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At least 1,765 records · Page 98Linked to original sources
PubMed1997

Changes in the sensitivity of frontal cortical neurones to acetylcholine after unilateral lesion of the nucleus basalis with alpha-amino-3-OH-4-isoxozole propionic acid (AMPA): effects of basal forebrain transplants into neocortex.

Unilateral S-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) lesions of the nucleus basalis magnocellularis (nbm), which produced persistent and extensive ChAT-positive cell loss within the nbm and depletion of cortical cholinergic markers in the frontal cortex, increased both the number and sensitivity of individual frontal cortical neurones responding to iontophoretic administration of ACh. The lesion also increased the sensitivity of individual neurones to carbachol but the increase in the number of neurones responding to carbachol was transient and had returned to normal 4 weeks after lesion. The sensitivity of individual neurones to glutamate was unchanged by the lesion. The percentage of cortical neurones responding to ACh, but not the sensitivity of individual neurones was restored to the prelesion level, 6-8 weeks after cholinergic transplants to the lesioned frontal cortex; cholinergic transplants to the more distant parietal cortex were only effective after 6 months whereas noncholinergic transplants were ineffective at both time intervals. Cholinergic transplants placed in the frontal cortex 6-8 weeks or 6 months before nbm lesion offered some protection from the effects of the lesion, particularly at 6 months but were ineffective when placed into the parietal cortex. Lesion of the nbm also reduced basal firing rate of spontaneously active neurones and this was not restored by any of the transplants. The results are discussed in the light of quantitative measurements of acetylcholinesterase-positive fibre outgrowth from the transplant into the recording area, which are described in the preceding manuscript [20].

Acetylcholine↗
PubMed1996

Inhibitors and promoters of thalamic neuron adhesion and outgrowth in embryonic neocortex: functional association with chondroitin sulfate.

When embryonic thalamic neurons are plated onto living slices of mouse forebrain, cell attachment and neurite outgrowth on different layers of the developing cerebral cortex vary dramatically, in ways that correlate with the timing and pattern of thalamocortical innervation. These layer-specific differences can be eliminated from embryonic day 16 slices by enzymatic removal of chondroitin sulfate (CS). The cortical plate (a zone avoided by thalamic axons in vivo) possesses inhibitory activity (anti-adhesive, neurite repelling) and the intermediate zone and subplate (in which thalamic axons normally grow) possess stimulatory activity (adhesive, neurite promoting), both of which are chondroitinase sensitive. These opposing activities appear not to reflect the presence of different CS proteoglycans (CSPGs) in different zones, but rather the presence of differentially localized CS-binding molecules, which can be competed away by soluble CS. This model reconciles conflicting reports on the actions of CSPGs in neural development, and suggests a role for CSPGs in the organization of matrix-bound cues in the brain.

Animals↗
PubMed1991

Electrophysiological analysis of human neocortex in vitro: experimental techniques and methodological approaches.

In this review we summarize a number of technical and methodological approaches that have been used in our laboratory to study human brain slices maintained in vitro. The findings obtained in the course of these studies appear to be relevant in establishing the mechanisms that underlie physiological phenomena of the human brain such as synaptic plasticity or responses to neuroactive drugs. Moreover, these data are important for understanding certain fundamental mechanisms of epilepsy. In this respect, however, we caution that the mechanisms that apply to different forms of clinical epilepsy might be difficult to find given the variability present in the pathogenesis of human epilepsy.

Cerebral Cortex↗
PubMed1987

Functional consequences of embryonic neocortex transplanted to rats with prefrontal cortex lesions.

In four experiments we reexamined the recent report by Labbe, Firl, Mufson, and Stein (1983) that fetal cortical tissue transplanted to an aspirative prefrontal cortical cavity in rats can ameliorate the learning impairments induced by the aspirative lesions. Healthy surviving grafts from young (E16) embryonic donors had no immediate effects on the rats' impairments in T-maze alternation, spatial navigation in the Morris swimming pool task, or locomotor activity, and they produced even greater impairments than the lesions alone when all three tests were conducted after longer (3-5 month) survival periods. Grafts taken from older (E21) donors did produce a short-lasting improvement in the T-maze alternation performance, replicating the previous report. However, this effect was not seen in the other two behavioral tests; the grafts survived poorly, and the beneficial effect was no longer apparent in the long-term tests. It is concluded that (a) functional benefits of embryonic cortical grafts are dependent on a precise combination of conditions rather than being a general phenomenon, and (b) the short-lasting recovery in delayed alternation performance is attributable to diffuse influences of the embryonic tissue on the lesioned host brain rather than to a reconnection of damaged circuitries.

Animals↗
PubMed1997

Differentiating the roles of the hippocampal complex and the neocortex in long-term memory storage: evidence from the study of semantic dementia and Alzheimer's disease.

Several computational models suggest that the hippocampal complex plays a key role in the establishment of new memories, but over time the storage of such memories becomes independent of this region. In support of such models, the authors demonstrate that patients with semantic dementia, who have relative sparing of the hippocampal complex, show a pattern of preserved recent memories and impaired distant memories. In a group study that used the Autobiographical Memory Interview, amnesic patients with Alzheimer's disease showed the more typical temporally graded loss (poor recall of recent memories), whereas patients with semantic dementia showed the reverse pattern. In a single-case study, using the Galton-Crovitz test, a patient with semantic dementia was significantly better at producing autobiographical memories from the most recent 5 years. By contrast, controls provided similarly detailed memories across all time periods back to childhood.

Aged↗
PubMed1975

Neocortex and feeding behavior in the rat.

Consummatory behavior and weight-regulation capacity were measured in 12 normal rats and in 43 rats that survived complete (C), sequential unilateral (U), anterolateral (A), or posterior (P) neocortical ablations. Groups C and A displayed aphagia and adipsia followed by a sequence of recovery stages gualitatively identical to, but shorter than, recovery typically seen following lateral hypothalamic lesions. After recovery, Group C displayed long-term effects of finickiness and pradial drinking. These effects as well as a measure of recovery of body-weight-regulation capacity were significantly intercorrelated with lesion size, and body-weight set point remained significantly lower than normal. Group U was relatively unaffected by the first unilateral ablation and showed, relative the second ablation but displayed the long-term effects. Group P, though significantly affected by the lesion, did not display the pattern or intensity of effects described for the other bilaterally ablated groups.

Animals↗
PubMed1995

Induction of heme oxygenase-1 mRNA and protein in neocortex and cerebral vessels in Alzheimer's disease.

Previous studies demonstrated the specific association of heme oxygenase (HO)-1 protein to the neurofibrillary pathology of Alzheimer's disease (AD). In this study, we used reverse transcription-polymerase chain reaction methods to show the increased expression of HO-1 but not HO-2 mRNA transcripts in cerebral cortex and cerebral vessels from subjects with AD compared with age-matched non-AD controls. Neither the HO-1 nor the HO-2 mRNA levels was altered in the cerebellum, a brain region usually spared from the pathological alterations of AD. There was no clear evidence that the expression of HO-1 in these tissues was related to postmortem interval, cause of death, or the age of the subjects studied. Using immunoblotting methods, we further showed that HO-1 protein content was increased in neocortical and vascular samples from AD subjects compared with controls. Our findings suggest the specific induction of HO-1 mRNA and protein in the cerebral cortex and cerebral vessels but not HO-2 mRNA or protein in association with the pathological lesions of the disease.

Aged↗