The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Jill Bolte Taylor - One of the best experts on this subject based on the ideXlab platform.
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differential distribution of tyrosine hydroxylase fibers on small and large neurons in layer ii of anterior cingulate cortex of schizophrenic brain
Synapse, 1997Co-Authors: Francine M Benes, Mark S Todtenkopf, Jill Bolte TaylorAbstract:A series of recent postmortem investigations of the anterior cingulate cortex in schizophrenic brain have suggested that there may be a loss and/or impairment of inhibitory interneurons in layer II. It has been postulated that changes of this type could secondarily result in a relative increase of dopaminergic inputs to GABAergic interneurons. To test this hypothesis, an immunoperoxidase technique was developed to extensively and reliably visualize tyrosine hydroxylase-immunoreactive (TH-IR) varicose fibers in human postmortem cortex. This method has been applied to the anterior cingulate (ACCx; Brodmann Area 24) and prefrontal (PFCx; Brodmann Area 10) cortices from a cohort of 15 normal control and 10 schizophrenic cases. The number of TH-IR varicosities in contact with large neurons (LN), small neurons (SN), and neuropil (NPL) was blindly analyzed using a computer-assisted microscopic technique. There was no significant difference in density of TH-IR varicosities in apposition with either LN or SN cell bodies observed in either ACCx or PFCx of schizophrenics when compared to normal controls. The density of varicosities was significantly reduced in NPL of layers V and VI in ACCx, but 2 neuroleptic-free cases did not show this change, suggesting that these decreases of TH-IR varicosities may be related to antipsychotic effects on corticostriatal projection cells in this region. When the density of TH-IR varicosities on SNs was compared to that observed on LNs, both groups showed a higher density on SNs. In ACCx, this pattern was much more pronounced for the schizophrenic group, particularly in layer II where the density on SNs was three times higher than that for LNs (P = 0.01). Unlike the changes in layer V, this latter change in layer II showed no relationship to neuroleptic exposure. There was a positive correlation between age and the density of TH-IR varicosities on SNs of layer II in ACCx; however, the patients were younger than the controls and would have been expected to show a lower density, rather than a higher one, if age considerations had accounted for the group differences. Overall, the results reported here suggest that there are no gross differences in the distribution of TH-IR varicosities in various laminae of the dorsolateral prefrontal cortex. In the anterior cingulate region, however, there may be a significant shift in the distribution of TH-IR varicosities from large neurons to small neurons that occurs selectively in layer II of schizophrenic subjects. Using size criteria, the majority of small neurons are likely nonpyramidal, while the majority of large neurons are predominantly pyramidal in nature. Taken together with other accumulating evidence of preferential abnormalities in this lamina of the cingulate region, the findings reported here are consistent with a model of schizophrenia in which a subtle “miswiring” of ventral tegmental inputs may result in a relative, though not absolute, hyperdopaminergic state with respect to an impaired population of GABAergic interneurons. Synapse 25:80–92, 1997. © 1997 Wiley-Liss, Inc.
Francine M Benes - One of the best experts on this subject based on the ideXlab platform.
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differential distribution of tyrosine hydroxylase fibers on small and large neurons in layer ii of anterior cingulate cortex of schizophrenic brain
Synapse, 1997Co-Authors: Francine M Benes, Mark S Todtenkopf, Jill Bolte TaylorAbstract:A series of recent postmortem investigations of the anterior cingulate cortex in schizophrenic brain have suggested that there may be a loss and/or impairment of inhibitory interneurons in layer II. It has been postulated that changes of this type could secondarily result in a relative increase of dopaminergic inputs to GABAergic interneurons. To test this hypothesis, an immunoperoxidase technique was developed to extensively and reliably visualize tyrosine hydroxylase-immunoreactive (TH-IR) varicose fibers in human postmortem cortex. This method has been applied to the anterior cingulate (ACCx; Brodmann Area 24) and prefrontal (PFCx; Brodmann Area 10) cortices from a cohort of 15 normal control and 10 schizophrenic cases. The number of TH-IR varicosities in contact with large neurons (LN), small neurons (SN), and neuropil (NPL) was blindly analyzed using a computer-assisted microscopic technique. There was no significant difference in density of TH-IR varicosities in apposition with either LN or SN cell bodies observed in either ACCx or PFCx of schizophrenics when compared to normal controls. The density of varicosities was significantly reduced in NPL of layers V and VI in ACCx, but 2 neuroleptic-free cases did not show this change, suggesting that these decreases of TH-IR varicosities may be related to antipsychotic effects on corticostriatal projection cells in this region. When the density of TH-IR varicosities on SNs was compared to that observed on LNs, both groups showed a higher density on SNs. In ACCx, this pattern was much more pronounced for the schizophrenic group, particularly in layer II where the density on SNs was three times higher than that for LNs (P = 0.01). Unlike the changes in layer V, this latter change in layer II showed no relationship to neuroleptic exposure. There was a positive correlation between age and the density of TH-IR varicosities on SNs of layer II in ACCx; however, the patients were younger than the controls and would have been expected to show a lower density, rather than a higher one, if age considerations had accounted for the group differences. Overall, the results reported here suggest that there are no gross differences in the distribution of TH-IR varicosities in various laminae of the dorsolateral prefrontal cortex. In the anterior cingulate region, however, there may be a significant shift in the distribution of TH-IR varicosities from large neurons to small neurons that occurs selectively in layer II of schizophrenic subjects. Using size criteria, the majority of small neurons are likely nonpyramidal, while the majority of large neurons are predominantly pyramidal in nature. Taken together with other accumulating evidence of preferential abnormalities in this lamina of the cingulate region, the findings reported here are consistent with a model of schizophrenia in which a subtle “miswiring” of ventral tegmental inputs may result in a relative, though not absolute, hyperdopaminergic state with respect to an impaired population of GABAergic interneurons. Synapse 25:80–92, 1997. © 1997 Wiley-Liss, Inc.
Peter Hagoort - One of the best experts on this subject based on the ideXlab platform.
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neural correlates of pragmatic language comprehension in autism spectrum disorders
Brain, 2009Co-Authors: Cathelijne M J Y Tesink, Jan K Buitelaar, Karl Magnus Petersson, R J Van Der Gaag, Cornelis C Kan, Indira Tendolkar, Peter HagoortAbstract:Difficulties with pragmatic aspects of communication are universal across individuals with autism spectrum disorders (ASDs). Here we focused on an aspect of pragmatic language comprehension that is relevant to social interaction in daily life: the integration of speaker characteristics inferred from the voice with the content of a message. Using functional magnetic resonance imaging (fMRI), we examined the neural correlates of the integration of voice-based inferences about the speaker's age, gender or social background, and sentence content in adults with ASD and matched control participants. Relative to the control group, the ASD group showed increased activation in right inferior frontal gyrus (RIFG; Brodmann Area 47) for speaker-incongruent sentences compared to speaker-congruent sentences. Given that both groups performed behaviourally at a similar level on a debriefing interview outside the scanner, the increased activation in RIFG for the ASD group was interpreted as being compensatory in nature. It presumably reflects spill-over processing from the language dominant left hemisphere due to higher task demands faced by the participants with ASD when integrating speaker characteristics and the content of a spoken sentence. Furthermore, only the control group showed decreased activation for speaker-incongruent relative to speaker-congruent sentences in right ventral medial prefrontal cortex (vMPFC; Brodmann Area 10), including right anterior cingulate cortex (ACC; Brodmann Area 24/32). Since vMPFC is involved in self-referential processing related to judgments and inferences about self and others, the absence of such a modulation in vMPFC activation in the ASD group possibly points to atypical default self-referential mental activity in ASD. Our results show that in ASD compensatory mechanisms are necessary in implicit, low-level inferential processes in spoken language understanding. This indicates that pragmatic language problems in ASD are not restricted to high-level inferential processes, but encompass the most basic aspects of pragmatic language processing.
Cathelijne M J Y Tesink - One of the best experts on this subject based on the ideXlab platform.
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neural correlates of pragmatic language comprehension in autism spectrum disorders
Brain, 2009Co-Authors: Cathelijne M J Y Tesink, Jan K Buitelaar, Karl Magnus Petersson, R J Van Der Gaag, Cornelis C Kan, Indira Tendolkar, Peter HagoortAbstract:Difficulties with pragmatic aspects of communication are universal across individuals with autism spectrum disorders (ASDs). Here we focused on an aspect of pragmatic language comprehension that is relevant to social interaction in daily life: the integration of speaker characteristics inferred from the voice with the content of a message. Using functional magnetic resonance imaging (fMRI), we examined the neural correlates of the integration of voice-based inferences about the speaker's age, gender or social background, and sentence content in adults with ASD and matched control participants. Relative to the control group, the ASD group showed increased activation in right inferior frontal gyrus (RIFG; Brodmann Area 47) for speaker-incongruent sentences compared to speaker-congruent sentences. Given that both groups performed behaviourally at a similar level on a debriefing interview outside the scanner, the increased activation in RIFG for the ASD group was interpreted as being compensatory in nature. It presumably reflects spill-over processing from the language dominant left hemisphere due to higher task demands faced by the participants with ASD when integrating speaker characteristics and the content of a spoken sentence. Furthermore, only the control group showed decreased activation for speaker-incongruent relative to speaker-congruent sentences in right ventral medial prefrontal cortex (vMPFC; Brodmann Area 10), including right anterior cingulate cortex (ACC; Brodmann Area 24/32). Since vMPFC is involved in self-referential processing related to judgments and inferences about self and others, the absence of such a modulation in vMPFC activation in the ASD group possibly points to atypical default self-referential mental activity in ASD. Our results show that in ASD compensatory mechanisms are necessary in implicit, low-level inferential processes in spoken language understanding. This indicates that pragmatic language problems in ASD are not restricted to high-level inferential processes, but encompass the most basic aspects of pragmatic language processing.
Mark S Todtenkopf - One of the best experts on this subject based on the ideXlab platform.
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differential distribution of tyrosine hydroxylase fibers on small and large neurons in layer ii of anterior cingulate cortex of schizophrenic brain
Synapse, 1997Co-Authors: Francine M Benes, Mark S Todtenkopf, Jill Bolte TaylorAbstract:A series of recent postmortem investigations of the anterior cingulate cortex in schizophrenic brain have suggested that there may be a loss and/or impairment of inhibitory interneurons in layer II. It has been postulated that changes of this type could secondarily result in a relative increase of dopaminergic inputs to GABAergic interneurons. To test this hypothesis, an immunoperoxidase technique was developed to extensively and reliably visualize tyrosine hydroxylase-immunoreactive (TH-IR) varicose fibers in human postmortem cortex. This method has been applied to the anterior cingulate (ACCx; Brodmann Area 24) and prefrontal (PFCx; Brodmann Area 10) cortices from a cohort of 15 normal control and 10 schizophrenic cases. The number of TH-IR varicosities in contact with large neurons (LN), small neurons (SN), and neuropil (NPL) was blindly analyzed using a computer-assisted microscopic technique. There was no significant difference in density of TH-IR varicosities in apposition with either LN or SN cell bodies observed in either ACCx or PFCx of schizophrenics when compared to normal controls. The density of varicosities was significantly reduced in NPL of layers V and VI in ACCx, but 2 neuroleptic-free cases did not show this change, suggesting that these decreases of TH-IR varicosities may be related to antipsychotic effects on corticostriatal projection cells in this region. When the density of TH-IR varicosities on SNs was compared to that observed on LNs, both groups showed a higher density on SNs. In ACCx, this pattern was much more pronounced for the schizophrenic group, particularly in layer II where the density on SNs was three times higher than that for LNs (P = 0.01). Unlike the changes in layer V, this latter change in layer II showed no relationship to neuroleptic exposure. There was a positive correlation between age and the density of TH-IR varicosities on SNs of layer II in ACCx; however, the patients were younger than the controls and would have been expected to show a lower density, rather than a higher one, if age considerations had accounted for the group differences. Overall, the results reported here suggest that there are no gross differences in the distribution of TH-IR varicosities in various laminae of the dorsolateral prefrontal cortex. In the anterior cingulate region, however, there may be a significant shift in the distribution of TH-IR varicosities from large neurons to small neurons that occurs selectively in layer II of schizophrenic subjects. Using size criteria, the majority of small neurons are likely nonpyramidal, while the majority of large neurons are predominantly pyramidal in nature. Taken together with other accumulating evidence of preferential abnormalities in this lamina of the cingulate region, the findings reported here are consistent with a model of schizophrenia in which a subtle “miswiring” of ventral tegmental inputs may result in a relative, though not absolute, hyperdopaminergic state with respect to an impaired population of GABAergic interneurons. Synapse 25:80–92, 1997. © 1997 Wiley-Liss, Inc.
