MISATTRIBUTION OF EMOTIONAL OVER-AROUSAL TO NEUTRAL FACES IN ACUTE PARANOID SCHIZOPHRENIA PSYCHOSIS.

INTRODUCTION: Misattribution of motivational salience to non-salient (neutral) stimuli could be viewed as a hallmark of psychosis in schizophrenia. Studies have recently revealed increased subjective experience of emotional arousal (EA) to neutral social stimuli in paranoid schizophrenia psychosis, suggesting a misattribution of emotional salience to them. We examined this phenomenon directly by quantifying the level of EA subjectively attributed to low-arousal, neutral-valenced faces. SUBJECTS AND METHODS: A task for EA attribution to neutral (in the context of affective) facial expressions was applied to 44 actively psychotic paranoid schizophrenia inpatients and 44 well-matched healthy controls. RESULTS: Psychotic patients, compared with healthy controls, rated the neutral faces as more aroused (t (86) = 3.15, p =.001) thus misattributing emotional salience to them. DISCUSSION: This finding supports the hypothesis that over-assignment of EA to neutral faces could be viewed as a subclinical affective mechanism of the clinically manifested experience of delusional perception. CONCLUSION: The study provides the first direct empirical evidence for misattribution of emotional salience in terms of over-attribution of EA to neutral faces during acute paranoid schizophrenia psychosis.

The maintained attention assessment in patients affected by Myalgic encephalomyelitis/chronic fatigue syndrome: a reliable biomarker?

The maintained attention is the cause of great functional limitations in CFS/ME, a disease that mainly affects women in the central period of life. Cognitive function is explored using the Montreal Cognitive Assessment, the maintained attention using the Toulouse-Piéron test with which the Global Index of Attention and Perception (GIAP) is obtained, the fatigue using the visual analog scale and the perception of effort using the modified Borg scale. The final sample were 84 patients (66 women/18 men) who met diagnostic criteria (Fukuda-1994, Carruthers-2011) and 22 healthy controls (14 women/8 men). Most of patients maintain normal cognitive function, showing low or very low attention score in the 70% of patients with a marked cognitive fatigue compared to the control group (p < 0.05). There were no significant differences between genders in GIAP or fatigue for CFS/ME; however, sick women perceive cognitive effort higher than men. Deficits in sustained attention and the perception of fatigue, so effort after performing the proposed test are a sensitive and reliable indicator that allows us to substantiate a clinical suspicion and refer patients for further studies in order to confirm or rule out CFS/ME.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Neurological Entity?

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disorder of unknown physiopathology with multisystemic repercussions, framed in ICD-11 under the heading of neurology (8E49). There is no specific test to support its clinical diagnosis. Our objective is to review the evidence in neuroimaging and dysautonomia evaluation in order to support the neurological involvement and to find biomarkers serving to identify and/or monitor the pathology. The symptoms typically appear acutely, although they can develop progressively over years; an essential trait for diagnosis is "central" fatigue together with physical and/or mental exhaustion after a small effort. Neuroimaging reveals various morphological, connectivity, metabolic, and functional alterations of low specificity, which can serve to complement the neurological study of the patient. The COMPASS-31 questionnaire is a useful tool to triage patients under suspect of dysautonomia, at which point they may be redirected for deeper evaluation. Recently, alterations in heart rate variability, the Valsalva maneuver, and the tilt table test, together with the presence of serum autoantibodies against adrenergic, cholinergic, and serotonin receptors were shown in a subgroup of patients. This approach provides a way to identify patient phenotypes. Broader studies are needed to establish the level of sensitivity and specificity necessary for their validation. Neuroimaging contributes scarcely to the diagnosis, and this depends on the identification of specific changes. On the other hand, dysautonomia studies, carried out in specialized units, are highly promising in order to support the diagnosis and to identify potential biomarkers. ME/CFS orients towards a functional pathology that mainly involves the autonomic nervous system, although not exclusively.

Small lesions of the dorsal or ventral hippocampus subregions are associated with distinct impairments in working memory and reference memory retrieval, and combining them attenuates the acquisition rate of spatial reference memory.

The importance of the hippocampus in spatial learning is well established, but the precise relative contributions by the dorsal (septal) and ventral (temporal) subregions remain unresolved. One debate revolves around the extent to which the ventral hippocampus contributes to spatial navigation and learning. Here, separate small subtotal lesions of dorsal hippocampus or ventral hippocampus alone (destroying 18.9 and 28.5% of total hippocampal volume, respectively) spared reference memory acquisition in the water maze. By contrast, combining the two subtotal lesions significantly reduced the rate of acquisition across days. This constitutes evidence for synergistic integration between dorsal and ventral hippocampus in mice. Evidence that ventral hippocampus contributes to spatial/navigation learning also emerged early on during the retention probe test as search preference was reduced in mice with ventral lesions alone or combined lesions. The small ventral lesions also led to anxiolysis in the elevated plus maze and over-generalization of the conditioned freezing response to a neutral context. Similar effects of comparable magnitudes were seen in mice with combined lesions, suggesting that they were largely due to the small ventral damage. By contrast, small dorsal lesions were uniquely associated with a severe spatial working memory deficit in the water maze. Taken together, both dorsal and ventral poles of the hippocampus contribute to efficient spatial navigation in mice: While the integrity of dorsal hippocampus is necessary for spatial working memory, the acquisition and retrieval of spatial reference memory are modulated by the ventral hippocampus. Although the impairments following ventral damage (alone or in combination with dorsal damage) were less substantial, a wider spectrum of spatial learning, including context conditioning, was implicated. Our results encourage the search for integrative mechanism between dorsal and ventral hippocampus in spatial learning. Candidate neural substrates may include dorsoventral longitudinal connections and reciprocal modulation via overlapping polysynaptic networks beyond hippocampus.

Effects of Cycloleucine in the Nucleus Accumbens Septi on the Elevated plus Maze Test in Rats.

INTRODUCTION: In recent years, an important number of studies have emphasized the psychopharmacological actions of cycloleucine (1-aminocyclopentanecarboxylic acid) acting on the NR1 subunit (glycine allosteric site) of NMDA (N-methyl-D-aspartic acid) receptor. We studied the effects of its injection in an anxiety test. METHODS: The elevated plus maze test was used. Male rats bilaterally cannulated into the nucleus accumbens septi (NAS) were employed. Rats were divided into 5 groups that received either 1 µL injections of saline or cycloleucine (0.5, 1, 2, or 4 µg) 15 min before testing. RESULTS: Time spent in the open arm was significantly increased by cycloleucine treatment with all doses (1 and 2 µg, p < 0.05; 0.5 and 4 µg, p < 0.01), like number of extreme arrivals (0.5 and 1 µg, p < 0.05; 2 µg, p < 0.01; and 4 µg, p < 0.001). Open arm entries were increased by the highest dose only (4 µg, p < 0.01). DISCUSSION/CONCLUSION: Present results show no difference between all doses in the time spent in the open arm, suggesting an indirect, noncompetitive action of the drug. The increase in extreme arrivals and open arm entries suggests a dose influence in these parameters. We conclude that cycloleucine influence on the NMDA receptors within NAS leads to anxiolytic-like effects and behavioral disinhibition, which once more confirms the involvement of NAS in anxiety processing.

Effects of antidepressants and soybean association in depressive menopausal women.

Depression in menopausal women has been widely described for many years ago and is related to hormonal decrease, mainly estrogens. The use of soy has been proposed as a possible coadjutant alternative to treat menopausal depressive disorder. In the present pilot clinical trial the effect of soybean, antidepressants and the association of soybean with antidepressants was studied in 40 depressive menopausal women for three months. Patients were divided in four groups of 10 women: fluoxetine (10 mg), soybean (100 mg), sertraline (50 mg), and sertraline (50 mg) plus soybean (100 mg). The Hamilton and Zung Depression Scales were used to measure the treatment effects. Values at the beginning and at the end of the study were compared. In all cases a significant difference was observed when the treated groups were compared vs. their untreated situation in both scales (p < 0.001). When a comparison between pre- minus post-treatment Zung scale scores was done, the effect induced by the association of sertraline and soybean was significantly higher than the other groups (p < 0.05). These effects were also seen using the Hamilton scale scores, showing significant differences between the association vs. soybean (p < 0.05) and setraline (p < 0.05) groups, but not vs. fluoxetine group. We conclude that soybean has an antidepressant effect per se, and the association of soybean and antidepressants increases their effects.

GAD-7 Generalised Anxiety Disorder scale in Colombian medical professionals during the COVID-19 pandemic: Construct validity and reliability.

INTRODUCTION: The detection of anxiety symptoms among health workers who care for patients infected with COVID-19 is a current priority. Fast and valid instruments are required for this population group. The objective is to establish the construct validity and reliability of the Generalised Anxiety Disorder (GAD-7) scale in Colombian doctors during the COVID-19 lockdown. METHODS: E-health study, in which cross-sectional data were collected online (n = 1030) from 610 COVID doctors and 420 non-COVID doctors, during the Colombian lockdown, between 20 April and 10 August 2020. Each subject was contacted, and they confirmed their participation, identity and professional role. RESULTS: A single factor factorial structure was found, made up of the 7 items of the instrument, which managed to explain 70% of the variance. The goodness of fit indices (RMSEA = 0.080; CFI = 0.995; SRMR = 0.053; p < 0.001) showed an "acceptable" unidimensionality and adequate factor loadings in each item of the GAD-7, >0.070. Finally, the internal consistency of the instrument was good, with a Cronbach's alpha of 0.920 (95%IC, 8.80-9.71). CONCLUSIONS: The GAD-7 is an instrument that presents adequate indicators of validity and reliability. It is an excellent tool that is reliable and easy and fast to use for the detection of generalised anxiety symptoms in medical personnel caring (or not) for patients infected with COVID-19.

[Psychological Impact of COVID-19 on Health Workers During the Second Year of the Pandemic in Latin America: Cross-Sectional Survey Study]. / Impacto psicológico del COVID-19 en los trabajadores sanitarios durante el segundo año de pandemia en Latinoamérica: estudio de encuesta transversal.

Introduction: The coronavirus pandemic continues to affect the mental health of healthcare personnel in Latin America (LA). Objective: To estimate the prevalence of psychological disturbances and associated risk factors for mental health in healthcare personnel in LA during the second year of the COVID-19 pandemic. Method: This multicenter cross-sectional study included a total sample of 5437 healthcare professionals from Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. The PHQ-9, GAD-7, and a brief demographic questionnaire were used. The prevalence of anxiety and depression was estimated based on the cut-off points of the instruments. Two multivariate logistic regressions were performed. Results: A population burden of anxiety (40.1%) and depression (62.2%) was found in healthcare personnel in LA. Among professionals in Argentina (OR = 1.374; P<.001), those working in state hospitals (OR = 1.536; P<.003), frontline healthcare workers for COVID patients (OR = 1.848; P<.001), general practitioners (OR = 1.335; P<.001), and specialists (OR = 1.298; P<.001), a higher risk of experiencing mental disorders was observed. Among women, younger personnel, and administrative staff, a higher probability of experiencing anxiety and depression was identified. Conclusions: The burden of mental disorders on healthcare personnel in Latin America is alarming. Psychological support services are necessary, aimed at providing measures for professionals to develop healthy coping mechanisms that mitigate the impact of the pandemic on their well-being and facilitate post-crisis adjustment.

Clinical utility of Phototest via teleneuropsychology in Chilean rural older adults.

The COVID-19 pandemic has shown the need for neuropsychological care for older adults with memory complaints in different contexts, including rural areas or areas with difficult access. Objective: This study aimed to analyze the clinical utility of the Phototest, through telemedicine, to identify mild cognitive impairment in rural older adults with memory complaints, during the COVID-19 pandemic. Methods: We performed a cross-sectional, case-control, and clinical utility comparison of brief cognitive tests (BCTs). The sample included 111 rural elderly people with mild cognitive impairment (MCI) and 130 healthy controls from the Los Lagos region, Chile. The instruments adopted were modified Mini-Mental State Examination (MMSEm) and adapted version of the Phototest (PT) for Chile. Results: To identify mild cognitive impairment, using a cutoff score of 27-28 points, the Phototest showed a sensitivity of 96.6% and a specificity of 81.8%; indicators superior to those of the MMSEm. Conclusions: The Phototest is more accurate than the MMSEm in identifying cognitive alterations in rural older adults with cognitive memory complaints through telemedicine. Therefore, its use in primary care is recommended in order to perform early detection of preclinical cognitive alterations in mild cognitive impairment or neurodegenerative diseases.

A pandemia de COVID-19 mostrou a necessidade de cuidados neuropsicológicos para adultos idosos com queixas de memória em diferentes contextos, incluindo áreas rurais ou áreas de difícil acesso. Objetivo: Analisar a utilidade clínica do Phototest, por meio da telemedicina, para identificar uma leve deficiência cognitiva em adultos idosos rurais com queixas de memória, durante a pandemia de COVID-19. Métodos: Realizamos uma comparação transversal, caso-controle e utilidade clínica dos testes cognitivos breves. Amostra: Cento e onze idosos rurais com deficiência cognitiva leve (DCL) e 130 controles saudáveis da região de Los Lagos, Chile. Instrumentos: Minimental modificado (MMSEm) e versão do teste fotográfico (PT) adaptada para o Chile. Resultados: Para identificar a DCL, usando pontuação de corte de 27-28 pontos, o Phototest mostrou sensibilidade de 96,6% e especificidade de 81,8%; indicadores superiores aos do MMSEm. Conclusões: O Phototest é mais preciso que o MMSEm para identificar, por meio da telemedicina, alterações cognitivas em adultos idosos rurais com queixas de memória cognitiva. Sendo assim, seu uso na atenção primária é recomendado para realizar a detecção precoce de alterações cognitivas pré-clínicas em DCL ou doenças neurodegenerativas.

Acute Thalamic Ischemic Stroke in an Older Patient Newly Vaccinated with COVID-19 Vaccine Based on Adenoviral Vectors.

Introduction: Recent reports have shown several cases of cerebrovascular events after vaccination against COVID-19. The effects have been described mainly in women within the first two weeks of receiving the vaccine. Clinical Case: We describe here the first Colombian case of a cerebrovascular event after vaccination against COVID-19 in a 67-year-old woman with a vascular history. Four days after application of the messenger ribonucleic acid (mRNA) vaccine, she exhibited deviation of the labial commissure, ipsilateral ptosis, and limitation of march with lateralization. The event was associated with a subacute ischemic event in the right thalamus in parasagittal situation, changes in chronic ischemic microangiopathy of small vessels, and vascular crossing in the right cerebellar angle, without other alternative causes. Conclusion: The development and rapid use of vaccines has allowed the hospitalization and mortality statistics associated with COVID-19 to be reduced, but at the same time, it has generated concern about the potential side effects, generating controversy among the general population, especially in individuals with cardiovascular diseases. In our case, we provided evidence for the discussion of potential cerebrovascular events related to the application of vaccines in older people with a history of cerebrovascular diseases. This was done in order to analyze and control in subsequent studies the modulation of medical history on the likely effects of vaccination. However, despite the unavoidable side effects, the benefits of vaccination are superior.

[Prevalence and factors associated with subjective cognitive complaints in Latin American health workers during the COVID-19 pandemic]. / Prevalencia y factores asociados con las quejas cognitivas subjetivas del personal sanitario latinoamericano durante la pandemia de COVID-19.

Background and objectives: An increase in emotional disturbances and complaints about cognitive performance has been observed in Latin American healthcare workers during the SARS-CoV-2 pandemic, which can affect attention capacity and increase the levels of stress and burnout of these professionals. The objective was to analyse subjective cognitive complaints (SCC) and associated factors in health personnel during the COVID-19 pandemic in five Latin American countries.Methods: Multicentre cross-sectional study, which included 3,738 professionals from Colombia, Chile, Argentina, Ecuador, Bolivia, and Peru. The Generalized Anxiety Disorder Scale (GAD-7) and the Patient Health Questionnaire (PHQ-9) was used to assess depression, and the Mini-Z to assess Burnout. For the SCC, an item on cognitive concerns in attention and memory was used.Results: The prevalence of cognitive complaints was 69.2%. The factors associated with a higher risk of SCC were the scores in the GAD-7, PHQ and Mini-Z, in addition to being part of the Ecuadorian health personnel.Conclusions: There is a high prevalence of SCC in health personnel, which is modulated by emotional states and stress.

Clinical Heterogeneity in ME/CFS. A Way to Understand Long-COVID19 Fatigue.

The aim of present paper is to identify clinical phenotypes in a cohort of patients affected of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Ninety-one patients and 22 healthy controls were studied with the following questionnaires, in addition to medical history: visual analogical scale for fatigue and pain, DePaul questionnaire (post-exertional malaise, immune, neuroendocrine), Pittsburgh sleep quality index, COMPASS-31 (dysautonomia), Montreal cognitive assessment, Toulouse-Piéron test (attention), Hospital Anxiety and Depression test and Karnofsky scale. Co-morbidities and drugs-intake were also recorded. A hierarchical clustering with clinical results was performed. Final study group was made up of 84 patients, mean age 44.41 ± 9.37 years (66 female/18 male) and 22 controls, mean age 45 ± 13.15 years (14 female/8 male). Patients meet diagnostic criteria of Fukuda-1994 and Carruthers-2011. Clustering analysis identify five phenotypes. Two groups without fibromyalgia were differentiated by various levels of anxiety and depression (13 and 20 patients). The other three groups present fibromyalgia plus a patient without it, but with high scores in pain scale, they were segregated by prevalence of dysautonomia (17), neuroendocrine (15), and immunological affectation (19). Regarding gender, women showed higher scores than men in cognition, pain level and depressive syndrome. Mathematical tools are a suitable approach to objectify some elusive features in order to understand the syndrome. Clustering unveils phenotypes combining fibromyalgia with varying degrees of dysautonomia, neuroendocrine or immune features and absence of fibromyalgia with high or low levels of anxiety-depression. There is no a specific phenotype for women or men.

[GAD-7 Generalised Anxiety Disorder scale in Colombian medical professionals during the COVID-19 pandemic: construct validity and reliability]. / Escala de ansiedad generalizada GAD-7 en profesionales médicos colombianos durante pandemia de COVID-19: validez de constructo y confiabilidad.

Introduction: The detection of anxiety symptoms among health workers who care for patients infected with COVID-19 is a current priority. Fast and valid instruments are required for this population group. The objective is to establish the construct validity and reliability of the Generalised Anxiety Disorder (GAD-7) scale in Colombian doctors during the COVID-19 lockdown.Methods: E-health study, in which cross-sectional data were collected online (n=1,030) from 610 COVID doctors and 420 non-COVID doctors, during the Colombian lockdown, between 20 April and 10 August 2020. Each subject was contacted, and they confirmed their participation, identity and professional role.Results: A single factor factorial structure was found, made up of the 7 items of the instrument, which managed to explain 70% of the variance. The goodness of fit indices (RMSEA = 0.080; CFI = 0.995; SRMR = 0.053; p <0.001) showed an "acceptable" unidimensionality and adequate factor loadings in each item of the GAD-7, >0.070. Finally, the internal consistency of the instrument was good, with a Cronbach's alpha of 0.920 (95%IC, 8.80-9.71).Conclusions: The GAD-7 is an instrument that presents adequate indicators of validity and reliability. It is an excellent tool that is reliable and easy and fast to use for the detection of generalised anxiety symptoms in medical personnel caring (or not) for patients infected with COVID-19.

Prevalence of Dementia and Associated Factors among Older Adults in Latin America during the COVID-19 Pandemic.

BACKGROUND: The COVID-19 pandemic has had a great impact on cognitive health in Latin American older adults, increasing the risk of cognitive impairment and dementia. Our objective was to analyze the prevalence of dementia and the associated factors in Latin American older adults during SARS-CoV-2 pandemic. METHODS: A multicentric first phase cross-sectional observational study was conducted during the SARS-CoV-2 pandemic. Five thousand two hundred and forty-five Latin American adults over 60 years of age were studied in 10 countries: Argentina, Bolivia, Chile, Colombia, Ecuador, Guatemala, Mexico, Peru, the Dominican Republic, and Venezuela. We used the telephone version of Montreal Cognitive Assessment, the "Alzheimer Disease 8" scale for functional and cognitive changes, and the abbreviated version of the Yesavage depression scale. We also asked for sociodemographic and lockdown data. All the evaluation was made by telephone. Cross-tabulations and χ2 tests were used to determine the variability of the prevalence of impairment by sociodemographic characteristics and binary logistic regression to assess the association between dementia and sociodemographic factors. RESULTS: We observed that the prevalence of dementia in Latin America is 15.6%, varying depending on the country (Argentine = 7.83 and Bolivia = 28.5%). The variables most associated with dementia were race and age. It does not seem to be associated with the pandemic but with social and socio-health factors. CONCLUSION: The prevalence of dementia shows a significant increase in Latin America, attributable to a constellation of ethnic, demographic, and socioeconomic factors.

Effects of atenolol injected into the nucleus accumbens septi in rats in the elevated plus-maze test.

Background In previous studies, we have observed that glutamate antagonists injected within the nucleus accumbens septi (NAS) induced an anxiolytic-like effect in the elevated plus maze (EPM) test in rats. In the present study, the effect of Atenolol, a specific Beta Adreno-receptor antagonist in the EPM was studied in male rats bilaterally cannulated NAS. Methods Rats were divided into five groups that received either 1 µL injections of saline or atenolol in different doses (0.75, 1 or 2 µg/1 µL, n=15-16) 15 min before testing. Results Time Spent in the Open Arm was modified by treatment (F=4.563, p=0.006, df 3). This was increased by the lowest dose of atenolol (p<0.05), by the medium doses (p<0.001) and also by the highest dose (p<0.01). Time per Entry was modified by treatment (F=4.54, p=0.06, df 3). This parameter was increased by the lowest dose of atenolol (p<0.01), but not for the medium and higher doses. Conclusions We conclude that Atenolol beta receptor blockade in the accumbens lead to an anxiolytic-like effect related to an increase in the time spent in the open arm and in the time per entry, showing specific behavioral patterns.

Alpha and beta noradrenergic mediation of NMDA glutamatergic effects on lordosis behaviour and plasmatic LH concentrations in the primed female rat.

In previous studies we have found that blockade of NMDA (N-Methyl-D-Aspartic-Acid)-type glutamatergic receptor with intracerebroventricular (ICV) selective drugs induces an inhibition of lordosis in ovariectomized (OVX) estrogen primed rats receiving progesterone or luteinizing hormone releasing hormone (LHRH). By the opposite way, stimulation with NMDA in OVX estrogen primed rats induced a significant increase of lordosis. In the present study the action of an alpha1-noradrenergic antagonist, HEAT (BE 2254/2-beta-4-Hydroxyphenyl-Ethyl-Aminomethyl-1-Tetralone), and Metoprolol, a beta-noradrenergic antagonist, were studied injecting them ICV previously to NMDA administration in treated OVX estrogen primed rats. In experiment 1, the enhancing effect on lordosis induced by NMDA at high dose (1 microg) was abolished by HEAT administration (P < 0.001 for 3 and 6 microg), and the LH plasma levels were decreased only with the higher dose (P < 0.05), suggesting that behavioral effects are quite more sensitive to the alpha-blockade than hormonal effects. In experiment 2, enhancing effects on lordosis behavior were not observed with neither the NMDA at low dose (0.5 microg) nor the metoprolol alone (5.71 microg), but a synergism was observed when both were simultaneously administered (P < 0.001). The LH plasma levels were increased by Metoprolol alone (P < 0.05), and powered by the combination with NMDA at low dose (P < 0.01 vs. SAL and NMDA alone); no differences were observed with Metoprolol. LH increase was observed with Metoprolol even without behavioural modifications. These findings strongly suggest that facilitatory and inhibitory effects of NMDA in this model are mediated by alpha- and beta-adrenergic transmission in both, behavioral and hormonal effects.

Erratum to: Short-Term Exposure to Enriched Environment in Adult Rats Restores MK-801-Induced Cognitive Deficits and GABAergic Interneuron Immunoreactivity Loss.

The original version of this article unfortunately contained a mistake. The name of author was changed from "Pascual Gargiulo" to "Pascual Ángel Gargiulo.

Short-Term Exposure to Enriched Environment in Adult Rats Restores MK-801-Induced Cognitive Deficits and GABAergic Interneuron Immunoreactivity Loss.

Perinatal injections of N-methyl-D-aspartate (NMDA) receptor antagonist in rodents emulate some cognitive impairments and neurochemical alterations, such as decreased GABAergic (gamma aminobutyric acid) interneuron immunoreactivity, also found in schizophrenia. These features are pervasive, and developing neuroprotective or neurorestorative strategies is of special interest. In this work, we aimed to investigate if a short exposure to enriched environment (EE) in early adulthood (P55-P73) was an effective strategy to improve cognitive dysfunction and to restore interneuron expression in medial prefrontal cortex (mPFC) and hippocampus (HPC). For that purpose, we administered MK-801 intraperitoneally to Long Evans rats from postnatal days 10 to 20. Twenty-four hours after the last injection, MK-801 produced a transient decrease in spontaneous motor activity and exploration, but those abnormalities were absent at P24 and P55. The open field test on P73 manifested that EE reduced anxiety-like behavior. In addition, MK-801-treated rats showed cognitive impairment in novel object recognition test that was reversed by EE. We quantified different interneuron populations based on their calcium-binding protein expression (parvalbumin, calretinin, and calbindin), glutamic acid decarboxylase 67, and neuronal nuclei-positive cells by means of unbiased stereology and found that EE enhanced interneuron immunoreactivity up to normal values in MK-801-treated rats. Our results demonstrate that a timely intervention with EE is a powerful tool to reverse long-lasting changes in cognition and neurochemical markers of interneurons in an animal model of schizophrenia.

Negative transfer effects between reference memory and working memory training in the water maze in C57BL/6 mice.

The water maze is one of the most widely employed spatial learning paradigms in the cognitive profiling of genetically modified mice. Oftentimes, tests of reference memory (RM) and working memory (WM) in the water maze are sequentially evaluated in the same animals. However, critical difference in the rules governing efficient escape from the water between WM and RM tests is expected to promote the adoption of incompatible mnemonic or navigational strategies. Hence, performance in a given test is likely poorer if it follows the other test instead of being conducted first. Yet, the presence of such negative transfer effects (or proactive interference) between WM and RM training in the water maze is often overlooked in the literature. To gauge whether this constitutes a serious concern, the present study determined empirically the magnitude, persistence, and directionality of the transfer effect in wild-type C57BL/6 mice. We contrasted the order of tests between two cohorts of mice. Performance between the two cohorts in the WM and RM tests were then separately compared. We showed that prior training of either test significantly reduced performance in the subsequent one. The statistical effect sizes in both directions were moderate to large. Although extended training could overcome the deficit, it could re-emerge later albeit in a more transient fashion. Whenever RM and WM water maze tests are conducted sequentially in the same animals - regardless of the test order, extra caution is necessary when interpreting the outcomes in the second test. Counterbalancing test orders between animals is recommended.