brain activations during verbal working memory task.

Neuroimaging methods have been used to study differences of brain function between males and females. Differences in working memory have been also investigated, but results of such studies are mixed with respect to behavioral data, reaction times and activated brain areas. We tried to analyze functional MRI data acquired during the working memory task and search for differences of brain activation between genders. 20 healthy right-handed volunteers (10 males and 10 females) participated in the study. All of them were university students or fresh graduates. Subjects underwent block designed verbal working memory task (Item Recognition Task) inside the MRI scanner. Standard single-subject pre-processing and group fMRI analyses were performed using the FEAT software from FSL library. In the behavioral data, there was no statistically significant difference in the number of correct responses during the task. The task activated similar bilateral regions of frontal, parietal, temporal and occipital lobes, basal ganglia, the brainstem and in the cerebellum, which corresponds to the previous verbal working memory neuroimaging research. In direct comparison, there was no statistically significant difference in brain activation between small samples of male and female young healthy volunteers.

[Influence of Cervical Spondylotic Spinal Cord Compression on Cerebral Cortical Adaptation. Radiological Study]. / Vliv cervikální spondylogenní mísní komprese na korové funkce mozku. Radiologická studie.

PURPOSE OF THE STUDY: The aim of the study was to measure the sensorimotor brain adaptation activity, shown on functional magnetic resonance images (fMRI), in relation to the degree and extent of spinal cord compression or cervical spondylotic myelopathy (CSM) detected by cervical spine MRI. MATERIAL AND METHODS: Twenty-one patients (average age, 57 years; 9 men and 12 women) with anterior cervical cord compression detected on cervical MRI scans were included. On the images, the degree of spinal canal stenosis, the spinal cord compression based on the antero-posterior diameter of the spinal canal and on transverse areas of the cervical spinal cord and cervical spinal canal, and changes in spinal cord signal intensity were identified. Clinical examination included neurological status, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI) and pain intensity assessment using the Visual Analogue Scale (VAS). Electrophysiological tests involving motor evoked and sensory evoked potential (MEP and SEP) recording were conducted and, using fMRI, brain activity during movement of both arms was measured. Based on the transverse spinal cord area of above or below 70 mm2, the patients were placed into two subgroups. According to changes in spinal cord signal intensity, the patients were included into three subgroups with normal findings, incipient myelopathy and advanced myelopathy, respectively. Surgery was carried out from the anterior approach and involved cervical disc replacement. All examinations were performed again at 6 months after surgery. Pre- and post-operative results were compared within each set of subgroups and statistically evaluated. RESULTS: The average pre-operative values were found to increase post-operatively as follows: from 6.4 mm to 8.9 mm (by 39%) for the antero-posterior diameter of the spinal canal; from 129.3 mm2 to 162.8 mm2 (by 26%) for the transverse area of the spinal canal; from 72.6 mm2 to 87.4 mm2 (by 20%) for the transverse spinal cord area; and from 16.3 to 17.4 for the JOA score. The average NDI decreased from 37.9 to 23.7 and the average VAS fell from 6.4 to 1.5. All patients with the change of spinal cord signal that indicated advanced myelopathy also had relevant pathological findings on MEP/SEP examination and this was statistically significant. There was no significant difference in fMRI scans between the two subgroups established on the basis of transverse spinal cord area measurements. In the patients grouped by a change in spinal cord signals, the pre-operative fMRI showed a significantly higher brain activation volume in the subgroup with advanced myelopathy, as compared with the two other subgroups. Surgery resulted in a moderate reduction of the volume of active brain tissue in all three groups. In the patients with advanced myelopathy evaluated in relation to local changes in brain activation, surgery led to a significant decrease in activation volumes in the ipsilateral primary motor cortex and cerebellar hemisphere. There was also a significant increase in activation of the contralateral supplementary motor cortex. DISCUSSION: It is evident that the brain responds to spinal cord damage by increased activity, but with a certain delay. A slightly altered spinal cord signal intensity, such as in incipient myelopathy, apparently does not result in brain activation. On the other hand, significant changes in signal intensity in advanced myelopathy are related to deterioration of spinal cord function, as shown by MEP and SEP examination results, and an increase in both the volume and intensity of cortical motor activation as a compensation mechanism for myelopathy. CONCLUSIONS Hyperintense spinal cord signals on T2-weighted images correlated with the pathological spinal cord function detected by electrophysiological test in all patients. The transverse spinal cord area (around 70 mm2) showed no significant correlation with either sensory and motor brain adaptations or the results of SEP and MEP testing; therefore, as a criterion for indication to surgery it is of no value. The patients with advanced myelopathy, as detected by spinal cord MRI, had a significantly higher pre-operative cortical motor activation on fMRI than patients with normal findings or those with incipient myelopathy. In addition, the patterns of cortical motor activation altered significantly at 6 months after spinal cord decompression, which was shown by an increase or decrease in activation of the relevant motor cortex areas.

[Effects of spinal cord decompression in patients with cervical spondylotic myelopathy oncortical brain activations]. / Efekt dekomprese krcní míchy pri spondylogenní myelopatii na korové funkce mozku.

INTRODUCTION: The aim of this project was to compare and evaluate cortical sensorimotor adaptations as measured by brain fMRI (functional magnetic resonance imaging) in patients before and after surgery for cervical spondylotic myelopathy (CSM), i.e., after spinal cord decompression. MATERIAL AND METHODS: Study inclusion required evidence of CSM on MRI of the cervical spine, anterior compression of the spinal cord by osteophytes, or disc herniation. We measured the antero-posterior diameter of the spinal canal stenosis before and 3 months after surgery. Surgery was performed at one or two levels from the anterior approach with implantation of radiolucent spacers, without plate fixation. Each participant underwent two fMRI brain examinations, the first one preoperatively and the second one 6 months following surgery. Subjects performed acoustically paced repetitive wrist flexion and extension of each upper extremity according to block design. MRI data were acquired using 1.5 Tesla scanners. Statistical analysis was carried out using the general linear model implemented in FEAT 6.00 (FMRI Expert Analysis Tool), part of the FSL 5.0 package (FMRIB Software Library). The group differences were evaluated using paired t-test and the resulting statistical maps evaluated as Z-score (standardised value of the t-test) were thresholded at a corrected significance level of p <0.05. The study group consisted of 7 patients including 5 female and 2 male patients, with the average age of 55.7 years. Patients with cervical spondylogenous radiculopathy were evaluated as a control group. RESULTS: The analysis of mean group effects in brain fMRI during flexion and extension of both wrists revealed significant activation in dorsal primary motor cortex contralaterally to the active extremity and in adjacent secondary motor and sensory areas, bilaterally in supplementary motor areas, the anterior cingulum, primary auditory cortex, in the region of the basal ganglia, thalamus and cerebellum. After surgery, the cortical activations and maximum Z-scores decreased in most areas. Analysis of differences between sessions before and after surgery showed a statistically significant activation decrease during movement of both extremities in the right parietal operculum and the posterior temporal lobe. During left wrist movement, there was additional activation decrease in the right superior parietal lobe, the supramarginal gyrus, insular cortex, and the central operculum. In contrast, an activation decrease was detected in the left middle temporal gyrus during right wrist movement. CONCLUSION: An average difference of anteroposterior cervical spinal canal distance before and after surgery of CSM was 2.67 millimetres, representing a 40% increase; the cross-sectional area of the spinal canal increased by 37% and that of the spinal cord by 36%. Functional MRI of the brain revealed significant activation especially in primary and secondary motor cortex and sensory areas in patients with CSM. After surgical decompression of the spinal cord, cortical activations and maximum Z-score decreased in the majority of areas. We proved decreased cortical activation on functional MRI of the brain after surgery in patients with CSM (evaluated according to MRI of cervical spine), even at an initial stage of the disease.

Modality effects in paced serial addition task: differential responses to auditory and visual stimuli.

Paced Auditory Serial-Addition Task (PASAT) is a complex task commonly used to examine patients with diffuse brain damage. A visual version of the neuropsychological test (Paced Visual Serial-Addition Task, PVSAT) has also been introduced to clinical practice, and both versions were adapted to be used in neuroimaging, namely functional magnetic resonance imaging (fMRI). The aim of our work was direct comparison of auditory and visual versions of the paced serial addition test (PASAT/PVSAT) in a within-subject and within-session study and description of the commonalities and differences in both activated and deactivated brain regions. Twenty young adult right-handed healthy volunteers participated in the study and underwent whole-brain fMRI examination during PASAT and PVSAT performance. Higher-level statistical analysis was performed to generate group mean activation and deactivation maps for both tasks, their conjunctions and differences across modalities. In PASAT/PVSAT activation conjunction analysis, we confirmed the existence of a modality-independent neural network similar to working memory tasks and to previous PASAT or PVSAT studies. In PASAT/PVSAT deactivation conjunction analysis, we observed a rather symmetrical extensive pattern of deactivated regions, overlapping the default mode network. Significant differences between PASAT and PVSAT were found in the right frontal eye field (FEF) and bilaterally in the striate and extrastriate cortices. Activation in one task and deactivation in the other jointly contributed to significant differences in all occipital and occipitotemporal regions. Both tasks activated right FEF, but activation during PASAT was significantly stronger than during PVSAT. Between-modality differences should be considered when preparing and interpreting neuroimaging experiments.

Thrombolytic treatment of ischaemic stroke occurring during a migrainous attack: a case report.

Authors report a case of young female suffering from the acute ischaemic stroke with right-sided hemiplegia, hemianopsia and hemihypoaesthesia during a migrainous attack without aura. Magnetic resonance imaging detected infarction in the left occipital lobe and occlusion of branches of the posterior cerebral artery (PCA). Combined treatment with systemic thrombolysis and sonothrombolysis was used, leading to the early PCA recanalization, and to a favourable clinical outcome after 1 month. Intravenous thrombolytic treatment administered within the therapeutic window may be useful in cerebral ischaemia associated with migraine when an arterial occlusion is documented.

New laboratory markers in diagnosis of alzheimer dementia.

OBJECTIVES: The aim of our work was to assess the role of tau protein, beta amyloid and cystatin C in diagnosis of Alzheimer dementia (AD) and other neurodegenerative diseases (NDs). METHODS: The levels of tau protein, beta amyloid and cystatin C were assessed in a set of 79 patients with ND (38 men and 41 women; aged 22-90 years; mean, 61.6 +/- 15.6 years) and in a control group of 79 subjects with a healthy central nervous system (38 men and 41 women; aged 20-91 years; mean, 61.5 +/- 15.1 years). RESULTS: When compared with the subjects in the control group, a statistically significant decrease in tau protein levels was found in patients with ND, an increase in tau protein levels in patients with AD and an increase in cystatin C cerebrospinal fluid/serum index in the ND + AD group. DISCUSSION: Our work only confirmed the previously reported results in part. Although tau protein seems to be a quite reliable marker of AD, the role of beta amyloid in AD diagnosis remains at the least questionable. In the case of cystatin C, our results would seem to confirm the views of certain authors that cystatin C will probably not become a new 'revolutionary' marker contributing to differential diagnostics.

The assessment of beta amyloid, tau protein and cystatin C in the cerebrospinal fluid: laboratory markers of neurodegenerative diseases.

To assess the role of tau protein, beta-amyloid(1-42) and cystatin C in the diagnostics of Alzheimer dementia (AD) and other neurodegenerative diseases (ND) by comparing to the control groups (CG). The levels of tau protein, beta-amyloid(1-42) and cystatin C were assessed in the set of 69 patients (AD + ND, 33 males, 36 females, aged 22-90, mean 60.5 + 16.1 years), and in a control group of 69 subjects without the affection of the central nervous system (CGAD + CGND, 33 males, 36 females, aged 20-91, mean 60.5 + 16.0 years). Statistically significant increased tau protein levels (P = 0.0001) and index tau/beta-amyloid(1-42) levels (P = 0.0002) were shown in the group of AD patients, compared to the group of ND patients. One-way ANOVA analysis with Bonferonni post hoc test did not show any significant differences of the cystatin C values between any of the compared groups. ROC analysis showed at least one tie between the positive actual state group (AD) and the negative actual state group (ND) by CSF cystatin C and at least one tie between the positive actual state group and the negative actual state group by CSF tau protein. Our study confirmed previously reported results only in part. While tau protein seems to be quite a reliable marker of AD, the role of beta-amyloid(1-42) and cystatin C in AD diagnosis remains at least questionable.

Occurrence of diabetes mellitus in spontaneous intracerebral hemorrhage.

The role of diabetes mellitus (DM) in the etiopathogenesis of spontaneous intracerebral hemorrhage (SICH) is controversial. The aim was to assess the role of DM in our SICH patients. In a hospital-based cross-section study, the occurrence of DM prior to a hemorrhagic stroke was observed in 80 SICH patients (44 males, aged 36-87 years, mean 67.1 +/- 11.9 years; 36 females, aged 56-86 years, mean 71.1 +/- 8.3 years), and in a control group (CG) of 80 age- and sex-matched patients with low back pain. All patients were treated at the Departments of Neurology and Neurosurgery, University Hospital, Olomouc, Czech Republic. Two-sample t test and Pearson's homogeneity chi(2) test were applied when assessing statistical significance. DM was found in 37.5% of SICH patients versus 22.5% of CG subjects (P < 0.05). DM occurs significantly more frequently in SICH patients in the Olomouc region of the Czech Republic when compared to the general population.

Cerebellar hemispheric activation ipsilateral to the paretic hand correlates with functional recovery after stroke.

An experimental lesion in the primary motor or sensory cortices in monkeys leads to functional reorganization in areas surrounding the lesion or in contralateral homologous regions. In humans, task-dependent brain activation after motor stroke seems to be multifocal and bilateral. Although many active structures are seen after stroke, their roles are unclear. For instance, the uninjured primary motor cortex may play a significant role in recovery or may be associated with mirror movements. Other motor areas, particularly those outside the affected middle cerebral artery distribution, have also been thought to play such a role, including the medial pre-motor areas and both cerebellar hemispheres. The lateral pre-motor areas might also contribute but the demarcation of primary motor and pre-motor cortices is not trivial. It is not known from existing studies how brain activation relates to behavioural change over the time course of recovery. We used functional MRI (fMRI) to study 12 patients longitudinally over the first 6 months of stroke recovery. All subjects had acute stroke causing unilateral arm weakness and had some ability to move the impaired hand within 1 month. Each patient had both motor testing and fMRI during finger and wrist movements at four points during the observed period. Six of these patients showed good motor recovery, whereas the other six did not. The imaging results support a role for the cerebellum in mediating functional recovery from stroke. The data suggest that patients with good recovery have clear changes in the activation of the cerebellar hemisphere opposite the injured corticospinal tract. Patients with poor recovery do not show such changes in cerebellar activation. No other brain region had a significant correlation with recovery. Interestingly, activation in the cerebellum ipsilateral to the injury increases transiently after stroke, independently of the success of recovery. The present work suggests a possible link between cerebellar activation and behavioural recovery from hand weakness from stroke. The underlying mechanism is not known, but it could relate to haemodynamic changes such as diaschisis or to the postulated role of the cerebellum in motor skill learning.

Lateralization of motor circuits and handedness during finger movements.

Although functional lateralization in the human brain has been studied intensively, there remains significant controversy over the brain mechanisms that instantiate it. The main objective of the present study is to characterize the regions associated with the generation of different movements by the fingers of both hands by right- and left-handed people. Thirteen right- and left-handers were studied using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) during performance of single and sequential finger movement tasks. We used single-shot whole-brain spiral fMRI to map the functional components of the motor system during these tasks. Regions of interest included the primary motor and sensory cortices, the pre-motor cortices and the cerebellum. Sequential movements were associated with intense brain activation in several bilateral regions, whereas single movements were associated with less activation in fewer regions, but with greater laterality. Right- and left-handers differed in their pattern of activation, sharing a pattern of activation on simple movements but responding differently to sequential movements. On simple movements, the brain activation patterns of left- and right-handers were similar in volume, number of areas and laterality. By contrast, on sequential movement, left-handers activated larger volumes and a larger number of brain areas than right-handers, and showed significantly less brain lateralization. These results highlight differences in the functional organization of motor areas in right- and left-handed people. The discrepancies that might reflect differences in the network features of motor systems in these two groups, could also determine differences in motor activity that occur during recovery from injury (e.g. after stroke).

Somatotopy in human primary motor and somatosensory hand representations revisited.

High-resolution functional magnetic resonance imaging of healthy volunteers was used to study the functional anatomy of the human primary motor (M1) and somatosensory (S1) cortical hand representations during simple movements of thumb, little finger and wrist and a sequential movement of the middle three fingers. Rest served as a control state. The results demonstrated an orderly somatotopy in both M1 and S1, even though the cortical areas active with individual movements significantly overlapped. Moreover, the activation patterns in M1 and S1 differed in three aspects: (i) S1 activation was distributed into significantly more clusters than M1 and the primary cluster was smaller; (ii) the overlaps of areas active with different movements were significantly larger in M1 than in S1; (iii) the difference between the three-finger sequential movement and the single-finger movements was more pronounced in S1 than in M1. The sequence-activated S1 cortex was distributed into significantly more clusters. There was also a trend for a bigger volume difference between sequence and the single finger movements in S1 than M1. These data suggest that while the distributed character dominates in M1 and S1, a somatotopic arrangement exists for both M1 and S1 hand representations, with the S1 somatotopy being more discrete and segregated, in contrast to the more integrated and overlapping somatotopy in M1.

Suppression of vascular artifacts in functional magnetic resonance images using MR angiograms.

This paper describes a method for processing functional magnetic resonance images that suppresses signal changes originating from macroscopic veins visible in acquired magnetic resonance angiograms. Finger tapping experiments were performed on a 1.5-T scanner and the response was evaluated with voxel-by-voxel cross-correlation of the time course with a sinusoid at the paradigm frequency. After applying a vascular mask to suppress signal changes under macroscopic vessels, the vascular and nonvascular subpopulations of the data were compared. By visual inspection, the method was found to remove extracortical activation while preserving activation in the parenchyma. The observed higher signal amplitudes and temporal phase lags of the vascular population agree with theoretical models and previous studies. A significant portion of negatively correlated voxels occurs adjacent to through-plane vessels. Finally, comparing the centers of mass of the activated area before and after vascular suppression showed significant shifts in some subjects.

Localizing the lexicon for reading aloud:replication of a PET study using fMRI.

Functional magnetic resonance imaging (fMRI) was used to investigate the neural basis of written word recognition in two normal subjects. With a 1.5T scanner and temporal surface coil, T2 gradient echo images were obtained while subjects read words aloud. As a control condition, subjects visualized false font strings and said the word "range' each time such a string appeared. These two conditions were presented in an oscillatory pattern, alternating 30 s of each condition for a total of 4 min. Comparison of the two conditions using cross-correlation demonstrated strong activation in both subjects in the left posterior superior temporal gyrus, near the site predicted for the visual input lexicon by Déjerine and recently demonstrated by positron emission tomography.

Advanced EMG techniques in diagnostics of spinal muscular atrophies and motor neuron disease--magnetic stimulation, single fiber EMG and macro EMG.

Motor neuron disease (MND) and spinal muscular atrophies (SMA) are difficult to diagnose with classical EMG methods because significant findings appear relatively late and both groups of diseases show neurogenic type of record differing only in a relatively greater amount of fasciculations and higher amplitude of motor unit potential (MUP) in MND compared with SMA. We examined 12 patients with MND-amyotrophic lateral sclerosis and 7 patients with SMA type III and IV according to Swash with advanced EMG techniques-magnetic stimulation, single fiber and macro EMG. With transcranial magnetic stimulation, a significant prolongation of cortical latency was found in MND (P < 0.0001 right hand and P < 0.0005 left hand) against SMA, where it was almost normal. With single fiber EMG, mean jitter was less markedly increased in MND (P < 0.05 against SMA) and fiber density was lower in MND (P < 0.005). With macro EMG, no significant difference was found in either macro amplitude or area. Macro fiber density was also lower in MND (P < 0.005). Advanced EMG techniques proved to differentiate clearly the III. (Kugelberg-Welander) and IV. (adult) type of SMA from MND-amyotrophic lateral sclerosis.

Preliminary experimental experiences with xenotransplantations.

In our xenotransplantation experiments has been a major aim to induce specific tolerance. The results from the meeting of the donor's and the recipient's immunocompetent systems already in the period of embryonic development and/or the influence of methylprednisolone are described.

Single fiber EMG in multiple sclerosis.

A group of 25 patients with sclerosis multiplex (SM) was examined by means of single fiber (SF) EMG. This group had the mean value of jitter 55.0 +/- 4.5 microseconds and fiber density (FD) 2.15 +/- 0.12. The findings of the patients with the first attack of illness and the findings of the patients with twenty-year duration are the same. A hypothesis is suggested that not only the peripheral neuron but also the CNS structures take part in the increase of jitter. The different results of stimulated single fiber (SSF) and SF EMG are discussed; the former reflects only the peripheral part of the nervous system due to peripheral stimulation. The higher levels of CNS cannot take part in it.

Single fiber EMG in cerebrovascular stroke (CVS).

This paper gives previously unpublished data about fiber density (FD) and jitter in patients with CVS. The cluster of these values is very similar to that found in sclerosis multiplex (SM). There is a problem whether both clusters represents the same disorder of CNS compared with amyotrophic lateral sclerosis (ALS) or spinal muscular atrophy which have different values. Another problem is the participation of presumed central lesion on the increased jitter, the mechanism of which is still unknown.

Tetanic syndrome and its examination.

The article presents a new electromyographic method; it describes the non-invasive examination of tetany with surface electrodes. This method is more sensitive than the classical needle technique and, moreover, the necessity to use expensive disposable needle electrodes is avoided.

[Stereotactically aimed biopsy of vertebral body l2.]. / Stereotakticky cílená biopsie z obratlového tela L2.

The authors describe successful use of an whole-body stereotactic apparatus for collection of pathological tissue samples from the vertebral body L2. Key words: whole-body aiming apparatus, stereotactic biopsy, vertebral body.