Contralateral Pattern Research Articles

Disruption of Resting-State Functional Connectivity in Acute Ischemic Stroke: Comparisons Between Right and Left Hemispheric Insults.

Few resting-state functional magnetic resonance imaging (RS-fMRI) studies evaluated the impact of acute ischemic changes on cerebral functional connectivity (FC) and its relationship with functional outcomes after acute ischemic stroke (AIS), considering the side of lesions. To characterize alterations of FC of patients with AIS by analyzing 12 large-scale brain networks (NWs) with RS-fMRI. Additionally, we evaluated the impact of the side (right (RH) or left (LH) hemisphere) of insult on the disruption of brain NWs. 38 patients diagnosed with AIS (17 RH and 21 LH) who performed 3T MRI scans up to 72h after stroke were compared to 44 healthy controls. Images were processed and analyzed with the software toolbox UF2C with SPM12. For the first level, we generated individual matrices based on the time series extraction from 70 regions of interest (ROIs) from 12 functional NWs, constructing Pearson's cross-correlation; the second-level analysis included an analysis of covariance (ANCOVA) to investigate differences between groups. The statistical significance was determined with p < 0.05, after correction for multiple comparisons with false discovery rate (FDR) correction. Overall, individuals with LH insults developed poorer clinical outcomes after six months. A widespread pattern of lower FC was observed in the presence of LH insults, while a contralateral pattern of increased FC was identified in the group with RH insults. Our findings suggest that LH stroke causes a severe and widespread pattern of reduction of brain networks' FC, presumably related to the impairment in their long-term recovery.

The changes of neuroactivity of Tui Na (Chinese massage) at Hegu acupoint on sensorimotor cortex in stroke patients with upper limb motor dysfunction: a fNIRS study

BackgroundTui Na (Chinese massage) is a relatively simple, inexpensive, and non-invasive intervention, and has been used to treat stroke patients for many years in China. Tui Na acts on specific parts of the body which are called meridians and acupoints to achieve the role of treating diseases. Yet the underlying neural mechanism associated with Tui Na is not clear due to the lack of detection methods.ObjectiveFunctional near-infrared spectroscopy (fNIRS) was used to explore the changes of sensorimotor cortical neural activity in patients with upper limb motor dysfunction of stroke and healthy control groups during Tui Na Hegu Point.MethodsTen patients with unilateral upper limb motor dysfunction after stroke and eight healthy subjects received Tui Na. fNIRS was used to record the hemodynamic data in the sensorimotor cortex and the changes in blood flow were calculated based on oxygenated hemoglobin (Oxy-Hb), the task session involved repetitive Tui Na on Hegu acupoint, using a block design [six cycles: rest (20 seconds); Tui Na (20 seconds); rest (30 seconds)]. The changes in neural activity in sensorimotor cortex could be inferred according to the principle of neurovascular coupling, and the number of activated channels in the bilateral hemisphere was used to calculate the lateralization index.Result1. For hemodynamic response induced by Hegu acupoint Tui Na, a dominant increase in the contralesional primary sensorimotor cortex during Hegu point Tui Na of the less affected arm in stroke patients was observed, as well as that in healthy controls, while this contralateral pattern was absent during Hegu point Tui Na of the affected arm in stroke patients. 2. Concerning the lateralization index in stroke patients, a significant difference was observed between lateralization index values for the affected arm and the less affected arm (P < 0.05). Wilcoxon tests showed a significant difference between lateralization index values for the affected arm in stroke patients and lateralization index values for the dominant upper limb in healthy controls (P < 0.05), and no significant difference between lateralization index values for the less affected arm in stroke patients and that in healthy controls (P = 0.36).ConclusionThe combination of Tui Na and fNIRS has the potential to reflect the functional status of sensorimotor neural circuits. The changes of neuroactivity in the sensorimotor cortex when Tui Na Hegu acupoint indicate that there is a certain correlation between acupoints in traditional Chinese medicine and neural circuits.

Survival rate of indirectly bonded brackets using single vs. two-component orthodontic adhesive: A 12-month split-mouth clinical trial

ObjectiveCompare the bonding survival rate of two distinct bonding materials: Ortho Solo + Gradia LoFlo Resin and single component GC Ortho Connect. Materials and MethodsIndirect bonding fixed appliance treatment was required for 26 consecutive patients, 8 males and 18 females, with a mean age of 22.1 +/- 4.2 years. All patients were treated with SWM (Straight-Wire Mirabella) technique (Sweden and Martina, Due Carrare, Padova, Italy). Each patient's bonding process followed a contralateral pattern. Firstly, a 37 % orthophosphoric acid etching gel was used for 20 s, subsequently the single or two components light-cured adhesives were applied through a split-mouth cross-arch procedure. The patients underwent a 12-month follow-up period and brackets failures were rebounded, but not further included in the study. Statistical analysis was performed to analyse the survival rate of the bonding materials and the influence of the variables, with a significant level of α = 0,05. ResultsThe GC Connect group was used on 349 teeth, while the Ortho Solo + Gradia group was used on 351 teeth, and the indirect debonding rate was respectively 17.5% and 12.8%. With respect to the total sample, statistically significant values were found for both sex and dental arch. The bracket’s survival rate for incisors, canines, premolars and molars was not significant. However, a higher debonding rate was clinically appreciable in upper and lower molars. ConclusionIn a 12-months observation period, considering all maxillary and mandibular teeth the indirect survival rate for the group GC Ortho Connect and Ortho Solo + Gradia was respectively 82.5% and 87.2%. Although the difference was not significant, a pronounced tendency to debonding for the single component group was appreciable from a clinically point of view.

Visual cues two-steps ahead are adequate to grasp an object while walking without compromising stability.

In our prior studies, participants walked and grasped a dowel using an anticipatory mode of control. However, it is unknown how this combined task would change in a less predictable environment. We investigated the online control aspects involved in the combined task of walking and grasping under different coordination patterns between upper- and lower-limbs in young adults. Fifteen young adults walked and grasped a dowel under several experimental conditions combining the instant of visual cue appearance and coordination pattern of upper and lower limbs used to grasp the dowel. Visual cues provided two steps ahead or earlier were enough for executing the combined task of walking and prehension appropriately. Visual cues provided within this window impacted both walking stability and the execution of the prehension movement. Although an ipsilateral arm-leg coordination pattern increased mediolateral stability, a contralateral pattern significantly decreased mediolateral center of mass stability when the visual cue appeared one-step before grasping the object. These results imply that acquiring information to plan the combined task of walking and reaching for an object two steps ahead allows the maintenance of the general movement characteristics present when the decision to reach out for the object is defined two or more steps ahead. These results indicate that the prehension movement is initiated well before heel contact on that side when given sufficient planning time, but that a disruption of the natural arm-leg coordination dynamics emerges to accomplish the task when the cue is provided one step before the object.

Reliability analysis of individual visual P1 and N1 maps indicates the heterogeneous topographies involved in early visual processing among human subjects

There is a lack of studies regarding the reliability of the event-related components (ERPs) of an electroencephalogram (EEG) used to assess cognitive processing in human subjects. To explore the reliability scores for the P1 and N1 components in two sessions (separated by an average of 116 days), twenty subjects performed a visual lateralized detection paradigm and EEG recording (58 channels) were employed. The session factor did not modulate the P1/N1 latencies. The visual field factor (left (LVF) or right (RVF)) was a determinant for the P1 and N1 topographical distributions as shown in previous studies. Moreover, topographical maps of the grand average showed a very strong correlation level between sessions (>0.9). Finally, individual maps demonstrated that the classic contralateral pattern for the P1 and N1 components was not always present in all subjects. In particular, compared to the N1 component, the P1 component exhibited a more complex set of individual topographical distributions, revealing that some steps are more heterogeneous among human subjects in early visual processing.

No Directional Scapular Asymmetry among Tamarines of the Genus Saguinus (Primates: Callitrichidae)

Bilateral asymmetry is defined as a deviation of a whole organism or a part of it from a perfect symmetry, and different categories can be recognized. One is the fluctuating asymmetry, defined as the random developmental variation of a trait (or character) that is expected to be perfectly symmetrical on average, and the other one is directional asymmetry, which occurs when one of the sides shows stronger morphological structures or marks than the other. The aim of this study was to determine the kind of scapula asymmetry in Saguinus scapulae. On lateral surface of each right and left scapula, a set of 5 landmarks and 3 curves with semi-landmarks along the margins, on a sample of 16 pairs from different Saguinus species, were considered. Asymmetries (fluctuating and directional) on size and shape of the scapulae were analysed by means of geometric morphometric methods. Directional asymmetry was not detected, demonstrating no side scapular shape bias. The absence of significant directional asymmetry may indicate a similar contralateral pattern of employment of the shoulder, at least for one-arm vertical suspension, as it needs stronger forces than those for terrestrial locomotion and thus would cause more asymmetry in case side loadings were different. To our knowledge, this is the first investigation on the symmetrical/asymmetrical nature of scapulae in Saguinus. Our findings increase knowledge and understanding of humeral joint and arboreal locomotion in primates.

Less-Affected Hand Function in Children With Hemiparetic Unilateral Cerebral Palsy: A Comparison Study With Typically Developing Peers

Background. Neurorehabilitation interventions in children with unilateral cerebral palsy (UCP) target motor abilities in daily life yet deficits in hand skills persist. Limitations in the less-affected hand may affect overall bimanual hand skills. Objective. To compare hand function, by timed motor performance on the Jebsen-Taylor Test of Hand Function (JTTHF) and grip strength of children with UCP to children with typical development (CTD), aged 8 to 18 years old. Exploratory analyses compared hand function measures with regard to neurophysiological outcomes measured by transcranial magnetic stimulation and between group comparisons of hemispheric motor threshold. Methods. Baseline hand skills were evaluated in 47 children (21 UCP; 26 CTD). Single-pulse transcranial magnetic stimulation testing assessed corticospinal tract and motor threshold. Results. The mean difference of the less-affected hand of children with UCP to the dominant hand of CTD on the JTTHF was 21.4 seconds (95% CI = 9.32-33.46, P = .001). The mean difference in grip strength was −30.8 N (95% CI = −61.9 to 0.31, P = .052). Resting motor thresholds between groups were not significant, but age was significantly associated with resting motor threshold (P < .001; P = .001). Children with UCP ipsilateral pattern of motor representation demonstrated greater mean differences between hands than children with contralateral pattern of motor representation (P < .001). All results were adjusted for age and sex. Conclusions. The less-affected hand in children with UCP underperformed the dominant hand of CTD. Limitations were greater in children with UCP ipsilateral motor pattern. Rehabilitation in the less-affected hand may be warranted. Bilateral hand function in future studies may help identify the optimal rehabilitation and neuromodulatory intervention.

Changes in hemodynamic responses during movements of the upper extremities in the acute phase after stroke: A fNIRS study

The acute phase of stroke is accompanied by functional changes and interplay of both hemispheres. However little is known on how the time course of functional motor recovery is related to the progression of symmetry in the motor areas of the brain. This study aimed to assess the time course of both hemodynamic patterns of cortical motor areas using functional near infrared spectroscopy (fNIRS) and functional recovery during the first months after stroke. Unaffected upper limb movements-related contralateral motor areas activity showed no significant changes. Eight right-handed first ischemic/hemorrhagic stroke patients (60 ± 8 yrs, 3 female and 5 men) with mild to severe hemiparesis were examined with fNIRS measurements and functional motor recovery (Fugl-Meyer score) tests every two weeks during two months (five sessions). We investigated hemodynamic changes over the contralateral and ipsilateral motor areas with a 2 × 8-channel fNIRS system (Oxymon MkIII ® ) during a unilateral intermittent isometric forearm task (1 Hz) at self-selected submaximal force levels. Laterality index (LI) was computed to evaluate the asymmetry of hemodynamic changes from the two hemispheres. Affected upper limb movements were associated early with a bilateral cortical activity before shifting to contralateral patterns ( P < 0.01). Progressive lateralization was observed with LI increases over the first 4 sessions (from −0.24 ± 0.18 to 0.36 ± 0.27, P < 0.05) prior to level off (session 5, 0.25 ± 0.39), as did the Fugl-Meyer score. These findings suggest that cortical reorganization monitoring with fNIRS during the first weeks after stroke should be considered further when assessing functional motor recovery in stroke rehabilitation services.

ADRENAL SURGICAL APPROACH IN A WOMAN WITH SYNCHRONOUS BILATERAL ADRENAL TUMORS

Bilateral adrenal tumours are very rare and display various endocrine profiles. The unilateralapproach is indicated if a nonsecretor contralateral pattern is suspected in order to avoid adrenal insufficiency.We present a 48-year-old woman with a history of bradimenorrhea at the age of 44.The gynecological evaluation was negative but two adrenal tumours were found. CT revealed aright adrenal tumour of 2 cm and a left one of 2.4 cm. Low-normal ACTH and high serumchromogranin A were confirmed. After one year, the left tumour increased to 4 cm so laparoscopictransabdominal left adrenalectomy (with 3 trocars) was successfully performed without anyincident. No conversion was required. Neither intraoperative nor postoperative complicationsoccurred. The patient was hospitalised 5 days and the wounds healed normally. The pathologicalreport revealed a benign corticoadenoma. The endocrine evaluation after one week showed thatafter surgery ACTH de-suppressed to normal and chromogranin A normalised. The right adrenaltumour was followed-up for another year and the diameters were stationary. The patient was stillhypertensive and she was offered adequate therapy (which we considered essential for high blood pressure). Life-long periodical check-up is necessary.Unilateral adrenalectomy in patients with both side tumours allows an adequate pathological report and avoids unnecessary contralateral surgery if an incidentaloma is revealed, thus allowing the preservation of adrenal function.

Sensory processing and the rubber hand illusion--an evoked potentials study.

The rubber hand illusion (RHI) paradigm--in which illusory bodily ownership is induced by synchronous tactile stimulation of a participant's (hidden) hand and a (visible) surrogate--allows one to investigate how the brain resolves conflicting multisensory evidence during perceptual inference. To identify the functional anatomy of the RHI, we used multichannel EEG, acquired under three conditions of tactile stimulation. Evoked potentials were averaged from EEG signals registered to the timing of brushstrokes to the participant's hand. The participant's hand was stroked either in the absence of an artificial hand (REAL) or synchronously with an artificial hand, which either lay in an anatomically plausible (CONGRUENT) or impossible (INCONGRUENT) position. The illusion was reliably elicited in the CONGRUENT condition. For right-hand stimulation, significant differences between conditions emerged at the sensor level around 55 msec after the brushstroke at left frontal and right parietal electrodes. Response amplitudes were smaller for illusory (CONGRUENT) compared with nonillusory (INCONGRUENT and REAL) conditions in the contralateral perirolandic region (pre- and postcentral gyri), superior and inferior parietal lobule, whereas veridical perception of the artificial hand (INCONGRUENT) amplified responses at a scalp region overlying the contralateral postcentral gyrus and inferior parietal lobule compared with the remaining two conditions. Left-hand stimulation produced similar contralateral patterns. These results are consistent with predictive coding models of multisensory integration and may reflect the attenuation of somatosensory precision that is required to resolve perceptual hypotheses about conflicting multisensory input.

Dynamic directed interictal connectivity in left and right temporal lobe epilepsy.

There is increasing evidence that epileptic activity involves widespread brain networks rather than single sources and that these networks contribute to interictal brain dysfunction. We investigated the fast-varying behavior of epileptic networks during interictal spikes in right and left temporal lobe epilepsy (RTLE and LTLE) at a whole-brain scale using directed connectivity. In 16 patients, 8 with LTLE and 8 with RTLE, we estimated the electrical source activity in 82 cortical regions of interest (ROIs) using high-density electroencephalography (EEG), individual head models, and a distributed linear inverse solution. A multivariate, time-varying, and frequency-resolved Granger-causal modeling (weighted Partial Directed Coherence) was applied to the source signal of all ROIs. A nonparametric statistical test assessed differences between spike and baseline epochs. Connectivity results between RTLE and LTLE were compared between RTLE and LTLE and with neuropsychological impairments. Ipsilateral anterior temporal structures were identified as key drivers for both groups, concordant with the epileptogenic zone estimated invasively. We observed an increase in outflow from the key driver already before the spike. There were also important temporal and extratemporal ipsilateral drivers in both conditions, and contralateral only in RTLE. A different network pattern between LTLE and RTLE was found: in RTLE there was a much more prominent ipsilateral to contralateral pattern than in LTLE. Half of the RTLE patients but none of the LTLE patients had neuropsychological deficits consistent with contralateral temporal lobe dysfunction, suggesting a relationship between connectivity changes and cognitive deficits. The different patterns of time-varying connectivity in LTLE and RTLE suggest that they are not symmetrical entities, in line with our neuropsychological results. The highest outflow region was concordant with invasive validation of the epileptogenic zone. This enhanced characterization of dynamic connectivity patterns could better explain cognitive deficits and help the management of epilepsy surgery candidates.

Conversion of intraovarian patterns from preovulation to postovulation based on location of dominant follicle and corpus luteum in heifers

The conversion of preovulatory intraovarian patterns based on location of the preovulatory follicle (PF) and the associated corpus luteum (cl) to postovulatory patterns based on location of the future and established dominant follicle (DF) and corpus luteum (CL) was studied daily in 26 heifers from Days −5 to 6 (Day 0 = ovulation). The two ipsilateral preovulatory patterns were PF–cl and devoid (neither PF nor cl), and the two contralateral patterns were PF and cl. The postovulatory patterns were DF–CL, devoid, DF, and CL. For the contralateral preovulatory relationships, a conversion from PF to DF–CL and the accompanying conversion from cl to devoid occurred most frequently (17 of 18 conversions, 94%). For the ipsilateral preovulatory relationships, a conversion from PF–cl to CL and from devoid to DF occurred most frequently (6 of 8, 75%). Number of 2-mm follicles during preovulation was greatest (P < 0.05) for the devoid and PF patterns, and number of 6-mm follicles during postovulation was greatest (P < 0.05) for the DF–CL and DF patterns. Blood flow resistance at a color Doppler signal in the ovarian pedicle indicated increasing ovarian perfusion over days in the PF to DF–CL and devoid to DF conversions and decreasing perfusion in the PF–cl to CL and cl to devoid conversions. In addition to formation of the CL from the PF, it was interpreted that the conversion of patterns involved number of newly emerging 2-mm follicles per ovary before ovulation and a continuation of the preovulatory angioarchitecture into postovulation. Results supported the novel hypothesis that the four preovulatory intraovarian patterns determine the frequency of the four postovulatory patterns.

Altered brain dynamics during voluntary movement in individuals with Down syndrome

Individuals with Down syndrome have well known cognitive and sensorimotor impairments, however, the underlying neural processes are poorly understood. The objective of this study was to investigate the underlying spatial localization and functional connectivity during voluntary movements of the right index finger. Adults with Down syndrome and healthy control adults participated in this study. Cortical responses were recorded with a 151-channel magnetoencephalographic system. In the Down syndrome group, we observed two distinct patterns of brain activation, an ipsilateral pattern and a contralateral pattern in the low-frequency band. The two distinct patterns of neural activation and the altered underlying network dynamics have not been reported previously, and may reflect differences in sensorimotor organization.

Spreading of complex regional pain syndrome: not a random process

Complex regional pain syndrome (CRPS) generally remains restricted to one limb but occasionally may spread to other limbs. Knowledge of the spreading pattern of CRPS may lead to hypotheses about underlying mechanisms but to date little is known about this process. The objective is to study patterns of spread of CRPS from a first to a second limb and the factors associated with this process. One hundred and eighty-five CRPS patients were retrospectively evaluated. Cox’s proportional hazards model was used to evaluate factors that influenced spread of CRPS symptoms. Eighty-nine patients exhibited CRPS in multiple limbs. In 72 patients spread from a first to a second limb occurred showing a contralateral pattern in 49%, ipsilateral pattern in 30% and diagonal pattern in 14%. A trauma preceded the onset in the second limb in 37, 44 and 91%, respectively. The hazard of spread of CRPS increased with the number of limbs affected. Compared to patients with CRPS in one limb, patients with CRPS in multiple limbs were on average 7 years younger and more often had movement disorders. In patients with CRPS in multiple limbs, spontaneous spread of symptoms generally follows a contralateral or ipsilateral pattern whereas diagonal spread is rare and generally preceded by a new trauma. Spread is associated with a younger age at onset and a more severely affected phenotype. We argue that processes in the spinal cord as well as supraspinal changes are responsible for spontaneous spread in CRPS.

Motor learning after stroke: Is skill acquisition a prerequisite for contralesional neuroplastic change?

Limited data directly characterize the dynamic evolution of brain activity associated with motor learning after stroke. The current study considered whether sequence-specific motor skill learning or increasing non-specific use of the hemiparetic upper extremity drive functional reorganization of the contralesional motor cortex after stroke. Eighteen individuals with chronic middle cerebral artery stroke practiced one of two novel motor tasks; a retention test occurred on a separate fifth day. Using the hemiparetic arm, participants performed a serial targeting task during two functional MRI scans (day one and retention). Participants were randomized into either a task-specific group, who completed three additional sessions of serial targeting practice, or a general arm use group, who underwent three training sessions of increased but non-task specific use of the hemiparetic arm. Both groups performed a repeated sequence of responses that may be learned, and random sequences of movement, which cannot be learned. Change in reaction and movement time for the repeated sequence indexed motor learning; shifts in the laterality index (LI) within primary motor cortex (M1) for repeated and random sequences illustrated training effects on brain activity. Task-specific practice of the repeated sequence facilitated motor learning and shifted the LI for M1 as shown by a reduced volume of contralesional cortical activity. Random sequence performance did not stimulate motor learning or alter the LI within the task-specific training group. Further, between-group comparisons showed that increasing general arm use did not induce motor learning or alter brain activity for either random or repeated sequences. Motor skill learning of a repeated sequence altered cortical activation by inducing a more normal, contralateral pattern of brain activation. Our data suggest that task-specific motor learning may be an important stimulant for neuroplastic change and can remediate maladaptive patterns of brain activity after stroke.

Influence of Posture on the Range of Axial Rotation and Coupled Lateral Flexion of the Thoracic Spine

Objective This study examines the influence of posture on the range of axial rotation of the thorax and the range and direction of the coupled lateral flexion. Methods The ranges of mid thoracic axial rotation and coupled lateral flexion were measured in 52 asymptomatic subjects (aged 18-43 years) using an optical motion analysis system. To examine the influence of posture on primary and coupled motion, we initiated axial rotation from a neutral sitting posture and from end-range thoracic flexion and extension. Results There was a significant decrease in the range of thoracic rotation in flexion compared with the neutral and extended postures ( P < .001). The mean range of coupled lateral flexion was 8.9% of the axial rotation range in the neutral posture and increased to 14.3% and 23.2% in the extended and flexed postures, respectively. Patterns of coupled motion varied between subjects, but an ipsilateral pattern was more common in the flexed posture, whereas a contralateral pattern was more common in the neutral and extended postures. Conclusions The ranges and patterns of coupled motion of the thorax appear to be strongly influenced by the posture from which the movement is initiated. This has important implications in relation to the interpretation of clinical tests of thoracic motion and in consideration of mechanisms of development of thoracic pain disorders.

Rhythmic coordination of hand and foot in children with Developmental Coordination Disorder

Children with Developmental Coordination Disorder (DCD) have difficulties producing stable rhythmic bimanual coordination patterns in comparison with age-related peers. Rhythmic coordination of non-homologous limbs (e.g. hand and foot) is even more difficult to perform because of mechanical differences between the limbs. The aim of the present study is to investigate the stability of hand-foot coordination patterns of children with DCD. Ten children with DCD (mean age 7.0 years, SD 1.1 years) and 16 control children (mean age 7.4 years, SD 1.3 years) participated in the study. They were asked to perform in-phase or anti-phase tapping movements in three different interlimb coordination combinations: (1) hand-hand (homologous), (2) hand-foot same body side (ipsilateral), and (3) hand-foot different body side (contralateral). Coordination stability was measured by the variability of the relative phase between the limbs under a 'steady state' (preferred) frequency condition, and by the critical frequency (i.e. the point at which loss of pattern stability was observed) in a condition in which the movement frequency was 'scaled' up (only anti-phase tapping). Coordination patterns of children in the DCD group were less stable in all three limb combinations compared with controls. Further, hand-foot coordination patterns were less stable than hand-hand coordination patterns. With regard to hand-foot coordination, ipsilateral patterns were equally stable compared with contralateral patterns in the in-phase task, but less stable in the anti-phase task. No differential effects were found between the DCD and control groups across the different limb combinations, except for steady-state anti-phase coordination in the ipsilateral limb condition. This effect was due to a relatively good performance of the control children in this condition in comparison with the other limb combination conditions. Children with DCD have difficulties producing stable rhythmic hand-foot coordination patterns compared with control children.

Attenuation of Sensory and Affective Responses to Heat Pain: Evidence for Contralateral Mechanisms

Attenuation of responses to repeated sensory events has been thoroughly studied in many modalities; however, attenuation of pain perception has not yet benefitted from such extensive investigation. Described here are two psychophysical studies that examined the effects of repeated exposure to thermal stimuli, assessing potential attenuation of the perception of pain and its possible spatial specificity. Twenty-two subjects were presented thermal stimuli to the volar surface of the right and left forearms. Twelve subjects in study 1 received the same stimuli and conditions on each of five daily experimental sessions, whereas 10 subjects in study 2 received thermal stimuli, which were restricted to one side for four daily sessions and then applied to the other side on the fifth session. Ratings of warmth intensity, pain intensity, and pain unpleasantness were recorded while the subjects performed a thermal sensory discrimination task. Results of study 1 demonstrate that repeated stimulation with noxious heat can lead to long-term attenuation of pain perception; results of study 2 extend these findings of attenuation to both pain intensity and unpleasantness and show that this effect is highly specific to the exposed body side for both aspects of the pain experience. We suggest that the functional plasticity underlying this attenuation effect lies in brain areas with a strong contralateral pattern of pain-related activation.

Measurement of Upper Cervical Flexion and Extension with the 3-Space Fastrak Measurement System: A Repeatability Study

Most external measurement devices do not allow ready differentiation of upper cervical flexion and extension from total cervical movement. This study investigated the "within" and "between-days" repeatability of measurement focused on upper cervical flexion and extension in three dimensions using the Fastrak, a 3-Space measurement system, on 21 subjects. To localize the measurement, one sensor of the Fastrak was centered over the subject's forehead and the other was held manually over the C2 spinous process. Three repetitions of upper cervical flexion (nod of the head) and extension (chin lift) were performed in each trial. Two trials were performed on the first day with the third trial one-week later. Results indicated high levels of repeatability for "within" and "between-days" measurements (ICC2,1: 0.97 to 0.99). The mean ranges of upper cervical flexion and extension were 15.03° ± 2.80° and 23.32° ± 4.20° respectively, were accompanied by a small amount of lateral flexion and rotation, predominantly in a contralateral pattern. The method appears suitable for clinical evaluation of upper cervical motion.

Typical and atypical perfusion patterns in periictal SPECT of patients with unilateral temporal lobe epilepsy.

To characterize perfusion patterns of periictal single-photon emission tomography (SPECT) in patients with unilateral temporal lobe epilepsy (TLE) and to determine their relationship to the epileptogenic zone (EZ). We studied periictal SPECT scans of 53 patients after anterior mesial temporal lobectomy who had good seizure outcome after surgery. Ictal SPECT scans were performed during video-EEG monitoring. Typical SPECT patterns consisted of ipsilateral ictal hyperperfusion or ipsilateral postictal hypoperfusion. Atypical ictal patterns included normal scans, bilateral temporal hyperperfusion, or contralateral patterns. These perfusion patterns were retrospectively analyzed searching for concordance rate with the EZ. We obtained 51 ictal and two early postictal scans. In the typical group, 40 (75.4%) patients had ipsilateral ictal temporal lobe hyperperfusion, and one (1.9%) patient had ipsilateral postictal temporal lobe hypoperfusion. Twelve (22.7%) patients exhibited atypical perfusion patterns: seven (13.2%) patients had bitemporal ictal hyperperfusion (four cases showed asymmetric temporal lobe changes), four (7.6%) patients had contralateral hyperperfusion, and one (1.9%) patient had a normal SPECT scan. All four patients with bitemporal asymmetric hyperperfusions showed greater perfusion lateralized to the side of the EZ. Three of the four patients who had contralateral hyperperfusion also had a complex postictal-like pattern in the ipsilateral temporal lobe consisting of anteromesial hyperperfusion with adjacent lateral hypoperfusion. This study analyzed typical and atypical perfusion patterns in unilateral TLE, and suggested that not only typical, but also some atypical perfusion patterns may contribute to the lateralization of EZ.