Extent Of Cortical Involvement Research Articles

Electrocortical activity in freely walking rats varies with environmental conditions

Longstanding theories in the field of neurophysiology have held that walking in rats is an unconscious, rhythmic locomotion that does not require cortical involvement. However, recent studies have suggested that the extent of cortical involvement during walking actually varies depending on the environmental conditions. To determine the impact of environmental conditions on cortical engagement in freely walking rats, we recorded limb kinematics and signals from implanted electroencephalography arrays in rats performing a series of natural behaviors. We found that rat gaits were significantly different across various locomotion terrains (e.g. walking on an upslope vs. downslope). Further, rat forelimbs and hindlimbs showed similar patterns of motion. The results also suggested that rat cortical engagement during walking varied across environmental conditions. Specifically, α band power significantly increased during 30° downslope walking in the posterior parietal, left secondary motor, and left somatosensory clusters. Additionally, during 30° upslope walking, the β band power was greater in the left primary motor and left and right secondary motor sources. Further, rats walking on up- or downslopes of varying steepness were found to have different cortical activities. Compared with 10° downslope walking, α band power was greater during 30° downslope locomotion in the left primary motor and somatosensory sources. These findings support the hypothesis that cortical contribution during walking in rats is influenced by environmental conditions, underlining the importance of goal-directed behaviors for motor function rehabilitation and neuro-prosthetic control in brain-machine interfaces.

Clinical radiological correlation in E200K familial Creutzfeldt-Jakob disease.

The use of diffusion MRI improved the accuracy of diagnosis in Creutzfeldt-Jakob disease (CJD) and expanded our knowledge of the changes occurring in the brain during the disease. The aim of this study was to test whether in patients with E200K familial CJD (fCJD) the clinical severity correlates with the disease burden as reflected by the extent of cortical involvement in DWI MRI. Consecutive fCJD patients were examined by a neurologist who performed several tests including the CJD neurological scale (CJD-NS), MiniMental status examination (MMSE), Frontal Assessment Battery (FAB), NIH Stroke Scale (NIHSS), and the expanded disability status scale (EDSS). A simultaneously acquired MRI was analyzed by measuring the extent of cortical involvement in the DWI axial sequence. Correlations were tested for using Pearson test. Fifty-two fCJD patients (35 males, mean age 59.4±5.7years) were recruited to the study. Significant negative correlation was found between the extent of cortical involvement and the cognitive performance of the patients as reflected by their MMSE and FAB scores. In addition, a significant positive correlation was found between the MRI and the clinical disease severity scales CJD-NS and EDSS. The correlation between clinical scales of severity and cognitive dysfunction and the disease burden confirms the reliability of the CJD-NS scale. Further studies are warranted to examine whether MRI may serve not only for diagnosis but also as a biomarker for follow-up of disease progression and the efficacy of potential treatments.

Laminar cortical damage in multiple sclerosis.

This scientific commentary refers to ‘A gradient in cortical pathology in multiple sclerosis by in vivo quantitative 7 T imaging’, by Mainero et al. (doi:10.1093/brain/awv011). Multiple sclerosis is widely regarded as an archetypical white matter disease. The early histopathological descriptions of grey matter involvement resurfaced only when MRI studies reiterated the frequent occurrence of cortical lesions in multiple sclerosis (Kidd et al. , 1999). In fact, cortical demyelination is seen in very few other CNS diseases (Lassmann, 2012) and the occurrence of juxtacortical lesions is one of the main differentiating features for multiple sclerosis (Barkhof et al. , 1997). Comparison of MRI and histopathology has been a humbling experience for radiologists, but also a learning opportunity for pathologists (Geurts and Barkhof, 2008). The use of sensitive immunohistochemical staining techniques (against major myelin proteins) has provided a wealth of data on the type and extent of cortical involvement in (progressive) multiple sclerosis. Subpial lesions in particular can be extensive (Kutzelnigg et al. , 2005) and have triggered debate as to the underlying causal factors, which are believed by some to be found in the CSF or to be related to inflammation in overlying meninges. One of the ‘grand challenges’ in imaging of cortical pathology is the in vivo detection of the most dominant cortical lesion type, the subpial lesion, by means of …

Extent of cortical involvement in amyotrophic lateral sclerosis – an analysis based on cortical thickness

BackgroundBesides the defining involvement of upper and lower motor neurons, the involvement of extramotor structures has been increasingly acknowledged in amyotrophic lateral sclerosis (ALS).MethodsHere we investigated a group of 14 mildly to moderately affected ALS patients and 14 age-matched healthy control participants using cortical thickness analysis. Cortical thickness was determined from high resolution 3D T1 magnetic resonance images and involved semiautomatic segmentation in grey and white matter, cortical alignment and determination of thickness using the Laplace method. In addition to a whole-cortex analysis a region of interest approach was applied.ResultsALS patients showed regions of significant cortical thinning in the pre- and postcentral gyri bilaterally. Further regions of cortical thinning included superior and inferior parietal lobule, angular and supramarginal gyrus, insula, superior frontal, temporal and occipital regions, thus further substantiating extramotor involvement in ALS. A relationship between cortical thickness of the right superior frontal cortex and clinical severity (assessed by the ALS functional rating scale) was also demonstrated.ConclusionsCortical thickness is reduced in ALS not only in motor areas but in widespread non-motor cortical areas. Cortical thickness is related to clinical severity.

Polymicrogyria: correlation of magnetic resonance imaging and clinical findings

The aim of this study is to evaluate the correlation between clinical presentation and the extent of cortical involvement in patients with polymicrogyria. The magnetic resonance imaging findings of 26 patients were evaluated for the location and distribution of polymicrogyria. Presence of asphyxia at birth and serological tests for TORCH infections, the presence and type (spastic, flaccid) of motor deficits, mental development,microcephaly, and epilepsy were noted. Nineteen patients had bilateral, whereas seven had unilateral involvement. Patients with unilateral polymicrogyria presented later with milder symptoms. The most encountered symptom in patients with bilateral involvement was mental motor retardation (MMR) (89%) and speech problems (84%).The clinical presentations of patients with asphyxia and positive serological tests for cytomegalovirus (CMV) were worse.All patients with positive serological tests for CMV had bilateral involvement. The perisylvian region was affected in five(71%) patients with unilateral involvement. The most encountered presenting symptom in these patients was epilepsy. Cerebral palsy was seen in three (43%) of the patients, and all of them had left hemiparesis. Microcephaly, MMR, and speech delay were detected in one (14%) of the patients. Late presenting epilepsy may be a predictor of aunilateral polymicrogyria and is associated with relatively good prognosis. CMV infection and the presence of asphyxia are predictors of worse prognosis.

Clinical and Pathological Characteristics of LRRK2 G2019S Patients with PD

The objective of this study is to describe the neuropathologic findings in three LRRK2 G2019S carriers with Parkinson's disease (PD). We cross-referenced a list of 956 PD individuals that had been previously genotyped in clinical studies at Columbia University, with 282 subjects with a parkinsonian syndrome who came to autopsy in our brain bank since 1991. We found three autopsies of G2019S mutation carriers. Pathological analyses of the samples were blind to the genetic findings. We retrospectively reviewed the clinical records of the three patients. All three had a clinical and pathological diagnosis of PD. Cognitive impairment was a late feature in two out of three patients. Cortical involvement varied significantly: one had diffuse Lewy body (LB) pathology, tau inclusions, and amyloid pathology consistent with advanced Alzheimer's disease; one had diffuse cortical LB; and one had only brainstem predominant LB pathology. Cognitive impairment may be a long-term complication in G2019S mutation carriers. However, the extent of cortical involvement is variable. Larger longitudinal follow-up of LRRK2 G2019S mutation carriers is required to assess for risk factors for cortical involvement and dementia.

Cortex-sparing infarctions in patients with occlusion of the middle cerebral artery

BackgroundIn patients with a middle cerebral artery (MCA) occlusion, the involvement of the cortex may be affected by the presence of leptomeningeal anastomoses between the cerebral arteries.MethodsThe authors enrolled consecutive...

MRI analysis of sulcation morphology in polymicrogyria

Polymicrogyria (PMG) is a malformation of cortical development in which the process of normal cortical development is interrupted during the late stages of neuronal migration and during the stages of cortical organization; the result is the abnormal development of the deeper layers of the cerebral cortex and the formation of multiple small gyri. Patients with polymicrogyria may present with developmental delay, focal neurologic signs and symptoms, or epilepsy, depending upon the portion(s) of brain involved. Affected patients may be micro-, normo-, or macrocephalic (Dobyns et al., 2008). Polymicrogyria may be associated with congenital infection (Barkovich and Linden, 1994, Wright et al., 1997), in utero ischemia (Hallervorden, 1949), or chromosomal mutations (Kuzniecky, 1994, Bingham et al., 1998, Leventer et al., 2001, Piao et al., 2002, Villard et al., 2002, Roll et al., 2006, Dobyns et al., 2008). No difference in neurologic manifestations has been detected in patients who have polymicrogyria of different causes (Guerrini et al., 1992, Barkovich and Linden, 1994, Barkovich and Kjos, 1992), but the severity of the clinical presentation depends upon the extent of cortical involvement; bilateral involvement and involvement of more than half of a single hemisphere are poor prognostic indicators, portending moderate to severe developmental delay and significant motor dysfunction (Barkovich and Kjos, 1992). Polymicrogyria has a range of histologic appearances, all having in common a derangement of the normal six-layered lamination of the cortex (Evrard et al., 1989), with an associated derangement of sulcation. Thus, it would seem likely that the gross morphologic appearance of polymicrogyria might vary, as well, perhaps depending upon the underlying cause or the pattern of distribution of the anomalous sulcation within the brain. However, this topic has not heretofore been addressed in the literature. We report the imaging characteristics of a large number of patients with polymicrogyria and attempt to determine specific sulcation patterns and their variability.

Hemispheric dominance for mental rotation: it is a matter of time

Mental rotation is often said to be a right-hemisphere function. The evidence for this claim, however, remains equivocal. To investigate whether right-hemispheric superiority relates to speed of processing, we measured the latencies and amplitudes of individual participant's mental-rotation event-related potential effects over the parietal electrodes. The results suggest that increases in parietal negativity begin around 400 ms after stimulus onset, and continue until 550 ms over the right hemisphere, and 610 ms over the left hemisphere. The effect of orientation on event-related potential amplitudes during those times do not differ between hemispheres. These results indicate that the lateralization effect is primarily related to timing, rather than the extent of cortical involvement.

Congenital Bilateral Perisylvian Syndrome: Familial Occurrence, Clinical and Psycholinguistic Aspects Correlated with MRI

Congenital bilateral perisylvian syndrome (CBPS) is frequently caused by polymicrogyria (PMG). The aim of this study was to correlate the clinical and psycholinguistic aspects with neuroradiological data of patients with CBPS. Thirty-one patients were studied. We performed a clinical investigation of the patients and their families, including MRI scanning, neuropsychological tests and language evaluation. The statistical analysis showed that: a) prenatal events are associated with the non-familial type of PMG; b) diffuse PMG is associated with pseudobulbar signs, as opposed to BPPP; c) motor deficit is associated with diffuse PMG; d) epilepsy is equally present in patients with both familial or non-familial PMG, but is more frequently seen in patients with diffuse PMG; e) dyslexia and SLI can be a feature of both the diffuse or BPPP, and either familial or sporadic cases of PMG. The severity of clinical manifestations in CBPS is correlated with the extent of cortical involvement. Most patients with CBPS have a history of speech delay or language difficulties and no epilepsy. Dyslexia can be found in patients with PMG.

Bilateral mesial temporal polymicrogyria: a case report

Polymicrogyria is a malformation of cortical organisation morphologically marked by an irregular brain surface with multiple excessively folded small gyri. Cortical thickness is reduced but appears increased in some areas...

Characterization of language and reading skills in familial polymicrogyria

Polymicrogyria (PMG) is a malformation of cortical development characterized by an excessive number of small gyri and abnormal cortical lamination, giving the cortical surface an irregular and gross appearance. The severity of clinical manifestations correlates with the extent of cortical involvement. The objective of the present study was to describe three families with linguistic features of developmental language disorder and reading impairment, and to establish a neuroanatomic correlation through neuroimaging. Subjects have been submitted to a comprehensive protocol including psychological assessment, language evaluation, neurological examination, and neuroimaging investigation. In our families, children usually had the diagnosis of developmental language disorder while adults had the diagnosis of reading impairment. MRI showed perisylvian polymicrogyria in several subjects of each family. Our data support the idea that there is a co-occurrence of developmental language disorder and reading impairment and both conditions may be associated with polymicrogyria.

Malformations of cortical development: clinical spectrum in a series of 101 patients and review of the literature (Part I)

Patients with malformations of cortical development (MCD) present with a wide spectrum of clinical manifestations ranging from asymptomatic cases to those with epilepsy and neurodevelopmental problems. Thorough clinical delineation of patients with MCD may provide clues for future phenotype-genotype correlation studies. We studied clinical features of patients with MCD, including developmental risk factors and family history. We evaluated 10 patients with MCD at Hacettepe University Children's Hospital, Department of Pediatric Neurology. All patients underwent neurological evaluation with detailed medical and family history, and neuropsychological evaluation. Routine EEG and MRI were obtained. The patients were between 1 month and 19 years of age (mean: 6.1 +/- 4.4 years). Fifty-four patients were diagnosed with polymicrogyria (PMG), 23 patients with lissencephaly, 12 patients with schizencephaly, and 12 patients with heterotopia. Parents were relatives in 31.7% of the cases; consanguinity was most common in patients with lissencephaly and other MCDs with diffuse/bilateral involvement. Initial clinical presentation was seizures in 61.4% of the cases, developmental delays in 12.9%, and microcephaly in 9.9%. Neurological evaluation revealed most severe abnormalities in patients with lissencephaly, and relatively better outcome in patients with heterotopias. Cognitive functions were better in patients with heterotopias compared to other groups. Overall, 71.3% of patients ha epilepsy. In conclusion, initial presentation and clinical course of patients with MCD are variable and seem to be correlated with the extent of cortical involvement. Epilepsy and mental retardation are the most common problems. The most severe clinical outcome was seen in patients with lissencephaly.

Disparity of Verbal and Performance IQ Following Early Bilateral Brain Damage

To examine the effects of early bilateral brain damage on Full Scale IQ (FSIQ), Verbal IQ (VIQ) and Performance IQ (PIQ). Early unilateral brain damage typically results in relatively spared intellectual function, with IQ in the normal range and no significant differences between VIQ and PIQ, regardless of the side of the lesion. However, little is known about intellectual function in children after bilateral damage. FSIQ, VIQ, and PIQ scores of 10 children, ages 6-12 years, with early-onset bilateral focal lesions (BFL), were compared with those of age- and sex-matched controls. FSIQ was in the average range for BFL and control children. A bimodal distribution of VIQ was identified, resulting in 2 distinct groups, one performing above the average range and the other below. The unimpaired group displayed a significant discrepancy between VIQ and PIQ, with VIQ in the superior range and PIQ in the low average range. The impaired group did not demonstrate disparate VIQ and PIQ: both were in the borderline range. The 2 groups were differentiated by greater degree of cortical brain damage in the impaired than in the unimpaired group. The striking difference between the outcome of the unimpaired and impaired groups may reflect different processes of reorganization that are associated with the extent of cortical involvement.

Visual evoked potentials during suppression in exotropic and esotropic strabismics: strabismic suppression objectified

We performed an electrophysiological study in order to objectify suppression in strabismus. The extent of cortical involvement in the process of interocular suppression was also explored. Possible differences in the suppressive process of esotropic and exotropic strabismics were also studied. An electroencephalographic recorder with eight leads was applied to the posterior one-third of the skull; three occipital, three parietal, and two temporal leads. We measured the activity of these visual cortical areas during stimulation of each eye under monocular as well as binocular viewing conditions with hemisinusoidal light pulses in a nature-like complex visual background. Recordings were made from six primary esotropic strabismic subjects and four primary exotropic and one consecutive exotropic strabismic subject. Also, five normal controls were studied. A characteristic, triphasic response complex was found at approximately 80 ms following the start of each light pulse under monocular viewing conditions in the dominant and the nondominant eye. However, under dichoptic viewing conditions in the nondominant eye of all esotropic cases as well as in the nondominant eye of three of five exotropic cases, this response complex was completely absent. They showed approximately 100% reduction of their cortical response activity. These results show the vast extent of the cortex that is involved in the suppressive process, giving a good insight in the power of suppression.