Marjorie LeMay

Asymmetries of the skull and handedness. Phrenology revisited.

Some of the asymmetries noted in cerebral computerized transaxial tomography (CTT) studies are reflected in the shape of the skull resulting most often in backward protrusion of the occipital bone on the left and a less striking forward protrusion of the right frontal bone. Asymmetries are less marked in left-handed individuals but the opposite features, i.e. forward protrusion of the left frontal bone and posterior protrusion of the right occipital bone, are more frequent in left handers than in right handers.

Autism and Unfavorable Left-Right Asymmetries of the Brain.

Utilizing computerized brain tomography, left-right morphologic asymmetries of the parietooccipital region were judged in 16 autistic patients, 44 mentally retarded patients, and 100 miscellaneous neurological patients. In 57% of the autistic patients the right parietooccipital region was wider than the left, while this pattern of cerebral asymmetry was found in only 23% of the mentally retarded patients and 25% of the neurological patients. It is suggested that unfavorable morphologic asymmetries of the brain near the posterior language zone may contribute to the difficulties autistic children experience in acquiring language.

Asymmetries of the Brains and Skulls of Nonhuman Primates

Morphological asymmetries in the bodies and facies of modern man have long been recognized, but only during the past 10 years has attention been given to the numerous anatomical asymmetries that are present in the human brain. In the past few years both functional and specific morphological cerebral asymmetries have also been noted in nonhuman primates and other vertebrates (Dewson, 1977; Glick et al., 1977; Nottebohm, 1970; Webster, 1972; Webster and Webster, 1974). The present study reviews the cerebral and cranial asymmetries that have been reported in the past and also presents some new findings made on endocranial casts of a number of nonhuman primate skulls.

Statistical assessment of perceptual CT scan ratings in patients with alzheimer type dementia

Three neuroradiologists perceptually evaluated CT of 24 patients with Alzheimer type dementia and 22 normal control subjects and made a dichotomous judgment for each case (i.e., normal control or Alzheimer type dementia). The mean percentage of patients correctly classified was 83.3%. The neuroradiologists also completed perceptual ratings on each scan. Thirteen regions were rated for atrophy on a scale of 0-4. Discriminant function analyses of several sets of perceptual atrophy ratings (optimized on an exploratory set and evaluated on a test set) showed that the perceptual ratings of temporal lobe regions produced an average accuracy of 88.57%. In contrast, only 74.26% of the cases were correctly classified when the discriminant functions were based on perceptual ratings of midventricular and supraventricular areas. Linear measures of atrophy correctly classified only 65.20% of the subjects. The results suggest that atrophy ratings of brain regions that show the characteristic macroscopic neuropathological changes of Alzheimer disease may be used by neuroradiologists to reach more accurate diagnostic decisions.

Can spatial and temporal motion integration compensate for deficits in local motion mechanisms

We studied the motion perception of a patient, AMG, who had a lesion in the left occipital lobe centered on visual areas V3 and V3A, with involvement of underlying white matter. As shown by a variety of psychophysical tests involving her perception of motion, the patient was impaired at motion discriminations that involved the detection of small displacements of random-dot displays, including local speed discrimination. However, she was unimpaired on tests that required spatial and temporal integration of moving displays, such as motion coherence. The results indicate that she had a specific impairment of the computation of local but not global motion and that she could not integrate motion information across different spatial scales. Such a specific impairment has not been reported before.

Functional and anatomical profile of visual motion impairments in stroke patients correlate with fMRI in normal subjects

We used six psychophysical tasks to measure sensitivity to different types of global motion in 45 healthy adults and in 57 stroke patients who had recovered from the initial results of the stroke, but a large subset of them had enduring deficits on selective visual motion perception tasks. The patients were divided into four groups on the basis of the location of their cortical lesion: occipito-temporal, occipito-parietal, rostro-dorsal parietal, or frontal-prefrontal. The six tasks were: direction discrimination, speed discrimination, motion coherence, motion discontinuity, two-dimensional form-from-motion, and motion coherence - radial. We found both qualitative and quantitative differences among the motion impairments in the four groups: patients with frontal lesions or occipito-temporal lesions were not impaired on any task. The other two groups had substantial impairments, most severe in the group with occipito-parietal damage. We also tested eight healthy control subjects on the same tasks while they were scanned by functional magnetic resonance imaging. The BOLD signal provoked by the different tasks correlated well with the locus of the lesions that led to impairments among the different tasks. The results highlight the advantage of using psychophysical techniques and a variety of visual tasks with neurological patients to tease apart the contribution of different cortical areas to motion processing.

Are there radiological changes in the brains of individuals with dyslexia

SummaryCT scans of a group of patients with developmental dyslexia have shown statistically a difference of mass distribution in the cerebral hemispheres from that seen in control patients studied during the same period. They have also shown an increased incidence of unusual ventricular asymmetries from that commonly occurring in normal individuals. The findings suggest there may be an increased incidence of early slight morphological changes in the brains of individuals with dyslexia but the changes are not diagnostic of dyslexia.

Enlargement of the Sylvian aqueduct: a sequel of head injuries.

A review of pneumoencephalography and clinical data in a large group of patients has shown that severe head injury may be followed by a consistent clinical-radiological syndrome. A prolonged period of unconsciousness is a characteristic initial feature of this syndrome. Clinically there is ataxia and dysarthria and, often, abnormal movements and oculomotor dysfunction. The characteristic radiological feature is an enlargement of the aqueduct of Sylvius. The clinical picture, together with the enlargement of the aqueduct, suggests that loss of neuronal and axonal substance in the midbrain is the probable pathology.

Aggression in temporal lobe epilepsy and limbic psychotic trigger reaction implicating vagus kindling of hippocampus/amygdala (in sinus abnormalites on MRIs)

Abstract Five aspects associated with potentially aggressive partial limbic seizures are interrelated: (1) Five out of six unselected (consecutively referred) White, male out-of-character aggressive felons (mean age 33) had histories of recurrent nasopharyngeal infections, four with congruent MRIs, two of these MRIs also showed cortical atrophy, three men had histories of various seizures, and one scalp EEG was “congruent with seizures in the temporal regions.” All men had histories of head injuries. The diagnoses of their bizarre acts during a brief psychosis were partial limbic seizures in an “exhibitionist” with temporal lobe epilepsy (TLE) and proposed limbic psychotic trigger reaction (LPTR) in four “murderers”, based on 13 specific symptoms and signs. (2) The mens nasopharyngeal (medical) conditions are hypothesized to be associated with intermittent mild stimulation of the vagus nerve. Supportive evidence shows that (3) experimental vagus stimulation has the most excitatory impact on hippocampus and amygdala, which are also (4) the most susceptible to limbic seizure kindling (by intermittent subthreshold stimuli). (5) even by contrast, high-voltage energy level and frequently applied vagus nerve stimulation (VNS), which is used as an antiepileptic treatment; however, VNS has elicited seizures in some patients.

Posterior scalloping of vertebral bodies in uncontrolled hydrocephalus

The spinal canal normally increases in size until about the tenth year when the epiphyses fuse between the arches of the spine and the vertebral bodies. Enlargement of the canal after this time is manifested by flattening and thinning of the pedicles, increase in the interpediculate and saggital diameters of the canal, and posterior scalloping of the vertebral bodies. The majority of intraspinal tumours do not cause enlargement of the spinal canal because some tumours invade the vertebral bodies rather than enlarge the canal, and most intraspinal tumours produce marked neurological symptoms so that surgery is performed before changes occur in the pedicles of the vertebral bodies. Posterior scalloping of vertebral bodies with localized enlargement of the spinal canal usually denotes the longstanding presence of a mass lesion but scalloping occasionally occurs in patients without a mass lesion being present within the canal. Most of those patients having a vertebral scalloping but no mass lesion have generalized neurofibromatosis and the bone changes have been attributed generally to a non-specific mesenchymal defect or developmental failure of the vertebrae. The discovery of two patients with generalized posterior scalloping throughout most of the spinal canal associated with communicating hydrocephalus has prompted a review of the pathogenesis of posterior scalloping of the vertebral bodies. Two less striking cases have also been found.