bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microglial tyrosine phosphorylation systems in normal and degenerating brain
Authors: Karp Heather L. , Tillotson Meryl Lee , Soria Jennie , Reich Caroline , Wood John G. 
Published: January 2005

AbstractPhosphotyrosine and protein tyrosine phosphatase antibodies have been used to assess the distribution and potential functions of tyrosine phosphorylation systems in normal brain and cell cultures, as well as in a model of neural degeneration. Western blot and immunohistochemical analysis showed that a panel of antiphosphotyrosine antibodies recognizing different tyrosine phosphorylated substrates all selectively labeled ramified microglia in sections of brain tissue. This significantly extends our previous observation (GLIA 2:412‐419, 1989) that a single, limited, phosphotyrosine antibody served as a histological marker for microglia. The present results show that tyrosine phosphorylation of a variety of substrates is quantitatively enriched in microglia compared to other neural cell types. We also show that the protein tyrosine phosphatase, CD45, is constitutively expressed by ramified microglia in vivo and by ameboid microglia in vitro. Thus, the major enzymes constituting tyrosine phosphorylation systems are present in normal microglia. Neuronal degeneration in the trigeminal nucleus, caused by a introduction of the neurotoxic lectin, ricin, into the peripheral nerve, is accompanied by a robust upregulation of phosphotyrosine signal in ramified microglial adjacent to the nucleus and in ameboid microglia in the degenerating nucleus. The presence of phosphotyrosine in ramified microglia is consistent with a role for tyrosine phosphorylation systems in the activation of microglia and in the signaling events accompanying conversion of resting microglia to the ameboid form. © 1994 Wiley‐Liss, Inc.
Social and environmental factors and depression in old age
Authors: Pahkala K. 
Published: January 2005

AbstractThis community‐based epidemiological study is concerned with relationships between social and environmental factors and depression in a Finnish population aged 60 years or over. A greater proportion of depressed than non‐depressed men had retired and did not work at all. The occurrence of depression in both sexes was related to retirement because of sickness rather than age, a small number of rooms in their homes, low numbers of hobbies, lack of intimate friendships, and the occurrence of many long‐standing and current social stress factors. Positive associations were also found in the men between the occurrence of depression and moving due to poor health, widowed or divorced marital status, being frequently alone and the fear of death, while a positive relationship was found between the occurrence of depression and low social participation in the women. In addition, the depressed women felt that elderly people were not appreciated. Also, the depressed women felt their relationships with their spouse, children, daughters‐in‐law and friends to be more distant than did their non‐depressed counterparts. This finding suggests that family dynamics plays an important role in depression in elderly women.
Capgras delusion in the elderly: The evidence for a possible organic origin
Authors: Förstl Hans , Almeida Osvaldo P. , Iacoponi Eduardo 
Published: January 2005

AbstractWe report the case of a 77‐year‐old right‐handed woman with early dementia of the Alzheimer type who developed the paranoid delusion that her husband had been replaced by an imposter (Capgras phenomenon). Her CT scan showed mild generalized cortical atrophy of the parieto‐occipital cortex. We reviewed the cases of 45 patients over 60 years who showed a Capgras delusion. Twenty‐five suffered from dementia or other chronic organic mental disorders, 20 were paranoid, 14 were at least moderatley depressed and 12 disorientated. CT scans (reported in 17 cases) showed global cerebral atrophy in 12 patients. Right hemisphere infarcts have been described in two elderly patients with Capgras delusions. Focal brain atrophy in Alzheimer type dementia has hitherto not been reported in association with this delusional symptom. We conclude from these observations that marked cerebral lesions and specific neuropsychological deficits are not required for the development of the Capgras phenomenon, which can occur in various functional or organic psychosis of old age.
Psychiatric presentation of intracranial tumour in the elderly
Authors: Fulton J. D. , Duncan G. , Caird F. I. 
Published: January 2005

AbstractFourteen patients aged 66–87 years are described, in whom major psychiatric problems dominated the presentation of intracranial tumour. Six had initially been referred to psychogeriatricians and eight to geriatricians. All showed intellectual failure, developing over a few weeks or months, with failure of self‐care, and a variety of disturbances of behaviour. Four had undoubted and two possible seizures. Their mental state was described as facile, or slow, with relatively unimpaired memory when it could be tested. Four were inaccessible or mute. Abnormal neurological signs were absent in two, but included unilateral or bilateral hypertonia and hyperreflexia in most; the plantar responses were flexor in seven, equivocal in three, and extensor on one or both sides in four. Computed tomographic (CT) scans shows frontal or bifrontal tumours in 13, and one occipital lobe tumour. The corpus callosum was involved in eight. Ten tumours were considered to be high‐grade astrocytomas (proven by biopsy in three and autopsy in one); one patient had bifrontal metastatic tumours, and three had meningiomas, all of them successfully resected. Clinical diagnosis was difficult, but a CT scan is indicated in all patients with a short history of intellectual failure.
Ideomotor and ideational apraxia in alzheimer's disease
Authors: Lucchelli Federica , Lopez Oscar L. , Faglioni Pietro , Boller Francois 
Published: January 2005

AbstractIdeomotor apraxia (IMA) and ideational apraxia (IA) were studied in 32 Alzheimer's disease (AD) patients and in 30 non‐demented elderly controls using a standardized apraxia battery. AD patients performed significantly worse than controls on all apraxia tests, and were more impaired when pantomiming movements than when imitating movements. IMA and IA scores correlated with severity of dementia as measured by the Mini‐Mental State Examination. Analysis of individual performances revealed dissociated apraxic disorders in four patients, which may be interpreted as a manifestation of focal damage to left hemisphere cortical systems involved in praxis. Furthermore, these results suggest a greater ideational than ideomotor defect in apraxic AD patients.
Network analysis of motor system connectivity in Parkinson's disease: Modulation of thalamocortical interactions after pallidotomy
Authors: Grafton Scott T. , Sutton James , Couldwell William , Lew Mark , Waters Cheryl 
Published: January 2005

AbstractStructural equation modeling was used to examine functional interactions between cortical and subcortical motor areas in Parkinson's disease patients and normal subjects. Neuronal activity was defined by positron emission tomography (PET) imaging of regional cerebral blood flow (rCBF) during performance of movement and control tasks. Patients were scanned before and 8‐12 weeks after stereotactic unilateral left posterovental globus pallidotomy. Pallidotomy attenuates basal ganglion inhibition of thalamocortical neurons involved in motor control and reduces the severity of bradykinesia in Parkinson's disease patients. It was hypothesized that with surgery there would be a similar alteration in thalamocortical interactions as measured with PET rCBF. A path analysis model of cortical and basal ganglia circuitry (defined by anatomic and electrophysiologic connectivity) was used to estimate unidirectional path coefficients describing the magnitude of region to region interactions. The resultant interactions defined a composite task‐and disease‐specific functional network of connectivity. After pallidotomy, there were significant reductions in the strength of interactions between the globus pallidus projection to thalamus, and the thalamus, projection to mesial frontal motor areas, consistent with the presumed physiologic interactions of these areas. This modeling approach can identify regional interactions that are not always apparent in categorical comparisons of inmaging data. ©1994 Wiley‐Liss, Inc.
Entorhinal cortex pathology in Alzheimer's disease
Authors: van Hoesen Gary W. , Hyman Bradley T. , Damasio Antonio R. 
Published: January 2005

AbstractThe anatomical distribution of pathological changes in Alzheimer's disease, although highly selective for only certain brain areas, can be widespread at the endstage of the illness and can affect many neural systems. Propriety for onset among these is a question of importance for clues to the etiology of the disease, but one that is formidable without an experimental animal model. The entorhinal cortex (Brodmann's area 28) of the ventromedial temporal lobe is an invariant focus of pathology in all cases of Alzheimer's disease with selective changes that alter some layers more than others. The authors'findings reveal that it is the most heavily damaged cortex in Alzheimer's disease. Neuroanatomical studies in higher mammals reveal that the entorhinal cortex gives rise to axons that interconnect the hippocampal formation bidirectionally with the rest of the cortex. Their destruction in Alzheimer's disease could play a prominent role in the memory deficits that herald the onset of Alzheimer's disease and that characterize it throughout its course.
Feedforward and feedback inhibition of hippocampal principal cell activity evoked by perforant path stimulation: GABA‐mediated mechanisms that regulate excitability In Vivo
Authors: Sloviter Robert S. 
Published: January 2005

AbstractHippocampal field potentials evoked by paired‐pulse perforant path stimulation were used to identify normal feedforward and feedback inhibitory influences on hippocampal principal cells. Three distinct aspects of inhibitory function were identified in the dentate gyrus. They are: (1) first spike amplitude‐dependent inhibition of the second spike, which at low stimulus frequency is primarily feedback in nature; (2) frequency‐dependent inhibition of a single spike of the first spike of a pair, which occurs as stimulus frequency is increased from 0.1 to 1.0 Hz and which is primarily a reflection of feedforward inhibition; and (3) frequency‐dependent inhibition of the second spike that is relatively independent of first spike amplitude and probably due to a combination of feedforward and feedback mechanisms. The results indicate that granule cell recurrent inhibition alone, evoked at low stimulus frequency, is relatively brief and weak. At higher frequencies, probably more relevant to physiological activity, feedforward inhibitory activity is recruited. The combination of feedforward and feedback mechanisms results in strong, maximal duration, granule cell inhibition. Similar frequency dependence of inhibition was not seen in area CA1 in response to ipsilateral perforant path stimulation since low frequency stimulation did not evoke CA1 spikes. CA3 stimulation did evoke large contralateral CA1 population spikes, but paired‐pulse inhibition was weaker than that evoked by ipsilateral perforant path stimulation in terms of the duration of inhibition and the ability to suppress the development of epileptiform behavior. The identification of simple tests that reflect distinct inhibitory processes in vivo permits similar studies to be conducted in vitro to determine how to preserve inhibitory processes for cellular studies of normal and human epileptic tissue in which the state of excitatory–inhibitory balance is the subject. These results also form the basis for the interpretation of the following study (Sloviter, 1991), which addresses the relationship between selective dentate interneuron loss and the pathophysiology that accompanies it.
On the hippocampus and learned conditional responding: Effects of aspiration versus ibotenate lesions
Authors: Jarrard Leonard E. , Davidson T. L. 
Published: January 2005

AbstractTo study the possible involvement of the hippocampus in learned conditional responding, rats with aspiration lesions of the hippocampus and others that had the hippocampus removed with ibotenic acid were trained on concurrent Pavlovian conditional and nonconditional discriminations. In agreement with the results reported by Ross et al. (1984), animals that had the hippocampus removed with aspiration were unable to learn the conditional discrimination, but learned the simple nonconditional discrimination without difficulty. In contrast, rats that had the hippocampus removed with ibotenic acid did not differ from controls in learning either discrimination. Furthermore, transfer test results were consistent with the hypothesis that ibotenatelesioned rats performed conditional operations to solve the conditional discrimination problem. Histological analysis indicated that the ibotenate lesions resulted in the removal of the hippocampus and dentate gyrus with minimal involvement of other structures. In aspiration hippocampal animals there was less overall damage to the hippocampus, but there was also extensive damage to the axons passing in alveus and fimbria, together with bilateral loss of cells in the subicular complex, the cingulate gyrus, and the cortex. Since rats with ibotenate lesions had more complete removal of the hippocampus, yet learned both discriminations, the impaired conditional responding found in aspiration hippocampals must be due to extrahippocampal damage.
Firing of human hippocampal units in relation to voluntary movements
Authors: Halgren Eric 
Published: January 2005

AbstractDuring certain movements (termed “type I,” “instrumental,” or “voluntary”), the rodent hippocampal EEG is domicated by regular 7–10 Hz waves. This “theta rhythm” is accompanied by increased firing of hippocampal interneurons and dentate gyrus granule cells. No obvious theta rhythm is present in comparable situations in humans or other primates. However, a widespread scalp negativity (the “readiness potential”) starts approximately 1 second before spontaneous key presses at long intervals. The readiness potential has been recorded in the monkey hippocampus. In this study, action potentials were recorded in the human hippocampus in relation to various movements. During a broadly ranging interview including various movements and memory tests, hippocampal units were found that fired during movements of the tongue and/or hands. Only movements that required a high degree of effort were effective. Other hippocampal units appeared to be correlated with either the transitions between tasks or the interruptions within tasks. In a second experiment, hippocampal units were found to change their firing in the seconds preceding spontaneous key presses. These data indicate that, like the rodent hippocampus, human hippocampal neuronal activity is strongly influenced by movement.
Learning‐related patterns of CA1 spike trains parallel stimulation parameters optimal for inducing hippocampal long‐term potentiation
Authors: Otto Tim , Eichenbaum Howard , Wible Cynthia G. , Wiener Sidney I. 
Published: January 2005

AbstractRecent studies have revealed 3 stimulation parameters that together comprise the temporal pattern of neuronal activation optimal for the induction of hippocampal LTP: high‐frequency bursts, activity 100–200 ms prior to a burst, and burst delivery in phase with the ongoing hippocampal theta rhythm. The present paper reports that these 3 aspects of patterned neural activity, collectively referred to as “theta‐bursting,” are characteristic of the spike trains of CA1 pyramidal cells in rats during the sampling and analysis of learning cues in an odor discrimination task and during performances of a spatial memory task. In contrast, theta‐bursting occurs relatively infrequently during behavioral events less directly related to task‐relevant mnemonic processing. These findings suggest that the optimal conditions for the induction of LTP occur naturally in behaving animals, time‐locked to behavioral events critical to learning.
Extrinsic modulation of theta field activity in the entorhinal cortex of the anesthetized rat
Authors: Dickson Clayton T. , Trepel Christopher , Bland Brian H. 
Published: January 2005

AbstractField recordings of the entorhinal cortex (EC) were studied and compared to those recorded concomitantly in the dentate region of the hippocampal formation (HPC) in the urethane anesthetized rat. The EC, like the HPC, showed two main variations of spontaneous field activity: a desynchronized, large amplitude irregular activity and a synchronized, rhythmic, slow frequency field activity (RSA or theta). Corroborating previous research, a phase reversal was seen across layer II of the EC and when recorded superficial to this layer, EC theta was phase‐locked to that recorded from the HPC (dentate). Entorhinal cortex (and HPC) theta could be evoked by the application of moderate tail pinches (sensory stimulation), by pharmacological treatments enhancing cholinergic transmission, and by electrical stimulation of the posterior hypothalamus. Spectral analysis revealed that in all cases, theta was produced coherently across the two limbic structures. Entorhinal cortex (and HPC) production of theta could be abolished by pharmacological treatments disrupting cholinergic transmission, and by reversible procaine inactivation of the medial septal region. Therefore, it was concluded that limbic theta is modulated spontaneously, and with sensory and hypothalamic stimulation through the activity of cells in the medial septal region via muscarinic neurotransmission. It was also hypothesized that the activation of cells in the posterior hypothalamus linearly codes the frequency, and to a lesser extent the power, of EC and HPC theta. Given these findings and the coincidence and coherence of the occurrence of theta across the EC and HPC, it was postulated that it occurs via a parallel mechanism in the two areas.
Transient decrease in calbindin immunoreactivity of the rat fascia dentata granule cells after repeated electroconvulsive shocks
Authors: Tønder Niels , Kragh Jørn , Bolwig Tom , Zimmer Jens 
Published: January 2005

AbstractChanges in hippocampal calbindin immunoreactivity were investigated after repeated electroconvulsive shocks. Adult rats were subjected to 10, 20, or 36 electroconvulsive shocks (50 mA, 0.5 seconds), given as on shock per day, 5 days a week. The rats were sacrificed and processed for calbindin immunohistochemistry 1, 2, and 30 days after the last electroconvulsive shock. In the rats receiving 10 or 20 electroconvulsive shocks, a selective reduction of the calbindin immunoreactivity of the dentate granule cell bodies, dendrites, and mossy fibers was noted 1 and 2 days after the last electroconvulsive shock. After 36 electroconvulsive shocks there was an almost complete loss of calbindin immunoreactivity from the granule cell bodies and dendrites, and the calbindin immunoreactivity of the mossy fibers was markedly reduced. Thirty days after the last of 36 electroconvulsive shocks, the calbindin immunoreactivity was back to normal. Besides demonstrating pronounced changes associated with repeated electroconvulsive shocks, the results confirm the transient nature of these changes.
Contribution of synapses in the medial supramammillary nucleus to the frequency of hippocampal theta rhythm in freely moving rats
Authors: McNaughton Neil , Logan Barbara , Panickar Kiran S. , Kirk Ian J. , Pan Wei‐Xing , Brown Nicola T. , Heenan Anna 
Published: January 2005

AbstractWe have previously shown that in urethane‐anesthetized rats the frequncy of rhythmical slow activity in the hippocampus (“theta”) is controlled by the medial supramammillary nucleus (SuM). In particular, injections of procaine into SuM in urethane‐anesthetized animals reduce the frequency of theta. However, it has been reported that, in freely moving animals, lesions of SuM do not affect theta. The present experiments were designed to resolve this anomaly. Injections of procaine or chlordiazepoxide into SuM in urethane‐anesthetized animals reduced the frequency of theta elicited by reticular stimulation. Mapping showed that procaine injections in freely moving animals were effective in the same locations as under urethane anesthesia. Injections of chlordiazepoxide were effective in a more restricted area than procaine, consistent with an action on synapses in SuM and sparing fibers afferent to SuM. Analysis of the functional spread indicated an effective radius of diffusion of the drugs of 500μm. With optimal placements, this implied an action on at least 80% of SuM. However, in contrast to the results under urethane, the maximal frequency reductions obtained were less than 50% of the theoretical maximum. In a number of animals receiving repeated injections into SuM, lesions developed which encompassed the whole of SuM. As previously reported, theta was largely intact in SuM‐lesioned animals. However, the frequency of theta produced by reticular stimulation was reduced after lesion by approximately the same amount as by procaine injections before lesion. These results suggest that in freely moving animals SuM is only one of two or more nuclei which jointly control the frequency of reticular‐elicited theta. © 1995 Wiley‐Liss, Inc.
Selective damage to the hippocampal region blocks long‐term retention of a natural and nonspatial stimulus‐stimulus association
Authors: Bunsey Michael , Eichenbaum Howard 
Published: January 2005

AbstractNormal rats rapidly acquire and remember associations between nonspatial stimuli as expressed in the social transmission of food preferences. In the present study, rats with selective neurotoxic lesions including all subdivisions of the hippocampal region (hippocampus proper, dentate gyrus, and subiculum) normally acquired and briefly retained the food odor association as demonstrated by intact memory immediately after social training. However, long‐term memory in these animals was severly impaired in contrast to strong 24‐h retention by intact rats. More selective lesions to the hippocampus proper plus dentate gyrus alone, or the subiculum alone had no effect on memory at either test interval. These finding indicate that the hippocampal region is required for long‐term retention of a nonspatial form of natural memory. © 1995 Wiley‐Liss, Inc.