Spatial signatures of anesthesia-induced burst-suppression differ between primates and rodents.

During deep anesthesia, the electroencephalographic (EEG) signal of the brain alternates between bursts of activity and periods of relative silence (suppressions). The origin of burst-suppression and its distribution across the brain remain matters of debate. In this work, we used functional magnetic resonance imaging (fMRI) to map the brain areas involved in anesthesia-induced burst-suppression across four mammalian species: humans, long-tailed macaques, common marmosets, and rats. At first, we determined the fMRI signatures of burst-suppression in human EEG-fMRI data. Applying this method to animal fMRI datasets, we found distinct burst-suppression signatures in all species. The burst-suppression maps revealed a marked inter-species difference: in rats, the entire neocortex engaged in burst-suppression, while in primates most sensory areas were excluded-predominantly the primary visual cortex. We anticipate that the identified species-specific fMRI signatures and whole-brain maps will guide future targeted studies investigating the cellular and molecular mechanisms of burst-suppression in unconscious states.

The development of anesthesia was a significant advance in medicine. It allows individuals to undergo surgery without feeling pain or remembering the experience. But scientists still do not know how anesthesia works. During anesthesia, scientists have measured brain activity using electroencephalograms (EEG) and found that the brain appears to turn on and off. Comatose patients also have similar switches between bursts of electrical activity and periods of silence. This burst-suppression pattern may be related to unconsciousness. But scientists still have many questions about how anesthesia causes burst-suppression. One challenge is that while an EEG can tell scientists when the brain turns on and off, it does not show exactly where this occurs. Another imaging method called functional Magnetic Resonance Imaging (fMRI) may fill this gap by allowing scientists to map where the brain activity occurs. Sirmpilatze et al. have created detailed maps of burst-suppression in humans, primates, and rats under anesthesia by analyzing brain scans using fMRI. In rats, the entire outer layer or cortex of the brain underwent a synchronized pattern of burst-suppression. In humans and primates, areas of the brain like those responsible for eyesight did not follow the rest of the cortex in switching on and off. The experiments reveal crucial differences in how rats and humans and other primates respond to anesthesia. The fMRI mapping technique Sirmpilatze et al. created may help scientists learn more about these differences and why some parts of human brains do not undergo burst-suppression. This may help scientists learn more about unconsciousness and help improve anesthesia or the care of comatose patients.

Temporal stability of fMRI in medetomidine-anesthetized rats.

Medetomidine has become a popular choice for anesthetizing rats during long-lasting sessions of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). Despite this, it has not yet been thoroughly established how commonly reported fMRI readouts evolve over several hours of medetomidine anesthesia and how they are affected by the precise timing, dose, and route of administration. We used four different protocols of medetomidine administration to anesthetize rats for up to six hours and repeatedly evaluated somatosensory stimulus-evoked BOLD responses and resting state functional connectivity. We found that the temporal evolution of fMRI readouts strongly depended on the method of administration. Intravenous administration of a medetomidine bolus (0.05 mg/kg), combined with a subsequent continuous infusion (0.1 mg/kg/h), led to temporally stable measures of stimulus-evoked activity and functional connectivity throughout the anesthesia. Deviating from the above protocol-by omitting the bolus, lowering the medetomidine dose, or using the subcutaneous route-compromised the stability of these measures in the initial two-hour period. We conclude that both an appropriate protocol of medetomidine administration and a suitable timing of fMRI experiments are crucial for obtaining consistent results. These factors should be considered for the design and interpretation of future rat fMRI studies.

What's in this crab? MRI providing high-resolution three-dimensional insights into recent finds and historical collections of Brachyura.

Museum collections may be viewed as a unique window onto the diversity and the functional evolution of species on earth. Detailed information about the inner structure of many precious collectors' items is, however, difficult to gain without destruction of the objects of interest. Here we applied magnetic resonance imaging (MRI) to freshly fixed as well as century-old museum specimens and compared the effects of fixative (formalin, ethanol, mercury chloride) on the image quality. Three-dimensional (3D) reconstruction of MRI was exemplarily used to non-invasively visualize anatomical structures of the brachyuran species Ilia nucleus, Ozius guttatus and Austinograea williamsi. Moreover, the potential of combining MRI and micro-computed tomography (µCT) was exemplarily analyzed for O. guttatus. The best MRI quality was achieved with formalin fixation and this also applied to specimens more than 100 years old. For specimens with a straight carapace width of about 30mm, an isotropic spatial resolution of 100µm allowed for the delineation of all major organ systems such as the nervous system, the gastrointestinal tract, the reproductive system and the heart. Moreover, combining MRI and µCT revealed new insights into the interaction of the heart and surrounding skeletal structures. As examples of its potential, MRI of a specimen of O. guttatus showed a very rare double infection with bopyrid isopods and 3D reconstruction of the reproductive tract of A. williamsi revealed a remarkable size of the ovaries as well as a shape and orientation of the seminal receptacles unusual for brachyurans. Thus, MRI may open up extensive possibilities to study evolutionary and ecological questions by utilizing the immense wealth of natural historical collections without any destruction of the items.

Cortical network dysfunction caused by a subtle defect of myelination.

Subtle white matter abnormalities have emerged as a hallmark of brain alterations in magnetic resonance imaging or upon autopsy of mentally ill subjects. However, it is unknown whether such reduction of white matter and myelin contributes to any disease-relevant phenotype or simply constitutes an epiphenomenon, possibly even treatment-related. Here, we have re-analyzed Mbp heterozygous mice, the unaffected parental strain of shiverer, a classical neurological mutant. Between 2 and 20 months of age, Mbp(+/-) versus Mbp(+/+) littermates were deeply phenotyped by combining extensive behavioral/cognitive testing with MRI, 1H-MR spectroscopy, electron microscopy, and molecular techniques. Surprisingly, Mbp-dependent myelination was significantly reduced in the prefrontal cortex. We also noticed a mild but progressive hypomyelination of the prefrontal corpus callosum and low-grade inflammation. While most behavioral functions were preserved, Mbp(+/-) mice exhibited defects of sensorimotor gating, as evidenced by reduced prepulse-inhibition, and a late-onset catatonia phenotype. Thus, subtle but primary abnormalities of CNS myelin can be the cause of a persistent cortical network dysfunction including catatonia, features typical of neuropsychiatric conditions. GLIA 2016;64:2025-2040.

Neural Correlates Differ in High and Low Fear-Avoidant Chronic Low Back Pain Patients When Imagining Back-Straining Movements.

UNLABELLED: The fear-avoidance model postulates that in an initial acute phase chronic low back pain (CLBP) patients acquire a fear of movement that results in avoidance of physical activity and contributes to the pain becoming chronic. The current functional magnetic resonance imaging study investigated the neural correlates of imagining back-straining and neutral movements in CLBP patients with high (HFA) and low fear avoidance (LFA) and healthy pain-free participants. Ninety-three persons (62 CLBP patients, 31 healthy controls; age 49.7 ± 9.2 years) participated. The CLBP patients were divided into an HFA and an LFA group using the Tampa Scale of Kinesiophobia. The participants viewed pictures of back-straining and neutral movements and were instructed to imagine that they themselves were executing the activity shown. When imagining back-straining movements, HFA patients as well as healthy controls showed stronger anterior hippocampus activity than LFA patients. The neural activations of HFA patients did not differ from those of healthy controls. This may indicate that imagining back-straining movements triggered pain-related evaluations in healthy controls and HFA participants, but not in LFA participants. Although heightened pain expectancy in HFA compared with LFA patients fits well with the fear-avoidance model, the difference between healthy controls and LFA patients was unexpected and contrary to the fear-avoidance model. Possibly, negative evaluations of the back-straining movements are common but the LFA patients use some kind of strategy enabling them to react differently to the back-straining events. PERSPECTIVE: It appears that low fear-avoidant back pain patients use some kind of strategy or underlying mechanism that enables them to react with less fear in the face of potentially painful movements. This warrants further investigation because countering fear and avoidance provide an important advantage with respect to disability.

Effects of age on negative BOLD signal changes in the primary somatosensory cortex.

In addition to a contralateral activation of the primary and secondary somatosensory cortices, peripheral sensory stimulation has been shown to elicit responses in the ipsilateral primary somatosensory cortex (SI). In particular, evidence is accumulating that processes of interhemispheric inhibition as depicted by negative blood oxygenation level dependent (BOLD) signal changes are part of somatosensory processes. The aim of the study was to analyze age-related differences in patterns of cerebral activation in the somatosensory system in general and processes of interhemispheric inhibition in particular. For this, a functional magnetic resonance imaging (fMRI) study was performed including 14 younger (mean age 23.3±0.9years) and 13 healthy older participants (mean age 73.2±8.3years). All subjects were scanned during peripheral electrical median nerve stimulation (40Hz) to obtain BOLD responses in the somatosensory system. Moreover, the individual current perception threshold (CPT) as a quantitative measure of sensory function was determined in a separate psychophysical testing. Significant increases in BOLD signal across the entire group could be measured within the contralateral SI, in the bilateral secondary somatosensory cortex (SII), the contralateral supplementary motor area and the insula. Negative BOLD signal changes were delineated in ipsilateral SI/MI as well as in the ipsilateral thalamus and basal ganglia. After comparing the two groups, only the cortical deactivation in ipsilateral SI in the early stimulation phase as well as the activation in contralateral SI and SII in the late stimulation block remained as statistically significant differences between the two groups. The psychophysical experiments yielded a significant age-dependent effect of CPT change with less difference in the older group which is in line with the significantly smaller alterations in maximal BOLD signal change in the contra- and ipsilateral SI found between the two groups. Healthy aging seems to be associated with a decrease in intracerebral inhibition as reflected by smaller negative BOLD signal changes during fMRI tasks. This finding could constitute an important link between age-related neurophysiological changes and behavioral alterations in humans.

Finger tapping-related activation differences in treatment-naïve pediatric Tourette syndrome: a comparison of the preferred and nonpreferred hand.

BACKGROUND: Disturbances of motor circuitry are commonly encountered in Tourette syndrome (TS). The aim of this study was to investigate simple motor performance differences between boys with TS and healthy controls. METHODS: We attempted to provide insight into motor network alterations by studying a group of treatment-naïve patients suffering from 'pure' TS, i.e., without comorbid symptomatology at an early stage of disease. We used functional MRI to compare activation patterns during right (preferred) and left (nonpreferred) index finger tapping between 22 TS boys (12.6 ± 1.7 years) and 22 age-matched healthy control boys. RESULTS: Boys with TS revealed altered motor network recruitment for right (dominant) and left (nondominant) index finger tapping. Brain activation patterns in response to index finger tapping of the nonpreferred left hand reflected the most prominent differences, including activation decrease in contralateral sensorimotor cortex while recruiting premotor and prefrontal regions along with the left inferior parietal lobule to a greater extent. CONCLUSIONS: This study demonstrates clear functional differences of simple index finger tapping in early-stage TS. We suggest that this reflects the requirement for additional brain networks to keep a normal performance level during the actual task and adaptive mechanisms due to continuous tic suppression and performance in TS.

Neural correlates of combinatorial semantic processing of literal and figurative noun noun compound words.

The right hemisphere's role in language comprehension is supported by results from several neuropsychology and neuroimaging studies. Special interest surrounds right temporoparietal structures, which are thought to be involved in processing novel metaphorical expressions, primarily due to the coarse semantic coding of concepts. In this event related fMRI experiment we aimed at assessing the extent of semantic distance processing in the comprehension of figurative meaning to clarify the role of the right hemisphere. Four categories of German noun noun compound words were presented in a semantic decision task: a) conventional metaphors; b) novel metaphors; c) conventional literal, and; d) novel literal expressions, controlled for length, frequency, imageability, arousal, and emotional valence. Conventional literal and metaphorical compounds increased BOLD signal change in right temporoparietal regions, suggesting combinatorial semantic processing, in line with the coarse semantic coding theory, but at odds with the graded salience hypothesis. Both novel literal and novel metaphorical expressions increased activity in left inferior frontal areas, presumably as a result of phonetic, morphosyntactic, and semantic unification processes, challenging predictions regarding right hemispheric involvement in processing unusual meanings. Meanwhile, both conventional and novel metaphorical expressions induced BOLD signal change in left hemispherical regions, suggesting that even novel metaphor processing involves more than linking semantically distant concepts.

The role of the amygdala in atypical gaze on emotional faces in autism spectrum disorders.

Reduced focus toward the eyes is a characteristic of atypical gaze on emotional faces in autism spectrum disorders (ASD). Along with the atypical gaze, aberrant amygdala activity during face processing compared with neurotypically developed (NT) participants has been repeatedly reported in ASD. It remains unclear whether the previously reported dysfunctional amygdalar response patterns in ASD support an active avoidance of direct eye contact or rather a lack of social attention. Using a recently introduced emotion classification task, we investigated eye movements and changes in blood oxygen level-dependent (BOLD) signal in the amygdala with a 3T MRI scanner in 16 autistic and 17 control adult human participants. By modulating the initial fixation position on faces, we investigated changes triggered by the eyes compared with the mouth. Between-group interaction effects revealed different patterns of gaze and amygdalar BOLD changes in ASD and NT: Individuals with ASD gazed more often away from than toward the eyes, compared with the NT group, which showed the reversed tendency. An interaction contrast of group and initial fixation position further yielded a significant cluster of amygdala activity. Extracted parameter estimates showed greater response to eyes fixation in ASD, whereas the NT group showed an increase for mouth fixation. The differing patterns of amygdala activity in combination with differing patterns of gaze behavior between groups triggered by direct eye contact and mouth fixation, suggest a dysfunctional profile of the amygdala in ASD involving an interplay of both eye-avoidance processing and reduced orientation.

Mirrored or identical--is the role of visual perception underestimated in the mental rotation process of 3D-objects?: a combined fMRI-eye tracking-study.

The mental-rotation task is a well known research paradigm to examine cognitive processes of mental imaging and mental manipulation (Shepard & Metzler, 1971). So far, research has been focused on stimulus orientation which indicates the necessary amount of mental rotation. But little attention has been paid to stimulus parity, specifically if and how identical and mirror-reversed stimuli are processed differently. We wanted to fill this gap by combining performance, eye-tracking, and neurofunctional measures using pairwise presented three-dimensional Shepard-Metzler stimuli in a self-paced event-related fMRI design. Based on our results we tried to reason at which stage of the mental-rotation process the treatment of mirrored and identical stimuli begins to diverge. As a common finding, response times for tasks with mirrored stimuli were longer compared to tasks with identical stimuli reflecting their higher cognitive demand. Moreover, we observed smaller saccade amplitudes for mirrored than for identical stimuli suggesting a smaller functional field of view during stimulus perception. The eye-movement results were complemented by our neurofunctional findings. Here, the processing of mirrored stimuli led to less activation in parts of the early visual cortex that respond to the visual periphery than the processing of identical figures. This activation difference remained after eye-movement-associated activations had been excluded. We explain our findings by stimulus-parity-induced differences in saliency maps built up to enhance perception. Thus, the treatment of mirrored and identical stimuli begins to diverge very early in the mental-rotation process and is associated with differences in visual processing.

Neural correlates of fear of movement in high and low fear-avoidant chronic low back pain patients: an event-related fMRI study.

The fear-avoidance model postulates that in chronic low back pain (CLBP) a fear of movement is acquired in the acute phase, which leads to subsequent avoidance of physical activity and contributes to the pain syndrome's becoming chronic. In the present event-related functional magnetic resonance imaging (fMRI) study of the neural correlates of the fear of movement, 60 women (30 CLBP patients, 15 healthy controls, and 15 women with spider phobia; mean age 46.8±9.8 years) participated. The CLBP patients were divided into a high and low fear-avoidant group on the basis of the Tampa Scale of Kinesiophobia. The participants viewed photographs depicting neutral and aversive (back-stressing) movements, generally fear-inducing and neutral pictures from the International Affective Picture System, and pictures of spiders while fMRI data were acquired. It was hypothesized that the high fear-avoidant CLBP patients would show fear-related activations when viewing the aversive movements and that they would differ from CLBP patients with low fear-avoidance and controls in this regard. No such activations were found for high or low fear-avoidant CLBP patients. The random-effects analysis showed no differences between high and low fear-avoidant CLBP patients or high fear-avoidant CLBP patients and controls. Normal fear-related activations were present in the high fear-avoidant CLBP patients for the generally fear-inducing pictures, demonstrating the validity of the stimulation paradigm and a generally unimpaired fear processing of the high fear-avoidant CLBP patients. Our findings do not support the fear component of the fear avoidance model.

Impulsive personality and the ability to resist immediate reward: an fMRI study examining interindividual differences in the neural mechanisms underlying self-control.

The ability to resist immediate rewards is crucial for lifetime success and individual well-being. Using functional magnetic resonance imaging, we assessed the association between trait impulsivity and the neural underpinnings of the ability to control immediate reward desiring. Low and high extreme impulsivity groups were compared with regard to their behavioral performance and brain activation in situations, in which they had to forego immediate rewards with varying value to achieve a superordinate long-term goal. We found that highly impulsive (HI) individuals, who successfully compensated for their lack in behavioral self-control, engaged two complementary brain mechanisms when choosing actions in favor of a long-term goal, but at the expense of an immediate reward. First, self-controlled decisions led to a general attenuation of reward-related activation in the nucleus accumbens, which was accompanied by an increased inverse connectivity with the anteroventral prefrontal cortex. Second, HI subjects controlled their desire for increasingly valuable, but suboptimal rewards through a linear reduction of activation in the ventromedial prefrontal cortex (VMPFC). This was achieved by an increased inverse coupling between the VMPFC and the ventral striatum. Importantly, the neural mechanisms observed in the HI group differed from those in extremely controlled individuals, despite similar behavioral performance. Collectively, these results suggest trait-specific neural mechanisms that allow HI individuals to control their desire for immediate reward.

Altered motor network recruitment during finger tapping in boys with Tourette syndrome.

In Tourette syndrome (TS), not only the tics but also the findings on deficits in motor performance indicate motor system alterations. But our knowledge about the pathophysiology of the motor system in TS is still limited. To better understand the neuronal correlates of motor performance in TS, 19 treatment-naïve boys [age 12.5 (SD 1.4) years] with TS without comorbid symptomatology were compared to an age-matched healthy control group [n = 16; age 12.9 (SD 1.6) years] in regard to brain activation during right-hand index finger tapping by means of functional magnetic resonance imaging. Group differences were found mainly in the left (contralateral) precentral gyrus, which was less activated in boys suffering from TS and in caudate nucleus as well as in medial prefrontal cortex, which was more activated compared to healthy boys. These results show that even in the first years after the onset of the disorder, an altered brain network of motor performance is recruited. These alterations in brain regions frequently associated with TS are probably based on functional changes, which are discussed in terms of early compensatory mechanisms of the motor execution network.

Increased putamen and callosal motor subregion in treatment-naïve boys with Tourette syndrome indicates changes in the bihemispheric motor network.

BACKGROUND: Despite an increasing number of studies, findings of structural brain alterations in patients with Tourette syndrome are still inconsistent. Several confounders (comorbid conditions, medication, gender, age, IQ) might explain these discrepancies. In the present study, these confounders were excluded to identify differences in basal ganglia and corpus callosum size that can be ascribed more probably to Tourette syndrome per se. METHODS: High-resolution T1-weighted structural magnetic resonance images of 49 boys with Tourette syndrome were compared with those of 42 healthy boys. The groups were matched for IQ and age (9 to 15 years). Boys with comorbid conditions and previous treatment were excluded. Volumes of gray and white matter, cerebrospinal fluid as well as the size of the basal ganglia, the thalamus, the corpus callosum and its subregions were estimated. RESULTS: The left and right putamen and subregion 3 of the corpus callosum were larger in boys with Tourette syndrome than in healthy controls. No differences were found in volumes of caudate nucleus, globus pallidus or thalamus of each hemisphere or in total callosal size and its other subregions. CONCLUSIONS: Bilateral enlargement of the putamen may reflect dopaminergic dysfunction or neuroimmunologic alterations (PANDAS) underlying Tourette syndrome. The larger callosal motor subregion 3 might be a consequence of daily tic activity. Previous divergent volumetric findings might be ascribed to confounding variables like comorbid conditions or medication, or to different imaging methods.

The power of imagination--how anticipatory mental imagery alters perceptual processing of fearful facial expressions.

Expectancies strongly shape our perception of the world and preconceptions about stimulus characteristics can even bias the sensory system for illusory percepts. Here we assessed with functional magnetic resonance imaging how anticipatory mental imagery of a mildly fearful face created a predictive bias that proactively altered perception of highly fearful faces and generated the "illusion" of reduced fearfulness. We found that anticipatory activation of the fusiform gyrus (FG) was modulated by the fearfulness of the imagined face. Further during anticipatory imagery, regulatory influences from the lateral and ventromedial prefrontal cortex on the FG primed the perceptual system for a subsequent misperception. This was achieved by increasing perceptual activation in higher-order brain regions for the evaluation of affective valence and contextual framing, while at the same time restricting bottom-up arousal and attention to fearful expressions. Anticipatory mental imagery may thus represent an effective antecedent strategy through which emotional perception can be significantly altered.

Differential activation of the middle-temporal complex to visual stimulation in migraineurs.

OBJECTIVE: Differences between people with and without migraine on various measures of visual perception have been attributed to abnormal cortical processing due to the disease. The aim of the present study was to explore the dynamics of the basic interictal state with regard to the extrastriate, motion-responsive middle temporal area (MT-complex) with functional magnetic resonance imaging (fMRI) at 3 tesla using coherent/incoherent moving dot stimuli. METHOD: Twenty-four migraine patients (12 with aura [MwA], 12 without aura [MwoA]) and 12 healthy subjects participated in the study. The individual cortical folding pattern was accounted for by using a cortical matching approach. RESULTS: In the inferior-posterior portion of the MT-complex, most likely representing MT, control subjects showed stronger bilateral activation compared to MwA and MwoA patients. Compared with healthy controls MwoA and MwA patients showed significantly stronger activation mainly at the left side in response to visual stimulation in the superior-anterior portion of the MT-complex, representing the medial-superior temporal area (MST). CONCLUSION: Our findings strengthen the hypothesis that hyperresponsiveness of the visual cortex in migraine goes beyond early visual areas, even in the interictal period.

The human parahippocampal cortex subserves egocentric spatial learning during navigation in a virtual maze.

BACKGROUND: Present evidence suggests that the hippocampus (HC) and the parahippocampal cortex (PHC) are involved in allocentric (world-centered) spatial memory. However, the putative role of the PHC in egocentric (body-centered) spatial learning has received only limited systematic investigation. METHODS: To examine the role of the PHC in egocentric learning, 19 healthy volunteers learned to find their way in a virtual maze during functional magnetic resonance imaging (fMRI). The virtual maze presented a first-person view, lacked any topographical landmarks and could be learned only using egocentric navigation strategies. RESULTS: During learning, increased medial temporal lobe activity was observed in the PHC bilaterally. Activity was also observed in cortical areas known to project to the PHC and proposed to contribute to egocentric spatial navigation and memory. CONCLUSIONS: Our results point to a role of the PHC for the representation and storage of egocentric information. It seems possible that the PHC contributes to egocentric memory by its feedback projections to the posterior parietal cortex. Moreover, access to allocentric and egocentric streams of spatial information may enable the PHC to construct a global and comprehensive representation of spatial environments and to promote the construction of stable cognitive maps by translating between egocentric and allocentric frames of memory.

Consensus paper: combining transcranial stimulation with neuroimaging.

In the last decade, combined transcranial magnetic stimulation (TMS)-neuroimaging studies have greatly stimulated research in the field of TMS and neuroimaging. Here, we review how TMS can be combined with various neuroimaging techniques to investigate human brain function. When applied during neuroimaging (online approach), TMS can be used to test how focal cortex stimulation acutely modifies the activity and connectivity in the stimulated neuronal circuits. TMS and neuroimaging can also be separated in time (offline approach). A conditioning session of repetitive TMS (rTMS) may be used to induce rapid reorganization in functional brain networks. The temporospatial patterns of TMS-induced reorganization can be subsequently mapped by using neuroimaging methods. Alternatively, neuroimaging may be performed first to localize brain areas that are involved in a given task. The temporospatial information obtained by neuroimaging can be used to define the optimal site and time point of stimulation in a subsequent experiment in which TMS is used to probe the functional contribution of the stimulated area to a specific task. In this review, we first address some general methodologic issues that need to be taken into account when using TMS in the context of neuroimaging. We then discuss the use of specific brain mapping techniques in conjunction with TMS. We emphasize that the various neuroimaging techniques offer complementary information and have different methodologic strengths and weaknesses.

Cortical sensorimotor control in vocalization: a functional magnetic resonance imaging study.

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.

Normal response inhibition in boys with Tourette syndrome.

BACKGROUND: Inhibitory deficits are often a matter of debate in the pathophysiology of Tourette syndrome (TS). Previous neuropsychological studies on behavioral inhibition revealed equivocal results. METHODS: To overcome existing shortcomings (e.g. confounders like medication status, comorbid conditions) we compared medication naïve boys (10-14 years) suffering exclusively from TS with age, gender and IQ matched healthy controls using a highly demanding Go/Nogo task that controls for novelty effects. RESULTS: The performance did not differ between boys with TS and healthy boys. CONCLUSION: In TS normal response inhibition performance as measured by a Go/Nogo task can be assumed. However, there might be neurophysiological abnormalities in TS possibly related to compensatory mechanisms to control for tics. Hence, further studies combining neuropsychological and neurophysiological methods (e.g. electroencephalography, fMRI) using the same strictly controlled design along the whole range of development and tic severity are recommended.