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Wu N, Sun T, Wu X, Chen H, Zhang Z. Modulation of GABA B receptors in the insula bidirectionally affects associative memory of epilectic rats in both spatial and non-spatial operant tasks. Front Behav Neurosci 2023; 16:1042227. [PMID: 36688127 PMCID: PMC9846148 DOI: 10.3389/fnbeh.2022.1042227] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/12/2022] [Indexed: 01/05/2023] Open
Abstract
Background Stimulation of gamma-aminobutyric acid (GABA) activity through GABA receptor agonists is the basic mechanism of many anticonvulsant drugs. Nevertheless, many of these GABergic drugs have adverse cognitive effects. We previously found that GABAB receptors (GABABRs) in the insula regulate operant associative memory in healthy rats. The present study aimed at investigating the effects of GABABR modulation in the insula on operant associative memory in epileptic rats, along with the underlying mechanisms. Methods The lithium-pilocarpine model of temporal lobe epilepsy (TLE) was established in male Sprague-Dawley rats. A 22-gauge stainless-steel guide cannula was surgically implanted into the granular insula cortex of the epileptic rats. Baclofen (125 ng/μl, 1 μl), CGP35348 (12.5 μg/μl, 1 μl), or saline (1 μl) was slowly infused through the guide cannula. The Intellicage automated behavioral testing system was used to evaluate operant associative memory of the epileptic rats, including non-spatial operant tasks (basic nosepoke learning and skilled nosepoke learning) and spatial operant tasks (chamber position learning). The expression of the GABABR subunits GB1 and GB2 in the insula was examined by immunofluorescence and Western blotting. Results The Intellicage tests demonstrated that baclofen significantly impaired basic nosepoke learning, skilled nosepoke learning and chamber position learning of the epileptic rats, while CGP35348 boosted these functions. Immunofluorescence staining revealed that GB1 and GB2 were expressed in the insula of the epileptic rats, and Western blotting analysis showed that baclofen enhanced while CGP35348 inhibited the expression of these subunits. Conclusion GABABRs in the insula bidirectionally regulate both spatial and non-spatial operant associative memory of epileptic rats. Effects of GABABRs on cognition should be taken into account when evaluating new possible treatments for people with epilepsy.
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Affiliation(s)
- Nan Wu
- Department of Neurosurgery, Tianjin Children’s Hospital (Children’s Hospital of Tianjin University), Tianjin, China
| | - Tao Sun
- Ningxia Key Laboratory of Cerebrocranial Disease, Incubation Base of National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Xin Wu
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Hongguang Chen
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Zhen Zhang
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China,*Correspondence: Zhen Zhang,
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2
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Cediel ML, Stawarski M, Blanc X, Nosková L, Magner M, Platzer K, Gburek-Augustat J, Baldridge D, Constantino JN, Ranza E, Bettler B, Antonarakis SE. GABBR1 monoallelic de novo variants linked to neurodevelopmental delay and epilepsy. Am J Hum Genet 2022; 109:1885-1893. [PMID: 36103875 PMCID: PMC9606381 DOI: 10.1016/j.ajhg.2022.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 08/15/2022] [Indexed: 01/25/2023] Open
Abstract
GABAB receptors are obligatory heterodimers responsible for prolonged neuronal inhibition in the central nervous system. The two receptor subunits are encoded by GABBR1 and GABBR2. Variants in GABBR2 have been associated with a Rett-like phenotype (MIM: 617903), epileptic encephalopathy (MIM: 617904), and milder forms of developmental delay with absence epilepsy. To date, however, no phenotypes associated with pathogenic variants of GABBR1 have been established. Through GeneMatcher, we have ascertained four individuals who each have a monoallelic GABBR1 de novo non-synonymous variant; these individuals exhibit motor and/or language delay, ranging from mild to severe, and in one case, epilepsy. Further phenotypic features include varying degrees of intellectual disability, learning difficulties, autism, ADHD, ODD, sleep disorders, and muscular hypotonia. We functionally characterized the four de novo GABBR1 variants, p.Glu368Asp, p.Ala397Val, p.Ala535Thr, and p.Gly673Asp, in transfected HEK293 cells. GABA fails to efficiently activate the variant receptors, most likely leading to an increase in the excitation/inhibition balance in the central nervous system. Variant p.Gly673Asp in transmembrane domain 3 (TMD3) renders the receptor completely inactive, consistent with failure of the receptor to reach the cell surface. p.Glu368Asp is located near the orthosteric binding site and reduces GABA potency and efficacy at the receptor. GABA exhibits normal potency but decreased efficacy at the p.Ala397Val and p.Ala535Thr variants. Functional characterization of GABBR1-related variants provides a rationale for understanding the severity of disease phenotypes and points to possible therapeutic strategies.
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Affiliation(s)
- Maria Lucia Cediel
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Michal Stawarski
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Xavier Blanc
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Lenka Nosková
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Martin Magner
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic; Department of Pediatrics, First Faculty of Medicine, Charles University and University Thomayer Hospital in Prague, Prague, Czech Republic
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Janina Gburek-Augustat
- Division of Neuropaediatrics, Hospital for Children and Adolescents, University Hospital Leipzig, Leipzig, Germany
| | | | | | - Emmanuelle Ranza
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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3
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Keeping the Balance: GABAB Receptors in the Developing Brain and Beyond. Brain Sci 2022; 12:brainsci12040419. [PMID: 35447949 PMCID: PMC9031223 DOI: 10.3390/brainsci12040419] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 12/16/2022] Open
Abstract
The main neurotransmitter in the brain responsible for the inhibition of neuronal activity is γ-aminobutyric acid (GABA). It plays a crucial role in circuit formation during development, both via its primary effects as a neurotransmitter and also as a trophic factor. The GABAB receptors (GABABRs) are G protein-coupled metabotropic receptors; on one hand, they can influence proliferation and migration; and, on the other, they can inhibit cells by modulating the function of K+ and Ca2+ channels, doing so on a slower time scale and with a longer-lasting effect compared to ionotropic GABAA receptors. GABABRs are expressed pre- and post-synaptically, at both glutamatergic and GABAergic terminals, thus being able to shape neuronal activity, plasticity, and the balance between excitatory and inhibitory synaptic transmission in response to varying levels of extracellular GABA concentration. Furthermore, given their subunit composition and their ability to form complexes with several associated proteins, GABABRs display heterogeneity with regard to their function, which makes them a promising target for pharmacological interventions. This review will describe (i) the latest results concerning GABABRs/GABABR-complex structures, their function, and the developmental time course of their appearance and functional integration in the brain, (ii) their involvement in manifestation of various pathophysiological conditions, and (iii) the current status of preclinical and clinical studies involving GABABR-targeting drugs.
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4
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Gianaris T, Holland RM, Villelli NW, Lee AE. Prepontine placement of an intrathecal baclofen pump catheter for treatment of dystonia. Surg Neurol Int 2021; 12:477. [PMID: 34754527 PMCID: PMC8571247 DOI: 10.25259/sni_146_2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 12/13/2019] [Indexed: 11/24/2022] Open
Abstract
Background: Cerebral palsy with medically refractory spasticity and dystonia is a condition that often benefits from intrathecal baclofen pump therapy to treat these symptoms. In this case report, an intracranial baclofen catheter was placed in the prepontine space to improve withdrawal symptoms in a patient unable to undergo new lumbar catheter placement due to infection. Case Description: A 22-year-old female with past medical history of cerebral palsy presented with baclofen pump failure and was unable to undergo placement of a new lumbar baclofen catheter due to an infection in her lower back precluding safe and efficacious catheter placement. It was decided the patient would benefit from intrathecal baclofen administered in the prepontine space as a means to avoid a lumbar catheter and thus bypass this prior infection site. An endoscopic third ventriculostomy (ETV) was performed with the endoscope and the distal end of the baclofen pump catheter was fed through this ETV into the prepontine space. Placement in the prepontine space was confirmed by a follow-up head computed tomography. There was a significant improvement in autonomic symptoms and spasticity. By postoperative day 5, the patient was surgically and medically cleared for discharge. Conclusion: In cases of severe baclofen withdrawal due to dysfunctional pumps, immediate reversal is preferred but may not be feasible due to factors such as infection. This case report has demonstrated that prepontine catheter placement can be effective for the administration of baclofen to reverse withdrawal symptoms in these types of patients.
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Affiliation(s)
- Thomas Gianaris
- Department of Neurological Surgery, Indiana University, IN United States
| | - Ryan M Holland
- Department of Medicine, School of Medicine, Indiana University, Indianapolis, IN United States
| | - Nicolas W Villelli
- Department of Neurological Surgery, Indiana University, IN United States
| | - Albert E Lee
- Department of Neurological Surgery, Goodman Campbell Brain and Spine, Carmel, IN United States
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Abstract
GABAB receptors are implicated in numerous central nervous system-based behaviours and mechanisms, including cognitive processing in preclinical animal models. Homeostatic changes in the expression and function of these receptors across brain structures have been found to affect cognitive processing. Numerous preclinical studies have focused on the role of GABAB receptors in learning, memory and cognition per se with some interesting, although sometimes contradictory, findings. The majority of the existing clinical literature focuses on alterations in GABAB receptor function in conditions and disorders whose main symptomatology includes deficits in cognitive processing. The aim of this chapter is to delineate the role of GABAB receptors in cognitive processes in health and disease of animal models and human clinical populations. More specifically, this review aims to present literature on the role of GABAB receptors in animal models with cognitive deficits, especially those of learning and memory. Further, it aims to capture the progress and advances of research studies on the effects of GABAB receptor compounds in neurodevelopmental and neurodegenerative conditions with cognitive dysfunctions. The neurodevelopmental conditions covered include autism spectrum disorders, fragile X syndrome and Down's syndrome and the neurodegenerative conditions discussed are Alzheimer's disease, epilepsy and autoimmune anti-GABAB encephalitis. Although some findings are contradictory, results indicate a possible therapeutic role of GABAB receptor compounds for the treatment of cognitive dysfunction and learning/memory impairments for some of these conditions, especially in neurodegeneration. Moreover, future research efforts should aim to develop selective GABAB receptor compounds with minimal, if any, side effects.
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6
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Laverick T, Evans S, Freeston M, Baddeley A. The use of novel measures to detect Accelerated Long-term forgetting in people with epilepsy: The Crimes Test and Four Doors Test. Cortex 2021; 141:144-155. [PMID: 34051680 DOI: 10.1016/j.cortex.2021.03.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 10/21/2022]
Abstract
Most patients with memory disorders appear to forget at a relatively normal rate. Hence testing retention beyond the initial test session becomes unnecessary. However, it is now well established that a subsample of patients, most notably people with epilepsy, can show substantially increased forgetting rates even when acquisition rate is normal, raising the need for new tests focused on the assessment of long-term forgetting. Our study is part of the process of developing two such tests. Both focus on the need to test the same person several times and address the problem that each successive test may interfere with the memory of the event being tested. Depending on conditions, such effects can be substantial and may be either positive or negative. The Crimes and Four Doors Tests tackle this problem by presenting easily memorised episodes or scenes, from which a different sample of features is tested at each delay by telephone. We apply these two novel tests to assess rates of forgetting in groups of people with epilepsy and a matched control group. Both the visual and verbal tests showed clear evidence of accelerated forgetting in the epilepsy group supporting the potential value of the tests as convenient and sensitive measures of the rate of long-term forgetting.
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Affiliation(s)
- Tom Laverick
- Tees, Esk & Wear Valleys NHS Trust, Autism Assessment Team, Stockton-on-Tees, England, UK
| | - Stephen Evans
- South Tees Hospitals NHS Trust, Neuropsychology Department, James Cook University Hospital, Middlesbrough, England, UK; York Teaching Hospital NHS Foundation Trust, Department of Psychological Medicine, The Old Chapel, York, UK
| | - Mark Freeston
- School of Psychology, Newcastle University, England, UK
| | - Alan Baddeley
- Department of Psychology, University of York, England, UK.
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Costanzi M, Cianfanelli B, Santirocchi A, Lasaponara S, Spataro P, Rossi-Arnaud C, Cestari V. Forgetting Unwanted Memories: Active Forgetting and Implications for the Development of Psychological Disorders. J Pers Med 2021; 11:jpm11040241. [PMID: 33810436 PMCID: PMC8066077 DOI: 10.3390/jpm11040241] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/23/2021] [Indexed: 11/16/2022] Open
Abstract
Intrusive memories are a common feature of many psychopathologies, and suppression-induced forgetting of unwanted memories appears as a critical ability to preserve mental health. In recent years, biological and cognitive studies converged in revealing that forgetting is due to active processes. Recent neurobiological studies provide evidence on the active role of main neurotransmitter systems in forgetting, suggesting that the brain actively works to suppress retrieval of unwanted memories. On the cognitive side, there is evidence that voluntary and involuntary processes (here termed "intentional" and "incidental" forgetting, respectively) contribute to active forgetting. In intentional forgetting, an inhibitory control mechanism suppresses awareness of unwanted memories at encoding or retrieval. In incidental forgetting, retrieval practice of some memories involuntarily suppresses the retrieval of other related memories. In this review we describe recent findings on deficits in active forgetting observed in psychopathologies, like post-traumatic stress disorder, depression, schizophrenia, and obsessive-compulsive disorder. Moreover, we report studies in which the role of neurotransmitter systems, known to be involved in the pathogenesis of mental disorders, has been investigated in active forgetting paradigms. The possibility that biological and cognitive mechanisms of active forgetting could be considered as hallmarks of the early onset of psychopathologies is also discussed.
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Affiliation(s)
- Marco Costanzi
- Department of Human Sciences, Lumsa University, 00193 Rome, Italy; (B.C.); (S.L.)
- Correspondence:
| | - Beatrice Cianfanelli
- Department of Human Sciences, Lumsa University, 00193 Rome, Italy; (B.C.); (S.L.)
| | - Alessandro Santirocchi
- Department of Psychology, Sapienza University, 00185 Rome, Italy; (A.S.); (C.R.-A.); (V.C.)
| | - Stefano Lasaponara
- Department of Human Sciences, Lumsa University, 00193 Rome, Italy; (B.C.); (S.L.)
- Department of Psychology, Sapienza University, 00185 Rome, Italy; (A.S.); (C.R.-A.); (V.C.)
| | - Pietro Spataro
- Department of Economy, Universitas Mercatorum, 00100 Rome, Italy;
| | - Clelia Rossi-Arnaud
- Department of Psychology, Sapienza University, 00185 Rome, Italy; (A.S.); (C.R.-A.); (V.C.)
| | - Vincenzo Cestari
- Department of Psychology, Sapienza University, 00185 Rome, Italy; (A.S.); (C.R.-A.); (V.C.)
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8
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Baker J, Savage S, Milton F, Butler C, Kapur N, Hodges J, Zeman A. The syndrome of transient epileptic amnesia: a combined series of 115 cases and literature review. Brain Commun 2021; 3:fcab038. [PMID: 33884371 PMCID: PMC8047097 DOI: 10.1093/braincomms/fcab038] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 12/24/2022] Open
Abstract
The term transient epileptic amnesia was coined in 1990 to describe a form of epilepsy causing predominantly amnestic seizures which could be confused with episodes of Transient Global Amnesia. Subsequent descriptions have highlighted its association with ‘atypical’ forms of memory disturbance including accelerated long-term forgetting, disproportionate autobiographical amnesia and topographical amnesia. However, this highly treatment-responsive condition remains under-recognized and undertreated. We describe the clinical and neuropsychological features in 65 consecutive cases of transient epileptic amnesia referred to our study, comparing these to our previous cohort of 50 patients and to those reported in 102 literature cases described since our 2008 review. Findings in our two cohorts are substantially consistent: The onset of transient epileptic amnesia occurs at an average age of 62 years, giving rise to amnestic episodes at a frequency of around 1/month, typically lasting 15–30 min and often occurring on waking. Amnesia is the only manifestation of epilepsy in 24% of patients; olfactory hallucinations occur in 43%, motor automatisms in 41%, brief unresponsiveness in 39%. The majority of patients describe at least one of the atypical forms of memory disturbance mentioned above; easily provoked tearfulness is a common accompanying feature. There is a male predominance (85:30). Epileptiform changes were present in 35% of cases, while suspected causative magnetic resonance imaging abnormalities were detected in only 5%. Seizures ceased with anticonvulsant treatment in 93% of cases. Some clinical features were detected more commonly in the second series than the first, probably as a result of heightened awareness. Neuropsychological testing and comparison to two age and IQ-matched control groups (n = 24 and 22) revealed consistent findings across the two cohorts, namely elevated mean IQ, preserved executive function, mild impairment at the group level on standard measures of memory, with additional evidence for accelerated long-term forgetting and autobiographical amnesia, particularly affecting episodic recollection. Review of the literature cases revealed broadly consistent features except that topographical amnesia, olfactory hallucinations and emotionality have been reported rarely to date by other researchers. We conclude that transient epileptic amnesia is a distinctive syndrome of late-onset limbic epilepsy of unknown cause, typically occurring in late middle age. It is an important, treatable cause of memory loss in older people, often mistaken for dementia, cerebrovascular disease and functional amnesia. Its aetiology, the monthly occurrence of seizures in some patients and the mechanisms and interrelationships of the interictal features—amnestic and affective—all warrant further study.
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Affiliation(s)
- John Baker
- Cognitive & Behavioural Neurology, University of Exeter Medical School, College House, St Luke's Campus, Exeter EX1 2LU, UK
| | - Sharon Savage
- Cognitive & Behavioural Neurology, University of Exeter Medical School, College House, St Luke's Campus, Exeter EX1 2LU, UK.,School of Psychology, University of Newcastle, New South Wales 2308, Australia
| | - Fraser Milton
- Discipline of Psychology, University of Exeter, Washington Singer Laboratories, Exeter EX4 4QG, UK
| | - Christopher Butler
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.,Department of Brain Sciences, Imperial College, London W12 0NN, UK.,Departamento de Neurología, Pontificia Universidad Católica de Chile, Santiago 833007, Chile
| | - Narinder Kapur
- Research Department of Clinical, Educational and Health Psychology, University College London, London WC1E 6BT, UK
| | - John Hodges
- Brain and Mind Centre, University of Sydney, Sydney 2050, Australia
| | - Adam Zeman
- Cognitive & Behavioural Neurology, University of Exeter Medical School, College House, St Luke's Campus, Exeter EX1 2LU, UK
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9
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Oagawa S, Uchida Y, Kobayashi S, Takada K, Terada K, Matsukawa N. [GABA B receptor autoimmune encephalitis presenting as transient epileptic amnesia]. Rinsho Shinkeigaku 2021; 61:6-11. [PMID: 33328416 DOI: 10.5692/clinicalneurol.cn-001425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This case was a 50-year-old healthy woman. After repeated transient amnesia, she developed tonic-clonic seizures and was admitted to our hospital. The brain MRI showed FLAIR hyperintensities in the left temporal lobe and EEG showed an epileptic discharge starting from the left temporal region. Based on these findings, we diagnosed temporal lobe epilepsy associated with acute limbic encephalitis. While she experienced recurrent transient amnesia, her cognitive functions were preserved except for her memory. These symptoms and EEG findings were consistent with transient epileptic amnesia (TEA). Acute limbic encephalitis that occurred in a healthy middle-aged woman may be antibody-mediated encephalitis, requiring immediate immunotherapies. In this case, GABAB receptor antibodies in cerebrospinal fluid were found positive. This is the first report showing that TEA was caused by GABAB receptor autoimmune encephalitis.
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Affiliation(s)
| | - Yuto Uchida
- Department of Neurology, Toyokawa City Hospital
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences
| | | | - Koji Takada
- Department of Neurology, Toyokawa City Hospital
| | - Kiyohito Terada
- Department of Neurology, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders
- Yokohama Minoru Epilepsy & Developmental Clinic
| | - Noriyuki Matsukawa
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences
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10
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Mayes AR, Hunkin NM, Isaac C, Muhlert N. Are there distinct forms of accelerated forgetting and, if so, why? Cortex 2019; 110:115-126. [DOI: 10.1016/j.cortex.2018.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 09/05/2017] [Accepted: 04/08/2018] [Indexed: 12/14/2022]
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11
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Atherton KE, Filippini N, Zeman AZJ, Nobre AC, Butler CR. Encoding-related brain activity and accelerated forgetting in transient epileptic amnesia. Cortex 2018; 110:127-140. [PMID: 29861041 PMCID: PMC6335262 DOI: 10.1016/j.cortex.2018.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 04/06/2018] [Accepted: 04/30/2018] [Indexed: 12/25/2022]
Abstract
The accelerated forgetting of newly learned information is common amongst patients with epilepsy and, in particular, in the syndrome of transient epileptic amnesia (TEA). However, the neural mechanisms underlying accelerated forgetting are poorly understood. It has been hypothesised that interictal epileptiform activity during longer retention intervals disrupts normally established memory traces. Here, we tested a distinct hypothesis-that accelerated forgetting relates to the abnormal encoding of memories. We studied a group of 15 patients with TEA together with matched, healthy control subjects. Despite normal performance on standard anterograde memory tasks, patients showed accelerated forgetting of a word list over one week. We used a subsequent memory paradigm to compare encoding-related brain activity in patients and controls. Participants studied a series of visually presented scenes whilst undergoing functional MRI scanning. Recognition memory for these scenes was then probed outside the scanner after delays of 45 min and of 4 days. Patients showed poorer memory for the scenes compared with controls. In the patients but not the controls, subsequently forgotten stimuli were associated with reduced hippocampal activation at encoding. Furthermore, patients demonstrated reduced deactivation of posteromedial cortex regions upon viewing subsequently remembered stimuli as compared to subsequently forgotten ones. These data suggest that abnormal encoding-related activity in key memory areas of the brain contributes to accelerated forgetting in TEA. We propose that abnormally encoded memory traces may be particularly vulnerable to interference from subsequently encountered material and hence be forgotten more rapidly. Our results shed light on the mechanisms underlying memory impairment in epilepsy, and offer support to the proposal that accelerated forgetting may be a useful marker of subtle dysfunction in memory-related brain systems.
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Affiliation(s)
- Kathryn E Atherton
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK; Department of Experimental Psychology and Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK
| | - Nicola Filippini
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Adam Z J Zeman
- Cognitive & Behavioural Neurology, University of Exeter Medical School, Exeter, UK
| | - Anna C Nobre
- Department of Experimental Psychology and Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK
| | - Christopher R Butler
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK.
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Strikwerda‐Brown C, Mothakunnel A, Hodges JR, Piguet O, Irish M. External details revisited – A new taxonomy for coding ‘non‐episodic’ content during autobiographical memory retrieval. J Neuropsychol 2018; 13:371-397. [DOI: 10.1111/jnp.12160] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 03/29/2018] [Indexed: 12/29/2022]
Affiliation(s)
- Cherie Strikwerda‐Brown
- Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
- School of Psychology The University of Sydney Camperdown New South Wales Australia
- Australian Research Council Centre of Excellence in Cognition and its Disorders Camperdown New South Wales Australia
| | - Annu Mothakunnel
- Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
- School of Psychology The University of Sydney Camperdown New South Wales Australia
| | - John R. Hodges
- Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
- Australian Research Council Centre of Excellence in Cognition and its Disorders Camperdown New South Wales Australia
- Sydney Medical School The University of Sydney Camperdown New South Wales Australia
| | - Olivier Piguet
- Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
- School of Psychology The University of Sydney Camperdown New South Wales Australia
- Australian Research Council Centre of Excellence in Cognition and its Disorders Camperdown New South Wales Australia
| | - Muireann Irish
- Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
- School of Psychology The University of Sydney Camperdown New South Wales Australia
- Australian Research Council Centre of Excellence in Cognition and its Disorders Camperdown New South Wales Australia
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13
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Zeman A, Byruck M, Tallis P, Vossel K, Tranel D. Touching the void – First and third person perspectives in two cases of autobiographical amnesia linked to temporal lobe epilepsy. Neuropsychologia 2018; 110:55-64. [DOI: 10.1016/j.neuropsychologia.2017.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 06/07/2017] [Accepted: 07/09/2017] [Indexed: 10/19/2022]
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14
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The evolution of accelerated long-term forgetting: Evidence from the TIME study. Cortex 2017; 110:16-36. [PMID: 29122206 PMCID: PMC6330058 DOI: 10.1016/j.cortex.2017.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/10/2017] [Accepted: 09/09/2017] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Accelerated long-term forgetting (ALF) occurs when newly learned information decays faster than normal over extended delays. It has been recognised most frequently in temporal lobe epilepsy, including Transient Epileptic Amnesia (TEA), but can also be drug-induced. Little is known about the evolution of ALF over time and its impacts upon other memory functions, such as autobiographical memory (ABM). Here we investigate the long-term outcome of ALF and ABM in a group of patients with TEA and a single case of baclofen-induced ALF. METHODS Study 1 involved a longitudinal follow-up of 14 patients with TEA over a 10-year period. Patients repeated a neuropsychological battery, three ALF measures (with free recall probed at 30-min and 1-week), and a modified Autobiographical Memory Interview (MAMI). Performance was compared with a group of healthy age-matched controls. In Study 2, patient CS, who previously experienced baclofen-induced ALF, was followed over 4 years, and re-tested now, 18 months after ceasing baclofen. CS repeated a neuropsychological battery, three ALF experimental tasks (each probed after 30 min and 1 week), and a modified autobiographical interview (AI). Her performance was compared with healthy age-matched controls. RESULTS On ALF measures, the TEA group performed significantly below controls, but when analysed individually, 4 of the 7 patients who originally showed ALF no longer did so. In two, this was accompanied by improvements in ABM for recent but not remote memory. Patient CS no longer demonstrated ALF on standard lab-based tests and now appeared to retain new episodic autobiographical events with a similar degree of episodic richness as controls. CONCLUSION Long-term follow up suggests that ALF can resolve, with improvements translating to recent ABM in some cases.
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Hamad M, Holland R, Kamal N, Luceri R, Mammis A. Potential for Intrathecal Baclofen in Treatment of Essential Tremor. World Neurosurg 2017; 105:170-175. [PMID: 28559069 DOI: 10.1016/j.wneu.2017.05.112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 12/27/2022]
Abstract
INTRODUCTION Essential tremor (ET) is the most common movement disorder of adults, affecting an estimated 7 million Americans. Symptoms of ET range from slightly noticeable to debilitating, with 1 cohort study finding 15% of patients were forced into early retirement. Additionally, depression has also been correlated with the severity of disability of ET. Treatment options include propranolol and primidone. Current treatment options are not very effective, with more than half (56.3%) of patients discontinuing medications because of no changes in symptoms. METHODS Unfortunately, there is a relative void and controversy in the literature explaining ET pathophysiology; however, the gamma-aminobutyric acid (GABA) hypothesis is the strongest. We conducted a PubMed search on 30 September 2015 with no time constraints using the search terms "essential tremor" and "baclofen," which resulted in a total of 5 articles. RESULTS Neurohistopathologic studies have demonstrated decreased GABA-A and GABA-B receptors in the cerebellar cortex of ET patients. GABA, the major inhibitory neurotransmitter in the central nervous system, is proposed to have an inhibitory effect on pacemaker output activity of the cerebello-thalamo-cortical pathway, with lower receptors resulting in decreased inhibition of baseline tremors. Tariq et al showed delayed onset and intensity of tremor with oral administration of R-baclofen in a mouse model of ET. CONCLUSION With a better side-effect profile and success in a physiologically related condition, we propose more clinical trials and research be carried out on intrathecal baclofen as a potential treatment option, especially drug refractory ET, so as to increase the quality of life of this patient population.
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Affiliation(s)
- Mousa Hamad
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USA.
| | - Ryan Holland
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Naveed Kamal
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Robert Luceri
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Antonios Mammis
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey, USA
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Role of GABA(B) receptors in learning and memory and neurological disorders. Neurosci Biobehav Rev 2016; 63:1-28. [PMID: 26814961 DOI: 10.1016/j.neubiorev.2016.01.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/31/2015] [Accepted: 01/21/2016] [Indexed: 01/13/2023]
Abstract
Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations.
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