Contralateral Frontal Lobe Research Articles

USEFULNESS OF FIST-EDGE-PALM TEST IN A DEMENTIA CLINIC

The fist-edge-palm task (FEP) was believed this impairment to be closely related to contralateral frontal lobe damage. However, previous studies have shown that more extensive areas are activated during the task. In this study we aimed to evaluate whether FEP is able to differentiate mild cognitive impairment (MCI) or Alzheimer's disease (AD) from normal controls. We enrolled 24 AD, 27 MCI, 19 normal controls. In the FEP, the subjects were requested to place their hand in three different positions sequentially: a fist resting vertically, a palm resting vertically, and a palm resting horizontally. Before the subjects performed the task, one doctor showed three times of FEP, then instructed the subjects to repeat the movement 6 times and videotaped their performance. Unless they did ever, they were asked to follow the movement step by step shown by one doctor. We compared the score and speed of their performance among patients or controls. In addition, we analyzed common error patterns among patients. The mean age of the patients was 79.13 in AD, 71.74 in MCI, and 69.89 in normal controls. The proportion of man was 25% in AD, 29.6% in MCI, and 57.9% in normal controls. The mean education years were 4.54 in AD, 7.37 in MCI, and 7.79 in normal controls. The distribution of scores in each group was as follows: 3/2/1/0: 3(12.5%)/0(0%)/0(0%)/27(87.5%) in AD, 11(40.7%)/1(3.7%)/9(33.3%)/6(22.2%) in MCI, 11(57.9%)/1(5.3%)/7(36.8%)/0(0%)) in normal controls. A total of 25 patients were scored 3. The mean duration of their performance was 17.66 s in AD, 13.70 s in MCI, 14.70 s in normal controls. The most common error was omission of task, especially “edge” in AD whereas sequential error and addition of wrong motion were commonly observed in MCI. MCI patients showed more common errors than normal. Most of AD patients were not able to do FEP. Our study suggests that FEP can be used in bed-side screening tool in the dementia clinic.

Rhythmic ictal nonclonic hand (RINCH) motions in temporal lobe epilepsy: Invasive EEG findings, incidence, and lateralizing value

The main purpose of this retrospective analysis was to evaluate the incidence and lateralization value of rhythmic ictal nonclonic hand (RINCH) motions in patients with temporal lobe epilepsy (TLE), who were classified as Engel I at least 2 years after epilepsy surgery. We analyzed the distribution of ictal activity at the time of RINCH appearance in patients in whom RINCH motions were present during invasive EEG monitoring. A group of 120 patients was included in this study. In total, we reviewed 491 seizures: 277 seizures in patients with temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (TLE-HS group) and 214 in TLE caused by other lesions (TLE-OTH group). We analyzed 29 patients (79 of the seizures) during invasive EEG monitoring. Fisher's exact test and binomial test were used for the statistical analysis. RINCH motions were observed in 24 out of 120 patients (20%) and in 48 out of 491 seizures (9.8%). There was no significant difference between the occurrence of RINCH motions in patients with TLE-HS and in patients with TLE-OTH, or between gender, right/left-sided TLE, and language dominant/nondominant TLE. RINCH motions were contralateral to the seizure onset in 83.3% of patients and 91.7% of seizures (p=0.0015; p<0.001, respectively). There were no differences in the lateralizing value of RINCH motions in patients with TLE-HS or TLE-OTH. We analyzed RINCH motions in 5 patients/7 seizures during invasive EEG. In all 7 seizures with RINCH motions, we observed the widespread activation of the temporal lobe (mesial and lateral, opercular and polar regions) contralateral to the side of RINCH motions. In all 7 seizures, we observed that at the time of RINCH motion onset, at least 1 explored region of the frontal lobe was affected by the ictal activity. In 3 seizures, we observed time-locked epileptic activation associated with the appearance of RINCH motions, i.e., in the orbitofrontal cortex in 2 seizures and in both the orbitofrontal cortex and anterior cingulate gyrus in 1 seizure. RINCH motions are a relatively frequent ictal sign in patients with TLE. They have a high lateralizing value in these patients, occurring contralateral to the ictal onset. RINCH motions usually occur after the spread of ictal activity beyond the temporal lobe, and their appearance is usually associated with the presence of ictal activity in various regions of the contralateral frontal lobe, mainly the orbitofrontal cortex and anterior cingulate gyrus. This is the first study analysing this phenomenon during invasive EEG recording.

Contralateral hyperacute intracerebral hemorrhage after carotid artery stenting with contralateral internal carotid artery occlusion

An 87-year-old man sustained an intracerebral hemorrhage in the watershed area of the contralateral frontal lobe immediately after carotid artery stenting (CAS) for severe cervical internal carotid artery (ICA) stenosis. The contralateral cervical ICA was occluded. CAS resulted in increased cross-flow through the anterior communicating artery and increased flow in the contralateral middle cerebral artery. This case demonstrates that CAS in patients with contralateral ICA occlusion and insufficient collateral flow can cause dramatically increased collateral flow through the circle of Willis and result in contralateral hyperperfusion. In patients with severely compromised cerebral perfusion, measures should be taken to prevent hyperperfusion-related complications.

Malperfusion in Acute Type A Aortic Dissection: Unsolved Problem

Despite a reduced incidence of false lumen perfusion with preferential use of axillary arterial perfusion in acute type A aortic dissection, malperfusion remains a major cause of operative mortality and sequelae. The incidence of unpredictable malperfusion and its mechanism were examined. We examined the 59 consecutive cases of type A aortic dissection treated surgically, including 17cases (28.8%) with preoperative malperfusion. Whereasfemoral arterial perfusion was used in 7 cases withprofound shock, axillary arterial perfusion was employed in the remaining 52 cases. Organ perfusion was assessed with various modalities including transesophageal echocardiography, orbital Doppler, and near-infrared spectroscopy. Although false lumen perfusion was not encountered, persistent or new malperfusion was detected in 5 cases (8.5%) with unrestored true lumen. Malperfusion remained in 3 cases. Of these, bilateral axillary arterial perfusion in 1 case and selective perfusion through the femoral artery in 1 case were effective; however, additional ascending aortic cannulation in 1case was unsuccessful. In the remaining 2 cases, unilateral axillary arterial perfusion led to reduced oxygen saturation in the contralateral frontal lobe, which was restored by bilateral axillary arterial perfusion probably due to augmented collateral circulation. Subclavian steal due to occluded innominate artery was detected in 1 of them. Immediate decision making based on real-time information was beneficial. Despite preferential axillary arterial perfusion, new or persistent malperfusion occurred in 5 cases (8.5%). There is no perfect perfusion route but real-time assessment and individualized navigation may be beneficial in further improving the outcomes.

Direct measurement of the signal intensity of diffusion-weighted magnetic resonance imaging for preoperative grading and treatment guidance for brain gliomas

BackgroundMagnetic resonance diffusion-weighted imaging (DWI) has been widely used clinically in imaging diagnosis of intracranial disorders. The purpose of current study was to present a quantitative method of direct measuring the DWI signal intensity of brain gliomas on the monitors of hospital picture archiving and communicating system (PACS) for grading gliomas. MethodsThis study recruited 135 patients with treatment-naïve brain gliomas. Direct measurement of the signal intensity of selected tumoral regions of interest (ROIs) by DWI on the monitors of the hospital PACS was performed for all patients. From the measurements, we obtained three values, defined as DWIT (tumor), DWIN (the homologous normal-appearing area of the tumor ROI in the contralateral hemisphere), and DWIWM (normal-appearing white matter) in the contralateral frontal lobe. Two ratios, DWIT/WM and DWIT/N, were obtained for each tumoral ROI. The same method was used for apparent diffusion coefficient (ADC) ratios of the tumoral ROI. Fractional polynomial regression and the Mann–Whitney U test were applied to determine the correlation between tumor grading, MIB-1 labeling index, and DWI and ADC ratios. Logistic regression models and receiver operating characteristic curve analysis were used to establish diagnostic models. Measurements of intraobserver and interobserver agreement were also made at 1-month interval. ResultsThe DWI ratios correlated positively with tumor grade and MIB-1 value (p < 0.01). Cut-off ratios of 1.62 for DWIT/WM and 1.47 for DWIT/N generated the optimal combination of sensitivity (0.82, 0.80), specificity (0.79, 0.86), and sound discriminating power, with an area under the curve of 0.87 and 0.84, respectively, to differentiate low-grade from high-grade gliomas. ADC ratios showed relatively worse sensitivity, specificity, and discriminating power than DWI ratios. Almost all intraobserver and interobserver measurements were within 95% agreement. ConclusionThe proposed method – direct measuring of tumor signal intensity of DWI on PACS monitors – is feasible for grading gliomas in clinical neuro-oncology imaging services and has a high level of reliability and reproducibility.

Memory in frontal lobe epilepsy: An fMRI study

Focal epilepsies are often associated with structural and functional changes that may extend beyond the area of seizure onset. In this study we investigated the functional anatomy of memory in patients with frontal lobe epilepsy (FLE), focusing on the local and remote effects of FLE on the networks supporting memory encoding. We studied 32 patients with drug-resistant FLE and 18 controls using a functional magnetic resonance imaging (fMRI) memory encoding paradigm. During encoding of stimuli, patients with FLE recruited more widely distributed areas than healthy controls, in particular within the frontal lobe contralateral to the seizure onset. Normal memory performance was associated with increased recruitment of frontal areas, and conversely a poor performance was associated with an absence of this increased recruitment and decreased activation in mesial temporal lobe areas. In patients with FLE, recruitment of wider areas, particularly in the contralateral frontal lobe, appears to be an effective compensatory mechanism to maintain memory function. Impaired hippocampal activation is relatively rare and, in turn, associated with poor recognition memory.

Crossed Cerebro-Cerebellar Diaschisis

Each cerebellar hemisphere is connected with the contralateral cerebral hemisphere through the cortico-ponto-cerebellar projecting fibers.[1] The densest cortico-ponto-cerebellar projections arise from the precentral and prefrontal cortical areas. Connections between the cerebellar hemispheres and other areas within the contralateral frontal, parietal, and temporal lobes have also been reported. A functional disruption of the cortico-ponto-cerebellar pathways is the underlying pathomechanism of the crossed cerebro-cerebellar diaschisis (CCCD).[2] In neurology, diaschisis refers to the reduction of function of a part of the brain following the interruption of an afferent pathway at a remote site. In rats, reduced neuronal activity in the cerebral cortex was shown to lead to a decrease in Purkinje cell spike activity in the contralateral cerebellar hemisphere.[2] This is explained by deactivation resulting from reduced efferent, excitatory activity in crossed projections from the cerebral cortex to Purkinje cells. This deactivation underlies a depression of neuronal metabolism and blood flow in the affected cerebellar hemisphere as demonstrated using perfusion-weighted imaging and single-photon emission computed tomography.[3] [4] CCCD has been reported several times in adults with large hemispheric stroke, epileptic seizures, migraine, encephalitis, and brain tumors. Pediatric reports on CCCD are less common and include children with stroke,[5] seizures,[6] [7] [8] Rasmussen's encephalitis,[9] familial hemiplegic migraine,[10] and chronic unilateral cerebral injuries.[11]

Imaging language networks before and after anterior temporal lobe resection: Results of a longitudinal fMRI study

SummaryPurpose: Anterior temporal lobe resection (ATLR) controls seizures in up to 70% of patients with intractable temporal lobe epilepsy (TLE) but, in the language dominant hemisphere, may impair language function, particularly naming. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated reorganization of language in left-hemisphere–dominant patients before and after ATLR; whether preoperative functional magnetic resonance imaging (fMRI) predicts postoperative naming decline; and efficiency of postoperative language networks.Methods: We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left) on a 3T GE-MRI scanner. All subjects performed language fMRI and neuropsychological testing preoperatively and again 4 months after left or right ATLR.Key Findings: Postoperatively, individuals with left TLE had greater bilateral middle/inferior frontal fMRI activation and stronger functional connectivity from the left inferior/middle frontal gyri to the contralateral frontal lobe than preoperatively, and this was not observed in individuals with right TLE. Preoperatively, in left and right TLE, better naming correlated with greater preoperative left hippocampal and left frontal activation for verbal fluency (VF). In left TLE, stronger preoperative left middle frontal activation for VF was predictive of greater decline in naming after ATLR. Postoperatively, in left TLE with clinically significant naming decline, greater right middle frontal VF activation correlated with better postoperative naming. In patients without postoperative naming decline, better naming correlated with greater activation in the remaining left posterior hippocampus. In right TLE, naming ability correlated with left hippocampal and left and right frontal VF activation postoperatively.Significance: In left TLE, early postoperative reorganization to the contralateral frontal lobe suggests multiple systems support language function. Postoperatively, ipsilateral recruitment involving the posterior hippocampal remnant is important for maintaining language, and reorganization to the contralateral hemisphere is less effective. Preoperative left middle frontal activation for VF was predictive of naming decline in left TLE after ATLR.

1218 Frontal lobe activity during memory encoding in temporal lobe epilepsy

PurposeThe contribution of the frontal lobes to memory encoding has been recently appreciated. Functional MRI (fMRI) studies have demonstrated material specific prefrontal cortex (PFC) activations with verbal and non-verbal memory...

Crossed Transcortical Motor Aphasia, Left Spatial Neglect, and Limb and Magnetic Apraxia Due to Right Anterior Cerebral Artery Infarction

Crossed aphasia refers to language disturbance due to right-hemisphere lesions in right-handed individuals, while magnetic apraxia is described as 'forced grasping and groping' caused by lesions in the contralateral frontal lobe. This is a case report of a 70-year-old right handed woman who suffered from crossed transcortical motor aphasia and left hand magnetic apraxia due to right anterior cerebral artery infarction. The definite mechanism of this disorder is not yet understood, but neurophysiological observations suggest that affected supplementary motor areas may be responsible for this phenomenon.

An Unusual Case of Cerebral Penetrating Injury by a Driven Bone Fragment Secondary to Blunt Head Trauma

Temple trauma that appears initially localized to the skin might possess intracranial complications. Early diagnosis and management of such complications are important, to avoid neurologic sequelae. Non-penetrating head injuries with intracranial hemorrhage caused by a driven bone fragment are extremely rare. A 53-year-old male was referred to our hospital because of intracerebral hemorrhage. He was a mechanic and one day before admission to a local clinic, tip of metallic rod hit his right temple while cutting the rod. Initial brain computed tomography (CT) and magnetic resonance imaging demonstrated scanty subdural hematoma at right temporal lobe and left falx and intracerebral hematoma at both frontal lobes. Facial CT with 3-D reconstruction images showed a small bony defect at the right sphenoid bone's greater wing and a small bone fragment at the left frontal lobe, crossing the falx. We present the unusual case of a temple trauma patient in whom a sphenoid bone fragment migrated from its origin upward, to the contralateral frontal lobe, producing hematoma along its trajectory.

Long-term survival following metachronous intratumoral hemorrhage in an HIV-infected patient with lung cancer

Human immunodeficiency virus (HIV)-infected patients are likely to develop intracranial events. Due to the spread of highly active antiretroviral therapy (HAART), HIV-infected patients now survive longer, and metastatic non-AIDS-defining carcinoma is increasing. A 49-year-old man with HIV infection undergoing treatment with HAART developed an intratumoral hemorrhage in the right frontal lobe. He was diagnosed as having lung adenocarcinoma and was found to have a brain metastasis with bleeding. After treatment for intratumoral bleeding, a contralateral frontal lobe hemorrhage occurred within a month. The patient underwent a second craniotomy and removal of hematoma, followed by whole-brain radiotherapy. He was then treated with four cycles of cisplatin and gemcitabine combination chemotherapy while receiving HAART. A partial response was achieved, though he developed severe hematological toxicities for which the doses of chemotherapy needed to be decreased. However, as a result of treatment, his activities of daily life recovered gradually. This lung cancer patient had been alive for 17months despite the coexistence of two disorders with a poor prognosis, HIV infection and bleeding brain metastases from lung cancer. This case revealed that physicians must include non-AIDS-defining cancer metastasis to the brain in the differential diagnosis of HIV-infected patients when they show stroke-like symptoms, and such patients may respond to treatment as well as non-HIV-infected patients with advanced lung cancer.

Gray matter perfusion correlates with disease severity in ALS

The goal of this study is to determine if regional brain perfusion, as measured by arterial spin labeling (ASL) MRI, is correlated with clinical measures of amyotrophic lateral sclerosis (ALS) disease severity. The presence of such a relationship would indicate a possible role for ASL perfusion as a marker of disease severity and upper motor neuron involvement in ALS. Disease severity was assessed in 16 subjects with ALS (age 54 +/- 11) using the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS) and the pulmonary function measure, forced vital capacity (FVC). Upper motor neuron involvement was assessed by testing rapid tapping of the fingers and feet. Magnetic resonance perfusion images were coregistered with structural T1-weighted MRI, corrected for partial volume effects using the structural images and normalized to a study-specific atlas. Correlations between perfusion and ALS disease severity were analyzed, using statistical parametric mapping, and including age as a factor. Analyses were adjusted for multiple clusters. ALS severity, as measured by the ALSFRS and FVC, was correlated with gray matter perfusion. This correlation was predominantly observed in the hemisphere contralateral to the more affected limbs. ALSFRS scores correlated with perfusion in the contralateral frontal and parietal lobe (p < 0.001) and ipsilateral frontal lobe (p < 0.02). FVC scores correlated with gray matter perfusion in contralateral frontal lobe (p < 0.001). Upper motor neuron involvement, as measured by rapid finger tapping, correlated bilaterally with perfusion in the middle cingulate gyrus (p < 0.001). Amyotrophic lateral sclerosis (ALS) severity is correlated with brain perfusion as measured by arterial spin labeling (ASL) perfusion. This correlation appears to be independent of brain atrophy. ASL perfusion may be a useful tool for monitoring disease progression and assessing treatment effects in ALS.

Acute effects of sustained isometric knee extension on cerebral and muscle oxygenation responses

Cerebral contra-lateral frontal lobe and the dominant vastus lateralis muscle oxygenation (Cox, Mox) and blood volume (Cbv, Mbv) were recorded simultaneously using near infrared spectroscopy (NIRS) in 12 healthy volunteers (37.4 +/- 9.9 years; 72.3 +/- 16.1 kg; 171.0 +/- 9.6 cm) during 2 min resting baseline, an isometric knee extension with the 1 RM load sustained to the point of fatigue, and 3 min recovery. The mean exercise duration was 19.1 +/- 2.6 s. During the contraction, Cox and Cbv increased systematically with no sign of levelling off until the point of fatigue. In contrast, Mox and Mbv declined continuously until the termination of exercise. Qualitative analysis of these NIRS profiles suggested that maximal isometric performance under normoxic conditions was most likely not limited by central neuronal activation, but rather, was due to factors within the exercising muscle. It is likely that depletion of intramuscular stores of high energy phosphates and oxymyoglobin, as well as the accumulation of metabolites from anaerobic pathways, were implicated in fatigue during this sustained high intensity isometric contraction.

Voxel-based diffusion tensor imaging in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

BackgroundMesial temporal lobe epilepsy (mTLE) with hippocampus sclerosis (HS) is an important cause for focal epilepsy. In this study, we explored the integrity of connecting networks using diffusion tensor imaging (DTI) and two whole-brain voxel-based methods: statistical parametric mapping (SPM) and tract-based spatial statistics (TBSS). MethodsThirty-three consecutive patients with mTLE and HS undergoing presurgical evaluation were scanned at 3 T, a DTI data set was acquired and parametric maps of fractional anisotropy (FA) and mean diffusivity (MD) were calculated. Twenty-one patients had left hippocampal sclerosis (LHS) and 12 patients had right HS (RHS). These groups were compared to 37 normal control subjects using both SPM5 and TBSS. ResultsThe ipsilateral temporal lobe showed widespread FA reduction in both groups. The limbic system was clearly abnormal in the LHS group, also involving the arcuate fasciculus. In RHS, changes were more restricted but also showed involvement of the contralateral temporal and inferior frontal lobe. Increased MD was found in the ipsilateral hippocampus by SPM that was only marginally detected by TBSS. In white matter regions, however, TBSS was more sensitive to changes than SPM. ConclusionDTI detects extensive changes in mTLE with HS. The affected networks were principally in the ipsilateral temporal lobe and the limbic system but also the arcuate fasciculus. SPM and TBSS gave complementary information with higher sensitivity to FA changes using TBSS.

Distribution of regional gray matter abnormalities in a pediatric population with temporal lobe epilepsy and correlation with neuropsychological performance

Objective The goals of the work described here were to determine if hippocampal and extrahippocampal atrophy in children with temporal lobe epilepsy (TLE) follows a pattern similar to that in adult patients, and to assess the clinical and neuropsychological relevance of regional brain atrophy in pediatric TLE. Methods Children with symptomatic TLE ( n = 14: 9 with mesial TLE due to hippocampal atrophy and 5 with TLE due to neocortical lesions), healthy children ( n = 14), and 9 adults with mesial temporal lobe epilepsy (MTLE) were compared using voxel-based morphometry (VBM) of brain magnetic resonance imaging (MRI). The children underwent a comprehensive neuropsychological battery. Results Children with MTLE with unilateral hippocampal atrophy ( n = 9) exhibited a significant reduction in gray matter in the hippocampus ipsilateral to the seizure origin and significant atrophy in the ipsilateral cingulate gyrus and contralateral middle frontal lobe. Children with TLE ( n = 14) exhibited a significant reduction in the gray matter of the ipsilateral hippocampus and parahippocampal gyrus. There was a correlation between gray matter volume in children with TLE and scores on several neuropsychological tests. Atrophy in pediatric patients with MTLE was less extensive than that in adults, and involved the hippocampi and the frontal cortex. Conclusions Similar to adult MTLE, pediatric MTLE is associated with hippocampal and extrahippocampal cell loss. However, children display less intense quantifiable gray matter atrophy, which affects predominantly frontal lobe areas. There was a significant association between volume of gray matter in medial temporal and frontal regions and scores on neuropsychological tests. In childhood, TLE and the concomitant cognitive/behavior disturbances are the result of a damaged neural network.

Corpus callosotomy: A palliative therapeutic technique may help identify resectable epileptogenic foci

Corpus callosotomy has a long history as a palliative treatment for intractable epilepsy. Identification of a single epileptogenic zone is critical to performing successful resective surgery. We describe three patients in which corpus callosotomy allowed recognition of unapparent seizure foci, leading to subsequent successful resection. We retrospectively reviewed our epilepsy surgery database from 2003 to 2005 for children who had a prior callosotomy and were candidates for focal resection. All underwent magnetic resonance imaging and scalp video electroencephalograph monitoring, and two had magnetoencephalography, electrocorticography and/or intracranial video electroencephalograph monitoring. The children were 8 and 9 years old, and seizure onset varied from early infancy to early childhood. One child had a history of head trauma preceding seizure onset, one had a large intracerebral infarct and dysplastic cortex in the contralateral frontal lobe, and the other had an anterior temporal lobe resection without improvement in seizure frequency. After medical management failed, callosotomy was performed with the expectation of decreasing the seizure types affecting both hemispheres. Following transection of the callosal fibers, a single focus was recognized and resected, with resultant dramatic improvement in seizure control. In medically refractory epilepsy, where rapid secondary bisynchrony is suspected but the electroencephalograph is non-localizing, callosotomy should be considered as a means of treating generalized seizure types, but may also assist in identifying potentially operable seizure foci. Study limitations include its retrospective nature and cohort size. The findings, however, suggest the need for prospective, systematic, well-controlled studies of the use of corpus callostomy in this intractable patient population.

Cerebral and Muscular Oxygenation/Blood Volume Responses to Resistance Exercise under Normoxia and Hypoxia in Healthy Subjects

During hypoxia (H), there is a systemic reduction in %SaO2 that can affect both cerebral and muscular oxygenation and blood volume (COX, MOX, CBV, MB V) at rest. We have demonstrated that H impairs resistance exercise (RE) performance. However, whether this decline is due to reduced neuronal activation or localized muscle impairment is not known. PURPOSE: To examine the effects of acute H on the COX, CBV, MOX and MBV responses to unilateral knee extensions (KEX) at 50, 75 and 100% of 1RM. METHODS: 24 healthy subjects (10 F, 14 M) consented to participate in 3 test sessions, at least 48 h apart. They randomly performed 1 set of KEX at 50, 75 or 100% 1 RM until volitional failure under normoxia (N; FiO2=0.21) and hypoxia (H; FiO2=0.14). The protocol consisted of 2-min baseline, 5-min rest (H or N), KEX, 4-min recovery, 5-min rest (N or H), KEX, and 4-min recovery. At 50 and 75% 1RM, KEX was performed dynamically with a controlled cadence (CON and ECC phase at 2 s each), and at 100%, isometrically (knee fully extended). Changes in COX, CBV, MOX, and MBV were monitored by continuous wave near infrared spectroscopy (MicroRunman, NIM Inc, PA). The probes were placed over the motor point of the vastus lateralis of the dominant leg and on the contralateral frontal lobe. Delta values (RE-rest) were used for analysis in a 3-way repeated measures ANOVA model. RESULTS: Endurance time was significantly reduced during H (50%: 55.4±9.3; 75%: 34.9±6.9; 100%: 38.5±14.3) compared to N (50%: 59.7±12.8; 75%: 37.9±8.0; 100%: 42.4±14.8). COX and CBV increased and MOX and MBV decreased during RE under both conditions. No significant differences between N and H for COX (N: 0.037±0.003, H: 0.042±0.005; P=0.215), CBV (N: 0.073±0.006, H: 0.078±0.007; P=0.274), MOX (N: −0.158±0.11, H: −0.153±0.012; P=0.479), and MBV (N: −0.205±0.017, H: −0.204±0.015; P=0.930) were observed at any of the intensities. CONCLUSION: These findings suggest that the lower endurance under H is not due to reductions in neuronal activation or oxygen availability in the muscle. At the point of fatigue, alterations in the cerebral and muscle oxygenation are independent of the intensity of muscle contractions.

A Diffusion Tensor Imaging Study of Fasciculi in Schizophrenia

Cognitive models propose that the symptoms and psychological impairments associated with schizophrenia arise as a consequence of impaired communication between brain regions, especially the prefrontal cortex and the temporal and parietal lobes. Functional imaging and electrophysiological data have provided evidence of functional dysconnectivity, but it is unclear whether this reflects an underlying problem with anatomical connectivity. This study used diffusion tensor imaging to examine the integrity of the major white matter fasciculi, which connects the frontal and temporal-parietal cortices, and the corpus callosum in patients with schizophrenia. A 1.5-T magnetic resonance scanner was used to acquire diffusion tensor images giving whole brain coverage at an isotropic 2.5-mm voxel size. Fractional anisotropy was measured in 33 patients with schizophrenia and 40 healthy comparison subjects with an automated voxel-based method of analysis. There was reduced fractional anisotropy in patients with schizophrenia in regions corresponding to the superior longitudinal fasciculi bilaterally and in the genu of the corpus callosum. However, within the patient group, the propensity to experience auditory hallucinations was associated with relatively increased fractional anisotropy in superior longitudinal fasciculi and in the anterior cingulum. Schizophrenia is associated with altered white matter integrity in the tracts connecting the frontal cortex with the temporal and parietal cortices and with the contralateral frontal and temporal lobes. The severity of these changes may vary with the pattern of symptoms associated with the disorder.

A Diffusion Tensor Imaging Study of Fasciculi in Schizophrenia

Objective: Cognitive models propose that the symptoms and psychological impairments associated with schizophrenia arise as a consequence of impaired communication between brain regions, especially the prefrontal cortex and the temporal and parietal lobes. Functional imaging and electrophysiological data have provided evidence of functional dysconnectivity, but it is unclear whether this reflects an underlying problem with anatomical connectivity. This study used diffusion tensor imaging to examine the integrity of the major white matter fasciculi, which connects the frontal and temporal-parietal cortices, and the corpus callosum in patients with schizophrenia. Method: A 1.5-T magnetic resonance scanner was used to acquire diffusion tensor images giving whole brain coverage at an isotropic 2.5-mm voxel size. Fractional anisotropy was measured in 33 patients with schizophrenia and 40 healthy comparison subjects with an automated voxel-based method of analysis. Results: There was reduced fractional anisotropy in patients with schizophrenia in regions corresponding to the superior longitudinal fasciculi bilaterally and in the genu of the corpus callosum. However, within the patient group, the propensity to experience auditory hallucinations was associated with relatively increased fractional anisotropy in superior longitudinal fasciculi and in the anterior cingulum. Conclusions: Schizophrenia is associated with altered white matter integrity in the tracts connecting the frontal cortex with the temporal and parietal cortices and with the contralateral frontal and temporal lobes. The severity of these changes may vary with the pattern of symptoms associated with the disorder.