Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 5 de 5
Filter
Add more filters










Database
Language
Publication year range
1.
Magn Reson Med ; 36(4): 620-6, 1996 Oct.
Article in English | MEDLINE | ID: mdl-8892216

ABSTRACT

A new method to perform rapid 3D fMRI in human brain is introduced and evaluated in normal subjects, on a standard clinical scanner at 1.5 Tesla. The method combines a highly stable gradient echo technique with a spiral scan method, to detect brain activation related changes in blood oxygenation with high sensitivity. A motor activation paradigm with a duration of less than 5 min, performed on 10 subjects, consistently showed significant changes in signal intensity in the area of the motor cortex. In all subjects, these changes survived high statistical thresholds.


Subject(s)
Brain/pathology , Magnetic Resonance Imaging/methods , Humans , Motor Cortex/pathology
3.
Radiology ; 194(3): 687-91, 1995 Mar.
Article in English | MEDLINE | ID: mdl-7862963

ABSTRACT

PURPOSE: To compare directly the two most widely used methods of functional magnetic resonance (MR) imaging--dynamic contrast material-enhanced MR imaging and blood oxygenation level-dependent (BOLD) MR imaging. MATERIALS AND METHODS: Five healthy volunteers underwent dynamic contrast-enhanced and BOLD MR imaging with a conventional 1.5-T MR unit during visual stimulation and a dark control state. BOLD studies were performed with a gradient-echo sequence, and dynamic MR imaging was performed with an echo-shifted gradient-echo sequence after intravenous administration of a bolus of gadopentetate dimeglumine. RESULTS: A significantly greater percentage signal change was found with dynamic MR imaging than with the BOLD technique. The extent of area activated was also significantly greater. CONCLUSION: With standard clinical imagers and these gradient-echo-based techniques, greater percentage activation and area of activation can be achieved with dynamic MR imaging than with BOLD MR imaging.


Subject(s)
Brain/anatomy & histology , Magnetic Resonance Imaging/methods , Brain/physiology , Cerebrovascular Circulation/physiology , Contrast Media , Drug Combinations , Gadolinium DTPA , Humans , Image Processing, Computer-Assisted/methods , Meglumine , Organometallic Compounds , Pentetic Acid/analogs & derivatives , Photic Stimulation
4.
Magn Reson Med ; 32(1): 150-5, 1994 Jul.
Article in English | MEDLINE | ID: mdl-8084232

ABSTRACT

A 3-dimensional MRI method has been developed for functional mapping of the human brain, based on blood oxygenation level dependent (BOLD) contrast mechanisms. The method uses recently introduced principles of echo-shifted FLASH to acquire a single 3D data set in 20 s. The technique was tested on a conventional 1.5 Tesla clinical scanner with a standard head coil using visual stimulation with a 8 Hz flashing white light, or a varying checkerboard pattern. Areas of increased signal intensity were identified in the visual cortex, consistent with the known functional organization.


Subject(s)
Brain Mapping/methods , Brain/physiology , Image Processing, Computer-Assisted , Magnetic Resonance Imaging/methods , Visual Cortex/physiology , Brain/anatomy & histology , Humans , Photic Stimulation , Visual Cortex/anatomy & histology
5.
Pharmacol Biochem Behav ; 46(1): 51-60, 1993 Sep.
Article in English | MEDLINE | ID: mdl-7902985

ABSTRACT

Behavioral responses to apomorphine and to the selective D1 and D2 dopamine receptor agonists SK&F38393 and quinpirole were evaluated in rats following ibotenic acid (IA) or sham lesion of the medial prefrontal cortex (MPFC). IA-lesioned rats showed an increased responsiveness to the postsynaptic effects of all of the dopamine agonists. Patterns of the responses to the selective agonists administered alone and in combination suggest that these effects might be due to selective increases in the sensitivity of postsynaptic D1 receptor-associated mechanisms. In addition, IA-lesioned rats pretreated with saline were hyperactive in comparison to sham-lesioned rats when animals were exposed to a novel open field, but spontaneous motor activity did not differ between these two groups when animals were pretreated with low doses (0.03 mg/kg) of quinpirole. The fact that hyperreactivity observed in lesioned animals is inhibited by a dose of quinpirole that is felt to act presynaptically, selectively attenuating endogenous dopaminergic tone, suggests that effects of the MPFC lesion may be mediated presynaptically as well.


Subject(s)
Behavior, Animal/drug effects , Dopamine Agents/pharmacology , Ibotenic Acid/toxicity , Prefrontal Cortex/physiology , 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology , Animals , Apomorphine/pharmacology , Ergolines/administration & dosage , Ergolines/pharmacology , Injections, Subcutaneous , Male , Motor Activity/drug effects , Prefrontal Cortex/anatomy & histology , Quinpirole , Rats , Rats, Sprague-Dawley , Receptors, Dopamine/drug effects , Receptors, Presynaptic/drug effects , Stereotyped Behavior/drug effects
SELECTION OF CITATIONS
SEARCH DETAIL
...