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Functional Magnetic Resonance Imaging Study (functional + magnetic_resonance_imaging_study)
Selected AbstractsCortical Sensorimotor Control in Vocalization: A Functional Magnetic Resonance Imaging Study,THE LARYNGOSCOPE, Issue 11 2008Arno Olthoff MD Abstract Background: Verbal communication is a human feature and volitional vocalization is its basis. However, little is known regarding the cortical areas involved in human vocalization. Methods: Therefore, functional magnetic resonance imaging at 3 Tesla was performed in 16 healthy adults to evaluate brain activations related to voice production. The main experiments included tasks involving motor control of laryngeal muscles with and without intonation. In addition, reference mappings of the sensorimotor hand area and the auditory cortices were performed. Results: Related to vocalization, in addition to activation of the most lateral aspect of the primary sensorimotor cortex close to the Sylvian fissure (M1c), we found activations medially (M1a) and laterally (M1b) of the well-known sensorimotor hand area. Moreover, the supplementary motor area and the anterior cingulate cortex were activated. Conclusions: Although M1a could be ascribed to motor control of breathing, M1b has been associated with laryngeal motor control. Consequently, even though M1c represents a laryngeal sensorimotor area, its exclusiveness as suggested previously could not be confirmed. Activations in the supplementary motor area and anterior cingulate cortex were ascribed to "vocal-motor planning." The present data provide the basis for further functional magnetic resonance imaging studies in patients with neurological laryngeal disorders. [source] Structural and functional neuroimaging in Klinefelter (47,XXY) syndrome: A review of the literature and preliminary results from a functional magnetic resonance imaging study of languageDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 4 2009Kyle Steinman Abstract Klinefelter (47,XXY) syndrome (KS), the most common form of sex-chromosomal aneuploidy, is characterized by physical, endocrinologic, and reproductive abnormalities. Individuals with KS also exhibit a cognitive/behavioral phenotype characterized by language and language-based learning disabilities and executive and attentional dysfunction in the setting of normal general intelligence. The underlying neurobiologic mechanisms are just now beginning to be elucidated through structural and functional neuroimaging. Here, we review the literature of structural and functional neural findings in KS identified by neuroimaging and present preliminary results from a functional magnetic resonance imaging study examining brain activity during a verb generation task in KS. © 2009 Wiley-Liss, Inc. Dev Disabil Res Rev 2009;15:295,308. [source] Motor foundations of higher cognition: similarities and differences in processing regular and violated perceptual sequences of different specificityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2009Andreja Bubic Abstract Processing perceptual sequences relies on the motor system, which is able to simulate the dynamics of the environment by developing internal representations of external events and using them to predict the incoming stimuli. Although it has previously been demonstrated that such models may incorporate predictions based on exact stimulus properties and single stimulus dimensions, it is not known whether they can also support abstract predictions pertaining to the level of stimulus categories. This issue was investigated within the present event-related functional magnetic resonance imaging study, which compared the processing of perceptual sequences of different specificity, namely those in which the sequential structure was based on the order of presentation of individual stimuli (token), and those in which such structure was defined by stimulus categories (type). The results obtained indicate a comparable engagement of the basic premotor,parietal network in processing both specific and categorical perceptual sequences. However, type sequences additionally elicited activations within the lateral prefrontal, occipital and posterior temporal regions that supported categorization in this task context. Introducing sequential deviants into token sequences activated parietotemporal and ventrolateral frontal cortices, whereas a less pronounced overall response, dominated by lateral prefrontal activation, was elicited by violations introduced into type sequences. Overall, the findings obtained suggest that, although forward models in perception may be able to incorporate expectations of lower specificity when compared to the motor domain, such processing is crucially dependent on additional contributions from lateral prefrontal as well as inferior occipital and temporal cortices that support categorization occurring in such a dynamic context. [source] Primary and secondary neural networks of auditory prepulse inhibition: a functional magnetic resonance imaging study of sensorimotor gating of the human acoustic startle responseEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Linda E. Campbell Abstract Feedforward inhibition deficits have been consistently demonstrated in a range of neuropsychiatric conditions using prepulse inhibition (PPI) of the acoustic startle eye-blink reflex when assessing sensorimotor gating. While PPI can be recorded in acutely decerebrated rats, behavioural, pharmacological and psychophysiological studies suggest the involvement of a complex neural network extending from brainstem nuclei to higher order cortical areas. The current functional magnetic resonance imaging study investigated the neural network underlying PPI and its association with electromyographically (EMG) recorded PPI of the acoustic startle eye-blink reflex in 16 healthy volunteers. A sparse imaging design was employed to model signal changes in blood oxygenation level-dependent (BOLD) responses to acoustic startle probes that were preceded by a prepulse at 120 ms or 480 ms stimulus onset asynchrony or without prepulse. Sensorimotor gating was EMG confirmed for the 120-ms prepulse condition, while startle responses in the 480-ms prepulse condition did not differ from startle alone. Multiple regression analysis of BOLD contrasts identified activation in pons, thalamus, caudate nuclei, left angular gyrus and bilaterally in anterior cingulate, associated with EMG-recorded sensorimotor gating. Planned contrasts confirmed increased pons activation for startle alone vs 120-ms prepulse condition, while increased anterior superior frontal gyrus activation was confirmed for the reverse contrast. Our findings are consistent with a primary pontine circuitry of sensorimotor gating that interconnects with inferior parietal, superior temporal, frontal and prefrontal cortices via thalamus and striatum. PPI processes in the prefrontal, frontal and superior temporal cortex were functionally distinct from sensorimotor gating. [source] Differential amygdala responses to winning and losing: a functional magnetic resonance imaging study in humansEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2000Tiziana Zalla Abstract The amygdala has been shown to respond to many distinct types of affective stimuli, including reward and punishment feedback in animals. In humans, winning and losing situations can be considered as reward and punishment experiences, respectively. In this study, we used functional magnetic resonance imaging (fMRI) to measure regional brain activity when human subjects were given feedback on their performance during a simple response time task in a fictitious competitive tournament. Lexical stimuli were used to convey positive ,win' or negative ,lose' feedback. The frequency of positive and negative trials was parametrically varied by the experimenters independently from the subjects' actual performance and unbeknownst to them. The results showed that the parametric increase of winning was associated with left amygdala activation whereas the parametric increase of losing was associated with right amygdala activation. These findings provide functional evidence that the human amygdala differentially responds to changes in magnitude of positive or negative reinforcement conveyed by lexical stimuli. [source] Frontolimbic responses to emotional face memory: The neural correlates of first impressionsHUMAN BRAIN MAPPING, Issue 11 2009Theodore D. Satterthwaite Abstract First impressions, especially of emotional faces, may critically impact later evaluation of social interactions. Activity in limbic regions, including the amygdala and ventral striatum, has previously been shown to correlate with identification of emotional content in faces; however, little work has been done describing how these signals may influence emotional face memory. We report an event-related functional magnetic resonance imaging study in 21 healthy adults where subjects attempted to recognize a neutral face that was previously viewed with a threatening (angry or fearful) or nonthreatening (happy or sad) affect. In a hypothesis-driven region of interest analysis, we found that neutral faces previously presented with a threatening affect recruited the left amygdala. In contrast, faces previously presented with a nonthreatening affect activated the left ventral striatum. A whole-brain analysis revealed increased response in the right orbitofrontal cortex to faces previously seen with threatening affect. These effects of prior emotion were independent of task performance, with differences being seen in the amygdala and ventral striatum even if only incorrect trials were considered. The results indicate that a network of frontolimbic regions may provide emotional bias signals during facial recognition. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source] A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging studyJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2002Adnan Z. Alwatban BSc Abstract Purpose To develop a safe functional magnetic resonance imaging (fMRI) procedure for auditory assessment of deaf subjects. Materials and Methods A gold-plated tungsten electrode has been developed which has zero magnetic susceptibility. Used with carbon leads and a carbon reference pad, it enables safe, distortion-free fMRI studies of deaf subjects following direct electrical stimulation of the acoustic nerve. Minor pickup of the radio frequency (RF) pulses by the electrode assembly is difficult to eliminate, and a SPARSE acquisition sequence is used to avoid any effects of unintentional auditory nerve stimulation. Results The procedure is demonstrated in a deaf volunteer. Activation is observed in the contralateral but not the ipsilateral primary auditory cortex. This is in sharp contrast to studies of auditory processing in hearing subjects, but consistent with the small number of previous positron emission tomography (PET) and MR studies on adult deaf subjects. Conclusion The fMRI procedure is able to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for preoperative assessment of candidates for cochlear implantation. J. Magn. Reson. Imaging 2002;16:6,12. © 2002 Wiley-Liss, Inc. [source] Seeing the phantom: A functional magnetic resonance imaging study of a supernumerary phantom limb,ANNALS OF NEUROLOGY, Issue 6 2009Asaid Khateb PhD Objective Supernumerary phantom limb (SPL) is a rare neurological manifestation where patients with a severe stroke-induced sensorimotor deficit experience the illusory presence of an extra limb that duplicates a real one. The illusion is most often experienced as a somesthetic phantom, but rarer SPLs may be intentionally triggered or seen. Here, we report the case of a left visual, tactile, and intentional SPL caused by right subcortical damage in a nondeluded woman. Methods Using functional magnetic resonance imaging, we investigated the multimodal nature of this phantom, which the patient claimed to be able see, use, and move intentionally. The patient participated in a series of sensorimotor and motor imagery tasks involving the right, the left plegic, and the SPL's hand. Results Right premotor and motor regions were engaged when she imagined that she was scratching her left cheek with her left plegic hand, whereas when she performed the same task with the SPL, additional left middle occipital areas were recruited. Moreover, comparison of responses induced by left cheek (subjectively feasible) versus right cheek scratching (reportedly unfeasible movement) with the SPL demonstrated significant activation in right somesthetic areas. Interpretation These findings demonstrate that intentional movements of a seen and felt SPL activate premotor and motor areas together with visual and sensory cortex, confirming its multimodal dimension and the reliability of the patient's verbal reports. This observation, interpreted for cortical deafferentation/disconnection caused by subcortical brain damage, constitutes a new but theoretically predictable entity among disorders of bodily awareness. Ann Neurol 2009;65:698,705 [source] A functional magnetic resonance imaging study of cortical asymmetry in bipolar disorderBIPOLAR DISORDERS, Issue 3 2004Michael P Caligiuri Objectives:, Individuals with bipolar disorder (BPD) exhibit motor, perceptual, and cognitive disturbances involving predominantly right hemisphere dysfunction. This asymmetry has been used to advance the hypothesis that the pathogenesis of bipolar disorder may be related to disturbances of the right cerebral hemisphere. We employed functional magnetic resonance imaging to examine hemispheric asymmetries in manic and depressed BPD. A secondary goal of the study was to examine effects of psychotropic medications on blood volume changes in the motor cortices. Methods:, We studied 18 right-handed BPD and 13 right-handed normal healthy comparison subjects. Blood oxygen level dependent (BOLD) responses in the primary motor area (M1) and supplementary motor area (SMA) of both hemispheres were elicited during reaction time (RT) tasks. Results:, Healthy subjects activated the SMA in a reciprocal fashion with significantly greater activity in the left SMA for right hand trials and the right SMA for left hand trials. Depressed BPD subjects failed to show this normal reciprocity indicating a failure to suppress unwanted activity in the ipsilateral right SMA, whereas manic BPD subjects failed to suppress unwanted ipsilateral SMA activity in both hemispheres. Manic and depressed BPD subjects exhibited greater activity in the left primary motor area suggesting increased cortical excitability. BPD subjects treated with antipsychotics or mood-stabilizing medications exhibited longer RTs, lower BOLD responses in M1 and SMA, and a loss of normal hemispheric asymmetry in the SMA than untreated subjects. Conclusions:, The presence of a right hemisphere disturbance in BPD is consistent with the hypothesis that the right hemisphere may be dominant in mood regulation. The presence of both left and right hemisphere disturbances in mania may explain the coexisting psychotic and affective symptoms observed in this condition. [source] Affect regulation in borderline personality disorder: experimental findings from psychophysiology and functional neuroimagingACTA NEUROPSYCHIATRICA, Issue 2 2002S. C. Herpertz Background: Intense and rapidly changing mood states are a major feature of borderline personality disorder (BPD), which is thought to arise from affective vulnerability. Objective: There have been only a few studies investigating affective processing in BPD, and particularly neither psychophysiological nor neurofunctional correlates of abnormal emotional processing have been identified so far. Methods:, Studies are reported using psychophysiological or functional neuroimaging methodology. Results:, The psychophysiological study did not indicate a general emotional hyperresponsiveness in BPD. Low autonomic arousal seemed to reflect dissociative states in borderline subjects experiencing intense emotions. In the functional magnetic resonance imaging study enhanced amygdala activation was found in BPD, and it is suggested to reflect the intense and slowly subsiding emotions commonly observed in response to even low-level stressors. Conclusions:, Implications for psychotherapy are discussed. [source] | |||||||||||||