Manic delirium and frontal-like syndrome with paramedian infarction of the right thalamus

A disinhibition syndrome affecting speech (with logorrhoea, delirium, jokes, laughs, inappropriate comments, extraordinary confabulations), was the main manifestation of a right-sided thalamic infarct involving the dorsomedian nucleus, intralaminar nuclei and medial part of the ventral lateral nucleus. Resolution of conflicting tasks was severely impaired, suggesting frontal lobe dysfunction. These abnormalities correlated with the finding on SPECT of a marked hypoperfusion in the overlying hemisphere predominating in the frontal region. We suggest that this behavioural syndrome was produced by disconnecting the dorsomedian nucleus from the frontal lobe and limbic system.

Alzheimer's disease: neurofibrillary tangles in nuclei that project to the cerebral cortex

We have used an antibody to the paired helical filament protein to immunohistochemically identify the regional distribution of subcortical nuclei containing neurofibrillary tangles in brains from Alzheimer's disease patients. Sections were examined from the cerebral cortex, diencephalon, midbrain and pons in seven Alzheimer's and three age-matched normal brains. The antibody sensitively stained the many tangles, and senile plaques, in the cerebral cortex of the Alzheimer's brains and the few tangles and senile plaques in the aged normal cortex. Ten subcortical nuclei contained many tangles in the Alzheimer's brains. The tangles were found not only within the locus coeruleus and dorsal raphe nucleus, which often have been shown to be involved in Alzheimer's neuropathology, but also within several other nuclei not previously related to this disease. For example, tangles were found in the nucleus paranigralis, peripeduncular nucleus, medial parabrachial nucleus and several midline thalamic nuclei. All of the nuclei which contained tangles have been shown, in neuroanatomical tracing studies, to project to the cerebral cortex. These data indicate that Alzheimer's disease is a disease of the cerebral cortex and the numerous subcortical nuclei which diffusely innervate it, and are consistent with the hypothesis that the cerebral cortex is the primary target of the disease and the interconnected subcortical nuclei are secondarily affected due to retrograde transport of a cortical pathogen or failure of normal transport of a trophic agent.

Peripheral nerve injury in developing rats reorganizes representation pattern in motor cortex

We investigated the effect of neonatal nerve lesions on cerebral motor cortex organization by comparing the cortical motor representation of normal adult rats with adult rats that had one forelimb removed on the day of birth. Mapping of cerebral neocortex with electrical stimulation revealed an altered relationship between the motor cortex and the remaining muscles. Whereas distal forelimb movements are normally elicited at the lowest threshold in the motor cortex forelimb area, the same stimuli activated shoulder and trunk muscles in experimental animals. In addition, an expanded cortical representation of intact body parts was present and there was an absence of a distinct portion of motor cortex. These data demonstrate that representation patterns in motor cortex can be altered by peripheral nerve injury during development.

Discharge patterns of afferent cutaneous nerve fibers from the rat's tail during prolonged noxious mechanical stimulation

Feedback controlled constant force stimuli of 4, 6 and 8 N intensities and of 120 s duration were applied to the receptive fields of cutaneous afferent fibers in the rat's tail. Two types of nociceptive units showed sustained discharges during these stimuli: "polymodal" unmyelinated C-units (MH-C units, N = 18, c.v. 0.5-0.9 m/s) and high-threshold mechanoreceptive A-delta-units (HTM-units, N = 10, c.v. 1.9-11.2 m/s). In addition two classes of sensitive low threshold mechanoreceptors, SA I (N = 6) and SA II (N = 5) units, responded to the prolonged mechanical stimuli. At the onset of a noxious pressure, 11 of the 18 polymodal nociceptors exhibited dynamic responses (lasting about 10 s) which were followed by slowly adapting tonic discharges that lasted for the duration of the stimuli. The remaining polymodal C-fiber units (8/18) did not show dynamic discharges at 4 and 6 N. Phasic and tonic discharges were positively correlated with stimulus strength. The HTM-units encoded stimulation intensity mainly by their dynamic discharges. The tonic discharges of these units displayed faster adaptation rates with stronger mechanical stimuli, i.e. encoding of stimulation intensity became progressively weaker during the tonic phase. The discharges of sensitive SA I and SA II units with A beta axons were not positively correlated with the strength of noxious pressure stimuli. Tonic discharge rates of SA I units were negatively correlated to stimulus strength, whereas SA II units usually stopped firing in the course of a stimulus and became reversibly irresponsive to mechanical stimulation. Possible afferent mechanisms underlying the induction of pain by sustained noxious mechanical stimulation are discussed.

Pure dysarthria due to anterior internal capsule and/or corona radiata infarction: a report of five cases

Five cases with a sudden onset of dysarthria in the setting of hypertension are presented. No case had limb weakness or other neurological deficits. Computed tomographic scan demonstrated a small low density lesion in the anterior part of the internal capsule or the adjacent corona radiata. All cases showed a good recovery from dysarthria within two to four weeks.

Selective suppression of neurofilament antigen expression in the hypothyroid rat cerebral cortex

As an integral component of the cytoskeleton neurofilaments play a central role in the establishment and maintenance of neuronal form. In particular, high neurofilament concentrations are characteristic of many classes of axons in the central nervous system. Isolated neurofilaments from rat brain consist of 3 distinct polypeptides with apparent molecular weights 210K, 160K and 68K. A murine monoclonal antibody, mabN210, has been produced which specifically recognizes an epitope associated with the high molecular weight subunit and this antibody has been used to explore the regulation of neurofilament expression during brain development. It has been shown that in the rat cerebellar cortex, the expression of mabN210-immunoreactivity in basket cell axons is severely suppressed in hypothyroidism while neurofilament antigen expression in other cerebellar axons seems not to require thyroid hormones. In view of the well-known cortical deficits in hypothyroidism, these studies have now been extended to include the developing rat cerebral cortex and selected cortical afferent and efferent axons. In hypothyroid rats there is a marked suppression of mabN210-immunoreactivity in the cerebral cortex and corpus callosum and, to a lesser extent, there is a reduction in staining in the internal capsule. By contrast, hypothyroidism did not reduce mabN210-immunoreactivity in the lateral olfactory tract or the stria medullaris. In rats, serum thyroid hormone starts to rise to adult levels on postnatal day 4. It appears that axons that have attained their mature distribution prior to the onset of thyroid hormone expression are not affected by hypothyroidism whereas mabN210-immunoreactivity is suppressed in those axonal tracts that reach a mature distribution after P4.

Acrylamide-induced ascending degeneration of ligated peripheral nerve: effect of ligature location

Acrylamide was administered to rats for 10 days (50 mg/kg/day) after ligation of either proximal (sciatic) or distal (posterior tibial) nerves. Morphologic evaluation of the nerves revealed severe degeneration 0.5 cm proximal to the ligature, with progressively less pronounced change at successively higher levels above the ligature, when compared with ligated non-treated controls. Although severe degeneration of the nerves was observed in both proximal- and distal-ligated groups of animals, the distal-ligated group showed slightly more change (at 0.5 cm above the ligature), suggesting a minor effect of distance of the site of nerve injury from the nerve cell body.

Topographical anatomy of the posterior columns of the spinal cord in man. The long ascending fibres

Nine cases are presented which illustrate the segmental anatomy of the posterior columns with respect to the long ascending fibres. It is concluded that the fasciculus gracilis (FG) and the fasciculus cuneatus (FC) should be considered as separate anatomical entities. It is shown that the shape of each fasciculus is different in, and characteristic of, each of the upper thoracic and cervical segments. A certain degree of segmental lamination is present in the FG, but with extensive overlapping of fibres from different segments. The orientation of the laminae is not the same in all segments, being very approximately parallel to the medial border of the posterior horn in most caudal segments, approximately parallel to the median septum in intermediate segments, and oblique in an anteromedial posterolateral direction in cranial sections. The pattern of lamination in the FC and the degree of overlapping of fibres resembles that in the caudal FG. There is no, or minimal, overlapping of fibres of the FC with those of the FG. The most medial fibres of the FC, lying along the lateral border of the FG, are in proximity with fibres, in that fasciculus, from many different segments.

Correlation between cortical plaque count and neuronal loss in the nucleus basalis in Alzheimer's disease

In order to substantiate the hypothesis of a cholinergic matrix for neuritic plaque formation in Alzheimer's disease (AD), the relationship between the loss of cholinergic neurons in the basal forebrain and formation of neuritic plaques in the cerebral cortex was studied in 5 cases of neuropathologically verified AD. Quantitative evaluation of the number of neuritic plaques in the cerebral cortex as calculated from 6 areas showed a strong correlation with the loss of neurons in the nucleus basalis of Meynert (NbM). This finding indicates that changes in cortical cholinergic innervation which arise from the neurons of the NbM are an important feature in the pathogenesis of neuritic plaques.

Absence of intraspinal sprouting in dorsal root axons caudal to a partial spinal hemisection: a horseradish peroxidase transport study

Primary afferent sprouting in the spinal cord was evaluated by comparing the central projection of horseradish peroxidase (HRP)-labeled sciatic nerve afferent axons in nonlesioned control rats, and in rats subjected to acute or chronic partial spinal hemisections as adults. The lesions were performed at various levels from T10 to L3, and removed supraspinal and varying amounts of descending propriospinal afferents to lumbar segments receiving the maximal sciatic projection. The hemisections typically involved all but the dorsal column, although in some cases a portion of the dorsal column, including the corticospinal tract, was also transected. The distribution pattern and density of spinal HRP reaction product was not significantly different in experimental and control preparations in any segment below the lesion, regardless of the quantity of denervation, or the density of the normal sciatic projection in a given terminal region. These results, together with our previous finding concerning an absence of primary afferent sprouting following long-term dorsal root ganglionectomies, suggest that current concepts concerning collateral sprouting as a factor in functional plasticity in the mature mammalian spinal cord warrant re-evaluation.

Dermatomic distributions of hypopigmented macular lesions of leprosy: neural dependence of melanocytic functions

Dermatomic analysis of the distribution of the hypopigmented patches of leprosy has revealed a pattern wherein patches are most frequent in dermatomes of the brachial plexus, decrease gradually in frequency in succeeding spinal segments and increase again in dermatomes of the lumbar plexus. The predilection of hypopigmented patches for certain dermatomes may be a reflection of easy vulnerability of the neural pigmentary mechanism and/or a reflection of selective multiplication of M. leprae in nerves of certain dermatomes, even though the organisms might have been seeded all over the body by hematogenous spread. These preliminary observations are discussed.

"Epileptic" brain damage in rats induced by sustained electrical stimulation of the perforant path. II. Ultrastructural analysis of acute hippocampal pathology

Sustained electrical stimulation of the perforant path evokes granule cell population spikes and epileptiform discharges, abolishes recurrent inhibition in the granule cell layer and induces a reproducible pattern of hippocampal damage (see preceding paper, this volume, for electrophysiological and light microscopic findings). Electron microscopic findings described here reveal that the hippocampal damage is identical in pattern and cytopathological detail to that associated with sustained limbic seizures induced by chemical convulsants such as kainic acid, folic acid and dipiperidinoethane. Acutely swollen dendritic segments distributed in a laminar pattern corresponding closely with the termination of putative glutamate or aspartate-containing fibers, including those of the perforant path, were a conspicuous finding. Cell bodies of CA1 and CA3 pyramidal neurons and various interneurons in the hilus and elsewhere displayed degenerative changes ranging from mild to severe. Both the dendritic and somal degenerative changes closely resemble the "excitotoxic" type of damage that the putative transmitters glutamate and aspartate are known to cause. It is proposed, therefore, that sustained electrical stimulation of the perforant path results in excessive synaptic release and accumulation of glutamate (or aspartate) at numerous dendrosomal receptors in the hippocampus with consequent degeneration of the dendrosomal structures housing these receptors. Early excitotoxic effects on interneurons that mediate recurrent inhibition may play an important role in the observed loss of recurrent inhibition and in the evolution of subsequent excitotoxic degeneration in the hippocampus.

[Interaction of the vestibulo-oculomotor and visual systems in young animals]

In two-month old rabbits rotated with closed and opened eyes during 20 or 140 sec, it was found that the interaction of vestibulooculomotor and visual systems depended on maturity as well as on the duration of the simultaneous action of these systems. The nystagmus is organized by the optic stimulus which increases the duration of the nystagmus and decreases the postnystagmus, increases the number and amplitude of the eye jerks, aids to maturity of the vestibulooculomotor reflex and organizes the beginning of the nystagmus, increases the number of mature nystagmus the first jerks of which have got the highest amplitude.

[Correlative aspects between function and structure in hippocampal processes (Ammon's formation)]

In post-mortem material with pronounced primary epilepsy-independent pathomorphic findings of Ammon's formation, the correlation with symptomatic epilepsy and the typical psychic disturbance phenomena was studied. While a connection between the lesion and the epileptic disease could be confirmed with a certain probability, this remains problematic with respect to impairments of memory, orientation capacity, working-up of experiences and drive and reaction capacity. Although in all examined subjects clinical deficiency phenomena of one type or the other were present, additional lesions, especially of nuclear regions which are associated with AF and cortical structures will certainly also be responsible.

An experimental study of early ultrastructural changes in the injured spinal cord

Experimental hemisection injury of rat spinal cord was undertaken in order to examine Wallerian degeneration of ascending and descending tracts, and alterations in neurons and synapses. By light microscopy degeneration of axons was recognized first at 72 hours post-operatively. On the other hand, EM study revealed axonal degeneration 24 hours post-operatively. There were several ultrastructural changes in the early stages after hemisection injury. Increase in number of lysosomes in neurones was believed to be related to "autolysis" of the injured spinal cord. Another noteworthy finding was the "separation" of boutons. The mechanisms considered to account for these findings were deafferentation and oedema.

[Cutaneous and muscular unmyelinated afferent fibres. Clinical, histological and experimental study. Possible explanation of muscular cramps (author's transl)]

Unmyelinated afferent fibres are the most numerous of the whole afferent component. Their function in nociception is now well established. However some recent data allow to think that their function is much more complex. Cutaneous unmyelinated afferences are evaluated in controls and in 3 groups of patients (painful neuropathies, painless neuropathies with hypesthesia, diabetic neuropathies). Amyelinic myelinic ratio is not in accordance with the gate control theory. Muscular afferent fibres are studied, especially the lateral gastrocnemius soleus nerve of cat. Their predominance is obvious. Our study was conducted by recording single unit activity from a micro electrod inserted in dorsal root ganglia. But 45% of unmyelinated fibres are not activated by various algesic stimuli. It is suggested that they have a function in cardio-pulmonary adaptation to effort and possibly segmental vascular control as homonymous reflex effect on moto-neuron. Their several properties are a possible explanation of muscular cramps.

Quantitative studies of dorsal root ganglia and neuropathologic observations on spinal cords in familial dysautonomia

Intrauterine development and postnatal maintenance of dorsal root ganglion neurons are abnormal in familial dysautonomia, an autosomal recessive disorder associated with autonomic, motor and sensory deficits. Normally, dorsal root ganglion weight increases with age. This does not occur in the cervical plexus ganglia of dysautonomic patients. Neurons in dorsal root ganglia are found to be markedly diminished in the youngest patients and slow degeneration causes further depletion with age. Quantitative studies on C8 dorsal root ganglia show the normal neuron content to be between 42,500 and 53,600. In 3 patients with familial dysautonomia the range was 4,090-8,590 with the smallest number being in the oldest patient. Lateral root entry zones and Lissauer's tracts are severely depleted of axons. In older patients loss of dorsal column myelinated axons becomes evident and is first seen in lumbar fasciculus gracilis, cervical fasciculus cuneatus and interfascicular fasciculus. Temperature sensation is markedly impaired from infancy in familial dysautonomia. Loss of pain sensation is prominent and worsens with age. Vibration sense diminishes in adolescence and coordination of limb movements becomes poor in older patients. Neuron depletion in dorsal root ganglia and the progressive pattern of cord changes correlate well with these clinical observations.

A neuroanatomical analysis of spinal cord injury in the rhesus monkey (Macaca mulatta)

Thirteen rhesus monkeys were subjected to impacts of either 200, 300, 400, oe 500 g-cm, on the dorsal surface of the spinal cord (Allen 1911). Six monkeys served as controls to determine the results of transection of the cord as well as the optimal survival time, and 2 additional subjects underwent the operative procedures only. Most of the animals were sacrificed 1 week postoperatively and the brains and spinal cords were processed by the Fink and Heimer (1967) technique for degenerating axons. Two contrils and 1 experimental subject, sacrificed at 1 week, were prepared for electron-microscopic analysis...