Brain Motor Function Research Articles

Heavy and Chronic Cannabis Addiction does not Impact Motor Function: A BOLD-fMRI Study

The goal of this to demonstrate the impact of heavy and chronic cannabis use on brain potential functional control, reorganization, and plasticity in the cortical area. 23 cannabis users were convened in 3 groups of users. The first group included 11 volunteers with an average of 15 joins/day; the second group included 6 volunteers with an average of 1.5 joins/day; the third group included 6 volunteers with an average of 2.8 joins/week. Besides, 6 healthy volunteers in the control group, All healthy and cannabis users underwent identical brain BOLD-fMRI assessments of their motor function. Besides, neuropsychological and full biological assessments were achieved. BOLD-fMRI maps of motor areas were obtained, including quantitative evaluation of the activations in the motor area. A statistical analysis of various groups was achieved. Groups of chronic cannabis addiction of varying level of use were setup. Namely heavy, moderate and low users groups; doses have been shown to have systematically equivalent effects on the control of brain motor function. Indeed, the BOLD-fMRI shows a remarkable sensitivity to brain plasticity and reorganization of the functional motor control of the studied cortical area, and such variation was not shown. Specific elucidation of the effect of cannabis effect in this unique function should clarify further protective pharmacological effects. This might illuminate the use of neuronal resources to prepare processes for pharmacological use and pharmaceutical forms. This suggests exploring any potential cannabis pharmaceutical form in diseases involving motor impairments.

Mapping Brain Motor Functions Using Transcranial Magnetic Stimulation with a Volume Conductor Model and Electrophysiological Experiments.

Transcranial magnetic stimulation (TMS) activates brain cells in a noninvasive manner and can be used for mapping brain motor functions. However, the complexity of the brain anatomy prevents the determination of the exact location of the stimulated sites, resulting in the limitation of the spatial resolution of multiple targets. The aim of this study is to map two neighboring muscles in cortical motor areas accurately and quickly. Multiple stimuli were applied to the subject using a TMS stimulator to measure the motor-evoked potentials (MEPs) in the corresponding muscles. For each stimulation condition (coil location and angle), the induced electric field (EF) in the brain was computed using a volume conductor model for an individualized head model of the subject constructed from magnetic resonance images. A post-processing method was implemented to determine a TMS hotspot using EF corresponding to multiple stimuli, considering the amplitude of the measured MEPs. The dependence of the computationally estimated hotspot distribution on two target muscles was evaluated (n = 11). The center of gravity of the first dorsal interosseous cortical representation was lateral to the abductor digiti minimi by a minimum of 2 mm. The localizations were consistent with the putative sites obtained from previous EF-based studies and fMRI studies. The simultaneous cortical mapping of two finger muscles was achieved with only several stimuli, which is one or two orders of magnitude smaller than that in previous studies. Our proposal would be useful in the preoperative mapping of motor or speech areas to plan brain surgery interventions.

Lack of changes in motor function of the brain in healthy older adults after participation in a cognitive walking program.

A walking-based exercise program, called the cognitive walking program (CWP), has been shown to be beneficial for improving cognitive function in healthy older adults. It remains unknown whether it is beneficial for improving motor function of the brain. We investigated the effects of CWP on motor function of the brain by examining changes in interlimb transfer of visuomotor adaptation in older adults. Subjects were divided based on their physical activity level (active vs. sedentary) and participated in CWP. A control group performed normal walking. Fifty-two healthy older adults, 67–78 years old, were studied. All subjects participated in CWP or normal walking for 6 months. To assess brain motor function, all subjects adapted to a rotated visual display during reaching movements with the right arm first, then with the left arm. Interlimb transfer of visuomotor adaptation was assessed at baseline, 3 months, and 6 months after training onset. It was hypothesized that if CWP had beneficial effects, the extent of transfer would change over time. The subject’s physical fitness was also assessed. Significant transfer from the right to the left arm occurred in all subject groups. Improvements in physical fitness were also observed. However, the extent of transfer did not change even after 6 months, with no group difference. Findings suggest that though beneficial for improving cognitive function in older adults, participating in CWP for 6 months is not long enough to improve brain motor function when the motor function is reflected as changes in interlimb transfer of visuomotor adaptation.

G-Causality Brain Connectivity Differences of Finger Movements between Motor Execution and Motor Imagery.

Motor imagery is one of the classical paradigms which have been used in brain-computer interface and motor function recovery. Finger movement-based motor execution is a complex biomechanical architecture and a crucial task for establishing most complicated and natural activities in daily life. Some patients may suffer from alternating hemiplegia after brain stroke and lose their ability of motor execution. Fortunately, the ability of motor imagery might be preserved independently and worked as a backdoor for motor function recovery. The efficacy of motor imagery for achieving significant recovery for the motor cortex after brain stroke is still an open question. In this study, we designed a new paradigm to investigate the neural mechanism of thirty finger movements in two scenarios: motor execution and motor imagery. Eleven healthy participants performed or imagined thirty hand gestures twice based on left and right finger movements. The electroencephalogram (EEG) signal for each subject during sixty trials left and right finger motor execution and imagery were recorded during our proposed experimental paradigm. The Granger causality (G-causality) analysis method was employed to analyze the brain connectivity and its strength between contralateral premotor, motor, and sensorimotor areas. Highest numbers for G-causality trials of 37 ± 7.3, 35.5 ± 8.8, 36.3 ± 10.3, and 39.2 ± 9.0 and lowest Granger causality coefficients of 9.1 ± 3.2, 10.9 ± 3.7, 13.2 ± 0.6, and 13.4 ± 0.6 were achieved from the premotor to motor area during execution/imagination tasks of right and left finger movements, respectively. These results provided a new insight into motor execution and motor imagery based on hand gestures, which might be useful to build a new biomarker of finger motor recovery for partially or even completely plegic patients. Furthermore, a significant difference of the G-causality trial number was observed during left finger execution/imagery and right finger imagery, but it was not observed during the right finger execution phase. Significant difference of the G-causality coefficient was observed during left finger execution and imagery, but it was not observed during right finger execution and imagery phases. These results suggested that different MI-based brain motor function recovery strategies should be taken for right-hand and left-hand patients after brain stroke.

The Usefulness of Near-Infrared Spectroscopy in Monitoring the Location of Eloquent Area and Function Preservation in Brain Surgery

Abstract The extent of resection has been shown to influence the outcome of brain tumours. The concept of brain plasticity is to prevent damage to the eloquent areas while maximizing the extent of tumor resection. The present case report describes the usefulness of the near-infrared spectroscopy (NIRS) in evaluation of the possibility of functional preservation for surgeries in eloquent areas. We present a 46-year-old woman, who had previously undergone four sessions of internal decompression surgery for left frontal anaplastic ependymoma. She later underwent radical tumor resection surgery involving the superior and middle frontal gyri, anterior parietal gyrus, corpus callosum, coronal radiation and basal ganglia. Postoperatively, her right hemiparesis did not deteriorate and she could ambulate without much aid. Multichannel NIRS system revealed that hot spot location was in the right superior frontal gyrus and parietal lobe by the same task of right knee joint movement. We judged that her right brain motor function shifted to the contralateral hemisphere by the long course of her illness. It might be possible that if the NIRS was used earlier around the third or fourth perioperative period, with a reliable confirmation of migration of the right motor function to opposite side, the option of a more aggressive tumor resection may have been attempted. NIRS can be a useful and sensitive tool for predicting the location of eloquent areas and monitoring the extent of brain plasticity between surgeries.

A high-resolution computational localization method for transcranial magnetic stimulation mapping

BackgroundTranscranial magnetic stimulation (TMS) is used for the mapping of brain motor functions. The complexity of the brain deters determining the exact localization of the stimulation site using simplified methods (e.g., the region below the center of the TMS coil) or conventional computational approaches. ObjectiveThis study aimed to present a high-precision localization method for a specific motor area by synthesizing computed non-uniform current distributions in the brain for multiple sessions of TMS. MethodsPeritumoral mapping by TMS was conducted on patients who had intra-axial brain neoplasms located within or close to the motor speech area. The electric field induced by TMS was computed using realistic head models constructed from magnetic resonance images of patients. A post-processing method was implemented to determine a TMS hotspot by combining the computed electric fields for the coil orientations and positions that delivered high motor-evoked potentials during peritumoral mapping. The method was compared to the stimulation site localized via intraoperative direct brain stimulation and navigated TMS. ResultsFour main results were obtained: 1) the dependence of the computed hotspot area on the number of peritumoral measurements was evaluated; 2) the estimated localization of the hand motor area in eight non-affected hemispheres was in good agreement with the position of a so-called “hand-knob”; 3) the estimated hotspot areas were not sensitive to variations in tissue conductivity; and 4) the hand motor areas estimated by this proposal and direct electric stimulation (DES) were in good agreement in the ipsilateral hemisphere of four glioma patients. Conclusion(s)The TMS localization method was validated by well-known positions of the “hand-knob” in brains for the non-affected hemisphere, and by a hotspot localized via DES during awake craniotomy for the tumor-containing hemisphere.

Understanding the Impact of Stroke on Brain Motor Function: A Hierarchical Bayesian Approach

ABSTRACTStroke is a disturbance in blood supply to the brain resulting in the loss of brain functions, particularly motor function. A study was conducted by the UCI Neurorehabilitation Lab to investigate the impact of stroke on motor-related brain regions. Functional MRI (fMRI) data were collected from stroke patients and healthy controls while the subjects performed a simple motor task. In addition to affecting local neuronal activation strength, stroke might also alter communications (i.e., connectivity) between brain regions. We develop a hierarchical Bayesian modeling approach for the analysis of multi-subject fMRI data that allows us to explore brain changes due to stroke. Our approach simultaneously estimates activation and condition-specific connectivity at the group level, and provides estimates for region/subject-specific hemodynamic response functions. Moreover, our model uses spike-and-slab priors to allow for direct posterior inference on the connectivity network. Our results indicate that motor-control regions show greater activation in the unaffected hemisphere and the midline surface in stroke patients than those same regions in healthy controls during the simple motor task. We also note increased connectivity within secondary motor regions in stroke subjects. These findings provide insight into altered neural correlates of movement in subjects who suffered a stroke. Supplementary materials for this article are available online.

Simultaneous transcranial direct current stimulation (tDCS) and whole-head magnetoencephalography (MEG): assessing the impact of tDCS on slow cortical magnetic fields

Transcranial direct current stimulation (tDCS) can influence cognitive, affective or motor brain functions. Whereas previous imaging studies demonstrated widespread tDCS effects on brain metabolism, direct impact of tDCS on electric or magnetic source activity in task-related brain areas could not be confirmed due to the difficulty to record such activity simultaneously during tDCS. The aim of this proof-of-principal study was to demonstrate the feasibility of whole-head source localization and reconstruction of neuromagnetic brain activity during tDCS and to confirm the direct effect of tDCS on ongoing neuromagnetic activity in task-related brain areas. Here we show for the first time that tDCS has an immediate impact on slow cortical magnetic fields (SCF, 0–4Hz) of task-related areas that are identical with brain regions previously described in metabolic neuroimaging studies. 14 healthy volunteers performed a choice reaction time (RT) task while whole-head magnetoencephalography (MEG) was recorded. Task-related source-activity of SCFs was calculated using synthetic aperture magnetometry (SAM) in absence of stimulation and while anodal, cathodal or sham tDCS was delivered over the right primary motor cortex (M1). Source reconstruction revealed task-related SCF modulations in brain regions that precisely matched prior metabolic neuroimaging studies. Anodal and cathodal tDCS had a polarity-dependent impact on RT and SCF in primary sensorimotor and medial centro-parietal cortices. Combining tDCS and whole-head MEG is a powerful approach to investigate the direct effects of transcranial electric currents on ongoing neuromagnetic source activity, brain function and behavior.

Cortical involvement during myotonia in myotonic dystrophy: an fMRI study.

Myotonic dystrophy type 1 (DM1) is a common adulthood muscular dystrophy, characterized by muscle wasting, myotonia, and multisystemic manifestations. The phenomenon of involuntary muscle contraction during myotonia offers a unique possibility of investigating brain motor functions. This study explores cortical involvement during grip myotonia in DM1. Sixteen DM1 patients were enrolled in the study. Eight patients had apparent grip myotonia, while eight patients did not (control subjects). All patients underwent functional MRI grip task examination twice: prior a warm-up procedure (myotonia was elicited in patients with apparent grip myotonia) and after a warm-up procedure (myotonia was attenuated in patients with apparent grip myotonia). No myotonia was elicited during either examination in patients without apparent grip myotonia. Cerebral blood oxygen level-dependent (BOLD) signals were compared both between groups with and without apparent myotonia, and between pre- and post-warm-up sessions. Significantly higher BOLD signal was found during myotonia phase in patients with apparent grip myotonia compared to corresponding non-myotonia phase of patients without apparent grip myotonia in the supplementary motor area and in the dorsal anterior cingulate cortex. Significant differences in BOLD signal levels of very similar pattern were detected between prewarm-up session myotonia phase and post-warm-up session myotonia absent phase in the group of patients with apparent grip myotonia. We showed that myotonia is related to cortical function in high-order motor control areas. This cortical involvement is most likely to represent action of inhibitory circuits intending motor termination.

Chapter 3 - Neuropsychologic evaluation and exposure to neurotoxicants

The history of neuropsychologic assessment describes the development of a psychometric approach to neuropsychologic measurement, based on the initial clinical/theoretical approach exemplified by pioneers, who also discussed different brain functions and hypotheses for clinical exploration and treatment. Early neuropsychologic assessment practices in the USA arose out of the need to screen, diagnose, and treat World War II veterans who returned with brain injuries. Clinical testing was used to determine treatment and rehabilitation potential. Clinical psychologists had previously developed educational tests to investigate students' abilities and disabilities. Using population studies, primarily in the USA, Canada and Europe, neuropsychologists developed standardized test scores, permitting comparisons of scores based on the normal curve and evolving knowledge of brain/behavior relationships. In clinical interpretations, neuropsychologists use extensive normative data based on cognitive, mood, executive, neurologic, and motor brain functions of groups with different cultural and educational backgrounds and psychiatric illnesses. Large groups of workers can be screened with a brief neuropsychologic screening test battery to assess the psychologic status of personnel. Commonly used tests by domain are described, as well as patterns of acute and chronic neurotoxicant exposures, treatment, and rehabilitation. Future developments will relate imaging studies to neuropsychologic performance.

Noninvasive and Painless Magnetic Stimulation of Nerves Improved Brain Motor Function and Mobility in a Cerebral Palsy Case

Motor deficits in cerebral palsy disturb functional independence. This study tested whether noninvasive and painless repetitive peripheral magnetic stimulation could improve motor function in a 7-year-old boy with spastic hemiparetic cerebral palsy. Stimulation was applied over different nerves of the lower limbs for 5 sessions. We measured the concurrent aftereffects of this intervention on ankle motor control, gait (walking velocity, stride length, cadence, cycle duration), and function of brain motor pathways. We observed a decrease of ankle plantar flexors resistance to stretch, an increase of active dorsiflexion range of movement, and improvements of corticospinal control of ankle dorsiflexors. Joint mobility changes were still present 15 days after the end of stimulation, when all gait parameters were also improved. Resistance to stretch was still lower than prestimulation values 45 days after the end of stimulation. This case illustrates the sustained effects of repetitive peripheral magnetic stimulation on brain plasticity, motor function, and gait. It suggests a potential impact for physical rehabilitation in cerebral palsy.

Dikkat Eksikliği Hiperaktivite Bozukluğu İle Prezente Olan Corpus Callosum Agenezisi: İki Olgu Bildirimi

ADHD is a treatable neuropsychiatric disorder which can continue till adulthood. There have been three subtypes including attention deficiency, hyperactivity and impulsivity. Its etiology remains unclear yet. It is hypothesized that there is an impairment of neurodevelopment in early developmental periods through the interactions between genetic and environmental processes. Corpus callosum provides an integration of cognitive, sensorial and motor functions of brain as a response to the impulses originating from the cortex. The damage of this region may result in deterioration of some cerebral functions such as cognitive functions, speaking, learning ability and impulse control. In this paper, we report two pediatric cases who had comorbid attention deficiency and corpus callosum agenesis without mental retardation.

Development of a three-axis acceleration signal measurement system for fMRI motor studies

The purpose of this study was to develop a three-axis acceleration signal measurement system that could measure acceleration signals without deteriorating the functional magnetic resonance imaging (fMRI) data and not affect the main magnetic field, the gradient magnetic field, which varies rapidly with time, or the radio frequency (RF) pulse during fMRI acquisition. A three-axis accelerometer was used to measure acceleration signals, and Velcro was used to attach the accelerometer module to a finger or wrist. To minimize the mutual interference effect between the fMRI system and the acceleration signal measurement system, an amplifier circuit was constructed of analog devices, and the amplifier was located in the shielded case, which was made of copper and aluminum. The acceleration signal was modulated to an optic signal using pulse width modulation (PWM), and the modulated optic signal was transmitted outside the fMRI room using a light emitting diode (LED) and optic cable. We were able to verify that fMRI data and the tri-directional acceleration signal were measured simultaneously and stably. Various movement variables such as position, velocity, and jerk could be obtained numerically. Therefore, this system could be used for studying of the relationship between various movement variables and brain motor function, especially for the study of the rehabilitation field.

MEG neuroimaging of perceptual, motor and cognitive brain function in preschool aged children

MEG neuroimaging of perceptual, motor and cognitive brain function in preschool aged children

Comparison of movement related cortical potential in healthy people and amyotrophic lateral sclerosis patients

Objective: To understand the brain motor functions and neurophysiological changes due to motor disorder by comparing electroencephalographic data between healthy people and amyotrophic lateral sclerosis (ALS) patients.Methods: The movement related cortical potential (MRCP) was recorded from seven healthy subjects and four ALS patients. They were asked to imagine right wrist extension at two speeds (fast and slow). The peak negativity (PN) and rebound rate (RR) were extracted from MRCP for comparison.Results: The statistical analysis has showed that there was no significant difference in PN between the healthy and the ALS subjects. However, the healthy subjects presented faster RR than ALS during both fast and slow movement imagination.Conclusions: The weaker RR of ALS patients might reflect the impairment of motor output pathways or the degree of motor degeneration.Significance: The comparison between healthy people and ALS patients provides a way to explain the movement disorder through brain electrical signal. In addition, the characteristics of MRCP could be used to monitor and guide brain plasticity in patients.

Cerebral motor function in very premature‐at‐birth adolescents: a brain stimulation exploration of kangaroo mother care effects

Given that prematurity has deleterious effects on brain networking development beyond childhood, the study explored whether an early intervention such as Kangaroo Mother Care (KMC) in very preterm preemies could have influenced brain motor function up to adolescence. Transcranial magnetic stimulation (TMS) was applied over the primary motor cortex (M1) of 39 adolescents born very prematurely (<33 weeks' gestational age, 21 having received KMC after birth, 18 Controls with no KMC) and nine adolescents born at term (>37 weeks' gestational age, >2500 g) to assess the functional integrity of motor circuits in each hemisphere (motor planning) and between hemispheres (callosal function). All TMS outcomes were similar between KMC and term adolescents, with typical values as in healthy adults, and better than in Controls. KMC adolescents presented faster conduction times revealing more efficient M1 cell synchronization (p < 0.05) and interhemispheric transfer time (p < 0.0001), more frequent inhibitory processes with a better control between hemispheres (p < 0.0001). The enhanced synchronization, conduction times and connectivity of cerebral motor pathways in the KMC group suggests that the Kangaroo Mother Care positively influenced the premature brain networks and synaptic efficacy up to adolescence.

Using virtual reality to characterize episodic memory profiles in amnestic mild cognitive impairment and Alzheimer's disease: Influence of active and passive encoding

Most neuropsychological assessments of episodic memory bear little similarity to the events that patients actually experience as memories in daily life. The first aim of this study was to use a virtual environment to characterize episodic memory profiles in an ecological fashion, which includes memory for central and perceptual details, spatiotemporal contextual elements, and binding. This study included subjects from three different populations: healthy older adults, patients with amnestic mild cognitive impairment (aMCI) and patients with early to moderate Alzheimer's disease (AD). Second, we sought to determine whether environmental factors that can affect encoding (active vs. passive exploration) influence memory performance in pathological aging. Third, we benchmarked the results of our virtual reality episodic memory test against a classical memory test and a subjective daily memory complaint scale. Here, the participants were successively immersed in two virtual environments; the first, as the driver of a virtual car (active exploration) and the second, as the passenger of that car (passive exploration). Subjects were instructed to encode all elements of the environment as well as the associated spatiotemporal contexts. Following each immersion, we assessed the patient's recall and recognition of central information (i.e., the elements of the environment), contextual information (i.e., temporal, egocentric and allocentric spatial information) and lastly, the quality of binding. We found that the AD patients’ performances were inferior to that of the aMCI and even more to that of the healthy aged groups, in line with the progression of hippocampal atrophy reported in the literature. Spatial allocentric memory assessments were found to be particularly useful for distinguishing aMCI patients from healthy older adults. Active exploration yielded enhanced recall of central and allocentric spatial information, as well as binding in all groups. This led aMCI patients to achieve better performance scores on immediate temporal memory tasks. Finally, the patients’ daily memory complaints were more highly correlated with the performances on the virtual test than with their performances on the classical memory test. Taken together, these results highlight specific cognitive differences found between these three populations that may provide additional insight into the early diagnosis and rehabilitation of pathological aging. In particular, neuropsychological studies would benefit to use virtual tests and a multi-component approach to assess episodic memory, and encourage active encoding of information in patients suffering from mild or severe age-related memory impairment. The beneficial effect of active encoding on episodic memory in aMCI and early to moderate AD is discussed in the context of relatively preserved frontal and motor brain functions implicated in self-referential effects and procedural abilities.

Movement Observation Activates Lower Limb Motor Networks in Chronic Complete Paraplegia

Background. In healthy subjects, observation of actions activates a motor network similar to that involved in the performance of the observed actions. Movement observation could perhaps be applied to functionally sustain brain motor functions when efferent motor commands and proprioceptive feedbacks are disconnected. Objective. The authors examined whether observation-induced brain activation is preserved in people with chronic complete spinal cord injury (SCI). Methods. Nine patients and 12 healthy subjects underwent behavioral assessment and functional magnetic resonance imaging. The SCI patients attempted to perform dorsal and plantar flexions of the right foot, and the controls also executed the same movement. Both groups observed subsequent video clips showing the same movement. Results. In the SCI group, attempted and observed foot movements activated a common observation–execution network including ventral premotor, parietal cortex, and cerebellum as in healthy subjects. Conclusions. Long after onset of complete SCI, the brain maintains its ability to respond to task-specific visual inputs, which suggests preservation of motor programs. This persistence might be a prerequisite for repair strategies of the spinal cord that rely on appropriate activation of the brain to try to restore limb function. The preserved cortical network may offer an additional motor rehabilitation approach for people with SCI.

Brain motor system function in a patient with complete spinal cord injury following extensive brain–computer interface training

Although several features of brain motor function appear to be preserved even in chronic complete SCI, previous functional MRI (fMRI) studies have also identified significant derangements such as a strongly reduced volume of activation, a poor modulation of function and abnormal activation patterns. It might be speculated that extensive motor imagery training may serve to prevent such abnormalities. We here report on a unique patient with a complete traumatic SCI below C5 who learned to elicit electroencephalographic signals beta-bursts in the midline region upon imagination of foot movements. This enabled him to use a neuroprosthesis and to "walk from thought" in a virtual environment via a brain-computer interface (BCI). We here used fMRI at 3T during imagined hand and foot movements to investigate the effects of motor imagery via persistent BCI training over 8 years on brain motor function and compared these findings to a group of five untrained healthy age-matched volunteers during executed and imagined movements. We observed robust primary sensorimotor cortex (SMC) activity in expected somatotopy in the tetraplegic patient upon movement imagination while such activation was absent in healthy untrained controls. Sensorimotor network activation with motor imagery in the patient (including SMC contralateral to and the cerebellum ipsilateral to the imagined side of movement as well as supplementary motor areas) was very similar to the pattern observed with actual movement in the controls. We interpret our findings as evidence that BCI training as a conduit of motor imagery training may assist in maintaining access to SMC in largely preserved somatopy despite complete deafferentation.

Dyspnea and asthma

Dyspnea--the perception of respiratory discomfort--is a primary symptom of asthma. This review examines possible ways to link mechanisms, measurement and treatment that will increase our understanding of this condition. Functional neuroimaging methods have proven to be powerful tools that serve as advanced models of sensor motor brain function. Studies examining functional neuroimaging methods have revealed activation of distinct brain areas associated with increased dyspnea. Pulmonary hyperinflation has been proposed to influence the perception of dyspnea. The association of hyperinflation with minor levels of bronchoconstriction reflects the partition of the sensory effect of airway narrowing per se from that of the attendant elastic loading of the inspiratory muscles. There is evidence to suggest, however, that hyperinflation does not play an important role in the pathogenesis of exercise dyspnea as it does during induced bronchoconstriction. Decreased levels of perception of airway obstruction may be a risk factor associated with life-threatening asthma. A poor perceiver may be vulnerable to further hypoxia-induced suppression of respiratory sensation. Monitoring the response to bronchodilator therapy with formoterol and salbutamol in patients with acute or chronic asthma has resulted in significantly faster improvement in dyspnea, within 2 min. Regardless of the factors involved, much variability in dyspnea scores remains unexplained. Quantitative and qualitative assessment of the perception of dyspnea, symptom measurement and quality of life complement physiological measurements and contribute to our understanding of dyspnea in asthma.