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Journal of Neuroscience Methods Feb 2016In order to understand the pathophysiology of temporal lobe epilepsy (TLE), and thus to develop new pharmacological treatments, in vivo animal models that present... (Review)
Review
In order to understand the pathophysiology of temporal lobe epilepsy (TLE), and thus to develop new pharmacological treatments, in vivo animal models that present features similar to those seen in TLE patients have been developed during the last four decades. Some of these models are based on the systemic administration of chemoconvulsants to induce an initial precipitating injury (status epilepticus) that is followed by the appearance of recurrent seizures originating from limbic structures. In this paper we will review two chemically-induced TLE models, namely the kainic acid and pilocarpine models, which have been widely employed in basic epilepsy research. Specifically, we will take into consideration their behavioral, electroencephalographic and neuropathologic features. We will also evaluate the response of these models to anti-epileptic drugs and the impact they might have in developing new treatments for TLE.
Topics: Animals; Convulsants; Disease Models, Animal; Electroencephalography; Epilepsy, Temporal Lobe; Kainic Acid; Nerve Net; Pilocarpine; Temporal Lobe
PubMed: 25769270
DOI: 10.1016/j.jneumeth.2015.03.009 -
Epilepsy & Behavior : E&B Jan 2018The objective of this study was to determine whether preoperative [F]fludeoxyglucose (FDG)-positron emission tomography (PET) asymmetry in temporal lobe metabolism...
OBJECTIVE
The objective of this study was to determine whether preoperative [F]fludeoxyglucose (FDG)-positron emission tomography (PET) asymmetry in temporal lobe metabolism predicts neuropsychological and seizure outcomes after temporal lobectomy (TL).
METHODS
An archival sample of 47 adults with unilateral temporal lobe epilepsy who underwent TL of their language-dominant (29 left, 1 right) or nondominant (17 right) hemisphere were administered neuropsychological measures pre- and postoperatively. Post-TL seizure outcomes were measured at 1year. Regional FDG uptake values were defined by an automated technique, and a quantitative asymmetry index (AI) was calculated to represent the relative difference in the FDG uptake in the epileptic relative to the nonepileptic temporal lobe for four regions of interest: medial anterior temporal (MAT), lateral anterior temporal (LAT), medial posterior temporal (MPT), and lateral posterior temporal (LPT) cortices.
RESULTS
In language-dominant TL, naming outcomes were predicted by FDG uptake asymmetry in the MAT (r=-0.38) and LPT (r=-0.45) regions. For all patients, visual search and motor speed outcomes were predicted by FDG uptake asymmetry in all temporal regions (MPT, r=0.42; MAT, r=0.34; LPT, r=0.47; LAT, r=0.51). Seizure outcomes were predicted by FDG uptake asymmetry in the MAT (r=0.36) and MPT (r=0.30) regions. In all of these significant associations, greater hypometabolism in regions of the epileptic temporal lobe was associated with better postoperative outcomes.
CONCLUSIONS
Our results support the conclusion that FDG uptake asymmetry is a useful clinical tool in assessing risk for cognitive changes in patients being considered for TL.
Topics: Adult; Anterior Temporal Lobectomy; Epilepsy, Temporal Lobe; Female; Fluorodeoxyglucose F18; Humans; Male; Memory; Middle Aged; Neuropsychological Tests; Positron-Emission Tomography; Postoperative Period; Seizures; Temporal Lobe; Treatment Outcome
PubMed: 29175222
DOI: 10.1016/j.yebeh.2017.10.006 -
Cold Spring Harbor Perspectives in... Mar 2015The ability to remember life's events, and to leverage memory to guide behavior, defines who we are and is critical for everyday functioning. The neural mechanisms... (Review)
Review
The ability to remember life's events, and to leverage memory to guide behavior, defines who we are and is critical for everyday functioning. The neural mechanisms supporting such mnemonic experiences are multiprocess and multinetwork in nature, which creates challenges for studying them in humans and animals. Advances in noninvasive neuroimaging techniques have enabled the investigation of how specific neural structures and networks contribute to human memory at its many cognitive and mechanistic levels. In this review, we discuss how functional and anatomical imaging has provided novel insights into the types of information represented in, and the computations performed by, specific medial temporal lobe (MTL) regions, and we consider how interactions between the MTL and other cortical and subcortical structures influence what we learn and remember. By leveraging imaging, researchers have markedly advanced understanding of how the MTL subserves declarative memory and enables navigation of our physical and mental worlds.
Topics: Humans; Magnetic Resonance Imaging; Memory, Episodic; Spatial Memory; Temporal Lobe
PubMed: 25780085
DOI: 10.1101/cshperspect.a021840 -
Anatomical Record (Hoboken, N.J. : 2007) Sep 2019In the human brain, the mid-fusiform sulcus (MFS; sulcus sagittalis gyri fusiformis) divides the fusiform gyrus (FG) into lateral and medial partitions. Recent studies... (Review)
Review
In the human brain, the mid-fusiform sulcus (MFS; sulcus sagittalis gyri fusiformis) divides the fusiform gyrus (FG) into lateral and medial partitions. Recent studies show that the MFS is identifiable in every hemisphere and is a landmark that identifies (a) cytoarchitectonic transitions among four areas of the FG, (b) functional transitions in many large-scale maps, and (c) the location of fine-scale functional regions. Thus, simply identifying the MFS in a person's brain provides researchers with knowledge regarding: (a) how cells are organized across layers within a particular cortical location, (b) how functional representations will be laid out in cortex, and (c) the precise location of functional regions from cortical folding alone. The predictive power of the MFS can guide future studies examining the anatomical-functional organization of the FG, as well as the development of translational applications for different patient populations. Nevertheless, progress has been slow in incorporating the MFS into the broader anatomical community and into neuroanatomical reference sources. For example, even though the MFS is a rare structural-functional landmark in human association cortex as just described, it is not recognized in the recently published Terminologia Neuroanatomica (TNA). In this review, I collate the anatomical and functional details of the MFS in one place for the first time. Together, this article serves as a comprehensive reference regarding the anatomical and functional details of the MFS, as well as provides a growing number of reasons to include the MFS as a recognized neuroanatomical structure in future revisions of the TNA. Anat Rec, 302:1491-1503, 2019. © 2018 American Association for Anatomy.
Topics: Humans; Neuroanatomy; Temporal Lobe
PubMed: 30471211
DOI: 10.1002/ar.24041 -
Epilepsia Jan 2012Surgical resection of the hippocampus is the most successful treatment for medication-refractory medial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis.... (Review)
Review
Surgical resection of the hippocampus is the most successful treatment for medication-refractory medial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis. Unfortunately, at least one of four operated patients continue to have disabling seizures after surgery, and there is no existing method to predict individual surgical outcome. Prior to surgery, patients who become seizure free appear identical to those who continue to have seizures after surgery. Interestingly, newly converging presurgical data from magnetic resonance imaging (MRI) and intracranial electroencephalography (EEG) suggest that the entorhinal and perirhinal cortices may play an important role in seizure generation. These areas are not consistently resected with surgery and it is possible that they continue to generate seizures after surgery in some patients. Therefore, subtypes of MTLE patients can be considered according to the degree of extrahippocampal damage and epileptogenicity of the medial temporal cortex. The identification of these subtypes has the potential to drastically improve surgical results via optimized presurgical planning. In this review, we discuss the current data that suggests neural network damage in MTLE, focusing on the medial temporal cortex. We explore how this evidence may be applied to presurgical planning and suggest approaches for future investigation.
Topics: Anterior Temporal Lobectomy; Electroencephalography; Epilepsy, Temporal Lobe; Humans; Magnetic Resonance Imaging; Nerve Net; Temporal Lobe; Treatment Outcome
PubMed: 22050314
DOI: 10.1111/j.1528-1167.2011.03298.x -
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 -
Brain Structure & Function Apr 2022The medial temporal lobe (MTL) is a set of interconnected brain regions that have been shown to play a central role in behavior as well as in neurological disease....
The medial temporal lobe (MTL) is a set of interconnected brain regions that have been shown to play a central role in behavior as well as in neurological disease. Recent studies using resting-state functional magnetic resonance imaging (rsfMRI) have attempted to understand the MTL in terms of its functional connectivity with the rest of the brain. However, the exact characterization of the whole-brain networks that co-activate with the MTL as well as how the various sub-regions of the MTL are associated with these networks remains poorly understood. Here, we attempted to advance these issues by exploiting the high spatial resolution 7T rsfMRI dataset from the Human Connectome Project with a data-driven analysis approach that relied on independent component analysis (ICA) restricted to the MTL. We found that four different well-known resting-state networks co-activated with a unique configuration of MTL subcomponents. Specifically, we found that different sections of the parahippocampal cortex were involved in the default mode, visual and dorsal attention networks; sections of the hippocampus in the somatomotor and default mode networks; and the lateral entorhinal cortex in the dorsal attention network. We replicated this set of results in a validation sample. These results provide new insight into how the MTL and its subcomponents contribute to known resting-state networks. The participation of the MTL in an expanded range of resting-state networks is in line with recent proposals on MTL function.
Topics: Brain; Brain Mapping; Connectome; Humans; Magnetic Resonance Imaging; Nerve Net; Temporal Lobe
PubMed: 35041057
DOI: 10.1007/s00429-021-02442-1 -
Canadian Association of Radiologists... Aug 2015Our goal is to pictorially review a wide spectrum of congenital and acquired conditions affecting the medial aspect of the temporal lobe. (Review)
Review
PURPOSE
Our goal is to pictorially review a wide spectrum of congenital and acquired conditions affecting the medial aspect of the temporal lobe.
CONCLUSION
After completing this article, the reader will have knowledge of the imaging appearance of diverse developmental, malformative, and acquired lesions of the mesial temporal lobe, which will be useful when evaluating pathology in this location.
Topics: Brain Diseases; Diagnosis, Differential; Humans; Magnetic Resonance Imaging; Temporal Lobe
PubMed: 25978865
DOI: 10.1016/j.carj.2014.12.006 -
Cortex; a Journal Devoted To the Study... Sep 2023Neuroimaging can capture brain restructuring after anterior temporal lobe resection (ATLR), a surgical procedure to treat drug-resistant temporal lobe epilepsy (TLE)....
Neuroimaging can capture brain restructuring after anterior temporal lobe resection (ATLR), a surgical procedure to treat drug-resistant temporal lobe epilepsy (TLE). Here, we examine the effects of this surgery on brain morphology measured in recently-proposed independent variables. We studied 101 individuals with TLE (55 left, 46 right onset) who underwent ATLR. For each individual we considered one pre-surgical MRI and one follow-up MRI 2-13 months after surgery. We used a surface-based method to locally compute traditional morphological variables, and the independent measures K, I, and S, where K measures white matter tension, I captures isometric scaling, and S contains the remaining information about cortical shape. A normative model trained on data from 924 healthy controls was used to debias the data and account for healthy ageing effects occurring during scans. A SurfStat random field theory clustering approach assessed changes across the cortex caused by ATLR. Compared to preoperative data, surgery had marked effects on all morphological measures. Ipsilateral effects were located in the orbitofrontal and inferior frontal gyri, the pre- and postcentral gyri and supramarginal gyrus, and the lateral occipital gyrus and lingual cortex. Contralateral effects were in the lateral occipital gyrus, and inferior frontal gyrus and frontal pole. The restructuring following ATLR is reflected in widespread morphological changes, mainly in regions near the resection, but also remotely in regions that are structurally connected to the anterior temporal lobe. The causes could include mechanical effects, Wallerian degeneration, or compensatory plasticity. The study of independent measures revealed additional effects compared to traditional measures.
Topics: Humans; Epilepsy, Temporal Lobe; Brain Mapping; Temporal Lobe; Brain; Magnetic Resonance Imaging; Drug Resistant Epilepsy
PubMed: 37399617
DOI: 10.1016/j.cortex.2023.04.018 -
Behavioural Neurology 2011
Topics: Humans; Language; Memory; Temporal Lobe
PubMed: 22063814
DOI: 10.3233/BEN-2011-0336