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Löscher W, Stafstrom CE. Epilepsy and its neurobehavioral comorbidities: Insights gained from animal models. Epilepsia 2023; 64:54-91. [PMID: 36197310 DOI: 10.1111/epi.17433] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/04/2022] [Accepted: 10/04/2022] [Indexed: 01/21/2023]
Abstract
It is well established that epilepsy is associated with numerous neurobehavioral comorbidities, with a bidirectional relationship; people with epilepsy have an increased incidence of depression, anxiety, learning and memory difficulties, and numerous other psychosocial challenges, and the occurrence of epilepsy is higher in individuals with those comorbidities. Although the cause-and-effect relationship is uncertain, a fuller understanding of the mechanisms of comorbidities within the epilepsies could lead to improved therapeutics. Here, we review recent data on epilepsy and its neurobehavioral comorbidities, discussing mainly rodent models, which have been studied most extensively, and emphasize that clinically relevant information can be gained from preclinical models. Furthermore, we explore the numerous potential factors that may confound the interpretation of emerging data from animal models, such as the specific seizure induction method (e.g., chemical, electrical, traumatic, genetic), the role of species and strain, environmental factors (e.g., laboratory environment, handling, epigenetics), and the behavioral assays that are chosen to evaluate the various aspects of neural behavior and cognition. Overall, the interplay between epilepsy and its neurobehavioral comorbidities is undoubtedly multifactorial, involving brain structural changes, network-level differences, molecular signaling abnormalities, and other factors. Animal models are well poised to help dissect the shared pathophysiological mechanisms, neurological sequelae, and biomarkers of epilepsy and its comorbidities.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany.,Center for Systems Neuroscience, Hannover, Germany
| | - Carl E Stafstrom
- Division of Pediatric Neurology, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Sun Y, Li Y, Sun J, Zhang K, Tang L, Wu C, Gao Y, Liu H, Huang S, Hu Z, Xiang J, Wang X. Functional reorganization of brain regions into a network in childhood absence epilepsy: A magnetoencephalography study. Epilepsy Behav 2021; 122:108117. [PMID: 34246893 DOI: 10.1016/j.yebeh.2021.108117] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Epilepsy is considered as a network disorder. However, it is unknown how normal brain activity develops into the highly synchronized discharging activity seen in disordered networks. This study aimed to explore the epilepsy brain network and the significant re-combined brain areas in childhood absence epilepsy (CAE). METHODS Twenty-two children with CAE were recruited to study the neural source activity during ictal-onset and interictal periods at frequency bands of 1-30 Hz and 30-80 Hz with magnetoencephalography (MEG) scanning. Accumulated source imaging (ASI) was used to analyze the locations of neural source activity and peak source strength. RESULTS Most of the participants had more active source activity locations in the ictal-onset period rather than in the interictal period, both at 1-30 Hz and 30-80 Hz. The frontal lobe (FL), the temporo-parietal junction (T-P), and the parietal lobe (PL) became the main active areas of source activity during the ictal period, while the precuneus (PC), cuneus, and thalamus were relatively inactive. CONCLUSIONS Some brain areas become more excited and have increased source activity during seizures. These significant brain regions might be re-combined to form an epilepsy network that regulates the process of absence seizures. SIGNIFICANCE The study confirmed that important brain regions are reorganized in an epilepsy network, which provides a basis for exploring the network mechanism of CAE development. Imaging findings may provide a reference for clinical characteristics.
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Affiliation(s)
- Yulei Sun
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Yihan Li
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Jintao Sun
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Ke Zhang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Lu Tang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Caiyun Wu
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Yuan Gao
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Hongxing Liu
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Shuyang Huang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China
| | - Zheng Hu
- Department of Neurology, Nanjing Children's Hospital, Nanjing, Jiangsu 210029, China
| | - Jing Xiang
- Division of Neurology, MEG Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Xiaoshan Wang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
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Xu Y, Yang F, Hu Z, He Y, Zhang Q, Xu Q, Weng Y, Bernhardt BC, Xie X, Xiao J, Peled N, Stufflebeam SM, Lu G, Zhang Z. Anti-seizure medication correlated changes of cortical morphology in childhood epilepsy with centrotemporal spikes. Epilepsy Res 2021; 173:106621. [PMID: 33873105 DOI: 10.1016/j.eplepsyres.2021.106621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 02/02/2021] [Accepted: 03/20/2021] [Indexed: 12/01/2022]
Abstract
To investigate the morphological changes of cerebral cortex correlating with anti-seizure medication in Childhood Epilepsy with Centrotemporal Spikes (CECTS), and their relationships with seizure control. This study included a total of 188 children, including 62 patients with CECTS taking anti-seizure drugs, 56 patients with drug-naive, and 70 healthy controls. A portion of cases were also followed-up for longitudinal analysis. Cortical morphological parameters were quantitatively measured by applying surface-based morphometry analysis to high-resolution three-dimension T1 weighted images. Among the three groups, the morphological indices were compared to quantify any cortical changes affected by seizures and medication. The relationships among anti-seizure medication, seizure controls and cortical morphometry were investigated using causal mediator analysis. The Rolandic cortex of the drug-naive patients showed abnormal cortical thickness by comparing with that of healthy controls, and thinning by comparing with that of patients with medication. The cortical thickness in the Rolandic regions was negatively correlated with duration of medication and duration of seizure-free. Longitudinal analysis further demonstrated that the thickness of Rolandic cortex thinned in post-medication state relative to the pre-medication state. Mediation analysis revealed that morphological alteration of the Rolandic cortex might act as a mediator in the path of anti-seizure medication on seizure control. Our findings highlighted that anti-seizure medication was associated with regression of abnormal increment of cortical thickness in the Rolandic regions in CECTS. The neuroanatomical alteration might be a mediating factor in the process of seizure control by anti-seizure medication.
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Affiliation(s)
- Yin Xu
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Institute of Neurology, Anhui University of Traditional Chinese Medicine, China
| | - Fang Yang
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Zheng Hu
- Department of Neurology, Children's Hospital of Nanjing Medical University, China
| | - Yan He
- Department of Neurology, Children's Hospital of Nanjing Medical University, China
| | - Qirui Zhang
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Qiang Xu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Yifei Weng
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Xinyu Xie
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Junhao Xiao
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Noam Peled
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA
| | - Steven M Stufflebeam
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, 210093, China.
| | - Zhiqiang Zhang
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, 210093, China; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA.
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Akyuz E, Eroglu E. Envisioning the crosstalk between environmental enrichment and epilepsy: A novel perspective. Epilepsy Behav 2021; 115:107660. [PMID: 33328107 DOI: 10.1016/j.yebeh.2020.107660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/16/2020] [Accepted: 11/21/2020] [Indexed: 12/31/2022]
Abstract
Epilepsies are a diverse group of neurological disorders characterized by an unprovoked seizure and a brain that has an enduring predisposition to seizures. The lack of disease-modifying treatment strategies against the same has led to the exploration of novel treatment strategies that could halt epileptic seizures. In this regard, environmental enrichment (EE) has gained increased attention in recent days. EE modulates the effects of interactions between the genes and the environment on the structure and function of the brain. EE therapy can improve seizure-related symptoms in neurological diseases such as epilepsy. EE therapy can have a significant effect on cognitive disorders such as learning and memory impairments associated with seizures. EE therapy in epileptic hippocampus tissue can improve seizure-related symptoms by inducing enhanced neurogenesis and neuroprotective mechanisms. In this context, the efficiency of EE is regulated in the epilepsy by the brain-derived neurotrophic factor (BDNF)/extracellular signal-regulated kinase (ERK) signaling pathway regulated by extracellular signaling. Herein, we provide experimental evidence supporting the beneficial effects of EE in epileptic seizures and its underlying mechanism.
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Affiliation(s)
- Enes Akyuz
- Yozgat Bozok University, Medical School, Department of Biophysics, 66100 Yozgat, Turkey.
| | - Ece Eroglu
- Yozgat Bozok University, Medical School, 66100 Yozgat, Turkey.
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Kim EH, Shim WH, Lee JS, Yoon HM, Ko TS, Yum MS. Altered Structural Network in Newly Onset Childhood Absence Epilepsy. J Clin Neurol 2020; 16:573-580. [PMID: 33029962 PMCID: PMC7541981 DOI: 10.3988/jcn.2020.16.4.573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 05/15/2020] [Accepted: 05/15/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Recent quantitative neuroimaging studies of childhood absence epilepsy (CAE) have identified various structural abnormalities that might be involved in the onset of absence seizure and associated cognitive and behavioral functions. However, the neuroanatomical alterations specific to CAE remain unclear, and so this study investigated the regional alterations of brain structures associated with newly diagnosed CAE. METHODS Surface and volumetric magnetic resonance imaging data of patients with newly diagnosed CAE (n=18) and age-matched healthy controls (n=18) were analyzed using Free-Surfer software. A group comparison using analysis of covariance was performed with significance criteria of p<0.05 and p<0.01 in global and regional analyses, respectively. RESULTS Compared with control subjects, the patients with CAE had smaller total and regional volumes of cortical gray-matter (GM) in the right rostral middle frontal, right lateral orbitofrontal, and left rostral middle frontal regions, as well as in the right precentral, right superior, middle, left middle, and inferior temporal gyri. The cortex in the right posterior cingulate gyrus and left medial occipital region was significantly thicker in patients with CAE than in controls. CONCLUSIONS Patients with CAE showed a reduced bilateral frontotemporal cortical GM volume and an increased posterior medial cortical thickness, which are associated with the default mode network. These structural changes can be suggested as the neural basis of the absence seizures and neuropsychiatric comorbidities in CAE.
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Affiliation(s)
- Eun Hee Kim
- Department of Pediatrics, Sejong Chungnam National University Hospital, Chungnam National University College of Medicine, Sejong, Korea.,Department of Pediatrics, CHA Gangnam Medical Center, CHA University, Seoul, Korea
| | - Woo Hyun Shim
- Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jin Seong Lee
- Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Hee Mang Yoon
- Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Tae Sung Ko
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Mi Sun Yum
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
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Kim EH, Yum MS, Shim WH, Yoon HK, Lee YJ, Ko TS. Structural abnormalities in benign childhood epilepsy with centrotemporal spikes (BCECTS). Seizure 2015; 27:40-6. [DOI: 10.1016/j.seizure.2015.02.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/05/2014] [Accepted: 02/24/2015] [Indexed: 01/25/2023] Open
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Stalin K. Investigating epilepsy in dogs. Vet Rec 2012; 170:333-4. [DOI: 10.1136/vr.e2340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Kate Stalin
- Tighmonadh; Cardross Road Cardross Glasgow G82 5HD UK
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Stewart I. Environmental risk factors for temporal lobe epilepsy – Is prenatal exposure to the marine algal neurotoxin domoic acid a potentially preventable cause? Med Hypotheses 2010; 74:466-81. [DOI: 10.1016/j.mehy.2009.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 10/04/2009] [Indexed: 01/29/2023]
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Haas KZ, Sperber EF, Opanashuk LA, Stanton PK, Moshé SL. Resistance of immature hippocampus to morphologic and physiologic alterations following status epilepticus or kindling. Hippocampus 2002; 11:615-25. [PMID: 11811655 DOI: 10.1002/hipo.1076] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Seizures in adult rats result in long-term deficits in learning and memory, as well as an enhanced susceptibility to further seizures. In contrast, fewer lasting changes have been found following seizures in rats younger than 20 days old. This age-dependency could be due to differing amounts of hippocampal neuronal damage produced by seizures at different ages. To determine if there is an early developmental resistance to seizure-induced hippocampal damage, we compared the effects of kainic acid (KA)-induced status epilepticus and amygdala kindling on hippocampal dentate gyrus anatomy and electrophysiology, in immature (16 day old) and adult rats. In adult rats, KA status epilepticus resulted in numerous silver-stained degenerating dentate hilar neurons, pyramidal cells in fields CA1 and CA3, and marked numerical reductions in CA3c pyramidal neuron counts (-57%) in separate rats. Two weeks following the last kindled seizure, some, but significantly less, CA3c pyramidal cell loss was observed (-26%). Both KA status epilepticus and kindling in duced mossy-fiber sprouting, as evidenced by ectopic Timm staining in supragranular layers of the dentate gyrus. In hippocampal slices from adult rats, paired-pulse stimulation of perforant path axons revealed a persistent enhancement of dentate granule-cell inhibition following KA status epilepticus or kindling. While seizures induced by KA or kindling in 16-day-old rats were typically more severe than in adults, the immature hippocampus exhibited markedly less KA-induced cell loss (-22%), no kindling-induced loss, no detectable synaptic rearrangement, and no change in dentate inhibition. These results demonstrate that, in immature rats, neither severe KA-induced seizures nor repeated kindled seizures produce the kind of hippocampal damage and changes associated with even less severe seizures in adults. The lesser magnitude of seizure-induced hippocampal alterations in immature rats may explain their greater resistance to long-term effects of seizures on neuronal function, as well as future seizure susceptibility. Conversely, hippocampal neuron loss and altered synaptic physiology in adults may contribute to increased sensitivity to epileptogenic stimuli, spontaneous seizures, and behavioral deficits.
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Affiliation(s)
- K Z Haas
- Department of Neuroscience, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York, USA.
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Sarkisian MR, Rattan S, D'Mello SR, LoTurco JJ. Characterization of seizures in the flathead rat: a new genetic model of epilepsy in early postnatal development. Epilepsia 1999; 40:394-400. [PMID: 10219263 DOI: 10.1111/j.1528-1157.1999.tb00732.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Disorders in normal central nervous system (CNS) development are often associated with epilepsy. This report characterizes seizures in a novel genetic model of developmental epilepsy, the Flathead (FH) rat. METHODS Animals (n = 76) ages P0-22 were monitored for clinical and electrographic seizure activity. The effects of various AEDs on seizure frequency and duration also were assessed: phenobarbital (PB; 40 mg/kg), valproate (VPA; 400 mg/kg), or ethosuximide (ESM; 600 mg/kg). RESULTS FHs display episodes of behavior characterized by whole-body tremor, strub tail, alternating forelimb clonus, and complete tonus. EEG recordings from neocortex reveal that FH seizures are bilateral and begin around P7. Seizures occur at a frequency of approximately six per hour from P7 to P18 and the average duration of seizures increases through development. PB, VPA, and ESM failed to prevent seizures; however, PB significantly increased the interval of seizures but had no effects on the duration of seizures, whereas VPA decreased the duration of seizures and not the interval. CONCLUSIONS Seizures in FH rats occur at a constant and high frequency through a defined period in early postnatal development, and these seizures are not completely blocked by high doses of PB, VPA, or ESM. Because FH is a single-locus mutant displaying a highly regular pattern of seizure activity, it is an ideal model for examining the process of epileptogenesis in the developing brain, evaluating new AED therapies, and determining the identity of a gene essential to the normal development of cortical excitability.
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Affiliation(s)
- M R Sarkisian
- Department of Physiology and Neurobiology, University of Connecticut, Storrs 06269, USA
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March PA. Seizures: classification, etiologies, and pathophysiology. CLINICAL TECHNIQUES IN SMALL ANIMAL PRACTICE 1998; 13:119-31. [PMID: 9775502 DOI: 10.1016/s1096-2867(98)80033-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Epilepsy is a disorder of recurrent seizures that are neural in origin. Partial seizures are usually due to a structural cerebrocortical lesion and may be simple or complex. Brain injuries may alter inherent neuronal properties and neuronal circuits and lead to recurrent excitatory activity. Potentiation of excitatory synapses and depression of inhibitory synapses are probable critical events in epileptogenesis. The pathogenic factors underlying primary or idiopathic generalized seizures are not as well understood. A more diffuse or multifocal state of neuronal excitability may be the result of early congenital events that are magnified over time. The progression of subclinical neuronal excitatory activity to a clinical seizure may relate directly to the phenomenon of cortical plasticity.
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Affiliation(s)
- P A March
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210, USA
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Flint AC, Maisch US, Kriegstein AR. Postnatal development of low [Mg2+] oscillations in neocortex. J Neurophysiol 1997; 78:1990-6. [PMID: 9325367 DOI: 10.1152/jn.1997.78.4.1990] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
One form of rhythmic activity intrinsic to neocortex can be induced in slices of adult somatosensory cortex by lowering [Mg2+]o to unblock N-methyl--aspartate (NMDA) receptors. It has been suggested that a population of intrinsically burst-firing (IB) neurons that are unique to cortical layer 5 may play a role in the rhythmic activity seen under these conditions. Whole cell patch-clamp and field-potential recordings in slices of somatosensory cortex from neonatal rats were used to study the development of IB cells and the development of 0 [Mg2+] oscillations. IB cells were not encountered before postnatal day 12 (P12) in layer 5, but from P13 to P19 an increasing proportion of cells had IB properties. Recordings from cells at P7, P17, and P19 in 0 [Mg2+] indicate that dramatic changes occur postnatally in 0 [Mg2+]-induced activity. At P7, cells largely showed trains of single action potentials. In contrast, at P19, cells showed organized bursts of rhythmic activity lasting 0.5-5 s separated by periods of relative quiescence. Cells recorded at P17 were found to have less organized rhythmic activity than cells from P19 cortex. Field-potential recordings in 0 [Mg2+] made at P7 showed infrequent and slowly occurring field depolarizations, whereas field-potential recordings at P19 consisted of spontaneous bursts of 4-12 Hz oscillations identical to those observed in the adult. Application of NE, which inhibits burst-firing of layer 5 IB cells, significantly altered the discharge pattern of 0 [Mg2+] oscillations at P19. These data suggest that the maturation of one type of rhythmic network activity intrinsic to neocortex is influenced by the development of the membrane properties of a single cell type.
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Affiliation(s)
- A C Flint
- Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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