Biology subjects

Grothe, B.

Publications and source records attributed to Grothe, B..

4 recordsLinked to original sources

bioRxiv2023

The Dynamics of Context-Dependent Space Representations in AC

Auditory space is not mapped onto the receptor surface in the inner ear but results from complex neuronal computations by our brain. However, there is no consensus about the resulting neuronal representation of space in auditory cortex (AC) owing to contradicting reports: While many studies found a tuning preference for sound source positions in the contralateral hemisphere, others have observed an additional population of cells tuned to midline positions or even context-dependent dynamic changes in the tuning of individual cells. A fundamental difference across studies was the animals brain state, which might affect AC processing and thus the apparent nature of its spatial code. Yet no study to date investigated spatial tuning of identified AC neurons across brain states. Here, we employed longitudinal two-photon calcium imaging in the AC of mice under distinct states of wakefulness: anesthetized, idle awake, and during involvement in a go/no-go localization task. We find that previously reported differences in coding regimes are directly linked to wakefulness: A strong contralateral tuning bias is present under anesthesia, while pronounced and stable mid-line tuning appeared in awake but idle animals. Intriguingly, in localizing mice, tuning was different again with a large proportion of AC neurons responding to the position of the currently relevant sound-source. These population regimes remained stable across imaging sessions despite the spatial tuning of individual neurons being highly variable. Our findings resolve apparent contradictions in the literature and thus give a dynamical explanation for the multiple space representations in the AC.

neuroscience↗

bioRxiv2021

Diverse spatial representations in primary auditory cortex during active localization simultaneously code source location and identity

Localizing and identifying sensory objects while navigating the environment are fundamental brain functions. However, how individual objects are neuronally represented during unrestricted self-motion is mostly unexplored. We trained gerbils on a behavioral foraging paradigm that required localization and identification of sound-sources during free navigation. Chronic multi-electrode recordings in primary auditory cortex during task performance revealed previously unreported sensory object representations. Strikingly, the egocentric angle preference of the majority of spatially sensitive neurons changed significantly depending on the task-specific identity (outcome association) of the sound-source. Spatial tuning also exhibited larger temporal complexity. Moreover, we encountered egocentrically untuned neurons whose response magnitude differed between source identities. Using a neural network decoder we show that together, these neuronal response ensembles provide spatio-temporally co-existent information about both the egocentric location and the identity of individual sensory objects during self-motion, revealing a novel cortical computation principle for naturalistic sensing. HighlightsO_LILocalization task during free navigation prompts diverse spatial tuning in gerbil A1 C_LIO_LISpatial preference of individual neurons changes with sound-source identity C_LIO_LIEgo- and allocentric information are spatio-temporally coexistent in A1 ensembles C_LIO_LIActive sensing reveals new cortical representations for sensory object identification C_LI

neuroscience↗

bioRxiv2019

Cooperative population coding facilitates efficient sound source separability by adaptation to spatial statistics

Our sensory environment changes constantly. Accordingly, neural systems continually adapt to the concurrent stimulus statistics to remain sensitive over a wide range of conditions. Such dynamic range adaptation (DRA) is assumed to increase both the effectiveness of the neuronal code and perceptual sensitivity. However, direct demonstrations of DRA-based efficient neuronal processing that also produces perceptional benefits are lacking. Here we investigated the impact of DRA on spatial coding in the rodent brain and the perception of human listeners. Naturalistic spatial stimulation with dynamically changing source locations elicited prominent DRA already on the initial spatial processing stage, the Lateral Superior Olive (LSO) of gerbils of either sex. Surprisingly, on the level of individual neurons, DRA diminished spatial tuning due to large response variability across trials. However, when considering single-trial population averages of multiple neurons, DRA enhanced the coding efficiency specifically for the concurrently most probable source locations. Intrinsic LSO population imaging of energy consumption combined with pharmacology revealed that a slow-acting LSO gain control mechanism distributes activity across a group of neurons during DRA, thereby enhancing population coding efficiency. Strikingly, such "efficient cooperative coding" also improved neuronal source separability specifically for the locations that were most likely to occur. These location-specific enhancements in neuronal coding were paralleled by human listeners exhibiting a selective improvement in spatial resolution. We conclude that, contrary to canonical models of sensory encoding, the primary motive of early spatial processing is efficiency optimization of neural populations for enhanced source separability in the concurrent environment. Author summaryThe renowned efficient coding hypothesis suggests that neural systems adapt their processing to the statistics of the environment to maximize information while minimizing the underlying energetic costs. It is further assumed that such neuronal adaptations also confer perceptual advantages. Yet direct demonstrations of adaptive mechanisms or strategies that result both in increased neuronal coding efficiency and perceptual benefits are lacking. Here we show that an auditory spatial processing circuit exploits slow-acting gain control to distribute activity across the neuronal population, thereby enhancing coding efficiency based on single-trial population averages. This population-efficiency maximization also results in improved neuronal spatial resolution for the concurrently most probable source locations, which was resembled in a focally improved spatial acuity of human listeners.

neuroscience↗

bioRxiv2019

De novo assembly of the Mongolian gerbil genome and transcriptome

BACKGROUNDThe Mongolian gerbil (Meriones unguiculatus) has historically been used as a model organism for the auditory and visual systems, stroke/ischemia, epilepsy and aging related research since 1935 when laboratory gerbils were separated from their wild counterparts. In this study we report genome sequencing, assembly, and annotation further supported by transcriptome data from 27 different tissues samples. FINDINGSThe genome was assembled using Illumina HiSeq 2000 and resulted in a final genome size of 2.54 Gbp with contig and scaffold N50 values of 31.4 Kbp and 500.0 Kbp, respectively. Based on the k-mer estimated genome size of 2.48 Gbp, the assembly appears to be complete. The genome annotation was supported by transcriptome data that identified 36 019 predicted protein-coding genes across 27 tissue samples. A BUSCO search of 3023 mammalian groups resulted in 86% of curated single copy orthologs present among predicted genes, indicating a high level of completeness of the genome. CONCLUSIONSWe report a de novo assembly of the Mongolian gerbil genome that was further enhanced by annotation of transcriptome data from several tissues. Sequencing of this genome increases the utility of the gerbil as a model organism, opening the availability of now widely used genetic tools. The data sets supporting the results of this article are available in the China National GeneBank CNSA repository, Accession id: CNP0000340.

genomics↗