RESUMO
Even if the use of distance learning and E-learning has a long tradition all over the world and both have been used to keep in contact with students and to provide lessons, support and learning materials, there is an open debate on the balance between advantages and disadvantages in the use of distance learning. This debate is even more central in their use to support students with Learning Disabilities (LDs), an overarching group of neurodevelopmental disorders that affect more than 5% of students. The current COVID-19 outbreak caused school closures and the massive use of E-learning all over the world and it put higher attention on the debate of the effects of E-learning. This paper aims to review papers that investigated the positive and negative effects of the use of Distance Learning and E-learning in students with LDs. We conducted a literature review on the relationship between Distance Learning, E-learning and Learning Disabilities, via Scopus, Eric and Google Scholar electronic database, according to Prisma Guidelines. The findings are summarized using a narrative, but systematic, approach. According to the data resulting from the papers, we also discuss issues to be analyzed in future research and in the use of E-learning during the current pandemic of COVID-19.
RESUMO
In the mammalian neocortex, segregated processing streams are thought to be important for forming sensory representations of the environment, but how local information in primary sensory cortex is transmitted to other distant cortical areas during behaviour is unclear. Here we show task-dependent activation of distinct, largely non-overlapping long-range projection neurons in the whisker region of primary somatosensory cortex (S1) in awake, behaving mice. Using two-photon calcium imaging, we monitored neuronal activity in anatomically identified S1 neurons projecting to secondary somatosensory (S2) or primary motor (M1) cortex in mice using their whiskers to perform a texture-discrimination task or a task that required them to detect the presence of an object at a certain location. Whisking-related cells were found among S2-projecting (S2P) but not M1-projecting (M1P) neurons. A higher fraction of S2P than M1P neurons showed touch-related responses during texture discrimination, whereas a higher fraction of M1P than S2P neurons showed touch-related responses during the detection task. In both tasks, S2P and M1P neurons could discriminate similarly between trials producing different behavioural decisions. However, in trials producing the same decision, S2P neurons performed better at discriminating texture, whereas M1P neurons were better at discriminating location. Sensory stimulus features alone were not sufficient to elicit these differences, suggesting that selective transmission of S1 information to S2 and M1 is driven by behaviour.
Assuntos
Discriminação Psicológica/fisiologia , Neurônios/fisiologia , Córtex Somatossensorial/fisiologia , Vias Aferentes , Animais , Comportamento Animal , Cálcio/análise , Camundongos , Neurônios/química , Córtex Somatossensorial/citologia , Vibrissas/inervaçãoRESUMO
UNLABELLED: The hippocampal dentate gyrus is critically involved in learning and memory. However, methods for imaging the activity of its principal neurons, the dentate gyrus granule cells, are missing. Here we demonstrate chronic two-photon imaging of granule cell population activity in awake mice using a cortical window implant that leaves the hippocampal formation intact and does not lead to obvious alteration of animal behavior. Using virus delivery, we targeted expression of genetically encoded calcium indicators specifically to dentate gyrus granule cells. Calcium imaging of granule cell activity 600-800 µm below the hippocampal surface was facilitated by using 1040 nm excitation of the red indicator R-CaMP1.07, but was also achieved using the green indicator GCaMP6s. We found that the rate of calcium transients was increased during wakefulness relative to an extremely low rate during anesthesia; however, activity still remained sparse with, on average, approximately one event per 2-5 min per cell across the granule cell population. Comparing periods of running on a ladder wheel and periods of resting, we furthermore identified state-dependent differences in the active granule cell population, with some cells displaying highest activity level during running and others during resting. Typically, cells did not maintain a clear state preference in their activity pattern across days. Our approach opens new avenues to elucidate granule cell function, plasticity mechanisms, and network computation in the adult dentate gyrus. SIGNIFICANCE STATEMENT: We describe a technique that allows for chronic, functional imaging of dentate gyrus granule cells in awake, behaving mice in an intact hippocampal circuitry using genetically encoded calcium indicators. This novel approach enables the analyses of individual granule cell activity over time and provides a powerful tool to elucidate the mechanisms underlying structural and functional plasticity of the adult dentate gyrus.
Assuntos
Giro Denteado/citologia , Rede Nervosa/fisiologia , Neurônios/fisiologia , Animais , Cálcio/metabolismo , Giro Denteado/diagnóstico por imagem , Comportamento Exploratório/fisiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Confocal , Rede Nervosa/diagnóstico por imagem , Neurônios/classificação , Optogenética , VigíliaRESUMO
In his book Aion, Jung describes something like a quasi-Hegelian progressive historical realization of the Self in a perspective similar to Fernand Braudel's longue durée history. This article deals with a similar perspective, as it tries to focus on what we may call a "cultural complex" yet within its unfolding in historical time and belonging not to just one specific cultural group, but to a large cultural basin, which we may indicate as the "West". This complex marks the birth and development of modernity. The depth, pervasiveness and duration of this cultural complex permeates the lives and psychologies of all of those that are part of it. Therefore, every analytical project must take into account the underlying emotional, epistemic and social field within which this complex constellates. One of the main features of this (trans)cultural complex, strictly connected with the progressive fragmentation of the self and the transformation of the numinosum with its meaning-giving force, is paranoia. This article analyses the historical and cultural features that produce paranoia and fragmentation and determine paranoid symptoms and attitudes.
Dans son livre Aïon, Jung décrit quelque chose comme une réalisation historique progressive quasi hégélienne du Soi dans une perspective similaire à l'histoire de longue durée de Fernand Braudel. Cet article aborde une perspective semblable, car il tente de se concentrer sur ce que nous pouvons appeler un « complexe culturel ¼. Mais ici il s'agit de son déroulement dans le temps historique et de son appartenance non pas à un groupe culturel spécifique, mais à un grand bassin culturel, que nous pouvons désigner comme « l'Occident ¼. Ce complexe marque la naissance et le développement de la modernité. La profondeur, l'omniprésence et la durée de ce complexe culturel imprègnent la vie et la psychologie de tous ceux qui en font partie. Par conséquent, tout projet analytique doit prendre en compte le champ émotionnel, épistémique et social sousjacent dans lequel ce complexe se constelle. L'une des principales caractéristiques de ce complexe (trans)culturel, étroitement lié à la fragmentation progressive du soi et à la transformation du numinosum et de sa capacité à donner du sens, c'est la paranoïa. Cet article analyse les caractéristiques historiques et culturelles qui produisent la paranoïa et la fragmentation et déterminent les symptômes et les attitudes paranoïdes.
En su libro 'Aion', Jung describe algo así como una realización histórica progresiva cuasihegeliana del Self en una perspectiva similar a la historia 'longue durée' de Fernand Braudel. El presente artículo aborda una perspectiva similar, ya que trata de centrarse en lo que podríamos denominar un "complejo cultural", pero dentro de su despliegue en el tiempo histórico y perteneciente no sólo a un grupo cultural concreto, sino a una gran cuenca cultural, que podríamos señalar como "Occidente". Este complejo marca el nacimiento y el desarrollo de la modernidad. La profundidad, la omnipresencia y la duración de este complejo cultural impregnan la vida y la psicología de todos los que forman parte de él. Por lo tanto, todo proyecto analítico debe tener en cuenta el campo emocional, epistémico y social subyacente en el que se inscribe este complejo. Uno de los principales rasgos de este complejo (trans)cultural, estrictamente relacionado con la progresiva fragmentación del self y la transformación de lo numinoso con su fuerza dadora de sentido, es la paranoia. Este artículo analiza los rasgos históricos y culturales que producen la paranoia y la fragmentación y determinan síntomas y actitudes paranoides.
Assuntos
Emoções , Transtornos Paranoides , HumanosRESUMO
One way to conceptualize human life is to describe it as a process through which the biological body is progressively transformed into a psychological one through its mentalization and symbolization. This process occurs through the relational field, which begins with caregiver-infant proto-conversations and develops through adolescence into the ongoing complex interpersonal relational network we call society and culture. The essence and the problems of adolescents are intricately tied to the social and cultural contexts in which they experience life. Therefore, adolescence cannot be understood if all the levels that it expresses (biological, psychological cultural/social) are not taken into consideration. We identify three psycho-historical phases through which adolescence has changed in the past century: (1) Oedipal; (2) Narcissistic; and (3) Post-narcissistic. In this last phase due to the psychological and historical failure of the narcissistic ideals, the ideal is mingling with the real in a wholly new way. This process has overturned Erikson's paradigm: identity, opposed and defined by a dichotomic otherness, must be transformed into a fluid integration of similarities and differences negotiated and developed through empirical interpersonal intersubjective experiences. This, in our perspective, is a possible key to understand the rapid change in the nature of consciousness, selfhood, and gendering in today's western world, together with some important psychopathological disorders which describe the new creative challenges of today's adolescents.
RESUMO
N-methyl-d-aspartate receptor-mediated ( spikes can be causally linked to the induction of synaptic long-term potentiation (LTP) in hippocampal and cortical pyramidal cells. However, it is unclear if they regulate plasticity at a local or global scale in the dendritic tree. Here, we used dendritic patch-clamp recordings and calcium imaging to investigate the integrative properties of single dendrites of hippocampal CA3 cells. We show that local hyperpolarization of a single dendritic segment prevents NMDA spikes, their associated calcium transients, as well as LTP in a branch-specific manner. This result provides direct, causal evidence that the single dendritic branch can operate as a functional unit in regulating CA3 pyramidal cell plasticity.
Assuntos
Dendritos , Receptores de N-Metil-D-Aspartato , Cálcio/metabolismo , Dendritos/metabolismo , Hipocampo/metabolismo , Potenciação de Longa Duração/fisiologia , Plasticidade Neuronal/fisiologia , Células Piramidais/fisiologia , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/metabolismoRESUMO
Neuronal population activity in the hippocampal CA3 subfield is implicated in cognitive brain functions such as memory processing and spatial navigation. However, because of its deep location in the brain, the CA3 area has been difficult to target with modern calcium imaging approaches. Here, we achieved chronic two-photon calcium imaging of CA3 pyramidal neurons with the red fluorescent calcium indicator R-CaMP1.07 in anesthetized and awake mice. We characterize CA3 neuronal activity at both the single-cell and population level and assess its stability across multiple imaging days. During both anesthesia and wakefulness, nearly all CA3 pyramidal neurons displayed calcium transients. Most of the calcium transients were consistent with a high incidence of bursts of action potentials (APs), based on calibration measurements using simultaneous juxtacellular recordings and calcium imaging. In awake mice, we found state-dependent differences with striking large and prolonged calcium transients during locomotion. We estimate that trains of >30 APs over 3 s underlie these salient events. Their abundance in particular subsets of neurons was relatively stable across days. At the population level, we found that co-activity within the CA3 network was above chance level and that co-active neuron pairs maintained their correlated activity over days. Our results corroborate the notion of state-dependent spatiotemporal activity patterns in the recurrent network of CA3 and demonstrate that at least some features of population activity, namely co-activity of cell pairs and likelihood to engage in prolonged high activity, are maintained over days.
Assuntos
Cálcio , Células Piramidais , Potenciais de Ação , Animais , Hipocampo , Humanos , Camundongos , NeurôniosRESUMO
The aim of this research was to investigate the impact of the COVID-19 pandemic on teachers, particularly on their self-esteem and self-efficacy, their difficulty in the transition to distance learning, the difficulty of students, and specially of students with learning disabilities (LDs students), as perceived by teachers. 226 teachers were invited to complete an online questionnaire. Our results showed lower self-esteem and lower self-efficacy by the teachers compared with the normative sample. Self-esteem and self-efficacy also decrease in teachers with greater service seniority at work. Teachers perceived a greater difficulty in students than in their own difficulty. The concentration of the school system's efforts on the massive and, for long periods, exclusive organisation of distance learning risks favouring only cognitive aspects to the detriment of affective dynamics. This aspect could make teaching more complex for teachers and learning poorer for students, impoverishing the complex relational process that forms the basis of the learning process.
Assuntos
COVID-19 , Pandemias , Humanos , Itália/epidemiologia , Projetos Piloto , SARS-CoV-2 , Autoeficácia , EnsinoRESUMO
Inference of action potentials ('spikes') from neuronal calcium signals is complicated by the scarcity of simultaneous measurements of action potentials and calcium signals ('ground truth'). In this study, we compiled a large, diverse ground truth database from publicly available and newly performed recordings in zebrafish and mice covering a broad range of calcium indicators, cell types and signal-to-noise ratios, comprising a total of more than 35 recording hours from 298 neurons. We developed an algorithm for spike inference (termed CASCADE) that is based on supervised deep networks, takes advantage of the ground truth database, infers absolute spike rates and outperforms existing model-based algorithms. To optimize performance for unseen imaging data, CASCADE retrains itself by resampling ground truth data to match the respective sampling rate and noise level; therefore, no parameters need to be adjusted by the user. In addition, we developed systematic performance assessments for unseen data, openly released a resource toolbox and provide a user-friendly cloud-based implementation.
Assuntos
Artefatos , Encéfalo/fisiologia , Aprendizado Profundo , Neuroimagem/métodos , Neurônios/fisiologia , Potenciais de Ação/fisiologia , Animais , Cálcio/metabolismo , Bases de Dados Factuais , Camundongos , Modelos Neurológicos , Peixe-ZebraRESUMO
The endocannabinoid system regulates neurotransmission in brain regions relevant to neurobiological and behavioral actions of addicting drugs. We recently demonstrated that inhibition by URB597 of fatty acid amide hydrolase (FAAH), the main enzyme that degrades the endogenous cannabinoid N-acylethanolamine (NAE) anandamide and the endogenous non-cannabinoid NAEs oleoylethanolamide and palmitoylethanolamide, blocks nicotine-induced excitation of ventral tegmental area (VTA) dopamine (DA) neurons and DA release in the shell of the nucleus accumbens (ShNAc), as well as nicotine-induced drug self-administration, conditioned place preference and relapse in rats. Here, we studied whether effects of FAAH inhibition on nicotine-induced changes in activity of VTA DA neurons were specific for nicotine or extended to two drugs of abuse acting through different mechanisms, cocaine and morphine. We also evaluated whether FAAH inhibition affects nicotine-, cocaine- or morphine-induced actions in the ShNAc. Experiments involved single-unit electrophysiological recordings from DA neurons in the VTA and medium spiny neurons in the ShNAc in anesthetized rats. We found that URB597 blocked effects of nicotine and cocaine in the ShNAc through activation of both surface cannabinoid CB1-receptors and alpha-type peroxisome proliferator-activated nuclear receptor. URB597 did not alter the effects of either cocaine or morphine on VTA DA neurons. These results show that the blockade of nicotine-induced excitation of VTA DA neurons, which we previously described, is selective for nicotine and indicate novel mechanisms recruited to regulate the effects of addicting drugs within the ShNAc of the brain reward system.
Assuntos
Amidoidrolases/antagonistas & inibidores , Cocaína/farmacologia , Dopamina/metabolismo , Morfina/farmacologia , Neurônios/efeitos dos fármacos , Nicotina/farmacologia , Núcleo Accumbens/efeitos dos fármacos , PPAR alfa/efeitos dos fármacos , Receptores Citoplasmáticos e Nucleares/efeitos dos fármacos , Área Tegmentar Ventral/efeitos dos fármacos , Animais , Benzamidas/farmacologia , Carbamatos/farmacologia , Potenciais Evocados/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , RecompensaRESUMO
What are the main learning difficulties or advantages encountered by students with learning disabilities (LDs) within e-environments? As a result of the Covid-19 emergency, e-learning is being increasingly used to support students' learning processes. A number of countries closed their schools altogether, so face-to-face lessons were and have been replaced by distance lessons. A search of current literature via Scopus, Eric and Google Scholar electronic databases was conducted according to Prisma Guidelines. Other sources of literature were also considered, starting from the references in the full text of the articles consulted. We used the following search keywords: "LDs" combined with the "AND/OR" Boolean operator and "e-learning platforms," "well-being," "psychological factors," "emotional distress," and "self-regulation." One body of literature highlights the lack of inclusive accessibility standards and a lack of attention to specific tools for addressing LDs, which causes students to develop high levels of stress/anxiety and emotional distress, in addition to low levels of well-being, self-esteem and self-efficacy. Another area of literature looks at how students can develop high levels of self-regulation and emotional awareness, as well as high levels of inclusion. Results are discussed in terms of the promotion of e-learning that focuses on the psychological well-being of students and teachers use of technological tools.
RESUMO
Recent neuro-psychoanalytic literature has emphasized the view that our subjective identity rests on ancient subcortical neuro-psychic processes expressing unthinking forms of experience, which are "affectively intense without being known" (Solms and Panksepp, 2012). Devoid of internal representations, the emotional states of our "core-Self" (Panksepp, 1998b) are entirely "projected" towards the external world and tend to be discharged through instinctual action-patterns. However, due to the close connections between the subcortical and the cortical midline brain, the emotional drives may also find a way to be reflected within an intrinsic self-referential processing, evident when the organism is not actively engaged with the external world. Thanks to such endogenous functioning, the core-Self emotional dispositions are not overtly executed, but they are organized within coherent dynamic mental structures, called "feeling-toned complexes" by C. G. Jung and "unconscious phantasies" by Melanie Klein. The intrinsic self-referential dynamism of the "brainmind" originated from REM sleep arousal and then evolved in the resting-state activity of a complex of cortico-limbic midline brain structures (CMS), also called Default Mode Network (DMN). From our neuro-ethological perspective, it is sustained by an "introverted" SEEKING activity leading to the subjective exploration of internally constructed virtual scenarios. This "mind wandering" function, implicated in dreaming, fantasy processing, remembering and thinking, is the essence of the imaginative function and constitutes the first form of reflection, where intentions and drives gain a primordial form of conscious (but not self-conscious) representation. During postnatal development, this original ("archetypal") imaginative function is slowly attuned in a relational "transitional" space and may be expressed first in non-verbal and eventually in abstract-verbal social communicative patterns. Our view has noticeable implications for psychotherapy. Instead of trying to directly modify interpersonal, extrinsic relationships (a top-down approach), dysfunctional emotional-relational patterns may be modified by a process in which the patient is helped to let-go of the perceived feeling-objects in favor of an immersion, via the actual feeling, from the superficial level of perception towards a void feeling-state, empty of images. Only starting from this "anoetic" feeling-state, the deep imaginal creative and re-structuring self-referential activity may be reactivated by a process of spontaneous imagination.
RESUMO
Sensory association cortices receive diverse inputs with their role in representing and integrating multi-sensory content remaining unclear. Here we examined the neuronal correlates of an auditory-tactile stimulus sequence in the posterior parietal cortex (PPC) using 2-photon calcium imaging in awake mice. We find that neuronal subpopulations in layer 2/3 of PPC reliably represent texture-touch events, in addition to auditory cues that presage the incoming tactile stimulus. Notably, altering the flow of sensory events through omission of the cued texture touch elicited large responses in a subset of neurons hardly responsive to or even inhibited by the tactile stimuli. Hence, PPC neurons were able to discriminate not only tactile stimulus features (i.e., texture graininess) but also between the presence and omission of the texture stimulus. Whereas some of the neurons responsive to texture omission were driven by looming-like auditory sounds others became recruited only with tactile sensory experience. These findings indicate that layer 2/3 neuronal populations in PPC potentially encode correlates of expectancy in addition to auditory and tactile stimuli.
Assuntos
Estimulação Acústica , Percepção Auditiva/fisiologia , Sinais (Psicologia) , Discriminação Psicológica/fisiologia , Neurônios/fisiologia , Lobo Parietal/fisiologia , Percepção do Tato/fisiologia , Animais , Comportamento Animal , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Neural stem and progenitor cells (NSPCs) generate neurons throughout life in the mammalian hippocampus. We used chronic in vivo imaging and followed genetically labeled individual NSPCs and their progeny in the mouse hippocampus for up to 2 months. We show that NSPCs targeted by the endogenous Achaete-scute homolog 1 (Ascl1) promoter undergo limited rounds of symmetric and asymmetric divisions, eliciting a burst of neurogenic activity, after which they are lost. Further, our data reveal unexpected asymmetric divisions of nonradial glia-like NSPCs. Cell fates of Ascl1-labeled lineages suggest a developmental-like program involving a sequential transition from a proliferative to a neurogenic phase. By providing a comprehensive description of lineage relationships, from dividing NSPCs to newborn neurons integrating into the hippocampal circuitry, our data offer insight into how NSPCs support life-long hippocampal neurogenesis.
Assuntos
Divisão Celular , Hipocampo/citologia , Hipocampo/crescimento & desenvolvimento , Células-Tronco Neurais/citologia , Neurogênese , Neuroimagem , Neurônios/citologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Morte Celular , Divisão Celular/genética , Camundongos , Rede Nervosa/citologia , Rede Nervosa/crescimento & desenvolvimento , Neurogênese/genética , Neuroglia/citologia , Regiões Promotoras GenéticasRESUMO
Psychologists usually considered the "Self" as an object of experience appearing when the individual perceives its existence within the conscious field. In accordance with such a view, the self-representing capacity of the human mind has been related to corticolimbic learning processes taking place within individual development. On the other hand, Carl Gustav Jung considered the Self as the core of our personality, in its conscious and unconscious aspects, as well as in its actual and potential forms. According to Jung, the Self originates from an inborn dynamic structure integrating the essential drives of our "brain-mind," and leading both to instinctual behavioral actions and to archetypal psychological experiences. Interestingly, recent neuroethological studies indicate that our subjective identity rests on ancient neuropsychic processes that humans share with other animals as part of their inborn constitutional repertoire. Indeed, brain activity within subcortical midline structures (SCMSs) is intrinsically related to the emergence of prototypical affective states, that not only influence our behavior in a flexible way, but alter our conscious field, giving rise to specific feelings or moods, which constitute the first form of self-orientation in the world. Moreover, such affective dynamics play a central role in the organization of individual personality and in the evolution of all other (more sophisticated) psychological functions. Therefore, on the base of the convergence between contemporary cutting-edge scientific research and some psychological intuitions of Jung, we intend here to explore the first neuroevolutional layer of human mind, that we call the affective core of the Self.
RESUMO
We use an ultrafast diode-pumped semiconductor disk laser (SDL) to demonstrate several applications in multiphoton microscopy. The ultrafast SDL is based on an optically pumped Vertical External Cavity Surface Emitting Laser (VECSEL) passively mode-locked with a semiconductor saturable absorber mirror (SESAM) and generates 170-fs pulses at a center wavelength of 1027 nm with a repetition rate of 1.63 GHz. We demonstrate the suitability of this laser for structural and functional multiphoton in vivo imaging in both Drosophila larvae and mice for a variety of fluorophores (including mKate2, tdTomato, Texas Red, OGB-1, and R-CaMP1.07) and for endogenous second-harmonic generation in muscle cell sarcomeres. We can demonstrate equivalent signal levels compared to a standard 80-MHz Ti:Sapphire laser when we increase the average power by a factor of 4.5 as predicted by theory. In addition, we compare the bleaching properties of both laser systems in fixed Drosophila larvae and find similar bleaching kinetics despite the large difference in pulse repetition rates. Our results highlight the great potential of ultrafast diode-pumped SDLs for creating a cost-efficient and compact alternative light source compared to standard Ti:Sapphire lasers for multiphoton imaging.
RESUMO
Genetically encoded calcium indicators (GECIs) enable imaging of in vivo brain cell activity with high sensitivity and specificity. In contrast to viral infection or in utero electroporation, indicator expression in transgenic reporter lines is induced noninvasively, reliably, and homogenously. Recently, Cre/tTA-dependent reporter mice were introduced, which provide high-level expression of green fluorescent GECIs in a cell-type-specific and inducible manner when crossed with Cre and tTA driver mice. Here, we generated and characterized the first red-shifted GECI reporter line of this type using R-CaMP1.07, a red fluorescent indicator that is efficiently two-photon excited above 1000 nm. By crossing the new R-CaMP1.07 reporter line to Cre lines driving layer-specific expression in neocortex we demonstrate its high fidelity for reporting action potential firing in vivo, long-term stability over months, and versatile use for functional imaging of excitatory neurons across all cortical layers, especially in the previously difficult to access layers 4 and 6.
Assuntos
Cálcio/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Fótons , Animais , Expressão Gênica , Camundongos , Camundongos Transgênicos , Imagem Molecular , Neocórtex/diagnóstico por imagem , Neocórtex/metabolismoRESUMO
The computational repertoire of neurons is enhanced by regenerative electrical signals initiated in dendrites. These events, referred to as dendritic spikes, can act as cell-intrinsic amplifiers of synaptic input. Among these signals, dendritic NMDA spikes are of interest in light of their correlation with synaptic LTP induction. Because it is not possible to block NMDA spikes pharmacologically while maintaining NMDA receptors available to initiate synaptic plasticity, it remains unclear whether NMDA spikes alone can trigger LTP. Here we use dendritic recordings and calcium imaging to analyse the role of NMDA spikes in associative LTP in CA3 pyramidal cells. We show that NMDA spikes produce regenerative branch-specific calcium transients. Decreasing the probability of NMDA spikes reduces LTP, whereas increasing their probability enhances LTP. NMDA spikes and LTP occur without back-propagating action potentials. However, action potentials can facilitate LTP induction by promoting NMDA spikes. Thus, NMDA spikes are necessary and sufficient to produce the critical postsynaptic depolarization required for associative LTP in CA3 pyramidal cells.