How the bat brain detects novel sounds (commentary on Wetekam et al., 2021)

[ES] Artículo de Manuel S. Malmierca, titulado: Cómo el cerebro del murciélago detecta sonidos novedosos (comentario sobre Wetekam et al., 2021)

Stimulus-specific adaptation and deviance detection in the inferior colliculus

[EN] Deviancy detection in the continuous flow of sensory information into the central nervous system is of vital importance for animals. The task requires neuronal mechanisms that allow for an efficient representation of the environment by removing statistically redundant signals. Recently, the neuronal principles of auditory deviance detection have been approached by studying the phenomenon of stimulus-specific adaptation (SSA). SSA is a reduction in the responsiveness of a neuron to a common or repetitive sound while the neuron remains highly sensitive to rare sounds (Ulanovsky et al., 2003). This phenomenon could enhance the saliency of unexpected, deviant stimuli against a background of repetitive signals. SSA shares many similarities with the evoked potential known as the “mismatch negativity,” (MMN) and it has been linked to cognitive process such as auditory memory and scene analysis (Winkler et al., 2009) as well as to behavioral habituation (Netser et al., 2011). Neurons exhibiting SSA can be found at several levels of the auditory pathway, from the inferior colliculus (IC) up to the auditory cortex (AC). In this review, we offer an account of the state-of-the art of SSA studies in the IC with the aim of contributing to the growing interest in the single-neuron electrophysiology of auditory deviance detection. The dependence of neuronal SSA on various stimulus features, e.g., probability of the deviant stimulus and repetition rate, and the roles of the AC and inhibition in shaping SSA at the level of the IC are addressed

Cholinergic Modulation of Stimulus-Specific Adaptation in the Inferior Colliculus

[EN] Neural encoding of an ever-changing acoustic environment is a complex and demanding process that depends on modulation by neuro-active substances. Some neurons of the inferior colliculus (IC) exhibit “stimulus-specific adaptation” (SSA), i.e., a decrease in their response to a repetitive sound, but not to a rare one. Previous studies have demonstrated that acetylcholine (ACh) alters the frequency response areas of auditory neurons and therefore is important in the encoding of spectral information. Here, we address how microion-tophoretic application of ACh modulates SSA in the IC of the anesthetized rat. We found that ACh decreased SSA in IC eurons by increasing the response to the repetitive tone. This effect was mainly mediated by muscarinic receptors. The strength of the cholinergic modulation depended on the baseline SSA level, exerting its greatest effect on neurons with intermediate SSA responses across IC subdivisions. Our data demonstrate that the increased availability of ACh exerts transient functional changes in partially adapting IC neurons, enhancing the sensory encoding of the ongoing stimulation. This effect potentially contributes to the propagation of ascending sensory-evoked afferent activity through the thalamus en route to the cortex

Modelo psicopedagógico de las aulas de teleenseñanza del Centro de Supercomputación de Galicia

El Centro de Supercomputación de Galicia le concede especial importancia a la TeleEnseñanza; es por ello que dispone de un Departamento de TeleEnseñanza en el que se llevan a cabo proyectos de investigación sobre el tema en cuestión a nivel autonómico, naThe Supercomputing Centre of Galicia (CESGA) grants special importance to distance-learning; therefore it counts with a distance-learning department where different research projects take place, at an autonomic, national and European levels. Besides, CES

Corticothalamic Pathways in Auditory Processing: Recent Advances and Insights From Other Sensory Systems

The corticothalamic (CT) pathways emanate from either Layer 5 (L5) or 6 (L6) of the neocortex and largely outnumber the ascending, thalamocortical pathways. The CT pathways provide the anatomical foundations for an intricate, bidirectional communication between thalamus and cortex. They act as dynamic circuits of information transfer with the ability to modulate or even drive the response properties of target neurons at each synaptic node of the circuit. L6 CT feedback pathways enable the cortex to shape the nature of its driving inputs, by directly modulating the sensory message arriving at the thalamus. L5 CT pathways can drive the postsynaptic neurons and initiate a transthalamic corticocortical circuit by which cortical areas communicate with each other. For this reason, L5 CT pathways place the thalamus at the heart of information transfer through the cortical hierarchy. Recent evidence goes even further to suggest that the thalamus via CT pathways regulates functional connectivity within and across cortical regions, and might be engaged in cognition, behavior, and perceptual inference. As descending pathways that enable reciprocal and context-dependent communication between thalamus and cortex, we venture that CT projections are particularly interesting in the context of hierarchical perceptual inference formulations such as those contemplated in predictive processing schemes, which so far heavily rely on cortical implementations. We discuss recent proposals suggesting that the thalamus, and particularly higher order thalamus via transthalamic pathways, could coordinate and contextualize hierarchical inference in cortical hierarchies. We will explore these ideas with a focus on the auditory system.This work was supported by the Spanish Agencia Estatal de Investigación [(AEI), PID2019-104570RB- I00] and Junta de Castilla y León, (SA252P20) to MSM. FMA held a postdoctoral fellowship from the University of Salamanca (Contratos Postdoctorales, USAL, Programa II)

É-galego : aprendiendo gallego en la red

É-galego es un curso multimedia de gallego en formato CD-Rom y web de nivel intermedio dirigido a hispanohablantes. El curso cuenta con un avanzado sistema de evaluación para el seguimiento del progreso del alumno/a y con un diseño de navegación y disposición de los contenidos adaptados a los diferentes tipos y ritmos de aprendizajeÉ-Galego is a multimedia course of Galician in CD-ROM and web format of intermediate level aimed at Spanish-speaking people. The course counts with an advanced system of evaluation for the monitoring of student’s progress and a browsing design and an adapted disposition of contents for the different types and paces of learning

Expression of the Neuregulin Receptor ErbB4 in the Brain of the Rhesus Monkey (Macaca mulatta)

We demonstrated recently that frontal cortical expression of the Neuregulin (NRG) receptor ErbB4 is restricted to interneurons in rodents, macaques, and humans. However, little is known about protein expression patterns in other areas of the brain. In situ hybridization studies have shown high ErbB4 mRNA levels in various subcortical areas, suggesting that ErbB4 is also expressed in cell types other than cortical interneurons. Here, using highly-specific monoclonal antibodies, we provide the first extensive report of ErbB4 protein expression throughout the cerebrum of primates. We show that ErbB4 immunoreactivity is high in association cortices, intermediate in sensory cortices, and relatively low in motor cortices. The overall immunoreactivity in the hippocampal formation is intermediate, but is high in a subset of interneurons. We detected the highest overall immunoreactivity in distinct locations of the ventral hypothalamus, medial habenula, intercalated nuclei of the amygdala and structures of the ventral forebrain, such as the islands of Calleja, olfactory tubercle and ventral pallidum, and medium expression in the reticular thalamic nucleus. While this pattern is generally consistent with ErbB4 mRNA expression data, further investigations are needed to identify the exact cellular and subcellular sources of mRNA and protein expression in these areas. In contrast to in situ hybridization in rodents, we detected only low levels of ErbB4-immunoreactivity in mesencephalic dopaminergic nuclei but a diffuse pattern of immunofluorescence that was medium in the dorsal striatum and high in the ventral forebrain, suggesting that most ErbB4 protein in dopaminergic neurons could be transported to axons. We conclude that the NRG-ErbB4 signaling pathway can potentially influence many functional systems throughout the brain of primates, and suggest that major sites of action are areas of the “corticolimbic” network. This interpretation is functionally consistent with the genetic association of NRG1 and ERBB4 with schizophrenia

Deviance detection in auditory subcortical structures: what can we learn from neurochemistry and neural connectivity?

[EN] A remarkable ability of animals that is critical for survival is to detect and respond to to unexpected stimuli in an ever-changing world. Auditory neurons that show stimulusspecific adaptation (SSA), i.e., a decrease in their response to frequently occurring stimuli while maintaining responsiveness when different stimuli are presented, might participate in the coding of deviance occurrence. Traditionally, deviance detection is measured by the mismatch negativity (MMN) potential in studies of evoked local field potentials.We present a review of the state-of-the-art of SSA in auditory subcortical nuclei, i.e., the inferior colliculus and medial geniculate body of the thalamus, and link the differential receptor distribution and neural connectivity of those regions in which extreme SSA has been found. Furthermore, we review both SSA and MMN-like responses in auditory and non-auditory areas that exhibit multimodal sensitivities that we suggest conform to a distributed network encoding for deviance detection. The understanding of the neurochemistry and response similarities across these different regions will contribute to a better understanding of the neural mechanism underlying deviance detection

Experiencias exitosas de e- learning en la universidad gallega

Este artículo resume la información obtenida en el marco de un proyecto de investigación, denominado "Observatorio gallego de e-learning". Dicha investigación fue dirigida por el Centro de Supercomputación de Galicia, con la participación activa de las tres universidades gallegas. Su principal objetivo fue realizar un análisis en profundidad sobre el estado del e-learning tanto en la universidad como en la empresa gallegas. Entre los elementos analizados, se encuentran algunas experiencias que se están desarrollando en la Universidad en Galicia en el campo del e-learning .This article summarizes some of the information obtained in a research conducted by the Supercomputing Center of Galicia (Spain) and the three public universities of Galicia, under the name of "Galician Elearning Observatory". Its main objective was to analyze the state of e-learning in companies and universities from Galicia. Among the elements taken into account, some successful experiences from elearning at Galician Universities were described. In addition to this, it seemed to us interesting to announce some experience that is developing nowadays in Galicia in the field of the e-learning in the university

Stimulus-Specific Adaptation in the Auditory Thalamus of the Anesthetized Rat

The specific adaptation of neuronal responses to a repeated stimulus (Stimulus-specific adaptation, SSA), which does not fully generalize to other stimuli, provides a mechanism for emphasizing rare and potentially interesting sensory events. Previous studies have demonstrated that neurons in the auditory cortex and inferior colliculus show SSA. However, the contribution of the medial geniculate body (MGB) and its main subdivisions to SSA and detection of rare sounds remains poorly characterized. We recorded from single neurons in the MGB of anaesthetized rats while presenting a sequence composed of a rare tone presented in the context of a common tone (oddball sequences). We demonstrate that a significant percentage of neurons in MGB adapt in a stimulus-specific manner. Neurons in the medial and dorsal subdivisions showed the strongest SSA, linking this property to the non-lemniscal pathway. Some neurons in the non-lemniscal regions showed strong SSA even under extreme testing conditions (e.g., a frequency interval of 0.14 octaves combined with a stimulus onset asynchrony of 2000 ms). Some of these neurons were able to discriminate between two very close frequencies (frequency interval of 0.057 octaves), revealing evidence of hyperacuity in neurons at a subcortical level. Thus, SSA is expressed strongly in the rat auditory thalamus and contribute significantly to auditory change detection