DSpace Repository :: Browsing by Subject "CEREBRO"

Browsing by Subject "CEREBRO"

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Classification based on dynamic mode decomposition applied to brain recognition of context
(2021-09) Martínez, Sebastián; Silva, Azul; García Violini, Demián; Piriz, Joaquin; Belluscio, Mariano; Sánchez-Peña, Ricardo
"Local Field Potentials (LFPs) are easy to access electrical signals of the brain that represent the summation in the extracellular space, of currents originated within the neurons. As such, LFPs could contain infor mation about ongoing computations in neuronal circuits and could potentially be used to design brain machine interface algorithms. However how brain computations could be decoded from LFPs is not clear. Within this context, a methodology for signal classification is proposed in this study, particularly based on the Dynamic Mode Decomposition method, in conjunction with binary clustering routines based on supervised learning. Note that, although the classification methodology is presented here in the context of a biological problem, it can be applied to a broad range of applications. Then, as a case-study, the proposed method is validated with the classification of LFP-based brain cognitive states. All the analysis, signals, and results shown in this study consider real data measured in the hippocampus, in rats perform ing exploration tasks. Consequently, it is shown that, using the measured LFP, the method infers which context was the animal exploring. Thus, evidence on the spatial codification in LFP signals is consequently provided, which still is an open question in neuroscience."
Differential neurophysiological correlates of retrieval of consolidated and reconsolidated memories in humans: an ERP and pupillometry study
(2020-10) Campos-Arteaga, G.; Forcato, Cecilia; Wainstein, G.; Lagos, R.; Palacios-García, I.; Artigas, C.; Morales, R.; Pedreira, María Eugenia; Rodríguez, E.
"Consolidated memories can return to a labile state if they are reactivated by unpredictable reminders. To persist, active memories must be re-stabilized through a process known as reconsolidation. Although there is consistent behavioral evidence about this process in humans, the retrieval process of reconsolidated memories remains poorly understood. In this context, one fundamental question is whether the same or different neurophysiological mechanisms are involved in retrieval of consolidated and reconsolidated memories. Because it has been demonstrated that the exposure to the reconsolidation process may restructure and strengthen memories, we hypothesized distinct neurophysiological patterns during retrieval of reconsolidated memories. In addition, we hypothesized that interfering with the reconsolidation process using a new learning can prevent these neurophysiological changes. To test it, consolidated, reconsolidated and declarative memories whose reconsolidation process was interfered (i.e., picture-word pairs) were evaluated in humans in an old/new associative recall task while the brain activity and the pupillary response were recorded using electroencephalography and eyetracking. Our results showed that retrieval of reconsolidated memories elicits specific patterns of brain activation, characterized by an earlier peak latency and a smaller magnitude of the left parietal ERP old/new effect compared to memories that were only consolidated or whose reconsolidation process was interfered by a new learning. Moreover, our results demonstrated that only retrieval of reconsolidated memories is associated with a late reversed mid-frontal effect in a 600–690 time window. Complementarily, memories that were reactivated showed an earlier peak latency of the pupil old/new effect compared to non-reactivated memories. These findings support the idea that reconsolidation has an important impact in how memories are retrieved in the future, showing that retrieval of reconsolidated memories is partially supported by specific brain mechanisms."
Dopamine D1/D5 receptors in the restrosplenial cortex are necessary to consolidate object recognition memory
(2022-07-22) de Landeta, Ana Belén; Medina, Jorge Horacio; Katche, Cynthia
"The retrosplenial cortex (RSC) has been widely related to spatial and contextual memory. However, we recently demonstrated that the anterior part of the RSC (aRSC) is required for object recognition (OR) memory consolidation. In this study, we aimed to analyze the requirement of dopaminergic inputs into the aRSC for OR memory consolidation in male rats. We observed amnesia at 24-h long-term memory when we infused SCH23390, a D1/D5 dopamine receptors antagonist, into aRSC immediately after OR training session. However, the same infusion had no effect on OR short-term memory. Then, we analyzed whether the ventral tegmental area (VTA) is necessary for OR consolidation. VTA inactivation by intra-VTA administration of muscimol, a GABAA agonist, immediately after an OR training session induced amnesia when animals were tested at 24 h. Moreover, we observed that this VTA inactivation-induced amnesia was reversed by the simultaneous intra-aRSC delivery of SKF38393, a D1/D5 receptor agonist. Altogether, our results suggest that VTA dopaminergic inputs to aRSC play an important modulatory role in OR memory consolidation."
K-complex localization and classification algorithm
(2021) Vázquez Chenlo, Aylin; Carbonari, Giulia; Carosi, Julia; Forcato, Cecilia; Ramele, Rodrigo
"K-Complexes (KCs) are events present in non-rapid eye movement (non-REM) sleep, which have cellular dynamics similar to slow waves and have 3 distinguishing components: an initial P200, a posterior N500 and a final P900. Sleep plays a fundamental role in memory consolidation, favoring the transfer of new information from the hippocampus to the neocortex and its cortico-cortical redistribution. There are currently no studies that directly link KCs with memory processes, so they are not being considered as a possible facilitating event of this hippocampal-cortical dialogue. "
Non-linear susceptibility to interferences in declarative memory formation
(2022-06-29) Moyano, Malen D.; Carbonari, Giulia; Bonilla, Matías; Pedreira, María Eugenia; Brusco, Luis Ignacio; Kaczer, Laura; Forcato, Cecilia
"After encoding, memories go through a labile state followed by a stabilization process known as consolidation. Once consolidated they can enter a new labile state after the presentation of a reminder of the original memory, followed by a period of re-stabilization (reconsolidation). During these periods of lability the memory traces can be modified. Currently, some studies show a rapid stabilization after 30 min, while others show that stabilization occurs after longer periods (e.g. > 6 h). Here we investigate the effect of an interference treatment on declarative memory consolidation, comparing distinct time intervals after acquisition. On day 1, participants learned a list of non- syllable pairs (List 1). 5 min, 30 min, 3 h or 8 h later, they received an interference list (List 2) that acted as an amnesic agent. On day 2 (48 h after training) participants had to recall List 1 first, followed by List 2. We found that the List 1 memory was susceptible to interference when List 2 was administered 5 min or 3 h after learning but not when it was administered 30 min or 8 h after. We propose the possibility that this rapid memory protection could be induced by a fast and transient neocortical integration. Our results open a discussion about the contribution of molecular and systemic aspects to memory consolidation."
Odor cueing during sleep improves consolidation of a history lesson in a school setting
(2022-03-22) Vidal, Vanesa; Barbuzza, Alejo R.; Tassone, Leonela M.; Brusco, Luis Ignacio; Ballarini, Fabricio; Forcato, Cecilia
"Sleep is a key factor in memory consolidation. During sleep, information is reactivated, transferred, and redistributed to neocortical areas, thus favoring memory consolidation and integration. Although these reactivations occur spontaneously, they can also be induced using external cues, such as sound or odor cues, linked to the acquired information. Hence, targeted memory reactivation during sleep represents an advantageous tool for improving memory consolidation in real-life settings. In this study, our goal was to improve the consolidation of complex information such as that of a history lesson, using a school study session in the presence of an odor, and a reactivation round while sleeping at home on the same night of the acquisition, without using additional study sessions. We found that complex information can be associated with an odor in the classroom and that one session of reactivation during the frst night of sleep in the students’ houses improves its consolidation. These results bring new evidence for the implementation of reactivation during sleep in real-life settings."
The role of 20-min naps on declarative memory persistence
(2021) Vázquez Chenlo, Aylin; Carosi, Julia; Ramele, Rodrigo; Forcato, Cecilia
"K-Complexes (KC) are events present in non-rapid eye movement (non-REM) sleep, which have cellular dynamics similar to slow waves and have 3 distinguishing components: an initial P200, a posterior N500 and a final P900. Sleep plays a fundamental role in memory consolidation, favoring the transfer of new information from the hippocampus to the neocortex and its cortico-cortical redistribution. KCs have been postulated as mediators of the hippocampal-cortical dialogue since they recruit distant neuronal populations that do not depend on cortical connections."
Software para facilitar la localización de estructuras subcorticales que son blanco de electroestimulación
(2019-08-09) Oxenford, Simón; Milano, Federico E.
"La localización de los ganglios basales en imágenes de Resonancia Magnética Nuclear de 1.5T y 3T es un problema difícil, inclusive para neurocirujanos especializados. Una correcta localización de estos núcleos es importante para lograr buenos resultados en procedimientos quirúrgicos de implantación de electrodos profundos para estimulación cerebral profunda (Deep Brain Stimulation, DBS). En este trabajo aplicamos métodos de registración deformable de atlas cerebrales de reciente publicación para obtener una localización adecuada de estas estructuras. A su vez, reconstruimos la localización de los electrodos a partir de imágenes de Tomografía Computada con la finalidad de ver la disposición de los contactos con respecto a los núcleos. De esta forma se plantea asistir al cirujano en la conguración de la estimulación de cada paciente. Evaluamos la localización de los núcleos por medio de la comparación con imágenes pre y post operatorias en base a casos reales que cuentan con dichos estudios. Por último, extendimos un software de análisis y visualización de imágenes médicas al que integramos los algoritmos ya mencionados para que los resultados puedan ser validados por médicos especialistas."
Training a gaming agent on brainwaves
(2020-12-07) Bartolomé, Francisco; Moreno, Juan; Navas, Natalia; Vitali, José; Ramele, Rodrigo; Santos, Juan Miguel
"Error-related potential (ErrP) are a particular type of Event-Related Potential (ERP) elicited by a person attending a recognizable error. These Electroencephalographic (EEG) signals can be used to train a gaming agent by a Reinforcement Learning (RL) algorithm to learn an optimal policy. The experimental process consists of an observational human critic (OHC) observing a simple game scenario while their brain signals are captured. The game consists of a grid, where a blue spot has to reach a desired target in the fewest amount of steps. Results show that there is an effective transfer of information and that the agent successfully learns to solve the game efficiently, from the initial 97 steps on average required to reach the target to the optimal number of 8 steps. Our results are expressed in threefold: (i) the mechanics of a simple grid-based game that can elicit the ErrP signal component, (ii) the verification that the reward function only penalizes wrong steps, which means that type II error (not properly identifying a wrong movement) does not affect significantly the agent learning process; (iii) collaborative rewards from multiple observational human critics can be used to train the algorithm effectively and can compensate low classification accuracies and a limited scope of transfer learning schemes."
Volume-conducted origin of the field potential at the lateral habenula
(2020-01) Bertone-Cueto, Nicolás I.; Makarova, Julia; Mosqueira, Alejo; García Violini, Demián; Sánchez-Peña, Ricardo; Herreras, Oscar; Belluscio, Mariano; Piriz, Joaquín
"Field potentials (FPs) are easily reached signals that provide information about the brain’s processing. However, FP should be interpreted cautiously since their biophysical bases are complex. The lateral habenula (LHb) is a brain structure involved in the encoding of aversive motivational values. Previous work indicates that the activity of the LHb is relevant for hippocampal-dependent learning. Moreover, it has been proposed that the interaction of the LHb with the hippocampal network is evidenced by the synchronization of LHb and hippocampal FPs during theta rhythm. However, the origin of the habenular FP has not been analyzed. Hence, its validity as a measurement of LHb activity has not been proven. In this work, we used electrophysiological recordings in anesthetized rats and feed-forward modeling to investigate biophysical basis of the FP recorded in the LHb. Our results indicate that the FP in the LHb during theta rhythm is a volume-conducted signal from the hippocampus. This result highlight that FPs must be thoroughly analyzed before its biological interpretation and argues against the use of the habenular FP signal as a readout of the activity of the LHb."

Browsing by Subject "CEREBRO"

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