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M M Mesulam

Publications and source records attributed to M M Mesulam.

At least 163 records · Page 9Linked to original sources
PubMed1983

Central cholinergic pathways in the rat: an overview based on an alternative nomenclature (Ch1-Ch6).

Monoclonal antibodies to choline acetyltransferase and a histochemical method for the concurrent demonstration of acetylcholinesterase and horseradish peroxidase were used to investigate the organization of ascending cholinergic pathways in the central nervous system of the rat. The cortical mantle, the amygdaloid complex, the hippocampal formation, the olfactory bulb and the thalamic nuclei receive their cholinergic innervation principally, from cholinergic projection neurons of the basal forebrain and upper brainstem. On the basis of connectivity patterns, we subdivided these cholinergic neurons into six major sectors. The Ch1 and Ch2 sectors are contained within the medial septal nucleus and the vertical limb nucleus of the diagonal band, respectively. They provide the major cholinergic projections of the hippocampus. The Ch3 sector is contained mostly within the lateral portion of the horizontal limb nucleus of the diagonal band and provides the major cholinergic innervation to the olfactory bulb. The Ch4 sector includes cholinergic neurons in the nucleus basalis, and also within parts of the diagonal band nuclei. Neurons of the Ch4 sector provide the major cholinergic innervation of the cortical mantle and the amygdala. The Ch5-Ch6 sectors are contained mostly within the pedunculopontine nucleus of the pontomesencephalic reticular formation (Ch5) and within the laterodorsal tegmental gray of the periventricular area (Ch6). These sectors provide the major cholinergic innervation of the thalamus. The Ch5-Ch6 neurons also provide a minor component of the corticopetal cholinergic innervation. These central cholinergic pathways have been implicated in a variety of behaviors and especially in memory function. It appears that the age-related changes of memory function as well as some of the behavioral disturbances seen in the dementia of Alzheimer's Disease may be related to pathological alterations along central cholinergic pathways.

Acetylcholinesterase↗
PubMed1983

Hemispheric specialization in nonverbal communication.

Subjects sustaining right hemisphere damage were impaired in the ability to evaluate emotional situations presented through nonverbal means, particularly through facial expressions. Left brain damage, even of considerable extent, led to significantly milder deficits. In agreement with these findings, a study in split-brain patients showed the isolated right hemisphere to be competent in evaluating facial expressions but less sensitive to body movements, while the left hemisphere showed the opposite pattern.

Adult↗
PubMed1983

Specificity of muscle reinnervation after epineurial and individual fascicular suture of the rat sciatic nerve.

We experimentally analyzed the specificity of muscle reinnervation after suture and regeneration of rat sciatic nerve. We used a horseradish peroxidase (HRP) technique of axon tracing to compare the number and location of motoneurons that innervate muscle via the peroneal nerve after epineurial and individual fascicular suture of the parent sciatic nerve. These motoneurons are significantly reduced in number from control levels and are often in spinal cord locations that indicate previous innervation of antagonistic muscle via the tibial nerve. This inappropriate reinnervation of peroneal muscle by tibial motoneurons is minimized by individual fascicular suture without compromise of overall reinnervation. Our findings thus support the hypothesis that individual fascicular suture may avoid distortion of the central connections of peripheral units.

Animals↗
PubMed1982

Insula of the old world monkey. I. Architectonics in the insulo-orbito-temporal component of the paralimbic brain.

The insula of the rhesus monkey has a surface area of approximately 160 mm2 and can be divided into three architectonic sectors. The agranular sector is coextensive with prepiriform allocortex and is characterized by three agranular cellular strata, a zonal layer of myelinated fibers, and a high level of intracortical acetylcholinesterase (AChE). The dysgranular sector adjoins the agranular sector and shows first the emergence of a granular L4 and then a gradual differentiation of L2. Cortical myelin is low and mostly within deep layers; the AChE level is less than in the agranular sector. The third and granular sector covers the posterior aspect of the insula and contains granular L4 and L2, incipient sublamination of L3, increased cortical myelin with an emergent outer line of Baillarger, and a very low density of AChE. These observations indicate that AChE histochemistry can be used for the architectonic analysis of cortex. The lateral orbital cortex and the temporal pole can also be subdivided into agranular, dysgranular, and granular regions. In the insula as well as in lateral orbital and temporopolar areas, the agranular sector is directly contiguous with prepiriform cortex. When these three brain regions are considered jointly, they are seen to be organized in the form of increasingly more differentiated agranular, dysgranular, granular, and hypergranular sectors arranged concentrically around prepiriform allocortex. The term paralimbic is suggested as a generic term for all regions where such transitions occur from allocortex to granular isocortex. The insula, lateral orbital surface, and temporal pole are paralimbic areas with an olfactory allocortical focus. The parahippocampal, retrosplenial, cingulate, and subcallosal regions constitute a second group of paralimbic areas with a hippocampal-induseal focus. In the most general sense, the functional specilizations of paralimbic areas are predominantly for behaviors which require an integration between extrapersonal stimuli and the internal milieu. The human insula has a plan of organization virtually identical to that in the rhesus monkey. In the human, the insulo-orbito-temporopolar component of the paralimbic brain may become involved in conditions which range from epilepsy to psychosomatic disease.

Acetylcholinesterase↗
PubMed1982

Insula of the old world monkey. II: Afferent cortical input and comments on the claustrum.

The afferent connections of the insula in the rhesus monkey were studied with axonal transport methods. Injections of horseradish peroxidase (HRP) in the insula revealed labeled neurons in the prefrontal cortex, the lateral orbital region, the frontoparietal operculum, the cingulate gyrus and adjacent medial cortex, the prepiriform olfactory cortex, the temporal pole, the cortex of the superior temporal sulcus, the rhinal cortex, the supratemporal plane, and the posterior parietal lobe. Tritiated amino acid (TAA) injections in some of the cortical regions which contained retrogradely labeled neurons confirmed projections to the insula from prefrontal granular cortex, orbital frontal cortex, prepiriform cortex, temporal pole, rhinal cortex, cingulate gyrus, frontal operculum, and parietal cortex. In these studies, cortical areas that projected to the insula also projected to the claustrum. However, the topographic and quantitative relationships between the projections into the insula and those into the claustrum were inconsistent. Moreover, the claustrum has additional connections which it does not share with the insula. A selected review of the literature suggests that the claustrum and insula differ widely also with respect to ontogenesis and functional specialization.

Afferent Pathways↗
PubMed1982

Insula of the old world monkey. III: Efferent cortical output and comments on function.

The insula sends neural efferents to cortical areas from which it receives reciprocal afferent projections. A collective consideration of afferents and efferents indicates that the insula has connections with principal sensory areas in the olfactory, gustatory, somesthetic (SI and SII), and auditory (AI and AII) modalities. There are additional connections with association areas for the visual (TEm), auditory (supratemporal plane), and somesthetic (posterior parietal cortex) modalities; with paramotor cortex (area 6 and perhaps MII); with polymodal association cortex; and with a wide range of paralimbic areas in the orbital, temporopolar, and cingulate areas. The topographic distribution of these connections suggests that the posterodorsal insula is specialized for auditory-somesthetic-skeletomotor function whereas the anteroventral insula is related to olfactory-gustatory-autonomic function. Most of the insula, especially its anteroventral portions, have extensive interconnections with limbic structures. Through its connections with the amygdala, the insula provides a pathway for somatosensory, auditory, gustatory, olfactory, and visceral sensations to reach the limbic system. The cortical areas connected with the granular sector of the insula are also granular in architecture whereas virtually all the connections of the agranular insula arise from allocortical, agranular, or dysgranular areas. Thus, there is a correspondence between the architecture of insular sectors and the areas with which they have connections. The insula is heavily interconnected with temporopolar and lateral orbital areas. Furthermore, many cortical connections of the lateral orbital cortex are quite similar to those of the insula. These common connectivity patterns support the conclusion, based on architectonic observations, that the insulo-orbito-temporopolar component of the paralimbic brain should be considered as an integrated unit of cerebral organization.

Animals↗
PubMed1982

Ultrastructural evidence in mice that transganglionically transported horseradish peroxidase-wheat germ agglutinin conjugate reaches the intraspinal terminations of sensory neurons.

Horseradish peroxidase conjugated to wheat germ agglutinin (HRP-WGA) has been localized by electron microscopy in the central projections of primary sensory neurons following injection of the tracer into the gastrocnemius muscle of mice. The tracer was taken up by nerve terminals in the muscle and transported transganglionically into the central spinal cord terminations of the primary sensory neurons. The HRP-WGA was localized using a new tetramethylbenzidine ultracytochemical method and the diaminobenzidine-glucose oxidase technique. The results demonstrate that the HRP-WGA is transported into the axon terminals after passing through the sensory ganglion. These data provide an experimental basis for the use of the conjugate to map the central projections of sensory neurons.

Animals↗
PubMed1982

Slowly progressive aphasia without generalized dementia.

Six right-handed patients experienced a slowly progressing aphasic disorder without the additional intellectual and behavioral disturbances of dementia. The symptoms almost universally started in the presenium. The initial difficulty was an anomic aphasia in five of the patients and pure word deafness in the sixth. Continuous and gradual deterioration occurred in the five patients who presented with an anomic aphasia. They eventually experienced additional impairment of reading, writing, and comprehension. In four patients, other areas of comportment were not involved within the 5 to 11 years of follow-up. A more generalized state of dementia may have emerged in the other two patients, but only after 7 years of progressive debilitating aphasia. Neurodiagnostic procedures were consistent with preferential involvement of the left perisylvian region. In one patient, cortical biopsy did not show any pathognomonic change; specifically, no neurofibrillary tangles, amyloid plaques, neuronal inclusions, or gliosis were seen. This condition may constitute a syndrome of relatively focal cerebral degeneration with a predilection for the left perisylvian region.

Adolescent↗
PubMed1982

Electron microscopic demonstration of neural connections using horseradish peroxidase: a comparison of the tetramethylbenzidine procedure with seven other histochemical methods.

Eight methods for the electron microscopic demonstration of horseradish peroxidase (HRP) labeling have been compared in adjacent series of vibratome sections of mouse lumbar spinal cord. The tracer, a HRP-wheat germ agglutinin (WGA) conjugate, was injected into the gastrocnemius muscle complex. Following retrograde axonal transport to the lumbar motor neurons and transganglionic anterograde transport of the tracer to the dorsal horn, the HRP activity was demonstrated in eight series of adjacent sections of lumbar spinal cord using eight methods. These included procedures using tetramethylbenzidine (TMB), benzidine dihydrochloride (BDHC), o-tolidine, paraphenylenediamine-pyrocatechol (PPD-PC), and 4 methods using 3,3'-diaminobenzidine (DAB). All eight methods were able to demonstrate both retrograde labeling of motor neurons and transganglionic anterograde transport into the dorsal horn. However, there were differences in the appearance of the various reaction products under the electron microscope. In addition, differences in the distribution of the reaction products were observed by both light and electron microscopy. The largest distribution of reaction product was observed with TMB. BDHC and o-tolidine were next, followed by the DAB procedures and PPD-PC. The TMB, BDHC, and o-tolidine reaction products were all found to be suitable for electron microscopy. The TMB reaction product was electron dense and had a very distinctive crystalloid appearance that made identification of HRP-labeled neuronal profiles easy and unequivocal.

Animals↗
PubMed1981

Organization of afferent input to subdivisions of area 8 in the rhesus monkey.

The sources of ipsilateral afferents to subdivisions of one frontal eye field (Walker, '40a area 8) were studied with horseradish peroxidase (HRP) in macaque monkeys. There were major differences in the distribution of cells projecting to the caudal and rostral parts of area 8. The majority (53%) of labeled cortical cells projecting to caudal regions were in visual association areas, and an additional 23% were in the ventral bank of the intraparietal sulcus, where neurons may have predominantly visual and visuomotor properties. In contrast, rostral area 8 had a much lower percentage of its cortical input originating in visual association areas (5%) or in the ventral bank of the intraparietal sulcus (8%). After HRP injection in this rostral part, 21% of labeled cells were in auditory association areas and 13% in paralimbic regions, whereas labeling in these two types of cortex was negligible after HRP administration to caudal parts of area 8. The percentage of cells in other association regions (portions of the banks of the superior temporal sulcus, dorsolateral parietal, medial parietal, and prefrontal cortices) was higher in the rostral (53%) than in the caudal case (21%). The results suggest that caudal area 8 may be involved in head and eye movements in response to visual stimuli, while its anterior subdivisions may be involved in directing the head and eyes in response to auditory stimuli. Furthermore, limbic input may also be relevant to the neural processing occurring in rostral frontal eye fields, perhaps by directing attention toward motivationally relevant stimuli.

Animals↗
PubMed1981

Adult-onset stuttering treated with anticonvulsants.

Stuttering and aphasia emerged as salient clinical features in an adult with multifocal brain damage and paroxysmal EEG activity. Anticonvulsant treatment was associated with reversal of the stuttering and with marked improvement in language abilities.

Adult↗
PubMed1981

Dissociative states with abnormal temporal lobe EEG. Multiple personality and the illusion of possession.

Twelve patients with clinical and EEG manifestations reminiscent of temporal lobe epilepsy reported symptoms of dissociative states. In seven of these patients, the clinical picture was consistent with multiple personality, whereas the other five had the illusion of supernatural possession. These cases suggest that in selected instances dissociative states may constitute complex behavioral manifestations of chronic limbic epilepsy.

Adult↗
PubMed1981

Disturbances in prosody. A right-hemisphere contribution to language.

In addition to grammar and semantics, prosody constitutes a third element of speech. Modulations of prosody can produce alterations in the meaning and affective tone of spoken language. Previous studies have suggested that right-hemisphere lesions may selectively disrupt a patient's ability to interpret and express the affective component of prosody. On the other hand, this study shows that the effect of right-hemisphere damage on prosody is more widespread. Thus, when discrimination, repetition, and spontaneous production of nonemotional prosody were tested in nine patients with right-sided brain injuries and ten control subjects without brain damage, the patients were found to be significantly worse than the control subjects in their ability to distinguish and express prosodic features that provide phonemic or emphatic information. These results suggest that right-hemisphere damage may affect prosody in a more general manner than was previously assumed.

Adult↗
PubMed1981

A cortical network for directed attention and unilateral neglect.

Unilateral neglect reflects a disturbance in the spatial distribution of directed attention. A review of unilateral neglect syndromes in monkeys and humans suggests that four cerebral regions provide an integrated network for the modulation of directed attention within extrapersonal space. Each component region has a unique functional role that reflects its profile of anatomical connectivity, and each gives rise to a different clinical type of unilateral neglect when damaged. A posterior parietal component provides an internal sensory map and perhaps also a mechanism for modifying the extent of synaptic space devoted to specific portions of the external world; a limbic component in the cingulate gyrus regulates the spatial distribution of motivational valence; a frontal component coordinates the motor programs for exploration, scanning, reaching, and fixating; and a reticular component provides the underlying level of arousal and vigilance. This hypothetical network requires at least three complementary and interacting representations of extrapersonal space: a sensory representation in posterior parietal cortex, a schema for distributing exploratory movements in frontal cortex, and a motivational map in the cingulate cortex. Lesions in only one component of this network yield partial unilateral neglect syndromes, while those that encompass all the components result in profound deficits that transcend the mass effect of the larger lesion. This network approach to the localization of complex functions offers an alternative to more extreme approaches, some of which stress an exclusive concentration of function within individual centers in the brain and others which advocate a more uniform (equipotential or holistic) distribution. In human beings, unilateral neglect syndromes are more frequent and severe after lesions in the right hemisphere. Also, right hemisphere mechanisms appear more effective in the execution of attentional tasks. Furthermore, the attentional functions of the right hemisphere span both hemispaces, while the left hemisphere seems to contain the neural apparatus mostly for contralateral attention. This evidence indicates that the right hemisphere of dextrals has a functional specialization for the distribution of directed attention within extrapersonal space.

Animals↗
PubMed1981

Efferent connections of the cingulate gyrus in the rhesus monkey.

Efferent cortical connections of the cingulate gyrus are investigated in rhesus monkey using autoradiographic technique. The results indicate that the rostralmost part of the cingulate gyrus (area 32) sends projections to the lateral prefrontal and midorbitofrontal cortex and to the rostral portion of the superior temporal gyrus. In contrast, the other two major subdivisions of the cingulate gyrus, areas 24 and 23, have widespread connections within the cortex. Area 24, for example, projects to the premotor region (areas 6 and 8), the fronto-orbital cortex (area 12), the rostral part of the inferior parietal lobule, the anterior insular cortex, the perirhinal area and the laterobasal nucleus of amygdala. Area 23, likewise, sends its connections to the dorsal prefrontal cortex (areas 9 and 10), the rostral orbital cortex (area 11), the parieto-temporal cortex (posterior part of the inferior parietal lobule and the superior temporal sulcus), the parahippocampal gyrus (areas TH and TF), the retrosplenial region and the presubiculum. It seems that the connections of the rostralmost part of the cingulate gyrus resemble the efferent cortical connectional patterns described for lateral prefrontal and orbito-frontal cortex, whereas the projections of areas 24 and 23 are directed to the neocortical, the paralimbic and the limbic areas.

Animals↗
PubMed1981

Concurrent acetylcholinesterase staining and gamma-aminobutyric acid uptake of cortical neurons in culture.

Gamma-aminobutyric acid (GABA) uptake and acetylcholinesterase (AChE) content were demonstrated concurrently in cortical neurons grown in tissue culture. Positive reactions either for GABA uptake or for AChE content were encountered in pyramidal and stellate, as well as spindle-shaped neurons. Neither reaction was confined to a specific morphological subtype. Nearly half the neurons were negative for either reaction. Most of the remaining neurons were positive only for GABA or only for AChE. However, a subpopulation of neurons showed not only a high AChE content, but also an avid GABA uptake. Thus, four types of neurons could be identified on the basis of these two reactions. The high AChE content in some of the cortical neurons that also showed GABA uptake indicates that there are at least two distinct types of GABAergic neurons.

Acetylcholinesterase↗