RESUMO
The structures of our mind may be understood as 'frames', which play a key role in our everyday goals, choices and decisions. Understanding these often unconscious processes may help us to understand the complex decisions we make in our clinical practice. Such frames may be many in number, being based, for example, on medical, psychological, social, trauma, or problem-solving models. The 'frames' we use in our clinical decisions should be tailored to the needs of our patients, and may need to be adapted at different phases of illness.
Assuntos
Tomada de Decisão Clínica , Psiquiatria/métodos , HumanosRESUMO
OBJECTIVE: Exposure to prenatal stress is a ubiquitous and non-specific risk factor for adverse outcomes in adulthood. In this study, we examined associations between exposure to subjective maternal stress during pregnancy and subsequent diagnosis of psychiatric disorders in offspring. METHOD: This study used the Helsinki Longitudinal Temperament Cohort, a prospective birth cohort of individuals born between 1 July 1975 and 30 June 1976 in Helsinki, Finland. The sample for this study comprised 3626 infants whose mothers had completed health and well-being assessments during pregnancy which included a measure of self-reported stress. We ran logistic regressions to assess potential associations between prenatal stress and offspring psychiatric disorder in adulthood, identified through the Finnish Hospital Discharge Register. RESULTS: Individuals whose mothers reported stress during pregnancy had significantly greater odds of developing a psychiatric disorder (OR = 1.41, 95% CI = 1.10-1.81) particularly a mood disorder (OR = 1.67, 95% CI = 1.10-2.54). These associations remained after adjusting for parental psychiatric history, and other prenatal factors. CONCLUSIONS: Individuals exposed to prenatal stress had significantly increased risk of developing psychiatric disorders later in life. This finding highlights the importance of supporting the mental health and emotional well-being of women during pregnancy.
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Transtornos Mentais/epidemiologia , Efeitos Tardios da Exposição Pré-Natal/epidemiologia , Sistema de Registros/estatística & dados numéricos , Estresse Psicológico/epidemiologia , Adulto , Transtornos de Ansiedade/epidemiologia , Feminino , Finlândia/epidemiologia , Humanos , Estudos Longitudinais , Masculino , Transtornos do Humor/epidemiologia , Gravidez , Transtornos Psicóticos/epidemiologiaRESUMO
Neurodevelopment is an area of psychiatry which has attracted huge interest in the last few decades. There is substantial evidence that perinatal events can contribute to later development of mental disorder. In the current perspective article we propose a novel polyvagal theory which attempts to link prenatal events with neurodevelopment and the later onset of psychiatric disorder.
Assuntos
Sistema Nervoso Autônomo/fisiologia , Transtornos Mentais/diagnóstico , Psiquiatria , Nervo Vago/fisiologia , Humanos , Modelos Neurológicos , Cuidado Pré-NatalRESUMO
Structuring metallic and magnetic materials on subwavelength scales allows for extreme confinement and a versatile design of electromagnetic field modes. This may be used, for example, to enhance magneto-optical responses, to control plasmonic systems using a magnetic field, or to tailor magneto-optical properties of individual nanostructures. Here we show that periodic rectangular arrays of magnetic nanoparticles display surface plasmon modes in which the two directions of the lattice are coupled by the magnetic field-controllable spin-orbit coupling in the nanoparticles. When breaking the symmetry of the lattice, we find that the optical response shows Fano-type surface lattice resonances whose frequency is determined by the periodicity orthogonal to the polarization of the incident field. In striking contrast, the magneto-optical Kerr response is controlled by the period in the parallel direction. The spectral separation of the response for longitudinal and orthogonal excitations provides versatile tuning of narrow and intense magneto-optical resonances.
RESUMO
Chirality is one of the most fundamental and essential structural properties of biological molecules. Many important biological molecules including amino acids and polysaccharides are intrinsically chiral. Conventionally, chiral species can be distinguished by interaction with circularly polarized light, and circular dichroism is one of the best-known approaches for chirality detection. As a linear optical process, circular dichroism suffers from very low signal contrast and lack of spatial resolution in the axial direction. It has been demonstrated that by incorporating nonlinear interaction with circularly polarized excitation, second-harmonic generation circular dichroism can provide much higher signal contrast. However, previous circular dichroism and second-harmonic generation circular dichroism studies are mostly limited to probe chiralities at surfaces and interfaces. It is known that second-harmonic generation, as a second-order nonlinear optical effect, provides excellent optical sectioning capability when combined with a laser-scanning microscope. In this work, we combine the axial resolving power of second-harmonic generation and chiral sensitivity of second-harmonic generation circular dichroism to realize three-dimensional chiral detection in biological tissues. Within the point spread function of a tight focus, second-harmonic generation circular dichroism could arise from the macroscopic supramolecular packing as well as the microscopic intramolecular chirality, so our aim is to clarify the origins of second-harmonic generation circular dichroism response in complicated three-dimensional biological systems. The sample we use is starch granules whose second-harmonic generation-active molecules are amylopectin with both microscopic chirality due to its helical structure and macroscopic chirality due to its crystallized packing. We found that in a starch granule, the second-harmonic generation for right-handed circularly polarized excitation is significantly different from second-harmonic generation for left-handed one, offering excellent second-harmonic generation circular dichroism contrast that approaches 100%. In addition, three-dimensional visualization of second-harmonic generation circular dichroism distribution with sub-micrometer spatial resolution is realized. We observed second-harmonic generation circular dichroism sign change across the starch granules, and the result suggests that in thick biological tissue, second-harmonic generation circular dichroism arises from macroscopic molecular packing. Our result provides a new method to visualize the organization of three-dimensional structures of starch granules. The second-harmonic generation circular dichroism imaging method expands the horizon of nonlinear chiroptical studies from simplified surface/solution environments to complicated biological tissues.
Assuntos
Dicroísmo Circular/métodos , Imageamento Tridimensional/métodos , Amido/química , Solanum tuberosum/químicaRESUMO
We provide evidence that the chirality of collagen can give rise to strong second-harmonic generation circular dichroism (SHG-CD) responses in nonlinear microscopy. Although chirality is an intrinsic structural property of collagen, most of the previous studies ignore that property. We demonstrate chiral imaging of individual collagen fibers by using a laser scanning microscope and type-I collagen from pig ligaments. 100% contrast level of SHG-CD is achieved with sub-micrometer spatial resolution. As a new contrast mechanism for imaging chiral structures in bio-tissues, this technique provides information about collagen morphology and three-dimensional orientation of collagen molecules.
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Proton magnetic resonance spectroscopy ((1)H MRS) neurometabolite abnormalities have been detected widely in subjects with and at risk for schizophrenia. We hypothesized that such abnormalities would be present both in patients with schizophrenia and in their unaffected twin siblings. We acquired magnetic resonance spectra (TR/TE=3000/30 ms) at voxels in the mesial prefrontal gray matter, left prefrontal white matter and left hippocampus in 14 twin pairs discordant for schizophrenia (2 monozygotic, 12 dizygotic), 13 healthy twin pairs (4 monozygotic, 9 dizygotic) and 1 additional unaffected co-twin of a schizophrenia proband. In the mesial prefrontal gray matter voxel, N-acetylaspartate (NAA), creatine+phosphocreatine (Cr), glycerophosphocholine+phosphocholine (Cho) and myo-inositol (mI) did not differ significantly between patients with schizophrenia, their unaffected co-twins or healthy controls. However, glutamate (Glu) was significantly lower in patients with schizophrenia (31%, percent difference) and unaffected co-twins (21%) than in healthy controls (collapsed across twin pairs). In the left hippocampus voxel, levels of NAA (23%), Cr (22%) and Cho (36%) were higher in schizophrenia patients compared with controls. Hippocampal NAA (25%), Cr (22%) and Cho (37%) were also significantly higher in patients than in their unaffected co-twins. Region-to-region differences in metabolite levels were also notable within all three diagnosis groups. These findings suggest that (1)H MRS neurometabolite abnormalities are present not only in patients with schizophrenia, but also in their unaffected co-twins. Thus, reduced mesial prefrontal cortical Glu and elevated hippocampal NAA, Cr and Cho may represent trait markers of schizophrenia risk and, when exacerbated, state markers of schizophrenia itself.
Assuntos
Espectroscopia de Ressonância Magnética/métodos , Esquizofrenia/metabolismo , Gêmeos Dizigóticos/metabolismo , Gêmeos Monozigóticos/metabolismo , Ácido Aspártico/análogos & derivados , Creatina/metabolismo , Feminino , Ácido Glutâmico/metabolismo , Glicerilfosforilcolina/metabolismo , Hipocampo/metabolismo , Humanos , Inositol/metabolismo , Masculino , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Amielínicas/metabolismo , Fosfocreatina/metabolismo , Fosforilcolina/metabolismo , Córtex Pré-Frontal/metabolismo , Prótons , Esquizofrenia/diagnóstico , Gêmeos Dizigóticos/psicologia , Gêmeos Monozigóticos/psicologiaRESUMO
BACKGROUND: Numerous mast cells are present in chronic leg ulcers. Tryptase and chymase are the major mediators of mast cells, but their significance is mostly dependent on their activity. In addition, the proteinases may affect ulcer epithelialization. OBJECTIVES: To study levels and activity of tryptase and chymase in wash samples and biopsies from chronic leg ulcers and the possible effect of these proteinases on keratinocyte growth and adherence. METHODS: Wash samples were taken from 16 patients and a superficial shave biopsy was taken in eight of these patients; a second biopsy series was obtained from the edge of chronic venous leg ulcers (n = 6). RESULTS: Significant levels of soluble tryptase activity and histamine, but low levels of chymase activity, were measured in wash samples from chronic ulcers. No tryptase-inhibiting activity, but clear chymase-inhibiting activity, was detected in the wash samples. In superficial wound bed biopsies, relatively marked levels of chymase activity together with histamine and tryptase activity were detected. In the second biopsy series, about 80% of the mast cells belonged to the MC(TC) type (tryptase- and chymase-immunopositive). However, about 55-61% of the chymase-immunopositive cells displayed chymase activity and 64 +/- 17% of the tryptase-positive cells revealed immunoreactivity of alpha(1)-antichymotrypsin. As the activity of chymase and tryptase was detected in the ulcer base in a ratio of 1:8, a preparation containing both chymase and tryptase was partially purified from human skin yielding a similar activity ratio of 1:11-13. Treatment of fibronectin-coated plastic surfaces with this preparation decreased the adherence of cultured human keratinocytes, this effect being attributable mainly to chymase. In 2-day cultures using growth factor/serum-deficient low- or high-calcium medium, the tryptase-chymase preparation inhibited the slow growth and at higher concentrations it even induced detachment of keratinocytes. This effect was attributed to chymase, and it was partially regulated by heparin and histamine. CONCLUSIONS: Even though chymase is partially inactivated in chronic leg ulcers, accumulated mast cells in the close proximity of the epithelium edge and their chymase may impair keratinocyte adherence and migration.
Assuntos
Queratinócitos/enzimologia , Úlcera da Perna/enzimologia , Mastócitos/enzimologia , Serina Endopeptidases/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Cálcio/metabolismo , Adesão Celular , Células Cultivadas , Doença Crônica , Quimases , Ativação Enzimática/efeitos dos fármacos , Epitélio/enzimologia , Feminino , Histamina/análise , Humanos , Úlcera da Perna/metabolismo , Masculino , Pessoa de Meia-Idade , Inibidores de Proteases/uso terapêutico , Triptases , Úlcera Varicosa/enzimologia , Cicatrização , alfa 1-Antiquimotripsina/análiseRESUMO
Two experiments were conducted to compare thec ries of the functional organization of spatial working memory within the human prefrontal cortex. In Experiment I, memory set size for locations was parametrically varied, allowing for the assessment of BOLD signal across maintenance requirements. In the sec ond experiment, manipulation of spatial information held in working memory was contrasted with simple maintenance of that information. Both experiment evoked significant activity in a distributed spatia working memory network. Although dorsolateral prefrontal activation increased monotonically with memory set size, this region was differentially engaged in task conditions involving explicit manipulation of in ternal representations. Activation in the superior frontal sulcal region was associated with maintenance of spatial information, increasing with memory se size. In contrast, ventrolateral prefrontal activation was present only at the highest memory set size, possibly due to the differential use of organizational strategies with more complex stimuli. These results sup port claims that the dorsolateral prefrontal cortex is involved in the manipulation of internal representa tions and that the superior frontal sulcal region is involved in the maintenance of spatial information but they suggest a complex role for the ventrolatera prefrontal region.
Assuntos
Memória de Curto Prazo/fisiologia , Córtex Pré-Frontal/fisiologia , Percepção Espacial/fisiologia , Algoritmos , Comportamento/fisiologia , Imagem Ecoplanar , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imaginação/fisiologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Córtex Pré-Frontal/anatomia & histologia , Desempenho Psicomotor/fisiologia , Campos Visuais/fisiologiaRESUMO
Here we report on detailed three-dimensional maps revealing how brain structure is influenced by individual genetic differences. A genetic continuum was detected in which brain structure was increasingly similar in subjects with increasing genetic affinity. Genetic factors significantly influenced cortical structure in Broca's and Wernicke's language areas, as well as frontal brain regions (r2(MZ) > 0.8, p < 0.05). Preliminary correlations were performed suggesting that frontal gray matter differences may be linked to Spearman's g, which measures successful test performance across multiple cognitive domains (p < 0.05). These genetic brain maps reveal how genes determine individual differences, and may shed light on the heritability of cognitive and linguistic skills, as well as genetic liability for diseases that affect the human cortex.
Assuntos
Padronização Corporal/genética , Mapeamento Encefálico , Córtex Cerebral/embriologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Inteligência/genética , Estudos em Gêmeos como Assunto , Gêmeos/genética , Adulto , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/fisiologia , Cognição/fisiologia , Metabolismo Energético/genética , Feminino , Lateralidade Funcional/genética , Humanos , Processamento de Imagem Assistida por Computador , Idioma , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Gêmeos Dizigóticos/genética , Gêmeos Monozigóticos/genética , Comportamento Verbal/fisiologiaRESUMO
The interactions of three neuroleptic drugs, clozapine (CLZ), chlorpromazine (CPZ), and haloperidol (HPD) with phospholipids were compared using DSC and Langmuir balance. Main emphasis was on the drug-induced effects on the lateral organization of lipid mixtures of the saturated zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and the unsaturated acidic phosphatidylserine, brainPS. In multilamellar vesicles (MLV) phase separation was observed by DSC at X(PS)> or =0.05. All three drugs bound to these MLVs, abolishing the pretransition at X(drug)> or =0.03. The main transition temperature (T(m)) decreased almost linearly with increasing contents of the drugs, CLZ having the smallest effect. In distinction from the other two drugs, CLZ abolished the phase separation evident in the endotherms for DPPC/brainPS (X(PS)=0.05) MLVs. Compression isotherms of DPPC/brainPS/drug (X(PS)=X(drug)=0.05) monolayers revealed the neuroleptics to increase the average area/molecule, CLZ being the most effective. Penetration into brainPS monolayers showed strong interactions between the three drugs and this acidic phospholipid (in decreasing order CPZ>HPD>CLZ). Hydrophobic interactions demonstrated using neutral eggPC monolayers decreased in a different order, CLZ>CPZ>HPD. Fluorescence microscopy revealed domain morphology of DPPC/brainPS monolayers to be modulated by these drugs, increasing the gel-fluid domain boundary length in the phase coexistence region. To conclude, our data support the view that membrane-partitioning drugs could exert part of their effects by changing the lateral organization and thus also the functions of biomembranes.
Assuntos
Clorpromazina/farmacologia , Clozapina/farmacologia , Haloperidol/farmacologia , Lipídeos de Membrana/metabolismo , Membranas Artificiais , Antipsicóticos/metabolismo , Antipsicóticos/farmacologia , Varredura Diferencial de Calorimetria/métodos , Clorpromazina/metabolismo , Clozapina/metabolismo , Haloperidol/metabolismo , Lipossomos/química , Lipossomos/metabolismo , Lipídeos de Membrana/química , Microscopia de Fluorescência/métodosRESUMO
Mast cells are suggested to participate in regenerative processes, but their influence on epithelialization and wound healing has not been well studied. Since mast cells can be found in contact with epidermis in chronic inflammatory skin diseases and venous ulcers, the effect of mast cells on keratinocyte growth was studied. Keratinocytes were cultured in serum-free conditions with (complete medium) or without (basal medium) epidermal growth factor (EGF) and bovine pituitary extract (BPE) to reach subconfluence in a 24-well plate, and the cells were treated with different mast cell mediators histamine, heparin and tryptase, or lysate from HMC-1 cells, a human leukemic mast cell line. Whole skin cultures were used as a model for in vitro wounds to study the effect of mast cells on epithelial outgrowth from skin specimens. Histamine inhibited 3H-thymidine incorporation of keratinocytes dose-dependently by 29% at 1 mM, and 89% at 5 mM histamine. In whole skin culture, histamine inhibited epithelial outgrowth dose-dependently by 64% already at 0.1 mM histamine and maximally (91%) at 1 mM histamine. Heparin inhibited 3H-thymidine incorporation dose-dependently by up to 33% at 2 microg/ml in the absence, but not in the presence, of EGF/BPE. In contrast, in whole skin culture, heparin first inhibited the epithelial outgrowth by up to 27% at 2 microg/ml, but then reversed the inhibition to 30% stimulation at 200 microg/ml. Skin tryptase (0.0285 to 2.85 microg/ml) with or without heparin (0.5 to 20 microg/ml) did not affect thymidine incorporation in keratinocytes. Lysate from HMC-1 cells, but not that from control, neuroblastoma cells, inhibited 3H-thymidine incorporation in keratinocytes dose-dependently, and maximal (47%) inhibition was reached with 16,700 lysed HMC-1 cells/ml. In whole skin culture, HMC-1 lysate inhibited the epithelial outgrowth by up to 36% at 67,000 lysed cells/ml. The results show that mast cells and their mediators are inhibitory to keratinocyte 3H-thymidine incorporation and epithelial outgrowth in vitro, although, the inhibitory effect of histamine was seen at high concentrations suggesting a requirement for close morphologic vicinity of mast cells to keratinocytes. Thus, mast cells are assumed to control epidermal regeneration and to impair epithelialization of chronic ulcers.
Assuntos
Queratinócitos/citologia , Mastócitos/fisiologia , Pele/citologia , Divisão Celular/fisiologia , Extratos Celulares/farmacologia , Células Cultivadas , Técnicas de Cultura , Heparina/farmacologia , Histamina/farmacologia , Humanos , Queratinócitos/metabolismo , Serina Endopeptidases/farmacologia , Timidina/antagonistas & inibidores , Timidina/metabolismo , Triptases , Células Tumorais Cultivadas/química , Células Tumorais Cultivadas/fisiologiaRESUMO
Several studies indicate an association between human leukocyte antigens (HLA) and clozapine-induced agranulocytosis. The authors have previously reported a significantly increased frequency of HLA-A1 among patients with schizophrenia who do not respond to conventional drugs, but do respond to clozapine treatment. In this study, the authors addressed the question of whether the same association is found in patients developing granulocytopenia or agranulocytosis. The frequency of the HLA-A1 allele in patients with clozapine-induced agranulocytosis or granulocytopenia was low (11.5%), whereas HLA-A1 was associated with a good therapeutic response to clozapine at an allele frequency of 58%. The frequency of HLA-A1 is 20% in the Finnish population. These results suggest that HLA-A1 may predict a good therapeutic outcome and a low risk of agranulocytosis and, thus, enable defining a subgroup of patients with schizophrenia in whom clozapine treatment could be started early to stop the disease from progressing.
Assuntos
Agranulocitose/genética , Antipsicóticos/uso terapêutico , Clozapina/uso terapêutico , Antígeno HLA-A1/genética , Esquizofrenia/genética , Adulto , Idoso , Agranulocitose/induzido quimicamente , Antipsicóticos/efeitos adversos , Clozapina/efeitos adversos , Feminino , Frequência do Gene , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Fatores de Risco , Esquizofrenia/complicações , Esquizofrenia/tratamento farmacológicoAssuntos
Identidade de Gênero , Comportamento Sexual , Socialização , Feminino , Humanos , Relações Interpessoais , Amor , Masculino , Sexualidade , Direitos da MulherAssuntos
Recursos em Saúde/tendências , Transtornos Mentais/terapia , Guias de Prática Clínica como Assunto , Competência Clínica , Medicina Baseada em Evidências , Recursos em Saúde/economia , Humanos , Transtornos Mentais/economia , Transtornos Mentais/prevenção & controle , Assistência ao Paciente/normas , Psiquiatria/tendências , Resultado do TratamentoRESUMO
Mast cells can be found in contact with epidermis in certain circumstances; especially in chronic inflammatory skin diseases and chronic ulcers, but the significance of this association is obscure. In this study, the association of mast cells with wound healing was studied by counting mast cells in the wound edges at different stages after wounding the donor site skin for pinch-grafting. Chronic venous leg ulcers were biopsed for comparison. Tryptase- and chymase-positive mast cells were stained enzyme-histochemically for active proteinases. Both the number of tryptase-positive, i.e. total mast cells, and chymase-positive mast cells decreased during wound healing, but only the change in chymase-positive mast cells was statistically significant (P< or =0.03) the maximal decrease being 63% on day 7. No mast cells could be found in the vicinity of epithelialization margin. In venous leg ulcers, significantly more mast cells were present in the perilesional skin near the epithelium margin than in the wound bed (P=0.03), and mast cells were also seen in close contact with the basement membrane. Immunoreactivity for IL-4 and TNF-alpha in mast cells was studied to see if either of these molecules was associated with wound healing. In normally healing wounds, only a minority of mast cells were immunoreactive for these cytokines and no change in positive mast cell numbers could be seen during wound healing. In chronic wounds, IL-4 was absent in mast cells, and TNF-alpha positive mast cells were present only in perilesional skin and in small numbers. These results show that mast cells especially chymase-positive - decrease in number and can not be found in the epithelialization zone in normal wound healing, whereas tryptase-positive mast cells are associated with delayed wound healing and epithelialization in chronic wounds. Thus it seems, that mast cells attempt to control hyperproliferation of epidermis in chronic wounds.
Assuntos
Mastócitos/enzimologia , Serina Endopeptidases/metabolismo , Pele/enzimologia , Pele/lesões , Adulto , Idoso , Idoso de 80 Anos ou mais , Contagem de Células , Doença Crônica , Quimases , Epitélio/enzimologia , Epitélio/patologia , Humanos , Mastócitos/patologia , Pessoa de Meia-Idade , Pele/patologia , Triptases , Úlcera Varicosa/enzimologia , Úlcera Varicosa/patologia , Cicatrização/fisiologiaRESUMO
While genetic influences in schizophrenia are substantial, the disorder's molecular genetic basis remains elusive. Progress has been hindered by lack of means to detect nonpenetrant carriers of the predisposing genes and by uncertainties concerning the extent of locus heterogeneity. One approach to solving this complexity is to examine the inheritance of pathophysiological processes mediating between genotype and disease phenotype. Here we evaluate whether deficits in neurocognitive functioning covary with degree of genetic relationship with a proband in the unaffected MZ and DZ co-twins of patients with schizophrenia. Twin pairs discordant for schizophrenia were recruited from a total population cohort and were compared with a demographically balanced sample of control twin pairs, on a comprehensive neuropsychological test battery. The following four neuropsychological functions contributed uniquely to the discrimination of degree of genetic loading for schizophrenia and, when combined, were more highly correlated within MZ pairs than within DZ pairs, in both discordant and control twins: spatial working memory (i.e., remembering a sequence of spatial locations over a brief delay), divided attention (i.e., simultaneous performance of a counting and visual-search task), intrusions during recall of a word list (i.e., "remembering" nonlist items), and choice reaction time to visual targets. Together with evidence from human and animal studies of mediation of these functions by partially distinct brain systems, our findings suggest that there are multiple independently inherited dimensions of neural deficit in schizophrenia and encourage a search for genes contributing to quantitative variation in discrete aspects of disease liability. On tests of verbal and visual episodic memory, but not on the liability-related measures, patients were more impaired than their own MZ co-twins, suggesting a preferential impact of nongenetic influences on long-term memory systems.