Brain Changes (brain + change)

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Brain Changes

  • structural brain change


  • Selected Abstracts


    Amygdala reduction in patients with ADHD compared with major depression and healthy volunteers

    ACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2010
    T. Frodl
    Frodl T, Stauber J, Schaaff N, Koutsouleris N, Scheuerecker J, Ewers M, Omerovic M, Opgen-Rhein M, Hampel H, Reiser M, Möller H.-J, Meisenzahl E. Amygdala reduction in patients with ADHD compared with major depression and healthy volunteers. Objective:, Results in adult attention deficit hyperactivity disorder (ADHD) on structural brain changes and the clinical relevance are contradictory. The aim of this study was to investigate whether in adult patients with ADHD hippocampal or amygdala volumes differs from that in healthy controls and patients with major depression (MD). Method:, Twenty patients with ADHD, 20 matched patients with MD and 20 healthy controls were studied with high resolution magnetic resonance imaging. Results:, Amygdala volumes in patients with ADHD were bilaterally smaller than in patients with MD and healthy controls. In ADHD, more hyperactivity and less inattention were associated with smaller right amygdala volumes, and more symptoms of depression with larger amygdala volumes. Conclusion:, This study supports findings that the amygdala plays an important role in the systemic brain pathophysiology of ADHD. Whether patients with ADHD and larger amygdala volumes are more vulnerable to affective disorders needs further investigation. [source]


    Effects of early seizures on later behavior and epileptogenicity

    DEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 2 2004
    Gregory L. Holmes
    Abstract Both clinical and laboratory studies demonstrate that seizures early in life can result in permanent behavioral abnormalities and enhance epileptogenicity. Understanding the critical periods of vulnerability of the developing nervous system to seizure-induced changes may provide insights into parallel or divergent processes in the development of autism. In experimental rodent models, the consequences of seizures are dependent on age, etiology, seizure duration, and frequency. Recurring seizures in immature rats result in long-term adverse effects on learning and memory. These behavioral changes are paralleled by changes in brain connectivity, changes in excitatory neurotransmitter receptor distribution, and decreased neurogenesis. These changes occur in the absence of cell loss. Although impaired cognitive function and brain changes have been well-documented following early-onset seizures, the mechanisms of seizure-induced dysfunction remain unclear. MRDD Research Reviews 2004;10:101,105. © 2004 Wiley-Liss, Inc. [source]


    Psychiatric epidemiology of old age: the H70 study , the NAPE Lecture 2003

    ACTA PSYCHIATRICA SCANDINAVICA, Issue 1 2004
    I. Skoog
    Objective: To describe methodological issues and possibilities in the epidemiology of old age psychiatry using data from the H70 study in Göteborg, Sweden. Method: A representative sample born during 1901,02 was examined at 70, 75, 79, 81, 83, 85, 87, 90, 92, 95, 97, 99 and 100 years of age, another during 1906,07 was examined at 70 and 79 years of age, and samples born between 1922 and 1930 were examined at 70 years of age. The study includes psychiatric examinations and key informant interviews performed by psychiatrists, physical examinations performed by geriatricians, psychometric testings, blood sampling, computerized tomographies of the brain, cerebrospinal fluid analyses, anthropometric measurements, and psychosocial background factors. Results: Mental disorders are found in approximately 30% of the elderly, but is seldom detected or properly treated. Incidence of depression and dementia increases with age. The relationship between blood pressure and Alzheimer's disease is an example of how cross-sectional and longitudinal studies yield completely different results. Brain imaging is an important tool in epidemiologic studies of the elderly to detect silent cerebrovascular disease and other structural brain changes. The high prevalence of psychotic symptoms is an example of the importance to use several sources of information to detect these symptoms. Dementia should be diagnosed in all types of studies in the elderly, as it influences several outcomes such as mortality, blood pressure, and rates of depression. Suicidal feelings are rare in the elderly and are strongly related to mental disorders. Conclusion: Modern epidemiologic studies in population samples should be longitudinal and include assessments of psychosocial risk factors as well as comprehensive sets of biologic markers, such as brain imaging, neurochemical analyses, and genetic information to maximize the contribution that epidemiology can provide to increase our knowledge about the etiology of mental disorders. [source]


    Positron emission tomography and magnetic resonance imaging in spinocerebellar ataxia type 2: a study of symptomatic and asymptomatic individuals

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2005
    A. Inagaki
    Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder characterized as an expanded CAG trinucleotide repeats in SCA2 gene resulting in abnormal polyglutamine sequence. We used positron emission tomography (PET) and magnetic resonance imaging (MRI) to clarify metabolic and atrophic changes of the brain in two symptomatic and three asymptomatic individuals who were genetically confirmed for SCA2. PET revealed decreased glucose metabolism in both patients and two of the three asymptomatic carriers in the cerebellum, pons, or both. No PET abnormality was found in the remaining one carrier who had only a very mildly expanded CAG repeat. MRI showed cerebellar and/or pontine atrophic changes in both patients and one of three carriers. The present study suggest that hypometabolism and atrophy of the cerebellum and pons may occur years before the clinical onset of SCA2. PET and MRI may be useful in the early detection of subclinical brain changes associated with SCA2. [source]


    Age- and division-of-labour-dependent differential expression of a novel non-coding RNA, Nb-1, in the brain of worker honeybees, Apis mellifera L.

    INSECT MOLECULAR BIOLOGY, Issue 6 2009
    H. Tadano
    Abstract To elucidate the molecular mechanisms underlying honeybee social behaviours, we identified a novel gene, Nb-1, whose expression in the worker brain changes according to the age-dependent division of labour in normal colonies. The open reading frames contained in the Nb-1 cDNA were not conserved in the homologue of a related species, suggesting that the Nb-1 gene product is a non-coding RNA. The distribution of Nb-1- expressing cells partially overlapped that of octopamine-immunoreactive cells and neurosecretory cells, the latter of which are involved in the synthesis and secretion of juvenile hormone (JH). Octopamine and JH control worker task transition, and thus Nb-1 might be involved in task transition through the modulation of octopamine/JH synthesis and secretion. [source]


    Coronary heart disease is associated with regional grey matter volume loss: implications for cognitive function and behaviour

    INTERNAL MEDICINE JOURNAL, Issue 7 2008
    O. P. Almeida
    Abstract Coronary heart disease (CHD) has been associated with impaired cognition, but the mechanisms underlying these changes remain unclear. We designed this study to determine whether adults with CHD show regional brain losses of grey matter volume relative to controls. We used statistical parametric mapping (SPM5) to determine regional changes in grey matter volume of T1 -weighted magnetic resonance images of 11 adults with prior history of myocardial infarction relative to seven healthy controls. All analyses were adjusted for total grey and white matter volume, age, sex and handedness. CHD participants showed a loss of grey matter volume in the left medial frontal lobe (including the cingulate), precentral and postcentral cortex, right temporal lobe and left middle temporal gyrus, and left precuneus and posterior cingulate. CHD is associated with loss of grey matter in various brain regions, including some that play a significant role in cognitive function and behaviour. The underlying causes of these regional brain changes remain to be determined. [source]


    Hippocampal volume and antidepressant response in geriatric depression

    INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 6 2002
    Ming-Hong Hsieh
    Abstract Background Biological markers of treatment response may include structural brain changes seen on neuroimaging. While most imaging studies have focused on cerebrovascular disease, evidence is growing that the hippocampus may play a role in depression, particularly geriatric depression. Method We studied 60 depressed elderly patients enrolled in a longitudinal study who were treated with antidepressant medications using a treatment guideline-based approach. Baseline and 12-week Montgomery-Asberg Depression Rating Scale (MADRS) scores were obtained via interview with a geriatric psychiatrist. All subjects had a baseline magnetic resonance imaging (MRI) brain scan. MRI scans were processed using standard protocols to determine total cerebral volume and right and left hippocampal volumes. Hippocampal volumes were standardized for total cerebral volume. MADRS scores less than 10 were used to define remission. Results When the group with the lowest quartile of standardized hippocampal volumes was compared to those above the first quartile, those with small right and total hippocampal volumes were less likely to achieve remission. In a subsequent logistic regression model controlling for age small standardized right hippocampal volumes remained significantly associated with remission. Conclusion Further studies with larger sample are needed to determine if left-right hippocampal volume differences do exist in depression, and basic neuroscience studies will need to elucidate the role of the hippocampus in geriatric depression. Copyright © 2002 John Wiley & Sons, Ltd. [source]


    Blood Pressure and Brain Injury in Older Adults: Findings from a Community-Based Autopsy Study

    JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 11 2009
    Lucy Y. Wang MD
    OBJECTIVES: To examine correlations between blood pressure (BP) and dementia-related pathological brain changes in a community-based autopsy sample. DESIGN: Prospective cohort study. SETTING: A large health maintenance organization in Seattle, Washington. PARTICIPANTS: A cohort of 250 participants aged 65 and older and cognitively normal at time of enrollment in the Adult Changes in Thought (ACT) Study and who underwent autopsy. MEASUREMENTS: BP and history of antihypertensive treatment were taken at enrollment. A linear regression model was used to examine the relationship between BP (systolic (SBP) and diastolic (DBP)) at enrollment and pathological changes in the cerebrum (cystic macroscopic infarcts, microinfarcts, neuritic plaques, neurofibrillary tangles, and cortical Lewy bodies). RESULTS: The presence of more than 2 microinfarcts, but not any other pathological change, was independently associated with SBP in younger participants (65,80, n=137) but not in older participants (>80, n=91). The relative risk (RR) for more than two microinfarcts with each 10-mmHg increase in SBP was 1.15 (95% confidence interval (CI)=1.00,1.33) in the younger participants, adjusted for age at entry, sex, and time to death. This RR was particularly strong in younger participants not taking antihypertensive medications (RR=1.48, 95% CI=1.21, 1.81); significant associations were not observed in participants treated for hypertension. Findings for DBP were negative. CONCLUSION: The association between high SBP and cerebrovascular damage in untreated older adults (65,80) suggests that adequate hypertension treatment may reduce dementia risk by minimizing microvascular injury to cerebrum. [source]


    Aging-dependent changes of microglial cells and their relevance for neurodegenerative disorders

    JOURNAL OF NEUROCHEMISTRY, Issue 5 2010
    Rommy Von Bernhardi
    J. Neurochem. (2010) 112, 1099,1114. Abstract Among multiple structural and functional brain changes, aging is accompanied by an increase of inflammatory signaling in the nervous system as well as a dysfunction of the immune system elsewhere. Although the long-held view that aging involves neurocognitive impairment is now dismissed, aging is a major risk factor for neurodegenerative diseases such as Alzheimer`s disease, Parkinson`s disease and Huntington's disease, among others. There are many age-related changes affecting the brain, contributing both to certain declining in function and increased frailty, which could singly and collectively affect neuronal viability and vulnerability. Among those changes, both inflammatory responses in aged brains and the altered regulation of toll like receptors, which appears to be relevant for understanding susceptibility to neurodegenerative processes, are linked to pathogenic mechanisms of several diseases. Here, we review how aging and pro-inflammatory environment could modulate microglial phenotype and its reactivity and contribute to the genesis of neurodegenerative processes. Data support our idea that age-related microglial cell changes, by inducing cytotoxicity in contrast to neuroprotection, could contribute to the onset of neurodegenerative changes. This view can have important implications for the development of new therapeutic approaches. [source]


    Preference Conditioning in Healthy Individuals: Correlates With Hazardous Drinking

    ALCOHOLISM, Issue 6 2010
    Iris M. Balodis
    Background:, Conditioned reward is a classic measure of drug-induced brain changes in animal models of addiction. The process can be examined in humans using the Conditioned Pattern Preference (CPP) task, in which participants associate nonverbal cues with reward but demonstrate low awareness of this conditioning. Previously, we reported that alcohol intoxication does not affect CPP acquisition in humans, but our data indicated that prior drug use may impact conditioning scores. Methods:, To test this possibility, the current study examined the relationship between self-reported alcohol use and preference conditioning in the CPP task. Working memory was assessed during conditioning by asking participants to count the cues that appeared at each location on a computer screen. Participants (69 female and 23 male undergraduate students) completed the Alcohol Use Disorders Identification Test (AUDIT) and the Rutgers Alcohol Problem Index (RAPI) as measures of hazardous drinking. Results:, Self-reported hazardous drinking was significantly correlated with preference conditioning in that individuals who scored higher on these scales exhibited an increased preference for the reward-paired cues. In contrast, hazardous drinking did not affect working memory errors on the CPP task. Conclusions:, These findings support evidence that repeated drug use sensitizes neural pathways mediating conditioned reward and point to a neurocognitive disposition linking substance misuse and responses to reward-paired stimuli. The relationship between hazardous drinking and conditioned reward is independent of changes in cognitive function, such as working memory. [source]


    Convergence, Degeneracy, and Control

    LANGUAGE LEARNING, Issue 2006
    David W. Green
    Understanding the neural representation and control of language in normal bilingual speakers provides insights into the factors that constrain the acquisition of another language, insights into the nature of language expertise, and an understanding of the brain as an adaptive system. We illustrate both functional and structural brain changes associated with acquiring other languages and discuss the value of neuroimaging data in identifying individual differences and different phenotypes. Understanding normal variety is vital too if we are to understand the consequences of brain damage in bilingual and polyglot speakers. [source]


    Cerebral oedema in minimal hepatic encephalopathy due to extrahepatic portal venous obstruction

    LIVER INTERNATIONAL, Issue 8 2010
    Amit Goel
    Abstract Background: Minimal hepatic encephalopathy (MHE) has recently been reported in patients with extrahepatic portal venous obstruction (EHPVO). Aims: To evaluate brain changes by magnetic resonance studies in EHPVO patients. Methods: Blood ammonia level, critical flicker frequency (CFF), brain metabolites on 1H-magnetic resonance (MR) spectroscopy and brain water content on diffusion tensor imaging and magnetization transfer ratio (MTR) were studied in 31 EHPVO patients with and without MHE, as determined by neuropsychological tests. CFF and magnetic resonance imaging studies were also performed in 23 controls. Results: Fourteen patients (14/31, 45%) had MHE. Blood ammonia level was elevated in all, being significantly higher in the MHE than no MHE group. CFF was abnormal in 13% (4/31) with EHPVO and in 21% (3/14) with MHE. On 1H-MR spectroscopy, increased Glx/Cr, decreased mIns/Cr, and no change in Cho/Cr were noted in patients with MHE compared with controls. Significantly increased mean diffusivity (MD) and decreased (MTR) were observed in the MHE group, suggesting presence of interstitial cerebral oedema (ICE). MD correlated positively with blood ammonia level (r=0.65, P=0.003) and Glx (r=0.60, P=0.003). Discussion: MHE was detected in 45% of patients with EHPVO while CFF was abnormal in only 13%. ICE was present in 7/10 brain regions examined, particularly in those with MHE. Hyperammonaemia elevated cerebral Glx levels correlated well with ICE. Conclusions: MHE was common in EHPVO; CFF could identify it only in a minority. ICE was present in EHPVO, particularly in those with MHE. It correlated with blood ammonia and Glx/Cr levels. Hyperammonaemia seems to contribute to ICE in EHPVO. [source]


    Structural white matter abnormalities in patients with idiopathic dystonia

    MOVEMENT DISORDERS, Issue 8 2007
    Leonardo Bonilha MD
    Abstract We investigated whether structural white matter abnormalities, in the form of disruption of axonal coherence and integrity as measured with diffusion tensor imaging (DTI), constitute an underlying pathological mechanism of idiopathic dystonia (ID), independent of genotype status. We studied seven subjects with ID: all had cervical dystonia as their main symptom (one patient also had spasmodic dysphonia and two patients had concurrent generalized dystonia, both DYT1-negative). We compared DTI MR images of patients with 10 controls, evaluating differences in mean diffusivity (MD) and fractional anisotropy (FA). ID was associated with increased FA values in the thalamus and adjacent white matter, and in the white matter underlying the middle frontal gyrus. ID was also associated with increase in MD in adjacent white matter to the pallidum and putamen bilaterally, left caudate, and in subcortical hemispheric regions, including the postcentral gyrus. Abnormal FA and MD in patients with ID indicate that abnormal axonal coherence and integrity contribute to the pathophysiology of dystonia. These findings suggest that ID is not only a functional disorder, but also associated with structural brain changes. Impaired connectivity and disrupted flow of information may contribute to the impairment of motor planning and regulation in dystonia. © 2006 Movement Disorder Society [source]


    Cognitive reserve hypothesis: Pittsburgh Compound B and fluorodeoxyglucose positron emission tomography in relation to education in mild Alzheimer's disease

    ANNALS OF NEUROLOGY, Issue 1 2008
    Nina M. Kemppainen MD
    Objective The reduced risk for Alzheimer's disease (AD) in high-educated individuals has been proposed to reflect brain cognitive reserve, which would provide more efficient compensatory mechanisms against the underlying pathology, and thus delayed clinical expression. Our aim was to find possible differences in brain amyloid ligand 11C-labeled Pittsburgh Compound B ([11C]PIB) uptake and glucose metabolism in high- and low-educated patients with mild AD. Methods Twelve high-educated and 13 low-educated patients with the same degree of cognitive deterioration were studied with PET using [11C]PIB and 18F-fluorodeoxyglucose as ligands. The between-group differences were analyzed with voxel-based statistical method, and quantitative data were obtained with automated region-of-interest analysis. Results High-educated patients showed increased [11C]PIB uptake in the lateral frontal cortex compared with low-educated patients. Moreover, high-educated patients had significantly lower glucose metabolic rate in the temporoparietal cortical regions compared with low-educated patients. Interpretation Our results suggesting more advanced pathological and functional brain changes in high-educated patients with mild AD are in accordance with the brain cognitive reserve hypothesis and point out the importance of development of reliable markers of underlying AD pathology for early AD diagnostics. Ann Neurol 2007 [source]


    Early magnetic resonance imaging findings in patients receiving tissue plasminogen activator predict outcome: Insights into the pathophysiology of acute stroke in the thrombolysis era,

    ANNALS OF NEUROLOGY, Issue 1 2004
    Julio A. Chalela MD
    We measured ischemic brain changes with diffusion and perfusion MRI in 42 ischemic stroke patients before and 2 hours (range approximately 1.5 to 4.5 hours) after standard intravenous tissue plasminogen activator (tPA) therapy. The median time from stroke onset to tPA was 131 minutes. Clinical and MRI variables (change in perfusion and/or diffusion weighted lesion volume) were compared between those with excellent outcome defined as 3-month modified Rankin score (mRS) of 0 to 1 and those with incomplete recovery (mRS >1). In multivariate logististic regression analysis, the most powerful independent predictor for excellent outcome was improved brain perfusion: hypoperfusion volume on mean transit time (MTT) map decrease >30% from baseline to 2-hour post tPA scan (p=0.009; odds ratio [95% confidence interval], 20.7 [2.1-203.9]). Except for age < 70 years, no other baseline clinical or imaging variable was an independent predictor of outcome. We propose MTT lesion volume decrease more than 30% 2 hours after tPA as an early marker of long-term clinical benefit of thrombolytic therapy. [source]


    Neuropsychological dysfunction in bipolar affective disorder: a critical opinion

    BIPOLAR DISORDERS, Issue 3 2005
    Jonathan Savitz
    Data from the imaging literature have led to suggestions that permanent structural brain changes may be associated with bipolar disorder. Individuals diagnosed with bipolar disorder display deficits on a range of neuropsychological tasks in both the acute and euthymic phases of illness, and correlations between experienced number of affective episodes and task performance are commonly reported. These findings have renewed interest in the neuropsychological profile of individuals with bipolar disorder, with deficits of attention, learning and memory, and executive function, asserted to be present. This paper critically reviews five different potential causes of neurocognitive dysfunction in bipolar disorder: (i) iatrogenic, (ii) acute functional changes associated with depression or mania, (iii) permanent structural lesions of a neurodegenerative origin, (iv) permanent structural lesions that are neurodevelopmental in origin, and (v) permanent functional changes that are most likely genetic in origin. Although the potential cognitive effects of residual symptomatology and long-term medication use cannot be entirely excluded, we conclude that functional changes associated with genetically driven population variation in critical neural networks underpin both the neurocognitive and affective symptoms of bipolar disorder. The philosophical implications of this conclusion for neuropsychology are briefly discussed. [source]


    Progressive brain changes in schizophrenia: a 1-year follow-up study of diffusion tensor imaging

    ACTA NEUROPSYCHIATRICA, Issue 6 2009
    Miho Ota
    Objective: Recent cross-sectional studies suggest that brain changes in schizophrenia are progressive during the course of the disorder. However, it remains unknown whether this is a global process or whether some brain areas are affected to a greater degree. The aim of this study was to examine the longitudinal brain changes in patients with chronic older schizophrenia by magnetic resonance imaging (MRI). Methods: Three-dimensional (3D) T1-weighted and diffusion tensor (DT) MRI were performed twice on each of 16 chronic older schizophrenia patients (mean age = 58.1 ± 6.7 years ) with an interval of 1 year between imaging sessions. To clarify the longitudinal morphological and white matter changes, volume data and normalised diffusion tensor imaging (DTI) metrics were compared between the first and follow-up studies using a paired t -test. Results: Focal cortical volume loss was observed in the left prefrontal lobe and anterior cingulate on volumetric study. In addition, DTI metrics changed significantly at the bilateral posterior superior temporal lobes, left insula, genu of the corpus callosum and anterior cingulate. Conclusion: There are ongoing changes in the brains of schizophrenic patients during the course of the illness. Discrepancies between volume data and DTI metrics may indicate that the pattern of progressive brain changes varies according to brain region. [source]


    Do psychotherapies produce neurobiological effects?

    ACTA NEUROPSYCHIATRICA, Issue 2 2006
    Veena Kumari
    Background:, An area of recent interest in psychiatric research is the application of neuroimaging techniques to investigate neural events associated with the development and the treatment of symptoms in a number of psychiatric disorders. Objective:, To examine whether psychological therapies modulate brain activity and, if so, to examine whether these changes similar to those found with relevant pharmacotherapy in various mental disorders. Methods:, Relevant data were identified from Pubmed and PsycInfo searches up to July 2005 using combinations of keywords including ,psychological therapy', ,behaviour therapy', ,depression', ,panic disorder', ,phobia', ,obsessive compulsive disorder', ,schizophrenia', ,psychosis', ,brain activity', ,brain metabolism', ,PET', ,SPECT' and ,fMRI'. Results:, There was ample evidence to demonstrate that psychological therapies produce changes at the neural level. The data, for example in depression, panic disorder, phobia and obsessive compulsive disorder (OCD), clearly suggested that a change in patients' symptoms and maladaptive behaviour at the mind level with psychological techniques is accompanied with functional brain changes in relevant brain circuits. In many studies, cognitive therapies and drug therapies achieved therapeutic gains through the same neural pathways although the two forms of treatment may still have different mechanisms of action. Conclusions:, Empirical research indicates a close association between the ,mind' and the ,brain' in showing that changes made at the mind level in a psychotherapeutic context produce changes at the brain level. The investigation of changes in neural activity with psychological therapies is a novel area which is likely to enhance our understanding of the mechanisms for therapeutic changes across a range of disorders. [source]


    Diagnosis of perinatal stroke I: definitions, differential diagnosis and registration

    ACTA PAEDIATRICA, Issue 10 2009
    P Govaert
    Abstract Introduction:, Perinatal stroke can be divided into three subtypes: ischaemic stroke, either arterial or sinovenous and haemorrhagic stroke. For the sake of universal registration and to perform intervention studies, we propose a detailed diagnostic registration system for perinatal stroke taking 10 variables into account. These variables are discussed here and in the accompanying article. Material and results:, Differentiation is needed from focal brain changes as a result of disorders other than stroke, whereby accurate timing is possible only when early neonatal imaging is available. Detailed templates are presented for arterial and venous vascular classification. AIS is further subdivided into single territory and complex infarction and some stratification is proposed in the complicated stroke group. This registration system has been applied to a retrospective cohort of 134 newborns with stroke (single-centre observation from 1999 to 2007) and the results are compared with published data. By applying this registration system, intervention studies for one homogeneous stroke type (e.g. complete middle cerebral artery stroke) may be facilitated. Conclusion:, Ten variables may be sufficient to register a perinatal stroke. These include gestational age, birthweight, gender, delivery mode, time of detection, presentation, type of stroke, vessel affected or type of cavity, imaging method at detection and clinical context. [source]