Papers by Bonifacio Zanutto
Neurocomputational cortical memory for spectro-temporal phonetic abstraction.
ZIP files of folders containing all the datasets (audio file corpora) employed in our research to... more ZIP files of folders containing all the datasets (audio file corpora) employed in our research to train the Encoder Layer (EL) and the SVMs and to test the complete CSTM. This folder includes a set of 840 corpora which are distributed in 2 corpora for each configuration organized by 2 sets of synthesized voices, 3 syllabic conditions (i.e. mono-, di- and tri-syllabic English words) and 10 completely different vocabularies all distributed in 6 acoustic variants, beyond the original version of the corpora. The 6 acoustic variants corresponds to: two levels of white noise (19.8 dB and 13.8 dB Signal to Noise Ratio (SNR) average Root Mean Square (RMS) power rate), two levels of reverberation (Reveberation-Time 60 dB (RT-60) value of 0.61 seconds and 1.78 seconds) and variations of pitch on both directions (from E to G and from E to C).
Quarterly Journal of Experimental Psychology, 2012
Most languages have a basic or “canonical” word order, which determines the relative positions of... more Most languages have a basic or “canonical” word order, which determines the relative positions of the subject (S), the verb (V), and the object (O) in a typical declarative sentence. The frequency of occurrence of the six possible word orders among world languages is not distributed uniformly. While SVO and SOV represent around 85% of world languages, orders like VSO (9%) or OSV (0.5%) are much less frequent or extremely rare. One possible explanation for this asymmetry is that biological and cognitive constraints for structured sequence processing make some word orders easier to be processed than others. Therefore, the high frequency of these word orders would be related to their higher learnability. The aim of the present study was to compare the learnability of different word orders between groups of adult subjects. Four artificial languages with different word orders were trained: two frequent (SVO, SOV) and two infrequent (VSO, OSV). In a test stage, subjects were asked to disc...
Brain Research, 2013
Artificial grammars have been widely applied to the study of sequential learning in language, but... more Artificial grammars have been widely applied to the study of sequential learning in language, but few studies have directly compared the neural correlates of artificial and native grammar processing. In this study, we examined Event Related Potentials (ERPs) elicited by structural anomalies in semantic-free artificial grammar sequences and sentences in the subjects' native language (Spanish). Although ERPs differed during early stages, we observed similar posterior negativities (N400) and P600 effects in a late stage. We interpret these results as evidence of at least partially shared neural mechanisms for processing of language and artificial grammars. We suggest that in both the natural and artificial grammars, the N400 and P600 components we observed can be explained as the result of unfulfilled predictions about incoming stimuli.
Brain Research, 2011
A wide range of studies have found late positive ERP components in response to anomalies during p... more A wide range of studies have found late positive ERP components in response to anomalies during processing of structured sequences. In language studies, this component is named Syntactic Positive Shift (SPS) or P600. It is characterized by an increase in potential peaking around 600 ms after the appearance of the syntactic anomaly and has a centroparietal topography. Similar late positive components were found more recently in non-linguistic contexts. These results have led to the hypothesis that these components index the detection of anomalies in rule-governed sequences, or the access to abstract rule representations, regardless of the nature of the stimuli. Additionally, there is evidence showing that the SPS/P600 is sensitive to probability manipulations, which affect the subjects' expectancy of the stimuli. Our aim in the present work was to address the hypothesis that the late positive component is modulated by the subject's expectancy of the stimuli. To do so, we employed an artificial grammar learning task, and controlled the frequency of presentation to different kind of sequences during training. Results showed that certain sequence types elicited a late positive component which was modulated by different factors in two distinct time windows. In an earlier window, the component was higher for sequences which had a low or null probability of occurrence during training, while in a later window, the component was higher for incorrect than correct sequences. Furthermore, this late window effect was absent in those subjects whose performance was not significantly above chance. Two possible explanations for this effect are suggested.
Parallel Computing: Technology Trends
The interdisciplinary field of neuroscience has made significant progress in recent decades, prov... more The interdisciplinary field of neuroscience has made significant progress in recent decades, providing the scientific community in general with a new level of understanding on how the brain works beyond the store-and-fire model found in traditional neural networks. Meanwhile, Machine Learning (ML) based on established models has seen a surge of interest in the High Performance Computing (HPC) community, especially through the use of high-end accelerators, such as Graphical Processing Units(GPUs), including HPC clusters of same. In our work, we are motivated to exploit these high-performance computing developments and understand the scaling challenges for new–biologically inspired–learning models on leadership-class HPC resources. These emerging models feature sparse and random connectivity profiles that map to more loosely-coupled parallel architectures with a large number of CPU cores per node. Contrasted with traditional ML codes, these methods exploit loosely-coupled sparse data ...
Psicolingüística en español: homenaje a Juan Seguí, 2013
Sociedad de Neuropsicología de Argentina, Dec 1, 2014
Neurocomputational cortical memory for spectro-temporal phonetic abstraction.
Neurocomputational cortical memory for spectro-temporal phonetic abstraction.
This repository holds three files: File S1 Data. Cortical Spectro-Temporal Model (CSTM) experimen... more This repository holds three files: File S1 Data. Cortical Spectro-Temporal Model (CSTM) experimental results data. It contains a spreadsheet including all the numerical results returned by the experiments as well as the complete Statistical Significance tests conducted in this work. File S2 Data. CSTM complementary experimental results data. It contains a spreadsheet that includes all the numerical results returned by a complementary set of experiments. File S1 Appendix. Computational Setup and Complementary Experiments. An appendix including the Computational Setup of our CSTM, which describes its object oriented inheritance structure as well as the parallelization strategy used for its implementation in High Performance Computing (HPC) resources. We also include Strong and Weak scaling tests of our implementation on HPC resources. An appendix including a battery of complementary experiments showing the classification accuracy levels of different instances of the EL in the CSTM.
Scientific Reports, 2021
Serotonin (5-HT) is a key neuromodulator of medial prefrontal cortex (mPFC) functions. Pharmacolo... more Serotonin (5-HT) is a key neuromodulator of medial prefrontal cortex (mPFC) functions. Pharmacological manipulation of systemic 5-HT bioavailability alters the electrical activity of mPFC neurons. However, 5-HT modulation at the population level is not well characterized. In the present study, we made single neuron extracellular recordings in the mPFC of rats performing an operant conditioning task, and analyzed the effect of systemic administration of fluoxetine (a selective serotonin reuptake inhibitor) on the information encoded in the firing activity of the neural population. Chronic (longer than 15 days), but not acute (less than 15 days), fluoxetine administration reduced the firing rate of mPFC neurons. Moreover, fluoxetine treatment enhanced pairwise entropy but diminished noise correlation and redundancy in the information encoded, thus showing how mPFC differentially encodes information as a function of 5-HT bioavailability. Information about the occurrence of the reward-p...
Perspectivas en Psicología, 2012
Classic theories of grammar processing propose a discrete combinatorial system that applies algeb... more Classic theories of grammar processing propose a discrete combinatorial system that applies algebraic-like rules to syntax parsing. An ERP elicited by syntactic anomalies, the P600 is considered an index of parsing processing demands. An alternative possibility is that syntax structure is processed as a probabilistic mapping of cooccurrences between word categories. Classic theories predict that grammatical but infrequent sentences will not elicit a P600, while probabilistic theories propose that infrequent word-combinations will be processed in a similar way to ungrammatical sentences. The present study compared potential frequency and grammaticality ERP effects during syntax processing. Three verbs were employed which could be followed by two structures with different frequencies of use: a) Infinitival clause (IC, 80%) and b) Complement clause (CC, 20%). Four types of sentences were shown: Frequent Grammatical (FG), Infrequent Grammatical (IG), syntax violation of FG, syntax viola...
Revista Argentina de Ciencias del Comportamiento, 2019
Se ha propuesto que la capacidad de adquirir lenguaje y relaciones de equivalencia están vinculad... more Se ha propuesto que la capacidad de adquirir lenguaje y relaciones de equivalencia están vinculadas. Estudios previos muestran que estímulos relacionados por equivalencia transfieren propiedades combinatorias en una gramática artificial. Recíprocamente, en el presente trabajo analizamos si estímulos que comparten las mismas propiedades combinatorias por entrenamiento en una gramática artificial verifican posteriormente las propiedades de una clase de equivalencia. Los resultados muestran que los estímulos de una misma clase combinatoria conforman una clase funcional que verifica las propiedades de la equivalencia (i.e. reflexividad, simetría y transitividad). El procesamiento de estas relaciones genera un potencial N400 que refleja un costo de procesamiento vinculado al número de estímulos nodales intervinientes. Este resultado podría explicarse en términos de un sistema proactivo que extrae y almacena regularidades estadísticas de los estímulos; conecta estímulos nuevos con las rep...
Fil: Lopes Da Cunha, Pamela Johanna. Consejo Nacional de Investigaciones Cientificas y Tecnicas. ... more Fil: Lopes Da Cunha, Pamela Johanna. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Biologia y Medicina Experimental. Fundacion de Instituto de Biologia y Medicina Experimental. Instituto de Biologia y Medicina Experimental; Argentina
Behavioural Brain Research, 2021
Serotonin (5-HT) neurotransmission has been associated with reward-related behaviour. Moreover, t... more Serotonin (5-HT) neurotransmission has been associated with reward-related behaviour. Moreover, the serotonergic system modulates the basolateral amygdala (BLA), a structure involved in reward encoding, and reward prediction error. However, the role played by 5-HT on BLA during a reward-driven task has not been fully elucidated. In this paper, we investigated whether serotonergic modulation of the BLA is involved in reward-driven learning. To this end, we trained Long Evans rats in an operant conditioning task, and examined the effects of fluoxetine treatment (a selective serotonin reuptake inhibitor, 10 mg/kg) in combination with BLA lesions with NMDA (20 mg/ml) on extinction learning. We also investigated whether intra-BLA injection of the serotonergic 5-HT1A receptor agonist 8-OH DPAT, or antagonist WAY-100635, alters extinction performance. We found that fluoxetine treatment strongly accelerated extinction learning, while BLA lesions partially reverted this effect and slightly impaired consolidation of extinction. Stimulation and inhibition of 5-HT1A receptors in BLA induced opposite effects to those of fluoxetine, impairing or accelerating extinction performance, respectively. Our findings suggest that 5-HT modulates reward-driven learning, and 5-HT1A receptors located in the BLA are relevant for extinction.
Neural network models are an invaluable tool to understand brain function, since they allow to co... more Neural network models are an invaluable tool to understand brain function, since they allow to connect the cellular and circuit levels with behaviour. Neural networks usually comprise a huge number of parameters, which must be chosen carefully such that networks reproduce anatomical, behavioural and neurophysiological data. These parameters are usually fitted with off-the-shelf optimization algorithms that iteratively change network parameters and simulate the network to evaluate the changes and improve fitting. Here we propose to invert the fitting process by proceeding from the network dynamics towards network parameters. Firing state transitions are chosen according to the transition graph followed by an agent when solving a given behavioural task. Then, a system of linear equations is constructed from the network firing states and membrane potentials, in such a way that system consistency in guarantee. This allows to uncouple the activity features of the model, like its neurons ...
Scientific Reports, 2018
It has been proposed that neuronal populations in the prefrontal cortex (PFC) robustly encode tas... more It has been proposed that neuronal populations in the prefrontal cortex (PFC) robustly encode task-relevant information through an interplay with the ventral tegmental area (VTA). Yet, the precise computation underlying such functional interaction remains elusive. Here, we conducted simultaneous recordings of single-unit activity in PFC and VTA of rats performing a GO/NoGO task. We found that mutual information between stimuli and neural activity increases in the PFC as soon as stimuli are presented. Notably, it is the activity of putative dopamine neurons in the VTA that contributes critically to enhance information coding in the PFC. The higher the activity of these VTA neurons, the better the conditioned stimuli are encoded in the PFC.
PLOS ONE, 2019
Cooperation is one of the most studied paradigms for the understanding of social interactions. Re... more Cooperation is one of the most studied paradigms for the understanding of social interactions. Reciprocal altruism-a special type of cooperation that is taught by means of the iterated prisoner dilemma game (iPD)-has been shown to emerge in different species with different success rates. When playing iPD against a reciprocal opponent, the larger theoretical long-term reward is delivered when both players cooperate mutually. In this work, we trained rats in iPD against an opponent playing a Tit for Tat strategy, using a payoff matrix with positive and negative reinforcements, that is food and timeout respectively. We showed for the first time, that experimental rats were able to learn reciprocal altruism with a high average cooperation rate, where the most probable state was mutual cooperation (85%). Although when subjects defected, the most probable behavior was to go back to mutual cooperation. When we modified the matrix by increasing temptation rewards (T) or by increasing cooperation rewards (R), the cooperation rate decreased. In conclusion, we observe that an iPD matrix with large positive reward improves less cooperation than one with small rewards, shown that satisfying the relationship among iPD reinforcement was not enough to achieve high mutual cooperation behavior. Therefore, using positive and negative reinforcements and an appropriate contrast between rewards, rats have cognitive capacity to learn reciprocal altruism. This finding allows to infer that the learning of reciprocal altruism has early appeared in evolution.
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Papers by Bonifacio Zanutto