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Inferior Parietal Lobule Encodes Visual Temporal Resolution Processes Contributing to the Critical Flicker Frequency Threshold in Humans  [PDF]
Andrea Nardella, Lorenzo Rocchi, Antonella Conte, Matteo Bologna, Antonio Suppa, Alfredo Berardelli
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098948
Abstract: The measurement of the Critical Flicker Frequency threshold is used to study the visual temporal resolution in healthy subjects and in pathological conditions. To better understand the role played by different cortical areas in the Critical Flicker Frequency threshold perception we used continuous Theta Burst Stimulation (cTBS), an inhibitory plasticity-inducing protocol based on repetitive transcranial magnetic stimulation. The Critical Flicker Frequency threshold was measured in twelve healthy subjects before and after cTBS applied over different cortical areas in separate sessions. cTBS over the left inferior parietal lobule altered the Critical Flicker Frequency threshold, whereas cTBS over the left mediotemporal cortex, primary visual cortex and right inferior parietal lobule left the Critical Flicker Frequency threshold unchanged. No statistical difference was found when the red or blue lights were used. Our findings show that left inferior parietal lobule is causally involved in the conscious perception of Critical Flicker Frequency and that Critical Flicker Frequency threshold can be modulated by plasticity-inducing protocols.
Morphological and laminar distribution of cholescystokinine - immunoreactive neurons in cortex of human inferior parietal lobule and their clinical significance  [PDF]
Pu?ka? Laslo,Dragani?-Gaji? Saveta,Malobabi? Slobodan,Pu?ka? Nela
Medicinski Pregled , 2008, DOI: 10.2298/mpns0810452p
Abstract: Introduction. Cholecystocinine is a neuropeptide whose function in the cortex has not yet been clarified, although its relation with some psychic disorders has been noticed. Previous studies have not provided detailed data about types, or arrangement of neurons that contain those neuropeptide in the cortex of human inferior parietal lobe. The aim of this study was to examine precisely the morphology and typography of neurons containing cholecytocinine in the human cortex of inferior parietal lobule. Material and methods. There were five human brains on which we did the immunocystochemical research of the shape and laminar distribution of cholecystocinine immunoreactive neurons on serial sections of supramarginal gyrus and angular gyrus. The morphological analysis of cholecystocinine-immunoreactive neurons was done on frozen sections using avidin-biotin technique, by antibody to cholecystocinine diluted in the proportion 1:6000 using diamine-benzedine. Results. Cholecystocinine immunorective neurons were found in the first three layers of the cortex of inferior parietal lobule, and their densest concentration was in the 2nd and 3rd layer. The following types of neurons were found: bipolar neurons, then its fusiform subtype, Cajal-Retzius neurons (in the 1st layer), reverse pyramidal (triangular) and unipolar neurons. The diameters of some types of neurons were from 15 to 35 μm, and the diameters of dendritic arborization were from 85-207 μm. A special emphasis is put on the finding of Cajal-Retzius neurons that are immunoreactive to cholecystocinine, which demands further research. Conclusion. Bearing in mind numerous clinical studies pointing out the role of cholecystokinine in the pathogenesis of schizophrenia, the presence of a great number of cholecystokinine immunoreactive neurons in the cortex of inferior parietal lobule suggests their role in the pathogenesis of schizophrenia.
Inferior parietal lobule volume and schneiderian first-rank symptoms in Antipsychotic-Naive schizophrenia: A 3-Tesla MRI study  [cached]
Danivas Vijay,Kalmady Sunil,Arasappa Rashmi,Behere Rishikesh
Indian Journal of Psychological Medicine , 2009,
Abstract: Background: As per Frith′s neuro-cognitive model, inferior parietal lobule (IPL) is implicated in the pathogenesis of Schneiderian first-rank symptoms (FRS) in schizophrenia. The specific role of IPL structural abnormalities in the pathogenesis of FRS is yet to be ascertained. Materials and Methods: Using 3-tesla MRI scanner, this first-time study examined antipsychotic-naοve schizophrenia patients ( n = 28) (patients with FRS [FRS +]: N = 14, M: F = 7:7; and patients without FRS [FRS-]: N = 14, M: F = 7:7) in comparison with sex-, handedness-, education- and socioeconomic status-matched healthy controls ( n = 14, M: F = 7:7). The volume of IPL was measured using a three-dimensional, interactive, semi-automated analysis, with good inter-rater reliability. Results: FRS + patients showed significant volume deficit in right IPL in comparison with healthy controls (F = 4.0; P=.028) after controlling for the potential confounding effects of age, sex and intracranial volume. Conclusions: Right IPL volume deficit in FRS+patients adds further support to the Frith′s model of FRS in schizophrenia.
Distinct Parietal and Temporal Pathways to the Homologues of Broca's Area in the Monkey  [PDF]
Michael Petrides,Deepak N. Pandya
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000170
Abstract: The homologues of the two distinct architectonic areas 44 and 45 that constitute the anterior language zone (Broca's region) in the human ventrolateral frontal lobe were recently established in the macaque monkey. Although we know that the inferior parietal lobule and the lateral temporal cortical region project to the ventrolateral frontal cortex, we do not know which of the several cortical areas found in those regions project to the homologues of Broca's region in the macaque monkey and by means of which white matter pathways. We have used the autoradiographic method, which permits the establishment of the cortical area from which axons originate (i.e., the site of injection), the precise course of the axons in the white matter, and their termination within particular cortical areas, to examine the parietal and temporal connections to area 44 and the two subdivisions of area 45 (i.e., areas 45A and 45B). The results demonstrated a ventral temporo-frontal stream of fibers that originate from various auditory, multisensory, and visual association cortical areas in the intermediate superolateral temporal region. These axons course via the extreme capsule and target most strongly area 45 with a more modest termination in area 44. By contrast, a dorsal stream of axons that originate from various cortical areas in the inferior parietal lobule and the adjacent caudal superior temporal sulcus was found to target both areas 44 and 45. These axons course in the superior longitudinal fasciculus, with some axons originating from the ventral inferior parietal lobule and the adjacent superior temporal sulcus arching and forming a simple arcuate fasciculus. The cortex of the most rostral part of the inferior parietal lobule is preferentially linked with the ventral premotor cortex (ventral area 6) that controls the orofacial musculature. The cortex of the intermediate part of the inferior parietal lobule is linked with both areas 44 and 45. These findings demonstrate the posterior parietal and temporal connections of the ventrolateral frontal areas, which, in the left hemisphere of the human brain, were adapted for various aspects of language production. These precursor circuits that are found in the nonlinguistic, nonhuman, primate brain also exist in the human brain. The possible reasons why these areas were adapted for language use in the human brain are discussed. The results throw new light on the prelinguistic precursor circuitry of Broca's region and help understand functional interactions between Broca's ventrolateral frontal region and posterior parietal and temporal association areas.
Distinct Parietal and Temporal Pathways to the Homologues of Broca's Area in the Monkey  [PDF]
Michael Petrides ,Deepak N. Pandya
PLOS Biology , 2009, DOI: 10.1371/journal.pbio.1000170
Abstract: The homologues of the two distinct architectonic areas 44 and 45 that constitute the anterior language zone (Broca's region) in the human ventrolateral frontal lobe were recently established in the macaque monkey. Although we know that the inferior parietal lobule and the lateral temporal cortical region project to the ventrolateral frontal cortex, we do not know which of the several cortical areas found in those regions project to the homologues of Broca's region in the macaque monkey and by means of which white matter pathways. We have used the autoradiographic method, which permits the establishment of the cortical area from which axons originate (i.e., the site of injection), the precise course of the axons in the white matter, and their termination within particular cortical areas, to examine the parietal and temporal connections to area 44 and the two subdivisions of area 45 (i.e., areas 45A and 45B). The results demonstrated a ventral temporo-frontal stream of fibers that originate from various auditory, multisensory, and visual association cortical areas in the intermediate superolateral temporal region. These axons course via the extreme capsule and target most strongly area 45 with a more modest termination in area 44. By contrast, a dorsal stream of axons that originate from various cortical areas in the inferior parietal lobule and the adjacent caudal superior temporal sulcus was found to target both areas 44 and 45. These axons course in the superior longitudinal fasciculus, with some axons originating from the ventral inferior parietal lobule and the adjacent superior temporal sulcus arching and forming a simple arcuate fasciculus. The cortex of the most rostral part of the inferior parietal lobule is preferentially linked with the ventral premotor cortex (ventral area 6) that controls the orofacial musculature. The cortex of the intermediate part of the inferior parietal lobule is linked with both areas 44 and 45. These findings demonstrate the posterior parietal and temporal connections of the ventrolateral frontal areas, which, in the left hemisphere of the human brain, were adapted for various aspects of language production. These precursor circuits that are found in the nonlinguistic, nonhuman, primate brain also exist in the human brain. The possible reasons why these areas were adapted for language use in the human brain are discussed. The results throw new light on the prelinguistic precursor circuitry of Broca's region and help understand functional interactions between Broca's ventrolateral frontal region and posterior parietal
The Role of the Caudal Superior Parietal Lobule in Updating Hand Location in Peripheral Vision: Further Evidence from Optic Ataxia  [PDF]
Joshua A. Granek, Laure Pisella, Annabelle Blangero, Yves Rossetti, Lauren E. Sergio
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046619
Abstract: Patients with optic ataxia (OA), who are missing the caudal portion of their superior parietal lobule (SPL), have difficulty performing visually-guided reaches towards extra-foveal targets. Such gaze and hand decoupling also occurs in commonly performed non-standard visuomotor transformations such as the use of a computer mouse. In this study, we test two unilateral OA patients in conditions of 1) a change in the physical location of the visual stimulus relative to the plane of the limb movement, 2) a cue that signals a required limb movement 180° opposite to the cued visual target location, or 3) both of these situations combined. In these non-standard visuomotor transformations, the OA deficit is not observed as the well-documented field-dependent misreach. Instead, OA patients make additional eye movements to update hand and goal location during motor execution in order to complete these slow movements. Overall, the OA patients struggled when having to guide centrifugal movements in peripheral vision, even when they were instructed from visual stimuli that could be foveated. We propose that an intact caudal SPL is crucial for any visuomotor control that involves updating ongoing hand location in space without foveating it, i.e. from peripheral vision, proprioceptive or predictive information.
Visuo-auditory interactions in the primary visual cortex of the behaving monkey: Electrophysiological evidence
Ye Wang, Simona Celebrini, Yves Trotter, Pascal Barone
BMC Neuroscience , 2008, DOI: 10.1186/1471-2202-9-79
Abstract: Behavioral or electrophysiological data were obtained from two behaving monkeys. One monkey was trained to maintain a passive central fixation while a peripheral visual (V) or visuo-auditory (AV) stimulus was presented. From a population of 45 V1 neurons, there was no difference in the mean latencies or strength of visual responses when comparing V and AV conditions. In a second active task, the monkey was required to orient his gaze toward the visual or visuo-auditory stimulus. From a population of 49 cells recorded during this saccadic task, we observed a significant reduction in response latencies in the visuo-auditory condition compared to the visual condition (mean 61.0 vs. 64.5 ms) only when the visual stimulus was at midlevel contrast. No effect was observed at high contrast.Our data show that single neurons from a primary sensory cortex such as V1 can integrate sensory information of a different modality, a result that argues against a strict hierarchical model of multisensory integration. Multisensory interaction in V1 is, in our experiment, expressed by a significant reduction in visual response latencies specifically in suboptimal conditions and depending on the task demand. This suggests that neuronal mechanisms of multisensory integration are specific and adapted to the perceptual features of behavior.The classical view of multisensory integration, based on anatomical grounds [1], proposes that each sensory modality is processed through separate channels from the sensory receptors to the primary sensory areas and then further integrated into associative unimodal areas converging at the level of cognitive polymodal areas [2]. Indeed, in primates, neuronal responses to more than one sensory modality have been described in areas higher-up in the hierarchy like the frontal, temporal and parietal lobes [3-9]. While these polysensory areas are the best candidates to support sensory fusion, recent studies in humans have surprisingly revealed that multisensory
Two-Photon Imaging of Calcium in Virally Transfected Striate Cortical Neurons of Behaving Monkey  [PDF]
Barbara Heider,Jason L. Nathanson,Ehud Y. Isacoff,Edward M. Callaway,Ralph M. Siegel
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013829
Abstract: Two-photon scanning microscopy has advanced our understanding of neural signaling in non-mammalian species and mammals. Various developments are needed to perform two-photon scanning microscopy over prolonged periods in non-human primates performing a behavioral task. In striate cortex in two macaque monkeys, cortical neurons were transfected with a genetically encoded fluorescent calcium sensor, memTNXL, using AAV1 as a viral vector. By constructing an extremely rigid and stable apparatus holding both the two-photon scanning microscope and the monkey's head, single neurons were imaged at high magnification for prolonged periods with minimal motion artifacts for up to ten months. Structural images of single neurons were obtained at high magnification. Changes in calcium during visual stimulation were measured as the monkeys performed a fixation task. Overall, functional responses and orientation tuning curves were obtained in 18.8% of the 234 labeled and imaged neurons. This demonstrated that the two-photon scanning microscopy can be successfully obtained in behaving primates.
Recency Effects in the Inferior Parietal Lobe during Verbal Recognition Memory  [PDF]
Bradley R. Buchsbaum,Donald Ye,Mark D’Esposito
Frontiers in Human Neuroscience , 2011, DOI: 10.3389/fnhum.2011.00059
Abstract: The most recently encountered information is often most easily remembered in psychological tests of memory. Recent investigations of the neural basis of such “recency effects” have shown that activation in the lateral inferior parietal cortex (LIPC) tracks the recency of a probe item when subjects make recognition memory judgments. A key question regarding recency effects in the LIPC is whether they fundamentally reflect the storage (and strength) of information in memory, or whether such effects are a consequence of task difficulty or an upswing in resting state network activity. Using functional magnetic resonance imaging we show that recency effects in the LIPC are independent of the difficulty of recognition memory decisions, that they are not a by-product of an increase in resting state network activity, and that they appear to dissociate from regions known to be involved in verbal working memory maintenance. We conclude with a discussion of two alternative explanations – the memory strength and “expectancy” hypotheses, respectively – of the parietal lobe recency effect.
Case Report of a Septum Pellucidum Cavernoma Surgically Resected via Inferior Parietal Approach and Short Literature Review  [PDF]
Constantinos Picolas, Konstantinos Faropoulos, Kyriaki Kekempanou, Georgios Gatzounis
Open Journal of Modern Neurosurgery (OJMN) , 2016, DOI: 10.4236/ojmn.2016.62013
Abstract: Background and Importance: Cavernomas of the septum pellucidum represent an extremely rare subtype of CNS cavernous angiomas which are a rare subtype of CNS tumors. Intraventricular cavernomas of the body of the lateral ventricle are usually treated by the transcallosal approach. Clinical Presentation: We present a case of a fifty-eight year old man with a septum pellucidum cavernoma successfully treated operatively by means of the inferior parietal transcortical transventricular approach. This unusual and scarcely documented tumor was situated at the posterior third of the septum pellucidum. The patient had a good recovery with no focal deficit. Conclusion: Septum pellucidum cavernomas are extremely rare lesions. Inferior parietal transcortical approach is a safe alternative to the commonly used transcallosal approach for lesions of the posterior half of the septum pellucidum.
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