Biology subjects

Angeloni, C. F.

Publications and source records attributed to Angeloni, C. F..

5 recordsLinked to original sources

bioRxiv2024

Cell-specific inhibitory modulation of sound processing in the auditory thalamus.

Inhibition plays an important role in controlling the flow and processing of auditory information throughout the central auditory pathway, yet how inhibitory circuits shape auditory processing in the medial geniculate body (MGB), the key region in the auditory thalamus, is poorly understood. The MGB gates the flow of auditory information to the auditory cortex, and it is inhibited largely by the thalamic reticular nucleus (TRN). The TRN contains two major classes of inhibitory neurons: parvalbumin (PVTRN)-positive and somatostatin (SSTTRN)-positive neurons. PV and SST neurons have been shown to play differential roles in controlling sound responses in auditory cortex. In the somatosensory and visual subregions of the TRN, PVTRN and SSTTRN neurons exhibit anatomical and functional differences. However, it remains unknown whether and how PVTRN and SSTTRN neurons differ in their anatomical projections from the TRN to the auditory thalamus, and whether and how they differentially modulate activity in the MGB. We find that PVTRN and SSTTRN neurons exhibit differential projection patterns within the auditory thalamus: PVTRN neurons predominantly project to ventral MGB, whereas SSTTRN neurons project to the dorso-medial regions of MGB. Optogenetic inactivation of PVTRN neurons bidirectionally modulated sound-evoked activity in MGB, increasing firing in 29% of MGB neurons, while suppressing firing in 41%. In contrast, inactivating SSTTRN neurons largely suppressed tone-evoked activity in MGB neurons. Cell type-specific computational models identified candidate circuit mechanisms for generating the differential effects of TRN inactivation on MGB sound responses. These distinct inhibitory pathways within the auditory thalamus reveal cell type-specific organization of thalamic inhibition in auditory computation.

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bioRxiv2021

Cortical efficient coding dynamics shape behavioral performance.

Neurons throughout the sensory pathway adapt their responses depending on the statistical structure of the sensory environment. Contrast gain control is a form of adaptation in the auditory cortex, but it is unclear whether the dynamics of gain control reflect efficient adaptation, and whether they shape behavioral perception. Here, we trained mice to detect a target presented in background noise shortly after a change in the contrast of the background. The observed changes in cortical gain and behavioral detection followed the dynamics of a normative model of efficient contrast gain control; specifically, target detection and sensitivity improved slowly in low contrast, but degraded rapidly in high contrast. Auditory cortex was required for this task, and cortical responses were not only similarly affected by contrast but predicted variability in behavioral performance. Combined, our results demonstrate that dynamic gain adaptation supports efficient coding in auditory cortex and predicts the perception of sounds in noise.

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bioRxiv2021

Sound improves neuronal encoding of visual stimuli in mouse primary visual cortex

In everyday life, we integrate visual and auditory information in routine tasks such as navigation and communication. Whereas concurrent sound can improve visual perception, the neuronal correlates of this audiovisual integration are not fully understood. Specifically, it remains unclear whether neuronal firing patters in the primary visual cortex (V1) of awake animals demonstrate similar sound-induced improvement in visual discriminability. Furthermore, presentation of sound is associated with movement in the subjects, but little is understood about whether and how sound-associated movement affects audiovisual integration in V1. We investigated how sound and movement interact to modulate V1 visual responses in awake, head-fixed mice and whether this interaction improves neuronal encoding of the visual stimulus. We presented visual drifting gratings with and without simultaneous auditory white noise to awake male and female mice while recording mouse movement and V1 neuronal activity. Sound modulated light-evoked activity of 80% of light-responsive neurons, with 95% of neurons increasing activity when the auditory stimulus was present. Sound consistently enhanced movement, however, a generalized linear model revealed that sound and movement had distinct and complementary effects of the neuronal visual responses. Furthermore, decoding of the visual stimulus from the neuronal activity was improved with sound, even when controlling for movement. Thus, sound and movement modulate visual responses in complementary ways, improving neuronal representation of the visual stimulus. This study clarifies the role of movement as a potential confound in neuronal audiovisual responses and expands our knowledge of how multimodal processing is mediated in the awake brain. Significance statementSound and movement are both known to modulate visual responses in the primary visual cortex, however sound-induced movement has largely remained unaccounted for as a potential confound in audiovisual studies in awake animals. Here, authors found that sound and movement both modulate visual responses in an important visual brain area, the primary visual cortex, in distinct, yet complementary ways. Furthermore, sound improved encoding of the visual stimulus even when accounting for movement. This study reconciles contrasting theories on the mechanism underlying audiovisual integration and asserts the primary visual cortex as a key brain region participating in tripartite sensory interactions.

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bioRxiv2021

Cortico-Fugal Regulation of Predictive Coding.

Sensory systems must account for both contextual factors and prior experience to adaptively engage with the dynamic external environment. In the central auditory system, neurons modulate their responses to sounds based on statistical context. These response modulations can be understood through a hierarchical predictive coding lens: responses to repeated stimuli are progressively decreased, in a process known as repetition suppression, whereas unexpected stimuli produce a prediction error signal. Prediction error incrementally increases along the auditory hierarchy from the inferior colliculus (IC) to the auditory cortex (AC), suggesting that these regions may engage in hierarchical predictive coding. A potential substrate for top-down predictive cues is the massive set of descending projections from the auditory cortex to subcortical structures, although the role of this system in predictive processing has never been directly assessed. We tested the effect of optogenetic inactivation of the auditory cortico-collicular feedback in awake mice on responses of IC neurons to stimuli designed to test prediction error and repetition suppression. Inactivation of the cortico-collicular pathway led to a decrease in prediction error in IC. Repetition suppression was unaffected by cortico-collicular inactivation, suggesting that this metric may reflect fatigue of bottom-up sensory inputs rather than predictive processing. We also discovered populations of IC neurons that exhibit repetition enhancement, a sequential increase in firing with stimulus repetition. Cortico-collicular inactivation led to a decrease in repetition enhancement in the central nucleus of IC, suggesting that it is a top-down phenomenon. Negative prediction error, a stronger response to a tone in a predictable rather than unpredictable sequence, was suppressed in shell IC units during cortico-collicular inactivation. These changes in predictive coding metrics arose from bidirectional modulations in the response to the standard and deviant contexts, such that neurons in IC responded more similarly to each context in the absence of cortical input. We also investigated how these metrics compare between the anesthetized and awake states by recording from the same neurons under both conditions. We found that metrics of predictive coding and deviance detection differ depending on the anesthetic state of the animal, with negative prediction error emerging in the central IC and repetition enhancement and prediction error being more prevalent in the absence of anesthesia. Overall, our results demonstrate that the auditory cortex provides cues about the statistical context of sound to subcortical brain regions via direct feedback, regulating processing of both prediction and repetition.

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bioRxiv2020

Neuronal activity in sensory cortex predicts the specificity of learning.

Learning to avoid dangerous signals while preserving normal responses to safe stimuli is essential for everyday behavior and survival. Fear learning has a high level of inter-subject variability. Following identical experiences, subjects exhibit fear specificities ranging from high (specializing fear to only the dangerous stimulus) to low (generalizing fear to safe stimuli). Pathological fear generalization underlies emotional disorders, such as post-traumatic stress disorder. The neuronal basis of fear specificity remains unknown. Here, we identified the neuronal code that underlies inter-subject variability in fear specificity using longitudinal imaging of neuronal activity before and after differential fear conditioning in the auditory cortex of mice. Neuronal activity prior to, but not after learning predicted the level of specificity following fear conditioning across subjects. Stimulus representation in auditory cortex was reorganized following conditioning. However, the reorganized neuronal activity did not relate to the specificity of learning. These results present a novel neuronal code that determines individual patterns in learning.

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