El procesamiento temporal en el Trastorno por Déficit de Atención e Hiperactividad

El procesamiento temporal es una actividad cerebral primordial para el adecuado funcionamiento de las personas en las actividades de la vida diaria y su afectación constituye uno de los signos de disfunción más importantes en el Trastorno por Déficit de Atención e Hiperactividad (TDAH). El objetivo de este trabajo es revisar los antecedentes y estudios científicos realizados sobre el procesamiento del tiempo en personas con TDAH, así como realizar una propuesta de valoración de esta función en poblaciones con este trastorno del neurodesarrollo. El procesamiento del tiempo ha sido poco estudiado clínicamente, aunque sí en el ámbito neurocientífico y experimental. La mayoría de los estudios se han basado en mecanismos relacionados con la percepción temporal y la reproducción de intervalos de tiempo a nivel motor, en los cuales se han descrito distorsiones en personas con TDAH. Se han propuesto diversas teorías basadas en una afectación primaria de la percepción del tiempo, aunque en otras ocasiones esta afectación se ha considerado secundaria a las alteraciones nucleares del trastorno. Entre las conclusiones del estudio destacamos que los procesos cognitivos relacionados con el procesamiento temporal son diversos y requieren del funcionamiento de distintos dominios cognitivos. Si bien se han desarrollado algunas pruebas para la evaluación de esta función, precisamos de nuevas herramientas para la adecuada valoración del procesamiento del tiempo en personas con TDAH. Palabras clave: Inatención; Hiperactividad; Impulsividad;Time Processing in Attention Deficit Hyperactivity Disorder. Time processing is a primary brain activity for the proper functioning of people in their daily activities. Its affectation is one of the most important signs of dysfunction in Attention Deficit Hyperactivity Disorder (ADHD). The aim was to review the background and scientific studies carried out on time processing in patients with ADHD, as well as top put forward a proposal for evaluating this function in populations with this neurodevelopmental disorder. Although time processing has not been studied clinically in detail, it has been approached experimentally in the neuroscientific field. Most studies of time processing have been based on functional phenomena related to time perception and timed motor reproductions; distortions of these two functions have been described in people with ADHD. Several theories based on a primary affectation of time processing have been proposed; however, on some occasions this affectation has been considered secondary to the nuclear alterations of the disorder. The cognitive processes related to temporal processing are rather diverse and require the functioning of different cognitive domains. Although some tests have been developed for the evaluation of this function, new tools are needed for the proper assessment of time processing in people with ADH

The spanish intergenerational study : beliefs, stereotypes, and metacognition about older people and grandparents to tackle ageism

Funding: The work received support from Memorial Mercedes Llort Sender 2021/80/09241941/4.Ageism can be seen as systematic stereotypes, prejudice, and discrimination of people because of their age. For a long time, society has accepted negative stereotypes as a norm. When referring to older adults, the United Nations Global Report on Ageism warns about a severe impact. The Intergenerational Study for a Healthy Aging, a questionnaire about believes, stereotypes, and knowledge about older people and grandparents, was administered to 326 Spanish biology and medical students. Here we report the results of stereotype analysis through adjective qualification of the youth and older people performed before the survey. Content analysis of two open questions about metacognition at the end of the survey is also presented. The results show that: (1) The questionnaire promoted metacognition; (2) Positive metacognition toward grandparents was higher than for the general old population; (3) Most participants were not conscious about ageism; (4) Gender was a key factor-male students were more ageist than females; (5) The feeling of guilt was higher in the questionnaire about older people; (6) The metacognition exercise elicited thoughts and, in few cases, the need to take action to tackle ageism. In conclusion, both activities promoted active thoughts about older people vs. grandparents and helped participants realize unconscious ageism-specifically toward the older population-serving as an awareness activity that may help tackle ageism

Effects of transcranial Direct Current Stimulation (tDCS) on cortical activity: A computational modeling study.

International audienceAlthough it is well-admitted that transcranial Direct Current Stimulation (tDCS) allows for interacting with brain endogenous rhythms, the exact mechanisms by which externally-applied fields modulate the activity of neurons remain elusive. In this study a novel computational model (a neural mass model including subpopulations of pyramidal cells and inhibitory interneurons mediating synaptic currents with either slow or fast kinetics) of the cerebral cortex was elaborated to investigate the local effects of tDCS on neuronal populations based on an in-vivo experimental study. Model parameters were adjusted to reproduce evoked potentials (EPs) recorded from the somatosensory cortex of the rabbit in response to air-puffs applied on the whiskers. EPs were simulated under control condition (no tDCS) as well as under anodal and cathodal tDCS fields. Results first revealed that a feed-forward inhibition mechanism must be included in the model for accurate simulation of actual EPs (peaks and latencies). Interestingly, results revealed that externally-applied fields are also likely to affect interneurons. Indeed, when interneurons get polarized then the characteristics of simulated EPs become closer to those of real EPs. In particular, under anodal tDCS condition, more realistic EPs could be obtained when pyramidal cells were depolarized and, simultaneously, slow (resp. fast) interneurons became de- (resp. hyper-) polarized. Geometrical characteristics of interneurons might provide some explanations for this effect

Time processing in attention deficit hyperactivity disorder

El procesamiento temporal es una actividad cerebral primordial para el adecuado funcionamiento de las personas en las actividades de la vida diaria y su afectación constituye uno de los signos de disfunción más importantes en el Trastorno por Déficit de Atención e Hiperactividad (TDAH). El objetivo de este trabajo es revisar los antecedentes y estudios científicos realizados sobre el procesamiento del tiempo en personas con TDAH, así como realizar una propuesta de valoración de esta función en poblaciones con este trastorno del neurodesarrollo. El procesamiento del tiempo ha sido poco estudiado clínicamente, aunque sí en el ámbito neurocientífico y experimental. La mayoría de los estudios se han basado en mecanismos relacionados con la percepción temporal y la reproducción de intervalos de tiempo a nivel motor, en los cuales se han descrito distorsiones en personas con TDAH. Se han propuesto diversas teorías basadas en una afectación primaria de la percepción del tiempo, aunque en otras ocasiones esta afectación se ha considerado secundaria a las alteraciones nucleares del trastorno. Entre las conclusiones del estudio destacamos que los procesos cognitivos relacionados con el procesamiento temporal son diversos y requieren del funcionamiento de distintos dominios cognitivos. Si bien se han desarrollado algunas pruebas para la evaluación de esta función, precisamos de nuevas herramientas para la adecuada valoración del procesamiento del tiempo en personas con TDAH

El procesamiento temporal en el Trastorno por Déficit de Atención e Hiperactividad

Time Processing in Attention Deficit Hyperactivity Disorder. Time processing is a primary brain activity for the proper functioning of people in their daily activities. Its affectation is one of the most important signs of dysfunction in Attention Deficit Hyperactivity Disorder (ADHD). The aim was to review the background and scientific studies carried out on time processing in patients with ADHD, as well as top put forward a proposal for evaluating this function in populations with this neurodevelopmental disorder. Although time processing has not been studied clinically in detail, it has been approached experimentally in the neuroscientific field. Most studies of time processing have been based on functional phenomena related to time perception and timed motor reproductions; distortions of these two functions have been described in people with ADHD. Several theories based on a primary affectation of time processing have been proposed; however, on some occasions this affectation has been considered secondary to the nuclear alterations of the disorder. The cognitive processes related to temporal processing are rather diverse and require the functioning of different cognitive domains. Although some tests have been developed for the evaluation of this function, new tools are needed for the proper assessment of time processing in people with ADHD.El procesamiento temporal es una actividad cerebral primordial para el adecuado funcionamiento de las personas en las actividades de la vida diaria y su afectación constituye uno de los signos de disfunción más importantes en el Trastorno por Déficit de Atención e Hiperactividad (TDAH). El objetivo de este trabajo es revisar los antecedentes y estudios científicos realizados sobre el procesamiento del tiempo en personas con TDAH, así como realizar una propuesta de valoración de esta función en poblaciones con este trastorno del neurodesarrollo. El procesamiento del tiempo ha sido poco estudiado clínicamente, aunque sí en el ámbito neurocientífico y experimental. La mayoría de los estudios se han basado en mecanismos relacionados con la percepción temporal y la reproducción de intervalos de tiempo a nivel motor, en los cuales se han descrito distorsiones en personas con TDAH. Se han propuesto diversas teorías basadas en una afectación primaria de la percepción del tiempo, aunque en otras ocasiones esta afectación se ha considerado secundaria a las alteraciones nucleares del trastorno. Entre las conclusiones del estudio destacamos que los procesos cognitivos relacionados con el procesamiento temporal son diversos y requieren del funcionamiento de distintos dominios cognitivos. Si bien se han desarrollado algunas pruebas para la evaluación de esta función, precisamos de nuevas herramientas para la adecuada valoración del procesamiento del tiempo en personas con TDAH

Cerebellar interpositus nucleus exhibits time-dependent errors and predictive responses

Abstract Learning is a functional state of the brain that should be understood as a continuous process, rather than being restricted to the very moment of its acquisition, storage, or retrieval. The cerebellum operates by comparing predicted states with actual states, learning from errors, and updating its internal representation to minimize errors. In this regard, we studied cerebellar interpositus nucleus (IPn) functional capabilities by recording its unitary activity in behaving rabbits during an associative learning task: the classical conditioning of eyelid responses. We recorded IPn neurons in rabbits during classical eyeblink conditioning using a delay paradigm. We found that IPn neurons reduce error signals across conditioning sessions, simultaneously increasing and transmitting spikes before the onset of the unconditioned stimulus. Thus, IPn neurons generate predictions that optimize in time and shape the conditioned eyeblink response. Our results are consistent with the idea that the cerebellum works under Bayesian rules updating the weights using the previous history

Neurodevelopmental Effects of Undernutrition and Placental Underperfusion in Fetal Growth Restriction Rabbit Models

&lt;b&gt;&lt;i&gt;Introduction:&lt;/i&gt;&lt;/b&gt; Chronic reduction of oxygen and nutrient delivery to the fetus has been related to neurodevelopmental problems. Placental underperfusion induces a significant reduction in oxygen and nutrient delivery, whereas maternal undernutrition causes mainly nutrient deficiency. A comparison of the neurodevelopmental effects of both situations in pregnant rabbits was performed. &lt;b&gt;&lt;i&gt;Materials and Methods:&lt;/i&gt;&lt;/b&gt; The placental underperfusion model was induced after uteroplacental vessel ligation at 25 days of pregnancy. The undernutrition model was induced after a reduction of 70% of the basal maternal intake at 22 days of pregnancy. Neurobehavioral tests were applied in the derived offspring at the neonatal period and over the long term. Structural brain differences were evaluated by brain networks obtained from diffusion magnetic resonance imaging. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Birth weight was significantly lower in both cases. However, stillbirth was only increased in the placental underperfusion model. Cases from both models presented poorer neurobehavioral performance and network infrastructure, being more pronounced in the placental underperfusion model. &lt;b&gt;&lt;i&gt;Discussion:&lt;/i&gt;&lt;/b&gt; Prenatal insults during the last third of gestation resulted in functional and structural disturbances. The degree of neurodevelopmental impairment and its association with structural brain reorganization seemed to be related to the type of the prenatal insult, showing stronger effects in the placental underperfusion model.</jats:p

Effects of transcranial direct current stimulation (tDCS) on sensory evoked potentials

We present a combined experimental/computational modeling approach aimed at studying the effects of transcranial Direct Current Stimulation (tDCS) on neuronal systems. More particularly, we introduce i) a neural mass model (neuronal population level) of the cerebral cortex and ii) a coupling model between the considered neuronal population and an externally-applied electric field. We then use this computational modeling approach to interpret evoked potentials (EPs) recorded from the somatosensory cortex of the rabbit under tDCS. Results showed that the model could accurately reproduce the time-course of actual EPs (polarity and latency of main peaks) recorded under control (i.e. “no tDCS stimulation”) condition. From real data, we also identified the “major” effects of tDCS on EPs in terms of shape modifications and we studied the necessary and sufficient conditions for which the model could reproduce these effects. We found that pyramidal cells should be depolarized (resp. hyperpolarized) in order to simulate the effects of anodal (resp. cathodal) currents. We also found that some interneurons are sensitive to externally-applied fields, indicating that modelling efforts need to also consider the role of these neurons to fully understand interactions between stimulation currents and underlying neuronal systems