10 research outputs found
The effect of a change in sleep-wakefulness timing, bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature
No full textExperiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post-treatment conditions
Effects of diazepam and buspirone on reaction-time of saccadic eye-movements
No full textItem does not contain fulltextEffects of the anxiolytic drugs diazepam and buspirone were studied on the reaction time of saccadic eye movements. The study was performed with 8 healthy volunteers in a double-blind, placebo-controlled way. The purpose was to investigate the putative drug effects on the first step of an attention shifting task: the disengagement of attention. Saccadic reaction time was measured in two conditions: the 'gap' and the 'overlap' condition. In the first condition a delay is present between the offset of a fixation spot and the onset of a target, while in the second condition the offset of the spot is overlapped by the onset of the target. Clear differences in saccadic reaction time in the expected direction were found between the two conditions, with longer reaction times of saccadic eye movements in the overlap condition. The nonsedative anxiolytic buspirone in a dose of 5 mg had no significant effects on saccadic reaction times, while clear effects of diazepam in a dose of 5 mg were established. Diazepam slowed down saccadic reaction times, reduced the number of fast saccades and facilitated the number of slow saccades. However, the effects induced by this drug were identical for the two conditions. The latter result implies that the disengagement of attention is not selectively disrupted by diazepam. Perhaps, the action of diazepam is expressed in other attention factors, such as in shifting attention or in the reengagement of attention. A slowing down of these processes by the vigilance-lowering properties of diazepam might be the cause of the prolonged latencies. The increased latencies of saccadic eye movements induced by a low dose of diazepam may have practical implications
Break and recovery points of fusion differentiate schizophrenia from bipolar disorder patients
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The subjective amplitude of the diurnal rhythm matters – Chronobiological insights for neuroimaging studies
No full textMultiple aspects of human psychophysiology, including mood and cognition, are subjected to diurnal rhythms. While the previous magnetic resonance imaging (MRI) studies have focused solely on the morningness-eveningness (ME) preference dichotomy, i.e. the circadian phase, the second key dimension of the diurnal rhythms, i.e. the strength of these preferences (amplitude; AM), has been completely overlooked. Uncovering the neural correlates of AM is especially important considering its link with negative emotionality. Structural T1-weighted neuroimaging data from 79 early (EC) and 74 late (LC) chronotypes were analysed to compare grey matter (GM) volume and cortical thickness. The study aimed to elucidate whether the subjective AM and its interaction with ME was a significant predictor of individual brain structure. Both GM volume and cortical thickness of the left primary visual cortex was negatively correlated with AM scores across the entire sample. Furthermore, EC and LC differed in their association between AM scores and the GM volume in the right middle temporal gyrus, with the positive and negative correlations reported respectively in the two groups. The current study underlines the importance of the visual system in circadian rhythmicity and provides possible neural correlates for AM-related differences in negative affect processing. Furthermore, the presence of the opposite correlations between brain anatomy and AM in the two groups suggests that the behavioural and neuronal chronotype differences might become more pronounced in individuals with extreme diurnal differences in mood and cognition, highlighting the necessity to additionally account for AM in neuroimaging studies.This work was supported by the National Science Centre, Poland (NCN) grants no. 2013/08/M/HS6/00042 and 2013/08/W/NZ3/00700, and by the Ministry of Science and Higher Education (Poland) as a project under the program Excellence Initiative – Research University (2020-2026) no. BOB-IDUB-622-28/2023 (IV.4.1.)
False recognitions in short-term memory: Age-differences in neural activity
No full textWhile the knowledge on age-related differences in susceptibility to episodic false memories is extensive, little is known about this phenomenon in visual short-term memory (STM). Our previous behavioural research indicated that older adults are more confident of their erroneous STM recognitions than young adults. However, unlike in episodic memory, we did not find support for older adults’ higher rate of false alarms. To further understand this specific age-difference, here we investigated its neural correlates. First, the pattern of behavioural results replicated the one from our previous experiment. Second, younger adults, when compared to older adults, exhibited higher false recognition-related activity of the visual cortex, the anterior cingulate cortex, the frontal operculum/insular cortex as well as regions within the anterior and dorsolateral prefrontal cortex. No age-differences were observed in hippocampal activity. Third, younger but not older adults presented higher activity in the anterior cingulate cortex and the frontal operculum/insular cortex for false recognitions when compared to highly confident correct rejections. Finally, frontal activity was influenced by both the individuals’ performance and their metacognitive abilities. The results suggest that age-related differences in confidence of STM false recognitions may arise from age-differences in performance monitoring and uncertainty processing rather than in hippocampal-mediated binding
Contributive sources analysis: A measure of neural networks' contribution to brain activations
No full textItem does not contain fulltextGeneral linear model (GLM) is a standard and widely used fMRI analysis tool. It enables the detection of hypothesis-driven brain activations. In contrast, Independent Component Analysis (ICA) is a powerful technique, which enables the detection of data-driven spatially independent networks. Hybrid approaches that combine and take advantage of GLM and ICA have been proposed. Yet the choice of the best method is still a challenge, considering that the techniques may yield slightly different results regarding the number of brain regions involved in a task. A poor statistical power or the deviance from the predicted hemodynamic response functions is possible cause for GLM failures in extracting some activations picked by ICA. However, there might be another explanation for different results obtained with GLM and ICA approaches, such as networks cancelation.
In this paper, we propose a new supplementary method that can give more insight into the functional data as well as help to clarify inconsistencies between the results of studies using GLM and ICA. We introduce a contributive sources analysis (CSA), which provides a measure of the number and the strength of the neural networks that significantly contribute to brain activation. CSA, applied to fMRI data of anti-saccades, enabled us to verify whether the brain regions involved in the task are dominated by a single network or serve as key nodes for particular networks interaction. Moreover, when applying CSA to the atlas-defined regions-of-interest, results indicated that activity of the parieto-medial temporal network was suppressed by the eye field network and the default mode network. Thus, this effect of networks cancelation explains the absence of parieto-medial temporal activation within the GLM results. Together, those findings indicate that brain activations are a result of complex network interactions. Applying CSA appears to be a useful tool to reveal additional findings outside the scope of the "fixed-model" GLM and data-driven ICA approaches
Deficits of semantic cognition in stroke aphasia: Underlying causes and ameliorating factors
No full textResearch suggests that semantic memory deficits can occur in at least three ways. Patients can (1) show amodal degradation of concepts within the semantic store itself, such as in semantic dementia (SD), (2) have an impairment of semantic control, leading to difficulty accessing appropriate knowledge in line with current goals or context, as in semantic aphasia (SA), and (3) experience a semantic deficit in only one modality following degraded input from sensory cortex. Patients with SA show damage to prefrontal cortex which extends posteriorly (PF+), or damage restricted to temporoparietal regions (TP-only), and have deficits of semantic control and ‘access’ across word and picture tasks, consistent with the view that their problems arise from impaired multimodal control processes. This thesis aims to explore the nature of these deficits, in four themes. (1) “Refractory effects” in SA patients are explored across modalities – i.e., these patients are shown to experience declining accuracy in cyclical matching tasks when semantically-related sets are presented rapidly and repeatedly. (2) We studied one case study with ‘verbal-only’ refractory effects, to investigate an apparent anomaly in the literature – the existence of patients who have ‘access’ deficits which are restricted to a single modality. These patients challenge the notion that semantic control processes are modality-general. We assessed the hypothesis that multimodal semantic control/ access impairments can follow a modality-specific pattern if paired with an input deficit of a single modality. (3) We explore the effect of lesion location on behavioural performance of semantic aphasia (SA) patients, who have PF+ or TP-only lesions by bringing together data published previously in different papers, together with some new SA cases. Past research suggests SA patients with these two lesions may show similar deficits of semantic control, yet the functional neuroimaging literature proposes a unique role for the prefrontal cortex. PF+ patients were less fluent, showed more associative picture naming errors, and overall somewhat stronger SA characteristics (e.g., they were more inconsistent, and less affected by frequency). (4) Semantic control recruits a wide cortical network, in both the left hemisphere (LH) and right hemisphere (RH). Semantic representations in the RH are partially distinct from the LH, including specialised knowledge of faces and metaphors. Our aim was to test whether damage to RH control regions would negatively affect performance on semantic control tasks which use items stored in the RH, in a similar way to our SA patients in the LH. Overall, the results suggest that semantic control operates in an amodal fashion, with deficits found across modalities. There was evidence to suggest a wide network involved in semantic control beyond the prefrontal cortex – including left posterior cortex and right hemisphere regions. However, these regions are subtly distinct in their role in semantic control
Prevalence of chest metastases in patients with thyroid cancer between 2016 and 2019 at a reference center in Bogotá, Colombia
No full textilustraciones, gráficas, tablasIntroducción: El cáncer de tiroides es una enfermedad oncológica considerada como la
neoplasia endocrina más frecuente y el tercer tumor más frecuente en las mujeres
colombianas. Tiene un buen pronóstico cuando la neoplasia está imitada a la glándula; sin
embargo, el pronóstico se ensombrece cuando compromete órganos a distancia, siendo
el pulmón, el órgano más comúnmente comprometido por metástasis. Existen pocos
estudios que caractericen las metástasis torácicas en pacientes con cáncer de tiroides.
Por lo tanto, determinar la prevalencia de cada tipo de metástasis torácicas en pacientes
con cáncer de tiroides y caracterizar las metástasis pulmonares, se traduce la
disponibilidad de más datos epidemiológicos que permitan a futuro plantear estudios en
torno a identificación de variables asociadas y factores pronósticos en pacientes con
carcinoma tiroideo y metástasis pulmonares.
Metodología: Estudio de corte transversal con muestreo no probabilístico de casos
consecutivos en pacientes mayores de 18 años con cáncer de tiroides que asistieron a
consulta externa de un centro de referencia en cáncer de la ciudad de Bogotá entre 2016
y 2019.
Resultados: Se incluyeron 241 pacientes. El promedio de edad fue de 54.08 años (DE +/-
14.31). El 85,48% pertenecieron al género femenino. El 95.02% presentó carcinoma
papilar, 2.49% carcinoma folicular, 1.24% carcinoma medular, 0.41% carcinoma
anaplásico, 0.82% dos subtipos histológicos. La prevalencia de metástasis torácicas fue
del 21.99% y de metástasis pulmonares del 20.75%. Las metástasis mediastinales,
pleurales, en la vía aérea y la pared torácica se presentaron en un 0.83% cada una. Los
pacientes con metástasis torácicas tenían una media de edad de 59.3 (DE +/- 12.8) años,
mediana de peso e IMC de 63 kg (RIQ 53-71) y 26.11 (RIQ 22.10 – 29.80)
respectivamente. El 90.57% presentaron carcinoma papilar y un estadio clínico al
momento del diagnóstico de I en el 33.96% y II en el 35.85%. Las comorbilidades más
frecuentes fueron hipertensión arterial (32.08%), hipoparatiroidismo (20.75%) y
compromiso ganglionar cervical (86.79%). El síntoma más frecuente fue la disnea en un
11.32% seguido de la tos presentada en un 3.77%. El 90.0% de los pacientes con
metástasis torácicas presentaron tiroglobulina mayor a 0.2ng/ml y un 20.7% tenían
anticuerpos anti-tiroglobulina (TgAb) detectables. Un 43.4% presentaron lesiones yodo
captantes en la gammagrafía con I131. Al comparar los pacientes que presentaron
metástasis torácicas con aquellos que no, se encontró que hubo una diferencia
estadísticamente significativa en variables tales como: la edad (p=0.002),el estadio clínico
(p<0.001), el peso (p=0.0046), índice de masa corporal (p=0.025), el antecedente de
enfermedad renal crónica (p=0.022), falla cardiaca (p=0.010), la parálisis de cuerda vocal
(p=0.013), compromiso ganglionar a nivel cervical (p=0.007), antecedente de exposición
a combustibles de biomasa (p=0.004); así como características clínicas y paraclínicas
como la presencia de disnea en los pacientes con metástasis (p=0.004) la ausencia de
síntomas en los pacientes sin metástasis (p=0.002). y valores de tiroglobulina mayores a
0,2ng/ml (p<0.001).
Conclusiones: El presente estudio, muestra una prevalencia de metástasis torácicas del
21.99% sin documentarse estudios similares comparables, sin embargo, sí se evidenció
una mayor prevalencia de metástasis pulmonares a la reportada tanto en la literatura
global, como en un estudio local de Manizales, Colombia. Los pacientes más afectados
con metástasis pulmonares fueron los mayores de 55 años, diferente a lo reportado en la
literatura global. El 69.81% de los pacientes con metástasis presentaron estadios I y II al
momento del diagnóstico, lo que sugiere progresión de la enfermedad; por otro lado, en
cohortes internacionales se presentó un estadio IV al momento del diagnóstico. Se
encontró asociación estadísticamente significativa con presencia de metástasis torácica,
a la presencia de linfadenopatías cervicales; hallazgo que fue contemplado y analizado en
una cohorte asiática. Sin embargo, en la literatura, se disponen de pocos estudios que
evalúen la prevalencia de metástasis torácicas, pulmonares, sus características y variables
asociadas; se requiere entonces estudios adicionales que evalúen dichos datos. (Texto tomado de la fuente)Introduction: Thyroid cancer is an oncological disease considered the most common
endocrine neoplasia and the third most common tumor in Colombian women. It has a good
prognosis when the neoplasia is limited to the gland; however, compromising organs at a
distance show a worse prognosis. The lung is most commonly site compromised by
metastases. There are few studies that characterize chest metastases in patients with
thyroid cancer. Therefore, to determine the prevalence of each type of thoracic metastases
in patients with thyroid cancer and to characterize pulmonary metastases, results in more
epidemiological data available, that will allow future studies regarding the identification of
associated variables and prognostic factors in patients with thyroid carcinoma and
pulmonary metastases.
Methodology: A cross-sectional study with non-probabilistic sampling of consecutive cases
in outpatients over 18 years of age with thyroid cancer who attended in a reference cancer
treatment center between 2016 and 2019.
Results: A total of 241 patients were included. The population age average was 54.08
years old (SD +/- 14.31). 85.48% were female. 95.02% had a papillary carcinoma, 2.49%
had a follicular carcinoma, 1.24% had a medullary carcinoma, 0.41% had an anaplastic
carcinoma, 0.82% had two histological subtypes. The chest metastases’ prevalence was
21.99% and the pulmonary metastases’ prevalence was 20.75%. Mediastinal, pleural,
airway and chest wall metastases occurred each in 0.83%. Patients with chest metastases
had an average age of 59.3 (SD +/- 12.8) years old, weight average was of 63 kg (RIQ 53-
71) and average BMI was 26.11 (RIQ 22.10 - 29.80). 90.57% had papillary carcinoma and
33.96% had I clinical stage at the time of diagnosis and 35.85% had II clinical stage. The
most common symptom was dyspnea in 11.32% followed by cough in 3.77%. 90.0% of
patients with chest metastases had thyroglobulin greater than 0.2ng/ml and 20.7% had
detectable anti-thyroglobulin (TgAb) antibodies. 43.4% had iodine-capturing lesions in the
scan with I131. According to chest metastases, there was a statistically significant
difference in variables such as age (p = 0.002), clinical stage (p < 0.001), weight (p = 0.0046), body mass index (p = 0.025), history of chronic kidney disease (p = 0.022), heart failure (p = 0.010), vocal cord paralysis (p = 0.013), ganglion involvement at the cervical
level (p = 0.007), history of exposure to biomass combustion (p = 0.004), presence of
dyspnea (p = 0.004) the absence of symptoms in patients in patients without metastases
(p = 0.002). and thyroglobulin values greater than 0.2ng/ml (p < 0.001).
Conclusions: This study shows a prevalence of thoracic metastases of 21.99% without
similar studies to compare, however, it shows a higher prevalence of pulmonary
metastases than reported in both global data and the one for Colombia. The oldest patients
(over 55-year-old) were most affected patients with pulmonary metastases. This data are
different from the reported global literature. 69.81% of metastasis’ patients had stages I
and II at diagnosis, suggesting disease progression; data that are different from an
international cohort. The stage IV was presented at the time of diagnosis in an international
cohort. Statistically significant association was find with the presence of chest metastasis
and cervical lymphadenopathies; a similar data founded in an Asian cohort. However, in
the literature, few studies are available to assess the prevalence of thoracic, pulmonary
metastases, the variables associated; more studies are required to evaluate such data.Especialidades MédicasEspecialista en Medicina InternaEstudio de corte transversal con muestreo no probabilístico de casos consecutivos en pacientes mayores de 18 años con cáncer de tiroides que asistieron a consulta externa de un centro de referencia en cáncer de la ciudad de Bogotá entre 2016 y 2019.Neumologí
