Biomedical subjects

Petr Hlustík

Publications and source records attributed to Petr Hlustík.

7 recordsLinked to original sources

PubMed2006

Paretic hand in stroke: from motor cortical plasticity research to rehabilitation.

Research in neural plasticity of adult cortical representations brought hope of significant potential for further improvement in therapy after cerebrovascular stroke, but the same processes involved in plasticity also allow for maladaptive changes whether spontaneous or caused by inappropriate therapeutic manipulations. Within the extensive network of multiple and bilateral motor cortical and subcortical areas, this paper focuses on the primary motor cortex. We review selected data from humans and primates regarding its functional anatomy and the mechanisms of adaptive neuroplasticity in the presence of brain insults, and the impact of motor skill learning in normals and rehabilitation therapy in patients. The discussion centers on the potential impact of the mechanisms of motor cortex neuroplasticity, especially of the phenomenon of competition among primary motor cortical representations, on the rehabilitation of paretic hand and shoulder after stroke. Application of results from neurophysiology and functional brain imaging research into the clinical practice is in the initial stages and remains a challenge for the future. Nevertheless, even the available research provides an important message for clinical rehabilitation of stroke patients: the need to widen multimodal and interdisciplinary approaches to rehabilitation of the paretic hand.

Brain Damage, Chronic↗

PubMed2005

Combined event-related fMRI and intracerebral ERP study of an auditory oddball task.

Event-related fMRI (efMRI) has been repeatedly used to seek the neural sources of endogenous event-related potentials (ERP). However, significant discrepancies exist between the efMRI data and the results of previously published intracranial ERP studies of oddball task. To evaluate the capacity of efMRI to define the sources of the P3 component of ERP within the human brain, both efMRI and intracerebral ERP recordings were performed in eight patients with intractable epilepsy (five males and three females) during their preoperative invasive video-EEG monitoring. An identical auditory oddball task with frequent and target stimuli was completed in two sessions. A total of 606 intracerebral sites were electrophysiologically investigated by means of depth electrodes. In accordance with the finding of multiple intracerebral generators of P3 potential, the target stimuli evoked MRI signal increase in multiple brain regions. However, regions with evident hemodynamic and electrophysiological responses overlapped only partially. P3 generators were always found within hemodynamic-active sites, if these sites were investigated by means of depth electrodes. On the other hand, unequivocal local sources of P3 potential were apparently also located outside the regions with a significant hemodynamic response (typically in mesiotemporal regions). Both methods should thus be viewed as mutually complementary in investigations of the spatial distribution of cortical and subcortical activation during oddball task.

Adult↗

PubMed2004

Handedness shift as a consequence of motor cortex reorganization after early functional impairment in left temporal lobe epilepsy--an fMRI case report.

The impact of epileptiform activity on the functional organization of various cortical regions is currently a widely discussed topic. Our patient, suffering from left-sided temporal lobe epilepsy with typical mesiotemporal sclerosis, had a remarkable history of a clear-cut handedness shift in early childhood. In this study, we considered the possibility of the functional reorganization of the motor cortex using functional MRI. The results reflect epileptiform activity as an important formative factor for motor cortex development in our patient.

Adolescent↗

PubMed2004

Can we identify patients with carotid occlusion who would benefit from EC/IC bypass? Review.

Occlusion of the internal carotid artery (CAO) is associated with a high mortality rate and frequent disability in survivors. Even in patients with good clinical recovery there is a high risk of recurrent stroke, mainly in those with impaired cerebral vasomotor reactivity (CVR). Current evidence based therapeutic options for patients with symptomatic CAO include antithrombotic medication and control of vascular risk factors. For stenosis of the contralateral internal or ipsilateral external carotid artery, endarterectomy or percutaneous transluminal angioplasty may be considered. Ongoing symptoms may cease after tapering antihypertensive medications. Extracranial to intracranial (EC/IC) arterial bypass surgery has been used since 1967 in patients with CAO. However, the international randomized EC/IC Bypass Study (1985) failed to confirm the effectiveness of EC/IC bypass for preventing cerebral ischemia in patients with symptomatic CAO when compared to those assigned to the best medical care. Nevertheless, the conclusion of the EC/IC Bypass Study has several objections and downfalls. Since then, there has been a revival of interest in cerebral revascularization procedures owing to the substantial progression of surgical techniques and the use of more advanced diagnostic methods. Thus, it has recently been reported that EC/IC bypass surgery can be useful in preventing stroke in patients with hemodynamic compromise. The main problem is to identify the small subgroup of surgical candidates. Presently, single photon emission computed tomography (SPECT), positron emission tomography (PET), transcranial Doppler sonography (TCD), computed tomography (CT) with administration of (133)Xe, perfusion CT, near infrared spectroscopy (NIRS), and functional magnetic resonance imaging (fMRI) are being used for this purpose.

Brain Ischemia↗

PubMed2003

Use of cystatin C determination in clinical diagnostics.

This paper presents a current view of the possible clinical uses of cystatin C determination. Cystatin C is an inhibitor of cysteine proteases, and relatively stable in the systemic circulation it is comparatively easily determined. Although in clinical practice it is known primarily as a relatively reliable and endogenous marker for glomerular filtration, lately cystatin C analysis has been discussed in connection with the diagnostics of a variety of diseases such as early atherosclerosis, Alzheimer's dementia, vascular aneurysms, hyperhomocysteinaemia and other neurodegenerative diseases.

Alzheimer Disease↗

PubMed2002

Functional lateralization of the human premotor cortex during sequential movements.

A neurological truism is that each side of the brain controls movements on the opposite side of the body. Yet some left hemisphere brain lesions cause bilateral impairment of complex motor function and/or ideomotor apraxia. We report that the left dorsal premotor cortex of normal right-handed people plays a fundamental role in sequential movement of both right and left hands. Subjects performed sequential finger movements during functional magnetic resonance imaging of the motor cortices. In right-handed subjects, the volume of activated dorsal premotor cortex showed a left hemispheric predominance during hand movements. We suggest that the observed left premotor dominance contributes to the lateralization found in lesion studies.

Adult↗

PubMedDate not supplied

Cortical plasticity during three-week motor skill learning.

The authors studied motor behavior and primary motor (M1) and somatosensory (S1) cortical representations of movement during hand motor skill acquisition over 3 weeks. During four functional MRI sessions 1 week apart, subjects performed simple movements of single fingers and wrist, and a sequential movement of the middle three fingers, contrasted with rest. Half of the subjects practiced the sequential movement, whereas the other half practiced a gross motor task (squeezing a sponge). In both groups, motor performance gradually improved both on the practiced sequence and also on unrelated tests of general hand performance. Similarly, gradual expansion of active M1 and S1 areas was observed with the practiced sequence and with the unpracticed single-finger and wrist movements. Motor practice enhanced overlaps and sharing of cortex (significantly more so in the fine-skill group), preserving somatotopy and the overall extent of the hand representations. Even a limited amount of practice on a complex task can thus lead to both specific and nonspecific improvements in behavior and to expansion of M1 and S1 movement representations. Finally, the extent of active M1 and S1 was significantly correlated with out-of-scanner performance on sequential finger movement and may reflect the current motor ability of the individual.

Adult↗