Petr Hluštík

The mind of expert motor performance is cool and focused

Extraordinary motor skills required for expert athletic or music performance require longstanding and intensive practice leading to two critical skills, a level of maximal performance that far exceeds that of non-experts and a degree of privileged focus on motor performance that excludes intrusions. This study of motor planning in expert golfers demonstrated their brain activation during their pre-shot routine to be radically different than in novices. The posterior cingulate, the amygdala-forebrain complex, and the basal ganglia were active only in novices, whereas experts had activation primarily in the superior parietal lobule, the dorsal lateral premotor area, and the occipital area. The fact that these differences are apparent before the golfer swings the club suggests that the disparity between the quality of the performance of novice and expert golfers lies at the level of the organization of neural networks during motor planning. In particular, we suggest that extensive practice over a long period of time leads experts to develop a focused and efficient organization of task-related neural networks, whereas novices have difficulty filtering out irrelevant information.

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.

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.

Hyperechogenicity of the substantia nigra in Parkinson's disease.

Substantia nigra (SN) was assessed by transcranial sonography (TCS) in 47 Parkinsons disease (PD) patients and in 39 healthy volunteers. A semiquantitative echogenicity scale was created with arbitrary values ranging from 1 to 5, zones with grade ≥3 and larger than 0.19 cm2 were recorded as hyperechogenic SN. TCS examination of SN as a diagnostic test for PD in our study showed 87.2% sensitivity and 94.9% specificity.

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.

Sensorimotor network in cervical dystonia and the effect of botulinum toxin treatment: A functional MRI study

BACKGROUNDnThe evidence suggests that the origin of primary dystonia is at least partly associated with widespread dysfunction of the basal ganglia and cortico-striato-thalamo-cortical circuits. The aim of the study was to assess the sensorimotor activation pattern outside the circuits controlling the affected body part in cervical dystonia, as well as to determine task-related activation changes induced by botulinum toxin type A (BoNT-A) treatment.nnnMETHODSnSeven patients suffering from cervical dystonia and nine healthy controls were examined with functional MRI during skilled hand motor task; the examination was repeated 4 weeks after BoNT-A application to dystonic neck muscles.nnnRESULTSnFunctional MRI data demonstrated overall reduced extent of hand movement-related cortical activation but greater magnitude of blood oxygenation level dependent signal change in the contralateral secondary somatosensory cortex in patients compared to controls. Effective BoNT-A treatment led to reduced activation of the ipsilateral supplementary motor area and dorsal premotor cortex in patients. The patients post-treatment sensorimotor maps showed significantly smaller basal ganglia activation compared to controls.nnnCONCLUSIONSnThese results provide imaging evidence that abnormalities in sensorimotor activation extend beyond circuits controlling the affected body parts in cervical dystonia. The study also supports observations that BoNT-A effect has a correlate at central nervous system level, and such effect may not be limited to cortical and subcortical representations of the treated muscles.

Modulation of Cortical Activity in Patients Suffering from Upper Arm Spasticity following Stroke and Treated with Botulinum Toxin A: An fMRI Study

Botulinum toxin (BTX) treatment can relieve focal arm spasticity after stroke, presumably through dynamic changes at multiple levels of the motor system, including the cerebral cortex. However, the neuroanatomical correlate of BTX spasticity relief is not known and should be reflected in changes of cortical activation during motor tasks assessed using repeated functional magnetic resonance imaging (fMRI).

Acute ischaemic stroke in pregnancy: a severe complication of ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of sterility treatment. It is characterised by ovarian enlargement, ascites, electrolyte disturbance, hypovolaemia and haemoconcentration. A case of ischaemic stroke due to right middle cerebral artery (MCA) occlusion in a young female with OHSS after pharmacological treatment of sterility is reported. Left central hemiparesis occurred suddenly within a few days after the embryo transfer. Magnetic resonance imaging diffusion-weighted images showed infarction in the right basal ganglia and magnetic resonance angiography (MRA) revealed the occlusion of the M1 segment of the right MCA. The haemodilution and the anticoagulation therapy were effective. Twenty-four hours after the stroke onset, MRA showed MCA recanalisation. The neurological deficit resolved completely within 3 months. The patient delivered 2 healthy infants at term. This case emphasises that the recent advent of ovulation induction and reproductive techniques is a newly recognised cause of cerebral stroke in otherwise healthy females.

Somatosensory cortical activation in cervical dystonia and its modulation with botulinum toxin: an fMRI study.

ABSTRACT Converging data on focal dystonias suggest a widespread disorder of somatosensory processing. The aims of our study were, first, to assess somatosensory activation patterns in cervical dystonia (CD) beyond the representation of the affected body parts and, second, to search for task-related activation changes induced by botulinum toxin type-A (BoNT-A) therapy. Functional magnetic resonance imaging (MRI) during electrical median nerve stimulation was employed in seven CD patients and nine controls; the examination was repeated 4 weeks after BoNT-A application to dystonic neck muscles. The pretreatment activation map of patients showed activation in the contralateral primary somatosensory cortex, but missing activation in the secondary somatosensory cortex and insula, in contrast to controls and patients after treatment. Clinically significant effect of BoNT-A therapy was associated with a significant increase of BOLD response in the contralateral secondary somatosensory, insular, and inferior parietal cortices. The posttreatment somatosensory maps of patients did not significantly differ from controls. This study has brought evidence of widespread disruption of somatosensory processing in CD and its modification with BoNT-A therapy.

Degenerative and inflammatory markers in the cerebrospinal fluid of multiple sclerosis patients with relapsing-remitting course of disease and after clinical isolated syndrome.

Abstract Background: Literature includes evidence of initial predominance of inflammation and later development of neurodegeneration in the pathogenesis of multiple sclerosis (MS). Objective: To search for differences in inflammatory and degenerative cerebrospinal fluid (CSF) markers between relapsing-remitting MS (RRMS) and the clinical isolated syndrome (CIS). Methods: A total of 148 subjects were evaluated, 65 MS patients (45 RRMS and 20 CIS) and 83 controls. The evaluated parameters included albumin quotient and prealbumin, transferrin, C3 and C4 complement factors, haptoglobin, beta-2-microglobulin, orosomucoid, alpha-1-antitrypsin, apolipoprotein A-I, apolipoprotein B, cystatin C, neuron-specific enolase, tau protein, beta-amyloid, oligoclonal IgG band (OCB), and IgG quotient (QIgG). Results: No differences were found in the inflammatory and degenerative CSF markers between patients with RRMS and CIS. QIgG was higher in RRMS than that in CIS but the number of OCB was higher after CIS. Cystatin C levels were significantly lower in RRMS compared to the other groups. It can be considered an indicator of the demyelination degree. Normal values of beta-amyloid were less frequent in RRMS compared to those in controls.