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At least 109 records · Page 6Linked to original sources
PubMed1997

Evolving isolated hand palsy: a parietal lobe syndrome associated with carotid artery disease.

Six patients with cerebral ischaemia who presented evolving isolated hand palsy were studied, five prospectively and one retrospectively. The motor deficit involved only the hand and the wrist in some cases. In almost all cases the motor deficit was pseudo-ulnar. None of them had a Babinski sign, all had mild sensory symptoms or signs in the affected hand. CT and MRI disclosed recent infarctions contralateral to the affected hand, in the white matter of the angular gyrus, in a vascular borderzone. Five had a tight stenosis of the internal carotid artery. The pyramidal tract was anatomically spared in three cases, even considering its parietal origin. Consistent with previous data, our study suggests that the parietal lobe is involved in the control of the motor function of the hand. We propose the existence of a new entity, characterized by an evolving non-pyramidal motor deficit in the hand following infarction of the angular gyrus of the inferior parietal lobe.

Aged↗
PubMed2005

Real and imaginary rotary motion processing: functional parcellation of the human parietal lobe revealed by fMRI.

Functional magnetic resonance imaging was performed in 16 healthy subjects while they undertook orientation discrimination tasks of real rotating and mentally rotating alphanumeric characters. Perception of rotating and stationary abstract characters was also performed. Mental rotation and the perception of alphanumeric characters undergoing real rotation activated equivalent cortical areas, in keeping with the analogue hypothesis of mental rotation. In addition, areas along the dorsal stream, including the V5/middle temporal complex and the intraparietal sulcus (IPS), were activated during both the real and imaginary rotary conditions. Within the parietal lobe there were areas of convergence (i.e., recruited by all three motion conditions) and areas of divergence (i.e., selectively activated by a particular condition). Tasks requiring canonical-mirror orientation discrimination revealed involvement of neural substrates localized to the ventrolateral bank of the IPS. Tasks in which this judgment was not performed and during which the subject viewed rotary motion of abstract stimuli recruited activity in the medial bank of the IPS. These results indicate subspecialization of the human posterior parietal lobe according to function.

Adult↗
PubMed2002

Conversion sensory symptoms associated with parietal lobe infarct: case report, diagnostic issues and brain mechanisms.

This case report suggests that diagnostic difficulties and brain mechanisms related to conversion disorder associated with cerebral lesions differ from those related to conversion disorder without cerebral lesions. A 35-year-old divorced woman was admitted to a psychiatric inpatient unit with multiple physical complaints. The symptoms first appeared 5 years previous and 2 months after a sexual assault. Three years later, she began to experience ill-defined sensory symptoms confined to the left half of her body (splitting the midline). Results of neurologic consultations were equivocal because of the subjective nature of the complaints, which were viewed as conversion symptoms. A magnetic resonance imaging scan demonstrated an old infarct in the right parietal lobe, suggesting a physical origin of the patient's symptoms. However, normal somatosensory-evoked responses from the affected area contributed little to establishing the diagnosis. The results of all further investigations to identify causes of the vascular pathology were negative. The multiple ill-defined somatic symptoms, the distribution of sensory symptoms and the resolution of symptoms with psychotherapy established the diagnosis of conversion disorder superimposed on a pre-existing right parietal lesion. This case highlights the importance of clinical features in establishing a diagnosis such as this. We suggest that reactivation of implicit sensory memories (represented at the thalamic level and resulting from decreased corticofugal inhibitions due to the lesion) may contribute to the formation of sensory conversion symptoms in individuals with parietal lobe lesions.

Adult↗
PubMed2000

Selective right parietal lobe activation during mental rotation: a parametric PET study.

Regional cerebral blood flow (rCBF) was measured with PET in seven healthy subjects while they carried out a mental rotation task in which they decided whether alphanumeric characters presented in different orientations were in their canonical form or mirror-reversed. Consistent with previous findings, subjects took proportionally longer to respond as characters were rotated further from the upright, indicating that they were mentally rotating the characters to the upright position before making a decision. We used a parametric design in which we varied the mental rotation demands in an incremental fashion while keeping all other aspects of the task constant. In four different scanning conditions, 10, 40, 70 or 100% of the stimuli presented during the scan required mental rotation while the rest were upright. The statistical parametric mapping technique was used to identify areas where changes in rCBF were correlated with the rotational demands of the task. Significant activation was found in only one area located in the right posterior parietal lobe, centred on the intraparietal sulcus (Brodmann area 7). The experimental literature on monkeys and humans suggests that this area is involved in a variety of spatial transformations. Our results contribute evidence that such transformations are recruited during mental rotation and add to a body of evidence which suggests that the right posterior parietal lobe is important for carrying out visuospatial transformations.

Adult↗
PubMed2003

Is there a role for the parietal lobes in the perception of pain?

Converging lines of evidence confirm a role for the anterior parietal cortex in pain processing and extend the traditional view of SI to include discriminative aspects of somatic stimulation that is potentially tissue-damaging (e.g., painful). Recent studies more specifically implicate SI in the sensory aspect of pain perception by demonstrating that SI activation is modulated by cognitive manipulations that alter perceived pain intensity, but not by manipulations that alter unpleasantness, independent of pain intensity. Nevertheless, despite the probable role of SI in the encoding of the various sensory features of pain, considerable evidence suggests that nociceptive input to SI may also serve to modulate tactile perception. Thus, SI cortex may be involved in both the perception and modulation of both painful and nonpainful somatosensory sensations. Defining a role in pain processing for the parietal operculum is somewhat more problematic. The absence of a fine somatotopic organization of cutaneous (or visceral) receptors virtually eliminates a substantial role for this region in localizing noxious stimuli. Several studies suggest separate representations for pain and touch within the posterior parietal cortex and SII, respectively; however, inter-species differences in cortical anatomy and inconsistencies in the designation of SII proper preclude a clear reconciliation of the data. Likewise, suggestions that SII activation is predominantly related to processing the nociceptive quality of the stimulus (60,61) are inconsistent with many studies in both human and nonhuman subjects, which show a strong functional relationship between SII activity and innocuous (especially, vibrotactile) stimulation. Nevertheless, the numerous studies indicating pain-related activation within the parietal operculum (and/or SII) underscore the potential importance of this region in the perception of pain and the need for continued research. Finally, a possible role of posterior parietal cortex (BA 5/7, 39/40) in orientation and attention toward painful sensory stimuli is consistent with existing literature describing this region as a poly modal association area concerned with intrapersonal and extrapersonal space; however, results from studies that actually manipulate the subjects' level of attention relative to painful stimuli have not uniformly supported this hypothesis (75). Future studies assessing both attentional demand and direct manipulation or motor interactions involving noxious stimuli may help to resolve this issue. In spite of some discrepant results concerning specific details of the nociceptive process, the weight of human pain research now firmly establishes a role for the parietal lobes in the conscious appreciation of the sensation of pain.

Animals↗
PubMed1987

The cortico-cortical connections of area 7b, PF, in the parietal lobe of the monkey.

The cortico-cortical connections of area 7b (or PF) in the parietal lobe of the monkey have been studied with the method of axoplasmic transport of horseradish peroxidase or with the method of axonal terminal degeneration. Area 7b is reciprocally and precisely connected with area 5, the second somatic sensory area (SII), area 23 of the cingulate cortex, the retroinsular area (Ri), the granular insular area (Ig), and with the cortex in the walls of the superior temporal sulcus.

Animals↗
PubMed2005

[A case of parietal lobe epilepsy with ictal laughter].

We report here about an 8-year-old boy with parietal lobe epilepsy (PLE) and ictal laughter. At the age of 6, he began to experience drop seizures, followed by sensory fits. Interictal EEG showed frequent spikes at C3, C4, P3 and Cz. Despite treatment with antiepileptic drugs, he often fell down in seizures after feeling abnormal sensations in the right shoulder. On ictal video EEG at the age of 7 years, (1) he became motionless and complained of fear and pain in the right hand, (2) he had clonic seizures of the right upper limb and fell down to his left, (3) he laughed though he did not feel funny. Ictal EEG showed spikes which originated in Pz and then were generalized. In many of the previously reported cases, ictal laughter is associated with hypothalamic hamartomas, infantile spasms,. complex partial seizures of frontal, temporal, or parietal origin. We diagnosed the present case as having PLE. However, other localization could not be roled out because the spikes were generalized quickly. To date, there are two reported cases of ictal laughter with PLE, but ictal EEG is lacking in these patients. Ictal laughter is rare in non-lesional cryptogenic PLE, but it may imply PLE's pathogenesis.

Child↗
PubMed1981

[Condition of interocortical connections in cranio-cerebral injuries with inferior parietal lobe lesions].

The intercortical pathways and the clinical picture of the condition developing after an injury of the parietal lobe of the human brain were studied pathomorphologically (10 cases) and clinically (103 observations). It was shown that in cases of injury of the lower parietal region there developed a degeneration of the nervous fibres in various areas of the cortex of both the ipsi- and the contralateral hemisphere. Certain regularities of the distribution of the degenerated nervous fibres among the cortex areas were revealed, and their topics in various parts of a groove shown. The changes in the nervous conductors that maintain the intercortical connections reflect a structural reconstitution of the nervous elements and point to development of the pathological process that leads to functional disturbances and appearance of cortical symptoms which arise in craniocerebral injury and are characteristic for not only the lower parietal, but also for other divisions of the brain.

Adult↗
PubMed2006

Parietal lobe volume deficits in schizophrenia spectrum disorders.

There has been little attention given to whether parietal lobe structural deficits are present in patients with schizophrenia and related personality disorders. The current study was designed to examine parietal volume alterations between schizophrenia and schizotypal personality disorder. Twenty-five patients with schizotypal disorder, 53 patients with schizophrenia, and 59 healthy volunteers were scanned using high-resolution magnetic resonance imaging (MRI). Volume measurements of the postcentral gyrus (PoCG), precuneus, superior parietal gyrus (SuPG), supramarginal gyrus (SMG), and angular gyrus (AGG) were performed on consecutive 1-mm coronal slices. Gray matter volumes were reduced in all parietal subregions in patients with schizophrenia compared with healthy controls. White matter volumes were also reduced in the SuPG and PoCG. In contrast, the schizotypal subjects had gray matter reductions only in the PoCG, while other regions were not affected. In addition, there was a lack of normal significant-leftward asymmetry in the SMG in schizophrenia. These findings demonstrate that volume reductions in the somatosensory cortices are common morphological characteristics in schizophrenia spectrum disorders. The additional volume alterations in schizophrenia may support the notion that a deficit in the posterior parietal region is critical for the manifestation of overt psychotic symptoms.

Adult↗
PubMed2004

Transcranial magnetic stimulation to the parietal lobes reduces detection of contralateral somatosensory stimuli.

OBJECTIVES: Neglect has been described in patients with lesions of the parietal cortex and has been interpreted as a disorder of the allocation of spatial attention. The persistence of neglect has been linked to poor rehabilitation outcome in patients suffering from acute stroke. Transcranial magnetic stimulation (TMS) applied to the parietal cortex has been shown to induce changes in the perception of stimuli including tactile stimulation of the fingers contra- and ipsilateral to the stimulated hemisphere. MATERIAL AND METHODS: In the current study, eleven normal young subjects performed a detection task for cutaneous electrical stimuli to the left or right forearm that had been precued by a preceding visual warning stimulus. To investigate the role of the parietal cortical areas for attentional processes TMS was applied to frontal and parietal scalp sites of each hemisphere in the cue-target interval before the somatosensory stimulus. RESULTS: Right and left parietal stimulation led to reduced detection sensitivity for near threshold stimuli to the forearm contralateral to the stimulated hemisphere without hemispheric differences. Ipsilateral tactile perception was not influenced by parietal TMS and there was no change in perception after frontal stimulation to left or right scalp sites. CONCLUSION: This pattern of results is consistent with a role of the right and left parietal lobe in the distribution of spatial attention and provides an experimental basis for possible therapeutical application of TMS to improve attentional deficits in stroke patients.

Adult↗
PubMed1985

Object reversals after parietal lobe infarction--a case report.

A case is described of a mixed manually dominant man with a right parietal infarction who demonstrated reversals in object manipulation. Although mirror reversals in parietal lobe dysfunction and right-left spatial reversal in conjunction with mirror writing have been reported previously, object and spatial reversal to this extent has not been reported. The theoretical implications of the absence of mirror writing here, in relation to side of brain lesion and handedness, are discussed.

Aged↗
PubMedDate not supplied

[Diagnostic value of angiographic studies of parietal lobe tumors].

Serial angiography is the principal method of examination in the study of problems concerning topical diagnosis of parietal lobe tumors, sources of blood supply to the new growth, routes of blood drainage, relation of the tumor to the major vessels and the venous collectors, and the collateral circulation, which is of essential importance in the choice of the optimal volume of the surgical intervention. The diagnostic possibilities of angiographic examination are becoming wider with tre use of the method of catheterization of the vessels by means of a balloon catheter and superselective angiography.

Brain Neoplasms↗
PubMed1986

The organization of the corticocortical projection of area 5 upon area 7 in the parietal lobe of the monkey.

The distribution of labelled cells and of extracellular granules in the cortex of area 5 of the parietal lobe of the monkey has been studied after injections of horseradish peroxidase into area 7. Area 5 is related only to area 7b (PF) and not to area 7a (PG). The corticocortical connections between area 5 and 7b are reciprocal and well organized so that the same representations in each area are interconnected. No corticocortical fibres pass between areas 7a (PG) and 7b (PF).

Animals↗
PubMed1995

Bone marrow infiltration by a parietal lobe grade III oligodendroglioma.

We report a patient with oligodendroglioma metastases 1 year after tumour debulking and postoperative radiotherapy to the parietal lobe primary. This treatment controlled the patient's tumour locally. Distant recurrence was manifest by back pain, weight loss and malaise. The serum alkaline phosphatase was raised and a bone scan showed generalized increased uptake. Bone marrow trephine revealed infiltration by oligodendroglioma. Bone marrow infiltration by gliomas is very rare. If the trephine had not been performed it might have been assumed that he had a disseminated second primary tumour.

Bone Marrow Neoplasms↗
PubMed2003

Effect of parietal lobe lesions on saccade targeting and spatial memory in a naturalistic visual search task.

The eye movements of two patients with parietal lobe lesions and four normal observers were measured while they performed a visual search task with naturalistic objects. Patients were slower to perform the task than the normal observers, and the patients had more fixations per trial, longer latencies for the first saccade during the visual search, and less accurate first and second saccades to the target locations during the visual search. The increases in response times for the patients compared to the normal observers were best predicted by increases in the number of fixations. In order to investigate the effects of spatial memory on search performance, in some trials observers saw a preview of the search display. The patients appeared to have difficulty using previously viewed information, unlike normal observers who benefit from the preview. This suggests a spatial memory deficit. The patients' deficits are consistent with the hypothesis that the parietal cortex has a role in the selection of targets for saccades, in memory for target location.

Adult↗