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Handbook of Clinical Neurology 2022The idea of a temporal lobe separated from the rest of the hemisphere by reason of its unique structural and functional properties is a clinically useful artifact. While... (Review)
Review
The idea of a temporal lobe separated from the rest of the hemisphere by reason of its unique structural and functional properties is a clinically useful artifact. While the temporal lobe can be safely defined as the portion of the cerebrum lodged in the middle cranial fossa, the pattern of its connections is a more revealing description of its functional subdivisions and specific contribution to higher cognitive functions. This chapter provides an historical overview of the anatomy of the temporal lobe and an updated framework of temporal lobe connections based on tractography studies of human and nonhuman primates and patients with brain disorders. Compared to monkeys, the human temporal lobe shows a relatively increased connectivity with perisylvian frontal and parietal regions and a set of unique intrinsic connections, which may have supported the evolution of working memory, semantic representation, and language in our species. Conversely, the decreased volume of the anterior (limbic) interhemispheric temporal connections in humans is related to a reduced reliance on olfaction and a partial transference of functions from the anterior commissure to the posterior corpus callosum. Overall the novel data from tractography suggest a revision of current dual stream models for visual and auditory processing.
Topics: Animals; Brain Mapping; Corpus Callosum; Humans; Neural Pathways; Parietal Lobe; Temporal Lobe
PubMed: 35964979
DOI: 10.1016/B978-0-12-823493-8.00001-8 -
Handbook of Clinical Neurology 2022The temporal cortex encompasses a large number of different areas ranging from the six-layered isocortex to the allocortex. The areas support auditory, visual, and... (Review)
Review
The temporal cortex encompasses a large number of different areas ranging from the six-layered isocortex to the allocortex. The areas support auditory, visual, and language processing, as well as emotions and memory. The primary auditory cortex is found at the Heschl gyri, which develop early in ontogeny with the Sylvian fissure, a deep and characteristic fissure that separates the temporal lobe from the parietal and frontal lobes. Gyri and sulci as well as brain areas vary between brains and between hemispheres, partly linked to the functional organization of language and lateralization. Interindividual variability in anatomy makes a direct comparison between different brains in structure-functional analysis often challenging, but can be addressed by applying cytoarchitectonic probability maps of the Julich-Brain atlas. We review the macroanatomy of the temporal lobe, its variability and asymmetry at the macro- and the microlevel, discuss the relationship to brain areas and their microstructure, and emphasize the advantage of a multimodal approach to address temporal lobe organization. We review recent data on combined cytoarchitectonic and molecular architectonic studies of temporal areas, and provide links to their function.
Topics: Auditory Cortex; Brain; Frontal Lobe; Humans; Language; Temporal Lobe
PubMed: 35964970
DOI: 10.1016/B978-0-12-823493-8.00009-2 -
Handbook of Clinical Neurology 2022Face perception is a socially important but complex process with many stages and many facets. There is substantial evidence from many sources that it involves a large... (Review)
Review
Face perception is a socially important but complex process with many stages and many facets. There is substantial evidence from many sources that it involves a large extent of the temporal lobe, from the ventral occipitotemporal cortex and superior temporal sulci to anterior temporal regions. While early human neuroimaging work suggested a core face network consisting of the occipital face area, fusiform face area, and posterior superior temporal sulcus, studies in both humans and monkeys show a system of face patches stretching from posterior to anterior in both the superior temporal sulcus and inferotemporal cortex. Sophisticated techniques such as fMRI adaptation have shown that these face-activated regions show responses that have many of the attributes of human face processing. Lesions of some of these regions in humans lead to variants of prosopagnosia, the inability to recognize the identity of a face. Lesion, imaging, and electrophysiologic data all suggest that there is a segregation between identity and expression processing, though some suggest this may be better characterized as a distinction between static and dynamic facial information.
Topics: Cerebral Cortex; Facial Recognition; Humans; Magnetic Resonance Imaging; Prosopagnosia; Temporal Lobe
PubMed: 35964972
DOI: 10.1016/B978-0-12-823493-8.00019-5 -
Neurosurgery Clinics of North America Jan 2016Medial temporal lobe epilepsy associated with mesial temporal sclerosis (MTS) is perhaps the most well-defined epilepsy syndrome that is responsive to structural... (Review)
Review
Medial temporal lobe epilepsy associated with mesial temporal sclerosis (MTS) is perhaps the most well-defined epilepsy syndrome that is responsive to structural interventions such as surgery. Several minimally invasive techniques have arisen that provide additional options for the treatment of MTS while potentially avoiding many of open surgery's associated risks. By evading these risks, they also open up treatment options to patients who otherwise are poor surgical candidates. Radiosurgery is one of the most intensively studied of these alternatives and has found a growing role in the treatment of medial temporal lobe epilepsy.
Topics: Epilepsy, Temporal Lobe; Humans; Radiosurgery; Sclerosis; Temporal Lobe
PubMed: 26615110
DOI: 10.1016/j.nec.2015.08.011 -
Neurosurgery Clinics of North America Apr 1993Temporal lobe epilepsy is not a single clinicopathologic entity but a group of syndromes requiring different surgical solutions. Anatomic resections planned for the... (Review)
Review
Temporal lobe epilepsy is not a single clinicopathologic entity but a group of syndromes requiring different surgical solutions. Anatomic resections planned for the treatment of these syndromes are aimed at pathologic substrates minimizing ablation of normal tissue. Most of these procedures involve mesial and lateral temporal resections. The syndrome of mesial temporal sclerosis should be treated with resection aimed at hippocampus and the PHG, including entorhinal cortex, and at part of the amygdala. Improvement in diagnostic methods and refinement of anatomic surgical procedures that maximize resection of hippocampus resulted in excellent outcome in the treatment of patients with this syndrome. Mass lesions in patients with intractable seizures should be resected with some surrounding margins, but additional clinical studies will be required to determine the role of anatomic resections, including hippocampectomy, in the treatment of these patients. Extrahippocampal temporal lobe epilepsy is the most difficult to evaluate and treat. Tailored individualized resections based on acute or chronic EEG recordings may be required until and if discrete anatomically based syndromes can be identified in this patient population.
Topics: Epilepsy, Temporal Lobe; Humans; Temporal Lobe
PubMed: 8467210
DOI: No ID Found -
Neurology Mar 1994
Topics: Epilepsy, Complex Partial; Humans; Temporal Lobe; Tomography, Emission-Computed
PubMed: 8145946
DOI: 10.1212/wnl.44.3_part_1.583-a -
Acta Neurologica Belgica Dec 2022Calcifying pseudoneoplasms of the neuraxis (CAPNONs) are rare and can occur along the neural axis. The pathogenesis of these masses is still unknown, and they are... (Review)
Review
Calcifying pseudoneoplasms of the neuraxis (CAPNONs) are rare and can occur along the neural axis. The pathogenesis of these masses is still unknown, and they are diagnosed by histopathological analysis. We report the largest CAPNON in the temporal lobe reported to date and a review of the literature on all previously reported CAPNON cases located in the temporal lobe. According to the literature review, prior to 2020, the largest CAPNON in the temporal lobe that had ever been reported measured 30 × 30 × 20 mm (Mohapatra et al.). However, we report a larger temporal lobe CAPNON (45 × 35 × 35 mm) in a female patient admitted to our hospital. In addition, among 22 patients with CAPNONs aged from 6 to 62 years, 45.5% were female and 54.5% were male. A total of 72.8% of patients presented with seizures, 9.1% had pituitary dysfunction and 9.1% did not have symptoms. Of the cases in the patients with seizures, 83.2% were completely surgically resected, 5.6% were partially surgically resected, and one was treated medically; one patient refused treatment. Except for one patient who had multiple lesions, all patients who underwent surgery exhibited improved or the disappearance of symptoms of epilepsy. The patient in whom epilepsy resolved had undergone total resection. CAPNON is a rare benign lesion that occurs throughout the nervous system, and the pathogenesis remains unclear. Although the hardness of these lesions vary, surgery is still the preferred treatment and yields good results, and total resection is recommended for patients with epilepsy in the temporal lobe.
Topics: Humans; Male; Female; Calcinosis; Temporal Lobe; Central Nervous System; Seizures; Epilepsy, Temporal Lobe
PubMed: 33675530
DOI: 10.1007/s13760-021-01641-1 -
Journal of Anatomy Oct 2015Recordings from individual neurons in patients who are implanted with depth electrodes for clinical reasons have opened the possibility to narrow down the gap between... (Review)
Review
Recordings from individual neurons in patients who are implanted with depth electrodes for clinical reasons have opened the possibility to narrow down the gap between neurophysiological studies in animals and non-invasive (e.g. functional magnetic resonance imaging, electroencephalogram, magnetoencephalography) investigations in humans. Here we provide a description of the main procedures for electrode implantation and recordings, the experimental paradigms used and the main steps for processing the data. We also present key characteristics of the so-called 'concept cells', neurons in the human medial temporal lobe with selective and invariant responses that represent the meaning of the stimulus, and discuss their proposed role in declarative memory. Finally, we present novel results dealing with the stability of the representation given by these neurons, by studying the effect of stimulus repetition in the strength of the responses. In particular, we show that, after an initial decay, the response strength reaches an asymptotic value after approximately 15 presentations that remains above baseline for the whole duration of the experiment.
Topics: Animals; Electrodes, Implanted; Humans; Magnetic Resonance Imaging; Memory; Neurons; Patch-Clamp Techniques; Temporal Lobe
PubMed: 25163775
DOI: 10.1111/joa.12228 -
Advances and Technical Standards in... 2003Performing temporal lobe epilepsy (TLE) surgery needs secure knowledge of the surgical anatomy. As regards morphological anatomy, the required knowledge includes ability... (Review)
Review
Performing temporal lobe epilepsy (TLE) surgery needs secure knowledge of the surgical anatomy. As regards morphological anatomy, the required knowledge includes ability to identify the temporal sulci and gyri with their posterior landmarks, the opercula and borders of the insula on the convexity surfaces, as well as the mesial structures. The anatomical structures delineating the temporal horn have also to be well-recognized by the surgeon from inside the ventricle, namely: the hippocampus with its tiny fimbria bundle, the choroidal fissure and its velum with the attached choroid plexus, fed by the anterior and postero-lateral choroidal arteries. As TLE surgery also consists of disconnections, knowledge has to include 1) the (fronto-temporal) uncinate fascicle which is divided by doing limen insulae incision, 2) the (intertemporal) anterior commissure which is laterally interrupted when doing total removal of amygdala and entorhinal cortex, 3) the (fornical) bihippocampal commissure, and more generally the ipsilateral limbic system, which are disconnected when sectionning posteriorly the hippocampal tail and the parahippocampal gyrus, 4) the interhemispheric fibers passing through the corpus callosum via the tapetum when dividing the temporal stem, and 5) many other associative fibers... Functional anatomy has to be perfectly known because the temporal lobe plays a major role, especially in language and memory. Also of paramount importance are the visual and auditory pathways; they are in close relationships with the temporal horn; then they project to the occipital calcarine banks and the temporal operculum, respectively. Surgery in the temporal lobe entails risks of vascular complications; almost all the targets have "dangerous" vascular relationships. Therefore good knowledge in vascular anatomy and regular and intensive training in microsurgery are important prerequisitives for being allowed to perform epilepsy surgery.
Topics: Blood Vessels; Cerebral Cortex; Epilepsy; Humans; Limbic System; Temporal Lobe
PubMed: 12627813
DOI: 10.1007/978-3-7091-0641-9_6 -
Epilepsia May 2023Lexical retrieval deficits are characteristic of a variety of different neurological disorders. However, the exact substrates responsible for this are not known. We...
OBJECTIVE
Lexical retrieval deficits are characteristic of a variety of different neurological disorders. However, the exact substrates responsible for this are not known. We studied a large cohort of patients undergoing surgery in the dominant temporal lobe for medically intractable epilepsy (n = 95) to localize brain regions that were associated with anomia.
METHODS
We performed a multivariate voxel-based lesion-symptom mapping analysis to correlate surgical lesions within the temporal lobe with changes in naming ability. Additionally, we used a surface-based mixed-effects multilevel analysis to estimate group-level broadband gamma activity during naming across a subset of patients with electrocorticographic recordings and integrated these results with lesion-deficit findings.
RESULTS
We observed that ventral temporal regions, centered around the middle fusiform gyrus, were significantly associated with a decline in naming. Furthermore, we found that the ventral aspect of temporal lobectomies was linearly correlated to a decline in naming, with a clinically significant decline occurring once the resection extended 6 cm from the anterior tip of the temporal lobe on the ventral surface. On electrocorticography, the majority of these cortical regions were functionally active following visual processing. These loci coincide with the sites of susceptibility artifacts during echoplanar imaging, which may explain why this region has been previously underappreciated as the locus responsible for postoperative naming deficits.
SIGNIFICANCE
Taken together, these data highlight the crucial contribution of the ventral temporal cortex in naming and its important role in the pathophysiology of anomia following temporal lobe resections. As such, surgical strategies should attempt to preserve this region to mitigate postoperative language deficits.
Topics: Humans; Epilepsy, Temporal Lobe; Anomia; Brain Mapping; Temporal Lobe; Language
PubMed: 36806185
DOI: 10.1111/epi.17555