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Barry S. Grunwerg - One of the best experts on this subject based on the ideXlab platform.
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Effect of superior colliculus lesions on sensory unit responses in the Intralaminar thalamus of the rat.
Brain research, 1992Co-Authors: George M. Krauthamer, Jennifer G. Krol, Barry S. GrunwergAbstract:The effects of kainic acid lesions of the intermediate and deep layers of the superior colliculus on the sensory input to the Intralaminar thalamus of the rat were determined. Ipsiversive circling and contralateral sensory neglect were consistently seen after lesion placement. Two to 7 days later, the Intralaminar thalamus was systematically explored for extracellular mechanoreceptive unit responses to high threshold and low threshold stimuli. On the side ipsilateral to the lesion the number of responsive units was reduced by 51%. The loss was particularly marked for nociceptive units (80%), and low threshold and complex units with orofacial receptive fields (73%). This effect may involve a partial deafferentation of the Intralaminar thalamus as well as altered excitatory thresholds of thalamic neurons. It is suggested that the functionally distinct direct tectothalamic projection as well as the indirect tecto-reticulo-thalamic pathway are implicated.
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Sensory responses of Intralaminar thalamic neurons activated by the superior colliculus.
Experimental brain research, 1992Co-Authors: Barry S. Grunwerg, George M. KrauthamerAbstract:The Intralaminar thalamus of anesthetized rats was explored for neurons activated by stimulation of the superior colliculus and responsive to sensory inputs. Neurons activated by stimulation of the intermediate and deep collicular layers were distributed throughout the Intralaminar thalamus. Approximately one half of them responded to tectal as well as sensory inputs. The majority were nociceptive or had a more complex response pattern including responses to auditory stimulation. A smaller population of low threshold units had contralateral orofacial receptive fields and responded to light taps; these units were preferentially localized anteriorly in the central lateral and paracentral nuclei. Neurons responsive to tectal and sensory stimulation were randomly intermingled with other neurons which had no detectable sensory input. The results indicate that ascending projection neurons of the intermediate and deep layers of the superior colliculus provide an input to functionally diverse subpopulations of Intralaminar thalamic neurons. In view of its projections to motor cortex and basal ganglia, the Intralaminar thalamus appears directly implicated in basal ganglia and superior colliculus related mechanisms of attention, arousal and postural orienting.
George M. Krauthamer - One of the best experts on this subject based on the ideXlab platform.
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Effect of superior colliculus lesions on sensory unit responses in the Intralaminar thalamus of the rat.
Brain research, 1992Co-Authors: George M. Krauthamer, Jennifer G. Krol, Barry S. GrunwergAbstract:The effects of kainic acid lesions of the intermediate and deep layers of the superior colliculus on the sensory input to the Intralaminar thalamus of the rat were determined. Ipsiversive circling and contralateral sensory neglect were consistently seen after lesion placement. Two to 7 days later, the Intralaminar thalamus was systematically explored for extracellular mechanoreceptive unit responses to high threshold and low threshold stimuli. On the side ipsilateral to the lesion the number of responsive units was reduced by 51%. The loss was particularly marked for nociceptive units (80%), and low threshold and complex units with orofacial receptive fields (73%). This effect may involve a partial deafferentation of the Intralaminar thalamus as well as altered excitatory thresholds of thalamic neurons. It is suggested that the functionally distinct direct tectothalamic projection as well as the indirect tecto-reticulo-thalamic pathway are implicated.
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Sensory responses of Intralaminar thalamic neurons activated by the superior colliculus.
Experimental brain research, 1992Co-Authors: Barry S. Grunwerg, George M. KrauthamerAbstract:The Intralaminar thalamus of anesthetized rats was explored for neurons activated by stimulation of the superior colliculus and responsive to sensory inputs. Neurons activated by stimulation of the intermediate and deep collicular layers were distributed throughout the Intralaminar thalamus. Approximately one half of them responded to tectal as well as sensory inputs. The majority were nociceptive or had a more complex response pattern including responses to auditory stimulation. A smaller population of low threshold units had contralateral orofacial receptive fields and responded to light taps; these units were preferentially localized anteriorly in the central lateral and paracentral nuclei. Neurons responsive to tectal and sensory stimulation were randomly intermingled with other neurons which had no detectable sensory input. The results indicate that ascending projection neurons of the intermediate and deep layers of the superior colliculus provide an input to functionally diverse subpopulations of Intralaminar thalamic neurons. In view of its projections to motor cortex and basal ganglia, the Intralaminar thalamus appears directly implicated in basal ganglia and superior colliculus related mechanisms of attention, arousal and postural orienting.
Masaaki Nishikawa - One of the best experts on this subject based on the ideXlab platform.
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Intralaminar fatigue crack growth properties of conventional and interlayer toughened CFRP laminate under mode I loading
Composites Part A: Applied Science and Manufacturing, 2015Co-Authors: N. Sato, Masaki Hojo, Masaaki NishikawaAbstract:Abstract Intralaminar and interlaminar fatigue crack growth behaviours under mode I loading were investigated with conventional and interlayer toughened unidirectional CFRP laminates. For Intralaminar crack growth tests, initial defects were introduced using “Intralaminar film insertion method”, in which a release film is inserted inside a single lamina prepreg. A fatigue test under a constant maximum energy release rate, Gmax, was carried out using DCB specimens. It was found that the Intralaminar fatigue crack growth property of the interlayer toughened CFRP laminates was the same as that of the conventional CFRP laminates. For the interlayer toughened CFRP laminates, the Gmax with a given crack growth rate, da/dN, was much lower for Intralaminar crack growth than for interlaminar crack growth. The da/dN-Gmax curve at zero crack extension, Δa = 0, which was estimated by extrapolating the da/dN-Δa relationship, was not affected by bridging fibres, and most conservative for the interlayer toughened CFRP laminates.
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Novel test method for accurate characterization of Intralaminar fracture toughness in CFRP laminates
Composites Part B: Engineering, 2014Co-Authors: N. Sato, Masaki Hojo, Masaaki NishikawaAbstract:Abstract A novel initial crack insertion method, “Intralaminar film insertion method”, was proposed to investigate the fracture toughness of unidirectional carbon fiber reinforced plastic (CFRP) laminates when the crack propagates inside the ply and not in the interlayer resin-rich area. Here, a release film was inserted inside a single lamina during the resin impregnation process of prepreg manufacturing. Mode I Intralaminar fracture toughness tests were carried out for conventional CFRP laminates and interlayer toughened CFRP laminates. For comparison, two conventional methods were used to introduce initial cracks. One is the “interlaminar film method”, where a release film is inserted between two prepreg plies during the lay-up process. The other is the “machined slit method”, where a slit notch is machined in parallel to the layer of CFRP laminates. It was demonstrated that the proposed “Intralaminar film method” can correctly evaluate the Intralaminar fracture toughness of both conventional CFRP laminate and interlayer toughened CFRP laminate from the initial value to the propagation value. For this range, it was also found that the Intralaminar fracture toughness of interlayer toughened CFRP laminate was the same as that of conventional CFRP laminate. Thus, the Intralaminar fracture toughness was not influenced by interlayer toughening.
Glenda M Halliday - One of the best experts on this subject based on the ideXlab platform.
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Intralaminar nuclei of the thalamus in Lewy body diseases.
Brain research bulletin, 2008Co-Authors: Daniel Brooks, Glenda M HallidayAbstract:Although the Intralaminar thalamus is a target of alpha-synuclein pathology in Parkinson's disease, the degree of neuronal loss in Lewy body diseases has not been assessed. We have used unbiased stereological techniques to quantify neuronal loss in Intralaminar thalamic nuclei concentrating alpha-synuclein pathology (the anterodorsal, cucullar, parataenial, paraventricular, central medial, central lateral and centre-median/parafascicular complex) in different clinical forms of Lewy body disease (Parkinson's disease with and without dementia, and dementia with Lewy bodies, N=21) compared with controls (N=5). Associations were performed in the Lewy body cases between Intralaminar cell loss and the main diagnostic clinical (parkinsonism, dementia, fluctuation in consciousness, and visual hallucinations) and pathological (Braak stage of Parkinson's disease) features of these diseases, as well as between cell loss and the scaled severity of the alpha-synuclein deposition within the Intralaminar thalamus. As expected, significant alpha-synuclein accumulation occurred in the Intralaminar thalamus in the cases with Lewy body disease. Pathology concentrated anteriorly and in the central lateral and paraventricular nuclei was related to the Braak stage of Parkinson's disease, ageing, and the presence of dementia. Across all types of Lewy body cases there was substantial atrophy and neuronal loss in the central lateral, cucullar and parataenial nuclei, and neuronal loss without atrophy in the centre-median/parafascicular complex. Cases with visual hallucinations showed a greater degree of atrophy of the cucullar nucleus, possibly due to amygdala denervation. The significant degeneration demonstrated in the Intralaminar thalamus is likely to contribute to the movement and cognitive dysfunction observed in Lewy body disorders.
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loss of thalamic Intralaminar nuclei in progressive supranuclear palsy and parkinson s disease clinical and therapeutic implications
Brain, 2000Co-Authors: Jasmine M Henderson, K Carpenter, H Cartwright, Glenda M HallidayAbstract:Whilst many reports mention neurofibrillary tangle pathology in the thalamus in progressive supranuclear palsy, there has been little detailed regional analysis of the distribution and density of thalamic pathology in this disease or in other parkinsonian syndromes. The caudal Intralaminar thalamic nuclei are the major thalamic regulators of the caudate nucleus and putamen, areas known to be dysfunctional in progressive supranuclear palsy and Parkinson's disease. We investigated whether these thalamic nuclei degenerate in patients with these disorders compared with age-matched, neurologically normal controls. Neurofibrillary tangle and Lewy body pathology was assessed and unbiased optical disector methods were used to quantify total neuronal number. Despite different thalamic pathology, there was a dramatic reduction in the total neuronal number in the caudal Intralaminar nuclei in both progressive supranuclear palsy and Parkinson's disease (40-55% loss). In contrast, there was no loss of volume or total neuronal number in the limbic thalamic nuclei in either disease group, indicating selective degeneration of the caudal Intralaminar nuclei. In Parkinson's disease, Lewy bodies were found in these regions, while in progressive supranuclear palsy abundant intracellular neurofibrillary tangles and glial tangles concentrated in the caudal Intralaminar nuclei. However, tangle formation accounted for only a small proportion of cell loss (thalamus in progressive supranuclear palsy. These findings have several implications. The caudal Intralaminar thalamus appears to be one of three basal ganglia sites commonly affected in both progressive supranuclear palsy and Parkinson's disease. These sites are the dopaminergic substantia nigra, the cholinergic pedunculopontine tegmental nucleus and, from our results, the glutamatergic caudal Intralaminar thalamus. In both diseases these sites contain characteristic but different pathologies, indicating disease-specific mechanisms of neurodegeneration. Interestingly, the proportion of remaining neurons affected by these pathologies is low. This may indicate additional (possibly common) cellular mechanisms responsible for the degeneration in these regions. Both the dopaminergic nigra and the glutamatergic caudal Intralaminar thalamus are the major regulators of basal ganglia function via the caudate nucleus and putamen. The pedunculopontine tegmental nucleus has major projections to both of these regulators. These findings indicate that dysregulation of two neurotransmitter systems within the basal ganglia may underlie common parkinsonian symptoms in these disorders. For patients with Parkinson's disease, this loss of glutamate regulation may help explain some problems with dopamine replacement therapies, particularly over time. For patients with progressive supranuclear palsy, more widespread degeneration of basal ganglia structures would contribute to poor treatment outcomes.
Henk J. Groenewegen - One of the best experts on this subject based on the ideXlab platform.
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The Intralaminar and midline nuclei of the thalamus. Anatomical and functional evidence for participation in processes of arousal and awareness.
Brain research. Brain research reviews, 2002Co-Authors: Ysbrand D Van Der Werf, Menno P. Witter, Henk J. GroenewegenAbstract:The thalamic midline and Intralaminar nuclei, long thought to be a non-specific arousing system in the brain, have been shown to be involved in separate and specific brain functions, such as specific cognitive, sensory and motor functions. Fundamental to the participation of the midline and Intralaminar nuclei in such diverse functions seems to be a role in awareness. It is unknown whether the midline and Intralaminar nuclei, together often referred to as the 'non-specific' nuclei of the thalamus, act together or whether each nucleus is involved idiosyncratically in separate circuits underlying cortical processes. Detailed knowledge of the connectivity of each of these nuclei is needed to judge the nature of their contribution to cortical functioning. The present account provides an overview of the results of neuroanatomical tracing studies on the connections of the individual Intralaminar and midline thalamic nuclei in the rat, that have been performed over the past decade in our laboratory. The results are discussed together with those reported by other laboratories, and with those obtained in other species. On the basis of the patterns of the afferent and efferent projections, we conclude that the midline and Intralaminar thalamic nuclei can be clustered into four groups. Each of the groups can be shown to have its own set of target and input structures, both cortically and subcortically. These anatomical relationships, in combination with functional studies in animals and in humans, lead us to propose that the midline and Intralaminar nuclei as a whole play a role in awareness, with each of the groups subserving a role in a different aspect of awareness. The following groups can be discerned: (1) a dorsal group, consisting of the paraventricular, parataenial and intermediodorsal nuclei, involved in viscero-limbic functions; (2) a lateral group, comprising the central lateral and paracentral nuclei and the anterior part of the central medial nucleus, involved in cognitive functions; (3) a ventral group, made up of the reuniens and rhomboid nucleus and the posterior part of the central medial nucleus, involved in multimodal sensory processing; (4) a posterior group, consisting of the centre médian and parafascicular nuclei, involved in limbic motor functions.
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The specificity of the ‘nonspecific’ midline and Intralaminar thalamic nuclei
Trends in neurosciences, 1994Co-Authors: Henk J. Groenewegen, Henk W. BerendseAbstract:The midline and Intralaminar thalamic nuclei have long been considered to be a 'nonspecific' nuclear complex that relays the activity of the brain-stem reticular formation to widespread cerebral-cortical areas. Over the past decade, it has become clear that individual midline and Intralaminar nuclei each receive specific sets of afferents and project to specific parts of the cerebral cortex and striatum. Moreover, the targets of the thalamocortical and thalamostriatal projections of a given nucleus are interconnected through corticostriatal projections. Therefore, the midline and Intralaminar nuclei might have a dual role in corticosubcortical interactions in the forebrain. Through distinct sets of inputs to individual midline or Intralaminar thalamic nuclei, these nuclei are in a position to interact selectively with particular, functionally segregated basal-ganglia-thalamocortical circuits. By way of nonselective inputs, in particular from cholinergic brain-stem nuclei, the midline and Intralaminar nuclei might act in concert to modify the level of activity of the entire basal-ganglia-thalamocortical system.
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Restricted cortical termination fields of the midline and Intralaminar thalamic nuclei in the rat.
Neuroscience, 1991Co-Authors: Henk W. Berendse, Henk J. GroenewegenAbstract:The projections from the midline and Intralaminar thalamic nuclei to the cerebral cortex were studied in the rat by means of anterograde tracing with Phaseolus vulgaris-leucoagglutinin. The midline and Intralaminar nuclear complex taken as a whole projects to widespread, predominantly frontal, cortical areas. Each of the constituent thalamic nuclei has a restricted cortical projection field that overlaps only slightly with the projection fields of adjacent midline and Intralaminar nuclei. The projections of the Intralaminar nuclei cover a larger cortical area than those of the midline nuclei. The laminar distributions of fibres from individual midline and Intralaminar thalamic nuclei are different and include both deep and superficial cortical layers. The parataenial, paraventricular and intermediodorsal midline nuclei each project to circumscribed parts of the prefrontal cortex and the hippocampal and parahippocampal regions. In the prefrontal cortex, the projections are restricted to the medial orbital, infralimbic, ventral prelimbic and agranular insular fields, and the rostral part of the ventral anterior cingular cortex. In contrast to the other midline nuclei, the rhomboid nucleus projects to widespread cortical areas. The rostral Intralaminar nuclei innervate dorsal parts of the prefrontal cortex, i.e. the dorsal parts of the prelimbic, anterior cingular and dorsal agranular insular cortical fields, the lateral and ventrolateral orbital areas, and the caudal part of the ventral anterior cingular cortex. Additional projections are aimed at the agranular fields of the motor cortex and the caudal part of the parietal cortex. The lateral part of the parafascicular nucleus sends fibres predominantly to the lateral agranular field of the motor cortex and the rostral part of the parietal cortex. The medial part of the parafascicular nucleus projects rather sparsely to the dorsal part of the prelimbic cortex, the anterior cingular cortex and the medial agranular field of the motor cortex. Individual midline and Intralaminar thalamic nuclei are thus in a position to directly influence circumscribed areas of the cerebral cortex. In combination with previously reported data on the organization of the midline and Intralaminar thalamostriatal projections and the prefrontal corticostriatal projections the present results suggest a high degree of differentiation in the convergence of thalamic and cortical afferent fibres in the striatum. Each of the recently described parallel basal ganglia-thalamocortical circuits can thus be expanded to include projections at both the cortical and striatal levels from a specific part of the midline and Intralaminar nuclear complex. The distinctive laminar distributions of the fibres originating from the different nuclei emphasize the specificity of the midline and Intralaminar thalamocortical projections.