Caudate Lesions Research Articles

Propagation of focal cortical epileptiform discharge to the entopeduncular nucleus: Effect of caudate lesions

Single-unit recordings were made in the entopeduncular nucleus of cats which had previously undergone ipsilateral caudate lesions. During penicillin-induced epileptiform discharge from the pericruciate cortex, the percentage of responsive entopeduncular neurons in animals with a lesion was less than 20%. In a previous study in intact cats and in control experiments in the present study the percentage of responsive entopeduncular cells was more than 75%. These results indicate that propagation of epileptic discharge through the basal ganglia depends on intact pathways from the cortex to the caudate and from the caudate to the entopeduncular nucleus.

Spontaneous lesions in the rat caudal artery Effects of diet-induced hypercholesterolaemia alone and in association with hypertension

Caudal arterial lesions form spontaneously with age in the male Wistar rat and are characterized by a break in the intermal elastic lamina (IEL), with associated damage to endothelium and underlying smooth muscle cells followed by rapid repair. Such lesions have been studied under conditions of hypercholesterolaemia. Diet-induced hypercholesterolaemia did not enhance the formation of these lesions compared to age-matched control rats. Lesioned areas of caudal arteries from hypercholesterolaemic rats showed marked or slight focal lipid deposits depending upon their location along the artery. Studies in rats of different ages suggest that the majority of lipid probably accumulates during the phase of lesion repair and that the absence of the IEL per se does not appear to be responsible for the lipid accumulation. The effect of hypertension associated with hypercholesterolaemia on caudal arterial lesions was studies using DOCA salt-Wistar and spontaneously hypertensive rats. The association of these two factors did not increase lesions either in the caudal artery or in the renal artery studied for comparison. In caudal artery the number of fatty lesions appeared to be related more to the level of cholesterolaemia than to blood pressure. The extent of lipid accumulation within lesions in the caudal artery appears not to correlate with that in the renal artery, demonstrating the importance of local factors.

Effects of caudate nuclear or frontal cortical ablation in neonatal kittens or adult cats on the spontaneous firing of forebrain neurons

In this paper we have determined the long-lasting consequences of caudate and frontal cortical lesions on spontaneous neuronal firing. Lesions were made both in neonatal and adult cats. All recordings were made in adults. Qualitatively, the effects of the caudate ablations were similar whether they had been carried out in kittens or in adult cats. Caudate lesions produced long-lasting (≥ 1 year) decreases in the spontaneous firing of cortical neurons. These changes were more pronounced when made in neonates than in adults. The distributions of mean interspike intervals were also altered by these caudate lesions in the pallidum and in the ventral lateral nucleus of the thalamus. Again these effects were more marked if the animals were lesioned as neonates than as adults. Frontal cortical lesions inflicted upon adult cats produced more widespread changes in spontaneous firing rates than similar lesions made in neonates. In both groups frontal lesions slowed spontaneous firing and changed the distributions of mean interspike intervals of caudate neurons. These effects were long-lasting (≥ 1 year in neonatally-ablated animals). Cortical lesions made in adult cats markedly altered thalamic and pallidal spontaneous activity. Similar lesions made in neonates produced relatively small changes in thalamic and pallidal activity.

Behavioral effects of lesions to the caudate nucleus or mediodorsal thalamus in neonatal, juvenile, and adult rats

The prefrontal cortex, caudate nucleus, and mediodorsal thalamus are anatomically and behaviorally related. In the present study, the age-dependent lesion effects of caudate nucleus or mediodorsal thalamus damage were assessed using a spatial delayed alternation task known to be sensitive to prefrontal cortex damage. Bilateral electrolytic lesions were placed in the caudate nucleus or mediodorsal thalamus in rats making up three different age-at-surgery groups: neonatal (8-10 days), juvenile (25-27 days), and adult (150-160 days). All animals were allowed a 110-120-day postoperative recovery interval prior to behavioral testing. The subjects given either caudate nucleus or mediodorsal thalamus lesions as neonates were unimpaired in comparison to the juvenile or adult operates sustaining comparable brain damage. Both caudate nucleus and mediodorsal thalamus lesions produced in both juvenile and adult subjects severely retarded acquisition of the alternation task. The results are consistent with the hypothesis that the subcortical components of the prefrontothalamic system mature earlier than do the cortical components.

Origins of cat somatosensory far-ffield and early near-field evoked potentials

A complex pattern of potentials evoked by forelimb cutaneous nerve stimulation was recorded from the skull surface of barbiturate anesthetized cats and was resolved by computer averaging. Seven far-field components (designated I–VII) and several larger early near-field components (designated P 1, N 1, P 2, N 2 and P 3) have been identified from averaged potentials. All far- and early nearfield components were elicited by activation of myelinated nerve fibers. Their latency and amplitude depended entirely on the number of large myelinated nerve fibers recruited into the nerve volley. Spinal lesions showed that peripherally evoked far- and early near-field potentials were generated from both lemniscal and extralemniscal sources. Far-field and early near-field potentials were evoked either from the lemniscal system by dorsal column stimulation or from the extralemniscal system by cutaneous nerve stimulation after dorsal column lesions. These potentials were similar in configuration to those evoked by cutaneous nerve stimulation in the intact cat. Sequential rostral to caudal ablations and lesions within the lemniscal or extralemniscal system eliminated the potentials selectively. The following sites of origin were proposed: I — peripheral nerve; II (IIa) — dorsal columns; IIb — spinothalamic tract; III — dorsal column nuclei or medial lemniscus; III, IV — spinocerebellar and spinoreticular tracts; V — lateral reticular nucleus or reticulocerebellar tract; VI, VII — cerebellum; P 1— lateral and medial thalamic nuclei or thalamocortical projection; N 1, P 2 — sensorimotor cortical areas; N 2, P 3 — association cortical areas. Lemniscal and extralemniscal far- and early near-field potentials were generated from common as well as separate sites. The latencies of somatosensory far- and early near-field potentials recorded extracranially in this study closely correlated with the latencies of local potentials recorded by others at the proposed lemniscal and extra-lemniscal sites of origin. The contribution of extralemniscal sources to far- and early near-field potentials and their importance to clinical measurement of somatosensory evoked potentials and diagnosis of neurological disorders are discussed.

Effects of caudate nuclei and frontal cortical ablations in cats: Testosterone and 17β-estradiol concentrations

Plasma testosterone and 17β-estradiol concentrations and lordotic behavior were measured in male cats which had received lesions of the caudate nuclei and frontal cortices and were compared with intact and other lesion controls. Only the acaudate cats showed significant increases in lordosis whereas all groups with lesions showed significant decreases in testosterone. Only the afrontal animals showed a significant increase in the concentrations of 17β-estradiol but it was unaccompanied by the behavioral change. It is concluded that the striking changes in lordotic behavior seen in the cats with extensive caudate lesions are most probably due to the increased somatosensory reactivity seen in these animals, rather than to a shift in sex hormone balance.

COMPUTED TOMOGRAPHY OF BRAIN TUMORS IN THE CAUDAL FOSSA OF THE DOG*

Computed tomography (CT) was used to investigate brain tumors in the caudal fossa of three dogs. Changes detected by CT included compression or distortion of cerebrospinal fluid spaces within the caudal fossa, and changes in parenchymal density before and after intravenous injection of a nondiffusible, iodinated contrast medium. CT provided information regarding tumor size, location, character, and relationships with normal caudal fossa structures. It was concluded that CT offered advantages over technics currently in use for diagnosis and assessment of caudal fossa lesions in the dog.

Effects of illumination on activity following superior colliculus and caudate lesions in young and older rats

Illumination dependent hyperactivity following lesions of the superior colliculus and the head of the caudate nucleus, separately and in combination, was studied in young and older rats tested in the light and dark. While control animals of both age groups exhibited an illumination effect, there were age related differences in the pattern of locomotor activity during the test session as well as over days that interacted with illumination level. None of the lesions appeared to alter activity in the young animals. In the older animals, separate lesions of the superior colliculus and the head of caudate produced hyperactivity in the light but not in the dark, which showed a recovery of function. Simultaneously lesioning these structures eliminated the light-dark effect immediately after surgery and delayed recovery of function. These results support the notion of a functional system regulating illumination dependent activity.

Diffuse enkephalin innervation from caudate to globus pallidus

The source of enkephalin in neuronal terminals of the rat globus pallidus was evaluated with electrolytic and knife cut lesions. Straight knife cuts medial to the globus pallidus or a curved knife cut just below the corpus callosum do not reduce immunofluorescence staining in the globus pallidus, indicating that cerebral cortex is not a major source of pallidal enkephalin. Electrolytic lesions of dorsal and ventral portions of the globus pallidus, and even lesions which sever medial from lateral globus, fail to reduce pallidal staining, ruling out long enkephalin neurons traversing the globus. Large electrolytic lesions of the head of the caudate do decrease dorsal pallidal fluorescence, though multiple small caudate lesions are without observable effect. Large pallidal lesions elicit a build-up of enkephalin fluorescence in the caudate. These results suggest that the caudate is the sole source of pallidal enkephalin and that the innervation diffusely converges on the smaller globus pallidus.

Effects of caudate and cortical lesions on place and response learning in rats

Rats with lesions in the caudate nucleus made fewer errors and took fewer trials to reach criterion than unoperated rats in acquisition and reversal performance on a T-maze task. On place and response performance, caudate and cortical rats did not differ from unoperated rats in number of errors and trials to criterion. Caudate rats were predominantly place learners, while cortical rats were mainly response learners. The results are discussed in relation to compensatory behavioral mechanisms following brain lesions.

Role of ventrolateral medulla in vasomotor response to cerebral ischemia

The ventrolateral medulla has been postulated to contain chemosensitive neurons. This study investigated the role of this region in the generation of the pressor response to cerebral ischemia (CIR) in anesthetized paralyzed artificially ventilated rabbits. A circumscribed and highly sensitive pressor area in the ventrolateral medullary reticular formation 2-4 mm rostral to the obex, separate from the well-known dorsal pressor area, was mapped by use of a stimulating electrode. Electrolytic destruction of this area resulted in a profound reduction in resting mean arterial pressure (MAP). After restoration of baseline MAP with norepinephrine infusion, the CIR was greatly reduced (by mean 70.2% of control), but pressor responses from the dorsal medulla were unaffected. In contrast, lesions of greater size placed in the ventrolateral medulla more caudally did not significantly alter resting MAP and only slightly reduced the CIR (by mean 17.0% of control). Vasomotor responses to stimulation of the ventrolateral pressor area were unaffected by caudal ventrolateral lesions, but greatly reduced by dorsomedial lesions in the same plane. It is concluded that the ventrolateral area is either the site of origin or an essential part of the central vasomotor pathway mediating the CIR and that this pathway projects dorsomedially before descending to the spinal cord.

Dexamethasone preservation of motor function in phospholipase A 2-induced caudate lesions

Unilateral lesions of the rat caudate nucleus produced by the direct application of phospholipase A 2 resulted in motor impairment manifested by rotation. Pretreatment with the glucocorticoid, dexamethasone (0.5 mg, 1.0 mg/kg), preserved motor function in the phospholipase A 2-treated rats. The number of rotations appared to correlate with alterations in caudate phospholipid content. Caudate sections from phospholipase A 2-treated animals exhibited lysolecithin and lysophosphatidylethanolamine, two phospholipids not detected in caudate sections from normal or dexamethasone-treated animals. We conclude that phospholipase A 2 produced caudate lesions associated with rotational behavior and alteration of neuronal phospholipids, both of which were prevented by dexamethasone treatment. The therapeutic action of dexamethasone may involve the maintenance of neuronal membrane phospholipids.

Aspartate, glutamate and GABA levels in pallidum, substantia nigra, center median and dorsal raphe nuclei after cylindric lesion of caudate nucleus in cat

Aspartate, glutamate and GABA levels were determined in afferent and efferent projection nuclei of the striatum after unilateral cylindric lesion in the head of the caudate nucleus in cats. Two and four weeks after operation, GABA content was significantly reduced in substantia nigra and pallidum ipsilateral to the lesion. Glutamate (GLU) level was decreased in substantia nigra and pallidum only 4 weeks after lesion, whereas aspartate content in substantia nigra decreased significantly already after 2 weeks. No changes in the contents of these amino acids were detected in the dorsal raphe nucleus, which receives a projection from the caudate, as well as in the center median nucleus, which projects to the striatum. These experiments using longer survival times substantiate the role of GABA in caudato-pallidal and caudato-nigral projections. The possibility is discussed that aspartate (ASP) could function as transmitter of cortico-nigral fibers.

Asymmetric distribution of side preference in hamsters can be reversed by lesions of the caudate nucleus

Side preferences were tested in Syrian hamsters (Mesocricetus auratus) by placing them on an elevated centerboard which divided a rectangular arena in two equal compartments. When descending from the centerboard all animals turned more often right (79%) than left (21%). After small electrolytic lesions of the left caudate nucleus the side preference was reversed: 31% to the right and 69% to the left. Combined lesions of the left caudate nucleus and left sensorimotor cortex showed similar results; lesions of the left cortex alone had only minor effects. These observations support the hypothesis [28] that side preferences depend on asymmetries of the nigrostriatal system.

Comparison of ocular motor effects of unilateral stereotactic midbrain lesions in man

A series of 22 patients with stereotactic lesions in the rostral dorsolateral mesencephalon are presented. Lesion I was larger than Lesion II. more irregular in size. and extended further laterally and dorsally at the level of the superior colliculus. Lesion II was maller and placed within 5 mm of the midline aqueduct and 5 mni caudally from the posterior commissure. Lesion I created paralysis of elevation. depression. and convergence and induced pupillary miosis in all patients. Lesion II appeared to spare elevation in all patients but one, and it tended to produce skew deviation in conjunction with divergence pnralysis in three patients and an associated convergence paralysis in only one patient. Three patients suffered a paralysis of convergence. Pupils were symmetrically miotic in three patients out of the six with Lesion II. Conclusions from this indicate that perhaps Lesion I at the posterior commissure was interfering with the crossing fibers subserving vertical gaze, convergence and pupillary reaction and thus by moving the lesion caudally below the posierior commissure and nearer the midline, these functions were less likely to be involved. The caudal Lesion II altered the function of divergence and produced a concurrent skew deviation. It should be emphasized that the stereotactic Lesions I and II were smaller in comparison to the destructive lesions found in disease states and therefore are valuable in [dying the neural pathways subserving ocular motility in the midbrain.

Effect of brain lesions on rat shuttle behavior in four different tests

Rats were trained to perform shuttle responses to a buzzer in four different situations: pseudoconditioning or D test (buzzers and footshocks presented at random), classical conditioning or DP test (buzzers and footshocks paired on every trial), avoidance without stimulus pairing or DC test (buzzer-shock intervals varied at random, shocks contingent upon non-emission of a shuttle response to the preceding buzzer), and standard two-way avoidance or DPC test (buzzers paired to shocks, but the latter omitted every time there was shuttling to the buzzer). The letters in each test designate the factors involved in the emission of responses in each one, which were shown in previous papers to be: a non-associative factor or “drive” (D), the Pavlovian or stimulus-stimulus relation (“pairing”, P), and the shuttle-no shock or main avoidance contingency (C). The effects of various brain lesions on these behaviors were studied. Ventral caudate and amygdala lesions depress both the Pavlovian (P) and the avoidance (C) component. Dorsal caudate lesions have an opposite influence on these two factors. Septal (n.medialis + lateralis, and n.accumbens) and tuberculum olfactorium lesions enhance the non-associative component (D); accumbens lesions, in addition, impair operation of the C factor. The effect of the diverse lesions on jumping responses to the buzzer or on performance of intertrial crossings does not correlate with the effect on shuttle responses.

Effects of caudate nuclei or frontal cortical ablations in kittens: Bar pressing performance

The bar pressing tasks which were used to test adult-operated cats were applied to juvenile and adult animals with bilateral caudate or frontal cortical lesions inflicted during the first month of life. Intact and sham-operated littermates served as controls. All three operated groups showed significantly slower rates of acquisition. Significantly fewer acaudate cats acquired the initial response, and only two each of the acaudates and afrontals reached the single alternation criterion. The acaudate cats, furthermore, showed significantly slower rates of transfer, overall responding, and alternation, but did not exhibit the postural adjustments seen in adult-operated animals and could bar press and drink simultaneously. There was a direct relationship between the magnitude of the deficit and the size of the caudate removal. The afrontals showed unsustained, erratic performances and were unmotivated and distractable. The data suggest that although there may be some savings in the more subtle nuances of behavior, the overall effects on bar pressing performance in the neonatally operated subjects can be just as great as when the lesions occurred later in life.

Effects of caudate nuclei or frontal cortical ablations in kittens: Motor activity and visual discrimination performance in neonatal and juvenile kittens

Motor activity and visual discrimination performance were assessed in kittens that had received either bilateral ablations of the caudate nuclei (acaudate) or frontal cortices (afrontal) during the first month of life. Kittens (tested between 36 and 60 days of age) with large bilateral caudate ablations were hyperactive compared to their intact littermates and a group of sham-operated kittens that underwent the same surgical procedures as the acaudates except for the caudate ablation. The afrontals were slightly more active than intact kittens but not as active as acaudates. Visual discrimination performance was assessed when the kittens were about 3 months old. Minimal group differences in performance occurred during acquisition of the discrimination. During reversal of the original discrimination the kittens with large caudate lesions continued responding to the previously reinforced cue significantly longer than animals in any other group. Those with frontal lesions did not perseverate in this manner but displayed highly variable performance on most aspects of the tasks. These results are consistent with the idea that a major consequence of caudate damage is a loss of flexibility in adopting new responses when the previously reinforced behavior is no longer appropriate. The results also indicate that some of the behavioral effects of neonatal and adult caudate and cortical lesions are qualitatively similar.

Alterations of ingestive behavior following trigeminal lemniscus lesions in rats

Previous research has suggested that inadvertent damage to the trigeminal lemniscus may account for some impairments of feeding behavior attributed to lateral hypothalamic lesions. In the present study, rostrally placed trigeminal lemniscus lesions produced no greater impairments in feeding or drinking behavior than observed in surgical control animals. Earlier reports of disturbed feeding following trigeminal lemniscus lesions may reflect damage to adjacent structures, particularly at caudal lesion sites.

Computerized Screening of the Human Vestibulospinal System

The vestibular nerve projects rostrally via the ascending medial longitudinal fasiculus (MLF) to eventually supply the ocular muscles and also projects caudally via the descending MLF to eventually supply the spinal and limb musculature. Electronystagmographic techniques are designed to evaluate only portions of the vestibulo-ocular and oculomotor systems. Vestibular lesions affecting only the caudal vestibular nerve distributions or lesions affecting both neural distributions, therefore, cannot be objectively assessed except for the vestibulo-ocular component. A promising recording technique for the evaluation of the vestibulospinal system has been developed and tested in the Raymond E. Jordan Human Vestibular Systems Laboratory. A comparison of two data analysis techniques in normal subjects, unilateral vestibular lesion patients and patients with unilateral lesions of the cerebellar hemispheres have provided pilot data which indicate that the vestibulospinal stability test technique holds considerable promise for both research and clinical evaluation of the human vestibulospinal system.