Biomedical subjects

C E Elger

Publications and source records attributed to C E Elger.

At least 55 records · Page 3Linked to original sources

PubMed2003

Cardiac asystole in epilepsy: clinical and neurophysiologic features.

PURPOSE: Cardiac asystole provoked by epileptic seizures is a rare but important complication in epilepsy and is supposed to be relevant to the pathogenesis of sudden unexplained death in epilepsy (SUDEP). We sought to determine the frequency of this complication in a population of patients with medically intractable epilepsy and to analyze the correlation between EEG, electrocardiogram (ECG), and clinical features obtained from long-term video-EEG monitoring. METHODS: Retrospective analysis of the clinical records of hospitalized patients from May 1992 to June 2001 who underwent long-term video-/EEG monitoring. RESULTS: Of a total of 1,244 patients, five patients had cardiac asystole in the course of ictal events. In these patients, 11 asystolic events, between 4 and 60 s long in a total of 19 seizures, were registered. All seizures had a focal origin with simple partial seizures (n = 13), complex partial seizures (n = 4), and secondarily generalized seizures (n = 2). One patient showed the longest asystole ever reported (60 s) because of a seizure. Cardiac asystole occurred in two patients with left-sided temporal lobe epilepsy (TLE) and in three patients with frontal lobe epilepsy (FLE; two left-sided, one bifrontal). Two patients reported previous cardiac disease, but only one had a pathologic ECG by the time of admission. Two patients had a simultaneous central ictal apnea during the asystole. None of the patients had ongoing deficits due to the asystole. CONCLUSIONS: These findings confirm that seizure-induced asystole is a rare complication. The event appeared only in focal epilepsies (frontal and temporal) with a lateralization to the left side. A newly diagnosed or known cardiac disorder could be a risk factor for ictal asystole. Abnormally long postictal periods with altered consciousness might point to reduced cerebral perfusion during the event because of ictal asystole. Central ictal apnea could be a frequent associated phenomenon.

Adolescent↗

PubMed2002

Diagnostic delay in psychogenic nonepileptic seizures.

Delay to diagnosis was studied in 313 consecutive patients with psychogenic nonepileptic seizures (PNES). On average, patients with PNES were diagnosed 7.2 years after manifestation (SD 9.3 years). Younger age, interictal epileptiform potentials in the EEG, and anticonvulsant treatment were associated with longer delays. Other patient factors did not explain the great variability of the time to diagnosis, suggesting that physician factors contributed to delays.

Adolescent↗

PubMed2002

Diagnosis and staging of Rasmussen's encephalitis by serial MRI and histopathology.

OBJECTIVE: To correlate MRI and histopathologic findings in patients with Rasmussen's encephalitis (RE). PATIENTS AND METHODS: MRI features of 10 patients with RE were studied on serial scans. In surgical specimens from these patients, densities of T lymphocytes, microglial cells and nodules, and reactive astrocytes were evaluated. RESULTS: Densities of T cells, microglial nodules, and astrocytes were inversely correlated to disease duration. MRI abnormalities had a focal onset and spread across one hemisphere. The following course of MRI abnormalities in a given brain region was observed: on very early scans, the cortex was swollen and showed a hyperintense T2/fluid-attenuated inversion recovery signal. Consecutively, progressive atrophy of the affected hemisphere occurred. Correlation of MRI features with quantitative histopathology revealed that there was a higher number of T cells and reactive astrocytes in the earlier MRI stages compared with the late (merely atrophic) stage. CONCLUSION: These data suggest a disease course in RE with the highest inflammatory intensity in the early stages and a subsequent decrease in inflammation. The MRI abnormalities and their characteristic sequence may help to identify patients with RE and to obtain informative biopsies.

Adolescent↗

PubMed2002

Time-efficient T2 relaxometry of the entire hippocampus is feasible in temporal lobe epilepsy.

OBJECTIVE: To test the clinical usefulness and reliability of a new dual-echo turbo-spin-echo (TSE) sequence for rapid and regional hippocampal T2 relaxometry. METHODS: Hippocampal T2 relaxation time (HRT) was determined by a TSE sequence on three to four consecutive coronal images in 16 control subjects and 12 patients with mesial temporal lobe epilepsy. HRT was related to neuropathology findings in hippocampal specimens including neuronal cell density (ND), results of visual analysis of MR images, clinical outcome after epilepsy surgery, and hippocampal volumetry. RESULTS: Rapid HRT differentiated patients from control subjects; all cases of hippocampal sclerosis (HS; n = 10) were correctly diagnosed. HRT showed a strong correlation with ND in CA1 (p < 0.02) and CA3 (p < 0.05). Diagnoses based on rapid relaxometry concurred fully with results of visual inspection. Mean HRT was prolonged ipsilaterally in all patients with excellent postoperative seizure outcome and bilaterally prolonged or normal in patients with poorer outcome. Rapid HRT was concordant with hippocampal volumetry in 10 of 12 patients. Regional HRT of control subjects revealed significantly higher values in the anterior than posterior hippocampus. In patients with unilateral HS, this gradient was absent. The gradient was also absent contralaterally to HS, although surgical outcome was excellent. CONCLUSIONS: Hippocampal dual-echo TSE-relaxometry can be regarded a reliable technique to detect and quantify HS. With a scan time of 3.31 minutes and immediate off-line analysis lasting a few minutes only, TSE-T2 relaxometry is easy to integrate in the routine diagnostic assessment of hippocampal morphology in large numbers of patients.

Adolescent↗

PubMed2002

New-onset psychogenic seizures after intracranial neurosurgery.

BACKGROUND: Patients with physical brain abnormalities have an increased risk of developing psychogenic nonepileptic seizures (PNES). Here we describe patients who developed PNES after intracranial neurosurgery for indications other than the control of refractory epileptic seizures and explore whether neurosurgical intervention is at risk factor for PNES. METHOD: We searched the database of 372 patients diagnosed with PNES at our department over the last 10 years and identified 17 patients (4.6%) in whom PNES first started after intracranial neurosurgery. Surgical procedures included the complete or partial resection of a meningioma, AV malformation, cavernoma, plexus papilloma, neurinoma, astrocytoma, oligodendroglioma, dysontogenetic cyst, the drainage of a brain abscess and removal of a subdural hematoma. PNES were documented by ictal video-EEG, ictal EEG, or ictal observation and examination in all cases. The diagnosis of additional epileptic seizures were confirmed by ictal EEG/video-EEG, or made on the basis of a clinical assessment by an experienced epileptologist. FINDINGS: Five patients had purely psychogenic postoperative seizure disorders, twelve had epileptic and psychogenic attacks. Median age at neurosurgery was 32 years (range 5-54), median latency between surgery and onset of PNES was 1 year (range 0-17 years). INTERPRETATION: PNES may develop after intracranial neurosurgery undertaken for other indications than the control of refractory epileptic seizures. Younger patients with a history of pre-operative psychiatric problems or epileptic seizures and surgical complications may be at higher risk. A diagnosis of PNES should be considered in patients who develop refractory seizures after neurosurgery.

Adaptation, Psychological↗

PubMed2002

Pre- and postoperative verbal memory in pediatric patients with temporal lobe epilepsy.

Outcome studies concerning memory after pediatric temporal lobe surgery in the treatment of epilepsy are rare and have not yielded consistent results. In the present study, 55 children and adolescents with temporal lobe epilepsy (TLE; 26 left, 29 right, 6-17 years) performed a verbal memory test before and 3 as well as 12 months after different types of temporal lobe resections (anterior lobectomy, amygdalo-hippocampectomy (AH), lesionectomy (LX)). Groups did not significantly differ before surgery. Three months after surgery, the left resected group showed a decline in learning and delayed recall, and performed significantly lower than the right resected group. Recoveries were evident 1 year after surgery. The postoperative memory declines were associated with a left-sided resection and a higher preoperative performance. Comparisons on the different resection types suggest a special risk in patients undergoing a left-sided AH. In summary, our results indicate a functional association of verbal memory functions with the left temporal lobe similar to findings in adult patients. Declines after left-sided temporal resections seem to be reversible at least for part of the children, perhaps due to the greater plasticity of the immature brain.

Adolescent↗

PubMed2002

Preoperative evaluation for epilepsy surgery (Bonn Algorithm).

SUMMARY: Epilepsy surgery has been established as a successful treatment in patients with drug-resistant focal epilepsies. Different standardized surgical approaches were developed for resective or functional treatment. Successful surgical treatment, however, necessitates a careful presurgical evaluation. Although there are international standards for non invasive and invasive presurgical procedures most centers differ in their diagnostic strategy. This article gives a survey of the Bonn Epilepsy surgery program within which more than 1300 patients have been treated. After the method of patient selection different we describe tools of non invasive and invasive evaluation. This article serves only as a description of current practice in one center with a relatively large volume of cases. It presents just one opinion of a specific group within a wide spectrum of possible algorithms for presurgical evaluation that have briefly been outlined for 33 centers in Engels book [4].

Electroencephalography↗

PubMed2002

The localizing value of ictal consciousness and its constituent functions: a video-EEG study in patients with focal epilepsy.

Using ictal neuropsychological testing in pre-surgical patients with focal epilepsies, we examined the localizing value of the constituent functions of consciousness as opposed to 'conscious behaviour' as a unitary variable. 'Conscious behaviour' was defined in terms of awareness and responsiveness. The constituent functions of consciousness examined included the orientation to the examiner, intentional behaviour demonstrated by expressive or receptive speech, and postictal memory. Frequency and patterns of impairment of constituent functions and 'conscious behaviour' were assessed. To achieve this, pre-surgical video-EEG (n = 40) or video-electrocorticography recordings (n = 76) of ictal neuropsychological assessments were reviewed retrospectively. Patients were divided into groups with frontal (n = 29), right temporal (n = 21), left temporal (n = 38) and bitemporal (n = 28) seizure activity. Consciousness was most commonly impaired in patients with bitemporal and left temporal seizure activity. There were different patterns of impairment of the assessed constituent functions in the four groups: patients with frontal seizure activity showed loss of orientation behaviour and expressive speech whereas patients with left temporal seizure activity had impairments of memory, expressive and receptive speech. Patients with seizure activity limited to the right temporal lobe rarely exhibited ictal impairment of any of the assessed functions. In contrast, patients with bitemporal seizure activity showed impairment of all examined functions. Hence, normal functioning of the left temporal lobe or both temporal lobes is necessary for the preservation of all constituent aspects of consciousness. The localizing value of patterns of impairment of constituent functions is superior to that of 'consciousness' as a whole.

Adolescent↗

PubMed2002

Reproductive dysfunction in women with epilepsy: recommendations for evaluation and management.

BACKGROUND: Epilepsy is commonly associated with reproductive endocrine disorders. These include polycystic ovary syndrome (PCOS), isolated components of this syndrome such as polycystic ovaries, hyperandrogenaemia, hypothalamic amenorrhoea, and functional hyperprolactinaemia. OBJECTIVE: To summarise the currently known relations between epilepsy and reproductive endocrine disorders. METHODS: A review of clinical experience and published reports. RESULTS: The most likely explanations for endocrine disorders related to epilepsy or antiepileptic drugs are: (1) a direct influence of the epileptogenic lesion, epilepsy, or antiepileptic drugs on the endocrine control centres in the brain; (2) the effects of antiepileptic drugs on peripheral endocrine glands; (3) the effects of antiepileptic drugs on the metabolism of hormones and binding proteins; and (4) secondary endocrine complications of antiepileptic drug related weight changes or changes of insulin sensitivity. Regular monitoring of reproductive function at visits is recommended, including questioning about menstrual disorders, fertility, weight, hirsutism, and galactorrhoea. Particular attention should be paid to patients on valproate and obese patients or those experiencing significant weight gain. Single abnormal laboratory or imaging findings without symptoms may not constitute a clinically relevant endocrine disorder. However, patients with these kinds of abnormalities should be monitored to detect the possible development of a symptomatic disorder associated with, for example, menstrual disorders or fertility problems. CONCLUSIONS: If a reproductive endocrine disorder is found, antiepileptic drug treatment should be reviewed to ensure that it is correct for the particular seizure type and that it is not contributing to the endocrine problem. The possible benefits of a change in treatment must be balanced against seizure control and the cumulative side effect of alternative agents.

Anticonvulsants↗

PubMed2002

Standard magnetic resonance imaging is inadequate for patients with refractory focal epilepsy.

OBJECTIVES: Patients with intractable epilepsy may benefit from epilepsy surgery especially if they have a radiologically demonstrable cerebral lesion. Dedicated magnetic resonance imaging (MRI) protocols as performed at epilepsy surgery centres can detect epileptogenic abnormalities with great sensitivity and specificity. However, many patients with epilepsy are investigated with standard MRI sequences by radiologist outside epilepsy centres ("non-experts"). This study was undertaken to compare standard MRI and epilepsy specific MRI findings in patients with focal epilepsy. METHODS: Comparison of results of standard MRI reported by "non-expert" radiologists, standard MRI evaluated by epilepsy "expert" radiologists, and epilepsy specific MRI read by "expert" radiologists in 123 consecutive patients undergoing epilepsy surgery evaluation between 1996 and 1999. Validation of radiological findings by correlation with postoperative histological examination. RESULTS: Sensitivity of "non-expert" reports of standard MRI reports for focal lesions was 39%, of "expert" reports of standard MRI 50%, and of epilepsy dedicated MRI 91%. Dedicated MRI showed focal lesions in 85% of patients with "non-lesional" standard MRI. The technical quality of standard MRI improved during the study period, but "non-expert" reporting did not. In particular, hippocampal sclerosis was missed in 86% of cases. Neuropathological diagnoses (n=90) were predicted correctly in 22% of "non-expert" standard MRI reports but by 89% of dedicated MRI reports. CONCLUSIONS: Standard MRI failed to detect 57% of focal epileptogenic lesions. Patients without MRI lesion are less likely to be considered candidates for epilepsy surgery. Patients with refractory epilepsy should be referred to an MRI unit with epileptological experience at an early point.

Brain↗

PubMed2001

Functional and molecular analysis of transient voltage-dependent K+ currents in rat hippocampal granule cells.

1. We have investigated voltage-dependent outward K+ currents of dentate granule cells (DGCs) in acute brain slices from young and adult rats using nucleated and outside-out patch recordings. 2. In adult DGCs, the outward current pattern was dominated by a transient K+ current component. One portion of this current (approximately 60%) was blocked by micromolar concentrations of tetraethylammonium (TEA; IC50 42 microM) and BDS-I, a specific blocker of Kv3.4 subunits (2.5 microM). A second component was insensitive to tetraethylammonium (10 mM) and BDS-I. The transient outward current could be completely blocked by 4-aminopyridine (IC50 296 microM). 3. The TEA- and BDS-I-sensitive and the TEA-resistant current components were isolated pharmacologically. The current component that was blocked by BDS-I and TEA showed a depolarized threshold of activation (approximately -30 mV) reminiscent of Kv3.4 subunits, while the current component resistant to TEA activated at more hyperpolarized potentials (approximately -60 mV). 4. In nucleated patches obtained by placing the patch pipette adjacent to the apical dendrite, only small Na+ currents and small BDS-I-sensitive transient currents were detected. Nucleated patches obtained from either the cell soma (see above) or the axon hillock showed significantly larger amplitude Na+ currents as well as larger BDS-I-sensitive currents, indicating that this current was predominantly localized within the axosomatic compartment. This result was in good agreement with the distribution of Kv3.4 protein as determined by immunohistochemistry. 5. Current-clamp as well as mock action potential-clamp experiments revealed that the BDS-sensitive current component contributes to action potential repolarization. 6. A comparison of the two age groups (4-10 days and 60-100 days) revealed a marked developmental up-regulation of the BDS-I-sensitive component. These functional changes are paralleled by a developmental increase in Kv3.4 mRNA expression determined by quantitative real-time RT-PCR, as well as a pronounced up-regulation of Kv3.4 on the protein level determined by immunohistochemistry. 7. These functional and molecular results argue that Kv3.4 channels located predominantly in the axosomatic compartment underlie a transient K+ current in adult DGCs, and that these channels are functionally important for regulating spike repolarization. The marked developmental regulation suggests an important role of Kv3.4 in neuronal maturation.

Animals↗

PubMed2001

Indications of nonlinear deterministic and finite-dimensional structures in time series of brain electrical activity: dependence on recording region and brain state.

We compare dynamical properties of brain electrical activity from different recording regions and from different physiological and pathological brain states. Using the nonlinear prediction error and an estimate of an effective correlation dimension in combination with the method of iterative amplitude adjusted surrogate data, we analyze sets of electroencephalographic (EEG) time series: surface EEG recordings from healthy volunteers with eyes closed and eyes open, and intracranial EEG recordings from epilepsy patients during the seizure free interval from within and from outside the seizure generating area as well as intracranial EEG recordings of epileptic seizures. As a preanalysis step an inclusion criterion of weak stationarity was applied. Surface EEG recordings with eyes open were compatible with the surrogates' null hypothesis of a Gaussian linear stochastic process. Strongest indications of nonlinear deterministic dynamics were found for seizure activity. Results of the other sets were found to be inbetween these two extremes.

Brain↗

PubMed2001

GluR3 antibodies: prevalence in focal epilepsy but no specificity for Rasmussen's encephalitis.

Eight patients with Rasmussen's encephalitis, 40 patients with noninflammatory focal epilepsy, 104 patients with various neurologic diseases, and 16 healthy donors were tested for the prevalence of antibodies against the GluR3 receptor in serum and CSF. Reactivities against different peptides derived from various portions of this glutamate receptor subtype were detectable in a significantly higher number of patients with focal epilepsy than in those with other neurologic diseases, but they were not specific for the diagnosis of Rasmussen's encephalitis.

Adolescent↗

PubMed2001

Messenger RNA of steroid 21-hydroxylase (CYP21) is expressed in the human hippocampus.

21-hydroxylase converts progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol, the substrates which are required for the production of the main adrenal steroids, corticosterone, aldosterone, and cortisol. As 21-hydroxylase activity has been detected in rodent and fetal human brain, we studied whether and to what extent 21-hydroxylase mRNA is expressed in hippocampal tissue specimens from patients undergoing epilepsy surgery (n=42). 21-hydroxylase mRNA was detected in the hippocampus with an expression 10 000 times lower than in adrenal gland tissue. There was no significant difference in expression levels between women (9.5+/-2.7 arbitrary units (aU); mean+/-SEM) and men (8.0+/-2.2 aU); however, mRNA concentrations in the hippocampus of children (n=4, 1.8+/-0.5 aU) were considerably lower than in adults (n=38, 8.6+/-1.7 aU). The expression of 21-hydroxylase mRNA in the hippocampus suggests that this human brain area has the enzymatic capability to convert progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol.

Adult↗

PubMed2001

Slow recovery from inactivation regulates the availability of voltage-dependent Na(+) channels in hippocampal granule cells, hilar neurons and basket cells.

1. Fundamental to the understanding of CNS function is the question of how individual neurons integrate multiple synaptic inputs into an output consisting of a sequence of action potentials carrying information coded as spike frequency. The availability for activation of neuronal Na(+) channels is critical for this process and is regulated both by fast and slow inactivation processes. Here, we have investigated slow inactivation processes in detail in hippocampal neurons. 2. Slow inactivation was induced by prolonged (10-300 s) step depolarisations to -10 mV at room temperature. In isolated hippocampal dentate granule cells (DGCs), recovery from this inactivation was biexponential, with time constants for the two phases of slow inactivation tau(slow,1) and tau(slow,2) ranging from 1 to 10 s and 20 to 50 s, respectively. Both (slow,1) and tau(slow,2) were related to the duration of prior depolarisation by a power law function of the form tau(t) = a (t/a)b, where t is the duration of the depolarisation, a is a constant kinetic setpoint and b is a scaling power. This analysis yielded values of a = 0.034 s and b = 0.62 for tau(slow,1) and a = 24 s and b = 0.30 for tau(slow,2) in the rat. 3. When a train of action potential-like depolarisations of different frequencies (50, 100, 200 Hz) was used to induce inactivation, a similar relationship was found between the frequency of depolarisation and both tau(slow,1) and tau(slow,2) (a = 0.58 s, b = 0.39 for tau(slow,1) and a = 3.77 s and b = 0.42 for tau(slow,2)). 4. Using nucleated patches from rat hippocampal slices, we have addressed possible cell specific differences in slow inactivation. In fast-spiking basket cells a similar scaling relationship can be found (a = 3.54 s and b = 0.39) as in nucleated patches from DGCs (a = 2.3 s and b = 0.48) and non-fast-spiking hilar neurons (a = 2.57 s and b = 0.49). 5. Likewise, comparison of human and rat granule cells showed that properties of ultra-slow recovery from inactivation are conserved across species. In both species ultra-slow recovery was biexponential with both tau(slow,1) and tau(slow,2) being related to the duration of depolarisation t, with a = 0.63 s and b = 0.44 for tau(slow,1) and a = 25 s and b = 0.37 for tau(slow,2) for the human subject. 6. In summary, we describe in detail how the biophysical properties of Na(+) channels result in a complex interrelationship between availability of sodium channels and membrane potential or action potential frequency that may contribute to temporal integration on a time scale of seconds to minutes in different types of hippocampal neurons.

Action Potentials↗

PubMed2001

Potassium channel openers depolarize hippocampal mitochondria.

We investigated the effect of the potassium channel openers diazoxide and RP66471 on mitochondrial membrane potential and mitochondrial respiration in digitonin-treated rat hippocampal homogenates. Both diazoxide and RP66471 induced a dose-dependent decrease of mitochondrial membrane potential. Concomitant with the depolarization was an increase of mitochondrial respiration. Furthermore, the mitochondrial membrane depolarization induced by diazoxide and RP66471 was significantly larger in the presence of potassium ions than in the presence of sodium ions. The diazoxide-induced (but not RP66471-induced) mitochondrial membrane depolarization was partially inhibited by blockers of the ATP-regulated potassium channel, 5-hydroxydecanoic acid or the antidiabetic sulfonylurea glibenclamide. In addition, the potassium channel openers diazoxide and RP66471 increased mitochondrial matrix volume and induced a release of cytochrome c from hippocampal mitochondria. These results indicate the presence of a mitochondrial ATP-regulated potassium channel in rat hippocampus being a target for potassium channel openers.

Adenosine Triphosphate↗

PubMed2001

Expression of the 17beta-hydroxysteroid dehydrogenase type 5 mRNA in the human brain.

An enzyme-mediated metabolism of androgens and estrogens including 17beta-HSD activity in the brain of vertebrates was discovered approximately 30 years ago. Mainly 5alpha-reductase and aromatase have been studied in detail. Recently we could demonstrate reductive and oxidative 17beta-HSD activity as well as considerable mRNA expression of the 17beta-HSD types 3 and 4 in the human brain. In the present study, we report on 17beta-HSD type 5 mRNA expression in brain tissue of women and men. Data analysis did not reveal sex specific differences, but we determined a significantly higher mRNA concentration in the subcortical white matter (SC) than in the cerebral cortex (CX). Investigation of reductive 17beta-HSD in vitro activity with 2 microM androstenedione as the substrate revealed no sex specific differences. Testosterone formation was significantly higher in SC than in CX. Moreover, enzyme activity was significantly higher in brain tissue of adults compared to that of children.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

Inferior temporal stream for word processing with integrated mnemonic function.

The participation of the inferior temporal cortex in visual word perception and recognition raises several questions: Is there a directed processing stream proceeding anteriorly by continuous cortical processing? How fast are words processed within such an inferior temporal stream? Does this stream support implicit or explicit memory? To answer these questions, we analyzed the spatio-temporal relationship of event-related potentials, recorded directly from the inferior temporal cortex in epilepsy patients performing a continuous visual word recognition paradigm. Event-related potentials elicited an inferior temporal positivity in a strip along the left collateral sulcus. This potential exhibited a linear (r = 0.74) peak latency progression from posterior to anterior inferior temporal regions (approximately 15 cm/sec), indicating a directed, intracortical processing stream. Peak amplitudes and latencies showed reliable old/new effects with smaller amplitudes and shorter latencies for old as opposed to new words. Although the amplitude-old/new-effect occurred for all repeated words (e.g., implicit memory), the latency-old/new-effect occurred for correctly recognized old words only (e.g., explicit recognition). These results seem to dissociate two distinct mnemonic processes. The graded decrease of mean ITP peak amplitudes and latencies, however, does not allow us to exclude a single trace model as assumed for explicit recognition memory based on familiarity (Mandler [1980]: Psychol Rev 87:252-271). Regardless whether there is a dissociation between implicit and explicit memory in inferior temporal cortex or not, our findings are in accordance with an integrated inferior temporal processing stream for words that performs continuously semantic and mnemonic operations supporting both implicit and explicit memory.

Adolescent↗