Compartir
Título
Functional Mechanisms of Neuronal Mismatch in the Auditory Midbrain and the Medial Prefrontal Cortex
Autor(es)
Director(es)
Palabras clave
Redes neuronales (Neurobiología)
SSA
Cells
MMN
Neuronal Activity
Neuronal stimulation
mPFC cells
Clasificación UNESCO
2490 Neurociencias
3205.07 Neurología
3207.11 Neuropatología
Fecha de publicación
2021
Resumen
[EN] Context in the environment around us highly influences our perceptions and the neural
processing of sensory information. This doctoral thesis studies the mechanisms that shape
the neural representations of sounds depending on the context in which they occur.
Neurons in all sensory systems adapt rapidly, preserving energy while simultaneously
enabling stimuli with potential survival or behavioral relevance to use additional
processing resources. Stimulus-specific adaptation (SSA) is a special type of neuronal
adaptation, specific to repeated and predictable stimuli, while preserving responsiveness to
other different, unexpected, and probably more informative input.
SSA has been linked to high-order brain processing such as deviance detection and
perceptual inference. The nonlemniscal subdivisions of the inferior colliculus (IC) are the
first sites in which these multifaceted coding properties emerge in the auditory hierarchy.
Nevertheless, the molecular, cellular, and network mechanisms contributing to the
generation of SSA are controversial and a matter of debate. SSA has been classically studied
at the somatic spiking output, which results from the interaction of the synaptic inputs, its
tuning characteristics, and membrane properties. Hence, in Study I, I report the passive
properties, intrinsic properties, and auditory postsynaptic potentials under the oddball
paradigm stimulation in 10 whole-cell patch-clamp recordings in vivo in the mouse IC
(Valdés-Baizabal et al., 2020b). Although passive properties were similar, data suggest that
intrinsic properties such as the firing patterns differed between lemniscal nonadapting and
nonlemniscal adapting cells. SSA is absent at the synaptic level of the recorded neurons,
which further demonstrates that SSA emerges in the nonlemniscal IC.
Ascending along the auditory hierarchy, the encoding of the spectral properties of
sound is subsequently substituted by more abstract representations allowing the detection
of contextual changes in prefrontal regions. These high-order areas have been classically
studied for the generation of automatic deviance detection using the scalp-recorded
mismatch negativity (MMN) using similar oddball paradigms that also elicit SSA.
However, the mechanisms that generate MMN and its neuronal correlate are neither
clearly located nor understood in frontal cortices. Thus, Study II analyses the mechanisms
governing deviance detection under the oddball paradigm in the rat medial prefrontal
cortex (mPFC) within the predictive processing framework (Casado-Román et al., 2020).
My results demonstrate in all mPFC fields and cortical layers that unpredictable auditory
stimulation elicited stronger responses than the weak or even absent activity driven by
predictable sounds. The time course of prefrontal spiking and LFP activity coincides with
the large-scale MMN-like signals in the rat providing the missing link at the microscopic,
mesoscopic, and macroscopic levels of automatic deviance detection. Hence, mPFC cells
could model the possible neuronal correlate of the frontal MMN generators. Mismatch
responses in mPFC are almost purely made of prediction error signaling activity and
different in nature from those at the IC, auditory thalamus, and auditory cortex with an
important effect of repetition suppression (comparisons with a previous study in our lab
by Parras et al., 2017).
Descripción
Tesis por compendio de publicaciones
URI
Collections
Files in this item
Tamaño:
17.89Mb
Formato:
Adobe PDF
Descripción:
Tesis