Males and females differ in brain activation during cognitive tasks

To examine the effect of gender on regional brain activity, we utilized functional magnetic resonance imaging (fMRI) during a motor task and three cognitive tasks; a word generation task, a spatial attention task, and a working memory task in healthy male (n = 23) and female (n = 10) volunteers. Functional data were examined for group differences both in the number of pixels activated, and the blood-oxygen-level-dependent (BOLD) magnitude during each task. Males had a significantly greater mean activation than females in the working memory task with a greater number of pixels being activated in the right superior parietal gyrus and right inferior occipital gyrus, and a greater BOLD magnitude occurring in the left inferior parietal lobe. However, despite these fMRI changes, there were no significant differences between males and females on cognitive performance of the task. In contrast, in the spatial attention task, men performed better at this task than women, but there were no significant functional differences between the two groups. In the word generation task, there were no external measures of performance, but in the functional measurements, males had a significantly greater mean activation than females, where males had a significantly greater BOLD signal magnitude in the left and right dorsolateral prefrontal cortex, the right inferior parietal lobe, and the cingulate. In neither of the motor tasks (right or left hand) did males and females perform differently. Our fMRI findings during the motor tasks were a greater mean BOLD signal magnitude in males in the right hand motor task, compared to females where males had an increased BOLD signal magnitude in the right inferior parietal gyrus and in the left inferior frontal gyrus. In conclusion, these results demonstrate differential patterns of activation in males and females during a variety of cognitive tasks, even though performance in these tasks may not vary, and also that variability in performance may not be reflected in differences in brain activation. These results suggest that in functional imaging studies in clinical populations it may be sensible to examine each sex independently until this effect is more fully understood.     

fMRI signal decreases in ipsilateral primary motor cortex during unilateral hand movements are related to duration and side of movement

Interactions between the primary motor cortices of each hemisphere during unilateral hand movements appear to be inhibitory, although there is evidence that the strengths of these interactions are asymmetrical. In the present study, functional magnetic resonance imaging (fMRI) was used to investigate the effects of motor task duration and hand used on unilateral movement-related BOLD signal increases and decreases in the hand region of primary motor cortex (M1) of each hemisphere in six right-handed volunteers. Significant task-related BOLD signal decreases were observed in ipsilateral M1 during single and brief bursts of unilateral movements for both hands. However, these negative-to-baseline responses were found to intensify with increasing movement duration in parallel with greater task-related increases in contralateral M1. Movement-related BOLD signal decreases in ipsilateral M1 were also stronger for the right, dominant hand than for the left hand in our right-handed subjects. These findings would be consistent with the existence of interhemispheric interactions between M1 of each hemisphere, whereby increased neuronal activation in M1 of one hemisphere induces reduced neuronal activity in M1 of the opposite hemisphere. The observation of a hemispheric asymmetry in inhibition between M1 of each hemisphere agrees well with previous neuroimaging and electrophysiological data. These findings are discussed in the context of current understanding of the physiological origins of negative-to-baseline BOLD responses.     

High frequency rTMS modulation of the sensorimotor networks: behavioral changes and fMRI correlates

Repetitive transcranial magnetic stimulation (rTMS) to the primary motor cortex (M1) may induce functional modulation of motor performance and sensory perception. To address the underlying neurophysiological modulation following 10 Hz rTMS applied over M1, we examined cortical activation using 3T functional magnetic resonance imaging (fMRI), as well as the associated motor and sensory behavioral changes. The motor performance measure involved a sequential finger motor task that was also used as an activation task during fMRI. For sensory assessment, current perception threshold was measured before and after rTMS outside the MR scanner, and noxious mechanical stimulation was used as an activation task during fMRI. We found that significant activation in the bilateral basal ganglia, left superior frontal gyrus, bilateral pre-SMA, right medial temporal lobe, right inferior parietal lobe, and right cerebellar hemisphere correlated with enhanced motor performance in subjects that received real rTMS compared with sham-stimulated controls. Conversely, significant deactivation in the right superior and middle frontal gyri, bilateral postcentral and bilateral cingulate gyri, left SMA, right insula, right basal ganglia, and right cerebellar hemisphere were associated with an increase in the sensory threshold. Our findings reveal that rTMS induced rapid changes in the sensorimotor networks associated with sensory perception and motor performance and demonstrate the complexity of such intervention.     

Combination of event-related fMRI and diffusion tensor imaging in an infant with perinatal stroke

Focal ischemic brain injury, or stroke, is an important cause of later handicap in children. Early assessment of structure-function relationships after such injury will provide insight into clinico-anatomic correlation and potentially guide early intervention strategies. We used combined functional MRI (fMRI) with diffusion tensor imaging (DTI) in a 3-month-old infant to explore the structure-function relationship after unilateral perinatal stroke that involved the visual pathways. With visual stimuli, fMRI showed a negative BOLD activation in the visual cortex of the intact right hemisphere, principally in the anterior part, and no activation in the injured hemisphere. The functional activation in the intact hemisphere correlated clearly with the fiber tract of the optic radiation visualized with DTI. DTI confirmed the absence of the optic radiation in the damaged left hemisphere. In addition, event-related fMRI (ER-fMRI) experiments were performed to define the characteristics of the BOLD response. The shape is that of an inverted gamma function (similar to a negative mirror image of the known positive adult BOLD response). The maximum decrease was reached at 5-7 s with signal changes of -1.7 +/- 0.4%.Thus, this report describes for the first time the combined use of DTI and event-related fMRI in an infant and provides insight into the localization of the fMRI visual response in the young infant and the characteristics of the BOLD response.     

Task demand modulations of visuospatial processing measured with functional magnetic resonance imaging

Brain imaging based on functional magnetic resonance imaging (fMRI) provides a useful tool to examine neural networks and cerebral structures subserving visuospatial function. It allows not only the qualitative determination of which areas are active during task processing, but also estimates the quantitative contribution of involved brain regions to different aspects of spatial processing. In this study, we investigated in 10 healthy subjects how the amount of task (computational) demand in an angle discrimination task was related to neural activity as measured with event-related fMRI. Task demand, indicated by behavioral performance, was modulated by presenting clocks with different angular disparity and length of hands. Significant activations were found in the cortical network subserving the visual and visuospatial processing, including the right and left superior parietal lobules (SPL), striate visual areas, and sensorimotor areas. Both blood oxygenation level-dependent (BOLD) signal strength and spatial extent of activation in right as well as left SPL increased with task demand. By contrast, no significant correlation or a very weak correlation was found between the task demand and the BOLD signal as well as between task demand and spatial extent of activations in the striate visual areas and in the sensorimotor areas. These results support the hypothesis that increased computational demand requires more brain resources. The brain regions that are most specialized for the execution of the visuospatial task can be assessed by relating the imposed task demand to the functional activation measured.     

脑卒中后运动性失语的功能磁共振成像研究

目的：探讨脑卒中后运动性失语症患者的语言功能恢复机制。方法：应用3T MR扫描仪对6例脑卒中患者失语后及康复后分别进行两次图片命名任务的BOLD fMRI扫描。实验采用组块设计方案,利用SPM5软件的总体线性模型（General linear model, GLM）进行后处理产生激活脑区图像。并对所有患者在发病后与康复后的脑内激活分布、大小、强度进行分析与比较。结果：所有患者在失语后左侧大脑半球语言相关脑区激活部分出现激活,其中3例右侧Broca’s镜像区出现激活。而在康复后所有患者的左侧大脑半球语言相关脑区激活增多,激活强度增加,其中左侧Broca’s区均出现激活,右侧Broca’s镜像区激活减弱。结论：失语后优势半球丧失功能的语言区移至对侧镜像区和优势半球未受累语言区的功能重组这两种机制都参与了语言功能恢复的过程,近期以右侧半球为主,远期左侧半球发挥更重要作用。     

Functional magnetic resonance imaging identifies somatotopic organization of nociception in the human spinal cord

Functional magnetic resonance imaging (fMRI) is a technique that uses blood oxygen–level–dependent (BOLD) signals to elucidate discrete areas of neuronal activity. Despite the significant number of fMRI human brain studies, few researchers have applied fMRI technology to investigating neuronal activity within the human spinal cord. Our study goals were to demonstrate that fMRI could reveal the following: (i) appropriate somatotopic activations in response to noxious stimuli in the deep and superficial dorsal horn of the human cervical spinal cord, and (ii) lateralization of fMRI activations in response to noxious stimulation in the right and left upper extremity. We subjected healthy participants to noxious stimulation during fMRI scans. Using a spiral in–out image sequence and retrospective correction for physiologic noise, we demonstrated that fMRI can create high-resolution, neuronal activation maps of the human cervical spinal cord. During nociceptive stimulation of all 4 sites (left deltoid, right deltoid, left thenar eminence and right thenar eminence), we found ipsilateral dorsal horn activation. Stimulation of the deltoid activated C5, whereas stimulation of the thenar eminence activated C6. Our study contributes to creating an objective analysis of pain transmission; other investigators can use these results to further study central nervous system changes that occur in patients with acute and chronic pain.     

Right parietal dominance in spatial egocentric discrimination

Egocentric tactile perception is crucial for skilled hand motor control. In order to better understand the brain functional underpinnings related to this basic sensorial perception, we performed a tactile perception functional magnetic resonance imaging (fMRI) experiment with two aims. The first aim consisted of characterizing the neural substrate of two types of egocentric tactile discrimination: the spatial localization (SLD) and simultaneity succession discrimination (SSD) in both hands to define hemispheric dominance for these tasks. The second goal consisted of characterizing the brain activation related to the spatial attentional load, the functional changes and their connectivity patterns induced by the psychometric performance (PP) during SLD. We used fMRI in 25 right-handed volunteers, applying pairs of sinusoidal vibratory stimuli on eight different positions in the palmar surface of both hands. Subjects were required either to identify the stimulus location with respect to an imaginary midline (SLD), to discriminate the simultaneity or succession of a stimuli pair (SSD) or to simply respond to stimulus detection. We found a fronto-parietal network for SLD and frontal network for SSD. During SLD we identified right hemispheric dominance with increased BOLD activation and functional interaction of the right supramarginal gyrus with contralateral intra-parietal sulcus for right and left hand independently. Brain activity correlated to spatial attentional load was found in bilateral structures of intra-parietal sulcus, precuneus extended to superior parietal lobule, pre-supplementary motor area, frontal eye fields and anterior insulae for both hands. We suggest that the right supramarginal gyrus and its interaction with intra-parietal lobule may play a pivotal role in the phenomenon of tactile neglect in right fronto-parietal lesions.     

Left hemisphere specialization for the control of voluntary movement rate

Although persuasive behavioral evidence demonstrates the superior dexterity of the right hand in most people under a variety of conditions, little is known about the neural mechanisms responsible for this phenomenon. As this lateralized superiority is most evident during the performance of repetitive, speeded movement, we used parametric rate variations to compare visually paced movement of the right and left hands. Twelve strongly right-handed subjects participated in a functional magnetic resonance imaging (fMRI) experiment involving variable rate thumb movements. For movements of the right hand, contralateral rate-related activity changes were identified in the precentral gyrus, thalamus, and posterior putamen. For left-hand movements, activity was seen only in the contralateral precentral gyrus, consistent with the existence of a rate-sensitive motor control subsystem involving the left, but not the right, medial premotor corticostriatal loop in right-handed individuals. We hypothesize that the right hemisphere system is less skilled at controlling variable-rate movements and becomes maximally engaged at a lower movement rate without further modulation. These findings demonstrate that right- and left-hand movements engage different neural systems to control movement, even during a relatively simple thumb flexion task. Specialization of the left hemisphere corticostriatal system for dexterity is reflected in asymmetric mechanisms for movement rate control.     

Functional MRI evidence for disparate developmental processes underlying intelligence in boys and girls

Previous research has shown evidence for sex differences in the neuroanatomical bases for intelligence in adults. Possible differences in the neuroanatomical correlates of intelligence and their developmental trajectories between boys and girls were investigated using functional MRI (fMRI). A large cohort of over 300 children, ages 5-18, performed the semantic processing task of silent verb generation. Regions were found in the left hemisphere exhibiting positive correlations of blood-oxygenation-level-dependent (BOLD) activation with IQ, including the middle temporal gyrus, prefrontal cortex (Broca's area), medial frontal gyrus, precuneus, and cingulate gyrus, while the superior temporal gyrus in the right hemisphere displayed a negative correlation of BOLD activation with IQ. Significant sex-X-IQ and sex-X-IQ-X-age interaction effects were also seen in the left middle temporal gyrus and left inferior frontal gyrus. Using a data-driven analysis procedure, a sex-X-IQ-X-age interaction was also demonstrated in the functional connectivity between regions in the left hemisphere, parameterized as a weighted sum of pairwise covariances between fMRI time courses. While young girls (<13 years) exhibited no correlation of connectivity with intelligence, older girls (>13 years) demonstrated a positive association of functional connectivity with intelligence. Boys, however, demonstrated the opposite developmental trajectory, from a positive association of connectivity with intelligence in young boys (ages <9 years), to a negative association in older boys (ages >13 years). Our results provide evidence for disparate neuroanatomical trajectories underlying intelligence in boys and girls.     

Proton-density-weighted spinal fMRI with sensorimotor stimulation at 0.2 T

Proton-density-weighted fMRI at low field (0.2 T) was carried out in the cervical spinal cord of healthy volunteers in this study to examine the feasibility of detecting proton density alteration accompanying activation in the spinal cord. Subjects were asked to grip both hands simultaneously, providing sensorimotor simulation for spinal fMRI. Over 70% subjects recruited had activation localized at C6-C7 spinal levels with discrete activation detected in both the anterior and posterior horns of the cervical spinal cord, and the average fractional signal change was 4.06%. The 0.2 T low magnetic field and the 24 ms short TE used in this study diminished the BOLD effect to a negligible level, thus the observed signal change was believed to be mainly attributable to proton density increase during neuronal stimulation. Our results suggested the existence of task-driven proton density change in the cervical spinal cord.     

Pain fMRI in rat cervical spinal cord: an echo planar imaging evaluation of sensitivity of BOLD and blood volume-weighted fMRI

Objective measure of pain is valuable in drug discovery research and development of analgesics. Spinal cord is an important relay of the pain pathway, and fMRI offers an excellent opportunity to quantify pain using activation in the spinal cord induced by painful stimuli. fMRI literature of cervical spinal cord with regard to the spatial extent, in both longitudinal and cross-sectional directions, of neuronal activation induced by noxious stimulation is ambiguous. This study investigates the feasibility of developing a robust pain assay using fMRI in the cervical spinal cord in alpha-chloralose anesthetized rats subjected to transcutaneous noxious electrical stimulation of the forepaw. Blood oxygenation level dependent (BOLD) and blood volume (BV)-weighted fMRI data were acquired without and with intravenous injection of ultra small superparamagnetic iron oxide particles (USPIO), respectively. BOLD data were acquired by gradient-echo (GE) and spin-echo (SE) echo planar imaging (EPI), while BV-weighted fMRI data were acquired only by GE EPI. Cervical spinal cord activity was robustly detected by all three fMRI techniques. The sensitivity of the fMRI signal was highest in GE BV-weighted fMRI followed in order by GE BOLD, and SE BOLD, respectively. Spatially, the fMRI signal extended approximately 9 mm in the longitudinal direction, covering C(4)-C(8) segments, coinciding with the synapse location of afferent terminals from the stimulated site. In the cross-sectional direction, the signal change is localized predominantly to the ipsilateral dorsal region. This study demonstrates that cervical spinal cord fMRI can be performed reliably in anesthetized rats offering it as a potential tool for analgesic drug development.     

Parametric analysis of rate-dependent hemodynamic response functions of cortical and subcortical brain structures during auditorily cued finger tapping: a fMRI study

A multitude of functional imaging studies revealed a mass activation effect at the level of the sensorimotor cortex during repetitive finger-tapping or finger-to-thumb opposition tasks in terms of either a stepwise or a monotonic relationship between movement rate and hemodynamic response. With respect to subcortical structures of the centralmotor system, there is, by contrast, some preliminary evidence for nonlinear rate/response functions within basal ganglia and cerebellum. To further specify these hemodynamic mechanisms, functional magnetic resonance imaging (fMRI) was performed during a finger-tapping task in response to acoustic stimuli (six different frequencies: 2.0, 2.5, 3.0, 4.0, 5.0 and 6.0 Hz; applied via headphones). Passive listening to the same auditory stimuli served as a control condition. Statistical evaluation of the obtained data considered two approaches: categorical and parametric analysis. As expected, the magnitude of the elicited hemodynamic response within left sensorimotor cortex (plateau phase at frequencies above 4 Hz) and mesiofrontal cortex paralleled movement rate. The observed bipartite mesial response pattern, most presumably, reflects functional compartmentalization of supplementary motor area (SMA) in a rostral component (pre-SMA) and in a caudal (SMA proper) component. At the level of the cerebellum, two significant hemodynamic responses within the hemisphere ipsilateral to the hand engaged into finger tapping (anterior/posterior quadrangular lobule and posterior quadrangular lobule) could be observed. Both activation foci exhibited a stepwise rate/response function. In accordance with clinical data, these data indicate different cerebellar contributions to motor control at frequencies below or above about 3 Hz, respectively. Caudate nucleus, putamen, and external pallidum of the left hemisphere displayed, by contrast, a negative linear rate/response relationship. The physiological significance of these latter findings remains to be clarified.     

脑内转移瘤切除术后手指运动M_1功能区重组的功能磁共振研究

目的探讨功能磁共振(bloodoxygenationleveldependentfunc-tionalMRI,BOLDfMRI)在临床医学方面的应用价值。方法对1例右侧顶叶单发转移瘤患者在手术前、后分别进行了双侧动手试验的脑功能成像。结果脑功能成像准确地反映了运动功能激活区的位置及激活程度,肿瘤侧运动区可因肿瘤占位效应产生移位,手术前的手动试验潜在功能区并未被激活,但是在肿瘤切除术后,主运动区M1以外可见潜在重组的功能区激活。结论脑内重要功能区肿瘤切除术患者,应常规进行术前和术后fMRI的研究,这对于提高术后患者生活质量、避免医源性损伤或将其减至最低水平有极大的帮助。     

Arterial spin labeling for motor activation mapping at 3T with a 32-channel coil: reproducibility and spatial accuracy in comparison with BOLD fMRI

Functional arterial spin labeling (fASL) is an innovative biomarker of neuronal activation that allows direct and absolute quantification of activation-related CBF and is less sensitive to venous contamination than BOLD fMRI. This study evaluated fASL for motor activation mapping in comparison with BOLD fMRI in terms of involved anatomical area localization, intra-individual reproducibility of location, quantification of neuronal activation, and spatial accuracy. Imaging was performed at 3T with a 32-channel coil and dedicated post-processing tools were used. Twelve healthy right-handed subjects underwent fASL and BOLD fMRI while performing a right hand motor activation task. Three sessions were performed 7days apart in similar physiological conditions. Our results showed an activation in the left primary hand motor area for all 36 sessions in both fASL and BOLD fMRI. The individual functional maps for fASL demonstrated activation in ipsilateral secondary motor areas more often than the BOLD fMRI maps. This finding was corroborated by the group maps. In terms of activation location, fASL reproducibility was comparable to BOLD fMRI, with a distance between activated volumes of 2.1mm and an overlap ratio for activated volumes of 0.76, over the 3 sessions. In terms of activation quantification, fASL reproducibility was higher, although not significantly, with a CVintra of 11.6% and an ICC value of 0.75. Functional ASL detected smaller activation volumes than BOLD fMRI but the areas had a high degree of co-localization. In terms of spatial accuracy in detecting activation in the hand motor area, fASL had a higher specificity (43.5%) and a higher positive predictive value (69.8%) than BOLD fMRI while maintaining high sensitivity (90.7%). The high intra-individual reproducibility and spatial accuracy of fASL revealed in the present study will subsequently be applied to pathological subjects.     

Investigations on spinal cord fMRI of cats under ketamine

Functional magnetic resonance imaging (fMRI) of the spinal cord has been the subject of intense research for the last ten years. An important motivation for this technique is its ability to detect non-invasively neuronal activity in the spinal cord related to sensorimotor functions in various conditions, such as after spinal cord lesions. Although promising results of spinal cord fMRI have arisen from previous studies, the poor reproducibility of BOLD activations and their characteristics remain a major drawback. In the present study we investigated the reproducibility of BOLD fMRI in the spinal cord of cats (N=9) by repeating the same stimulation protocol over a long period (approximately 2 h). Cats were anaesthetized with ketamine, and spinal cord activity was induced by electrical stimulation of cutaneous nerves of the hind limbs. As a result, task-related signals were detected in most cats with relatively good spatial specificity. However, BOLD response significantly varied within and between cats. This variability was notably attributed to the moderate intensity of the stimulus producing a low amplitude haemodynamic response, variation in end-tidal CO(2) during the session, low signal-to-noise ratio (SNR) in spinal fMRI time series and animal-specific vascular anatomy. Original contributions of the present study are: (i) first spinal fMRI experiment in ketamine-anaesthetized animals, (ii) extensive study of intra- and inter-subject variability of activation, (iii) characterisation of static and temporal SNR in the spinal cord and (iv) investigation on the impact of CO(2) end-tidal level on the amplitude of BOLD response.     

The functional neural architecture of components of attention in language-processing tasks

Using functional magnetic resonance imaging we examined three important dimensions of attentional control (selective attention, divided attention, and executive function) in 25 neurologically normal, right-handed men and women, using tasks involving the perception and processing of printed words, spoken words, or both. In the context of language-processing manipulations: selective attention resulted in increased activation at left hemisphere parietal sites as well as at inferior frontal sites, divided attention resulted in additional increases in activation at these same left hemisphere sites and was also uniquely associated with increased activation of homologous sites in the right hemisphere, and executive function (measured during a complex task requiring sequential decision-making) resulted in increased activation at frontal sites relative to all other conditions. Our findings provide support for the belief that specific functional aspects of attentional control in language processing involve widely distributed but distinctive cortical systems, with mechanisms associated with the control of perceptual selectivity involving primarily parietal and inferior frontal sites and executive function engaging specific sites in frontal cortex.     

Anatomy and time course of discrimination and categorization processes in vision: an fMRI study

Studies investigating the cerebral areas involved in visual processes generally oppose either different tasks or different stimulus types. This work addresses, by fMRI, the interaction between the type of task (discrimination vs. categorization) and the type of stimulus (Latin letters, well-known geometrical figures, and Korean letters). Behavioral data revealed that the two tasks did not differ in term of percentage of errors or correct responses, but a delay of 185 ms was observed for the categorization task in comparison with the discrimination task. All conditions activated a common neural network that includes both striate and extrastriate areas, especially the fusiform gyri, the precunei, the insulae, and the dorsolateral frontal cortex. In addition, interaction analysis revealed that the right insula was sensitive to both tasks and stimuli, and that stimulus type induced several significant signal variations for the categorization task in right frontal cortex, the right middle occipital gyrus, the right cuneus, and the left and right fusiform gyri, whereas for the discrimination task, significant signal variations were observed in the right occipito-parietal junction only. Finally, analyzing the latency of the BOLD signal also revealed a differential neural dynamics according to tasks but not to stimulus type. These temporal differences suggest a parallel hemisphere processing in the discrimination task vs. a cooperative interhemisphere processing in the categorization task that may reflect the observed differences in reaction time.     

Spinal cord functional MRI at 3 T: gradient echo echo-planar imaging versus turbo spin echo

The purpose of this study was to evaluate and compare turbo spin echo (TSE) with gradient echo echo-planar imaging (GE-EPI) pulse sequences for functional magnetic resonance imaging (fMRI) of spinal cord activation at 3 T field strength. Healthy volunteers underwent TSE and GE-EPI spinal fMRI. The activation paradigm comprised the temporal alternation of finger motion and rest. Pulse sequences were optimized to obtain sufficient image quality and optimal sensitivity to small T(2) or T(2)* relaxation time changes. Spinal cord activation measured by the two pulse sequences was evaluated with respect to spatial distribution of activation, signal sensitivity, and reproducibility. For the GE-EPI sequence, fMRI activation was maximal in the spinal cord segments at the levels of the fifth cervical down to the first thoracic vertebra. For the TSE sequence, fMRI measurements showed no distinct location with maximal activation. Percentage signal change and number of activated voxels were approximately twice as high for GE-EPI compared to TSE fMRI. Reproducibility of the signal changes was much better for GE-EPI than for TSE imaging. To conclude, multi-subjects averaged GE-EPI is more location specific for blood-oxygen-level-dependent (BOLD) activation, more sensitive, and is suggested to be more reproducible than TSE fMRI.     

Magnetic resonance imaging of neuronal function in the spinal cord: spinal FMRI

A review of the current literature on magnetic resonance imaging of neuronal function in the spinal cord (spinal fMRI) is presented. The unique challenges of spinal fMRI are identified as being the small cross-sectional dimensions of the spinal cord, magnetic field inhomogeneity caused by the bone and cartilage in the spine, and motion of cerebrospinal fluid, blood, adjacent tissues and organs and of the spinal cord itself. Techniques have been developed to overcome or compensate for these challenges and the result is a fMRI method which is distinct from that used for mapping function in the brain. Evidence that the current spinal fMRI method provides accurate and sensitive maps of neuronal function is also discussed. Studies presented in the literature have demonstrated areas of neuronal activity corresponding with spinal cord neuroanatomy as a result of thermal and electrical stimuli and motor tasks with the hands, arms and legs. Signal intensity changes detected in active areas have also been demonstrated to depend on the intensity of the stimuli with both thermal stimulation and a motor task, providing evidence of the correspondence between spinal fMRI results and neuronal activity in the spinal cord.