Biology subjects

Preuss, T.

Publications and source records attributed to Preuss, T..

6 recordsLinked to original sources

bioRxiv2023

Multisensory integration enhances audiovisual responses in the Mauthner cell

Multisensory integration combines information from multiple sensory modalities to create a coherent perception of the world. In contexts where sensory information is limited or equivocal, it also allows animals to integrate individually ambiguous stimuli into a clearer or more accurate percept and, thus, react with a more adaptive behavioral response. Although responses to multisensory stimuli have been described at the neuronal and behavioral levels, a causal or direct link between these two is still missing. In this study, we studied the integration of audiovisual inputs in the Mauthner cell, a command neuron necessary and sufficient to trigger a stereotypical escape response in fish. We performed intracellular recordings in adult goldfish while presenting a diverse range of stimuli to determine which stimulus properties affect their integration. Our results show that stimulus modality, intensity, temporal structure, and interstimulus delay affect input summation. Mechanistically, we found that the distinct decay dynamics of feedforward inhibition triggered by auditory and visual stimuli can account for certain aspects of input integration. Altogether, this is a rare example of the characterization of multisensory integration in a cell with clear behavioral relevance, providing both phenomenological and mechanistic insights into how multisensory integration depends on stimulus properties.

neuroscience↗

bioRxiv2022

Approaching object acceleration differentially affects the predictions of neuronal collision-avoidance models

The processing of visual information for collision avoidance has been investigated at the biophysical level in several model systems. In grasshoppers, the{eta} model captures reasonably well the visual processing performed by an identified neuron called the lobular giant movement detector (LGMD) as it tracks approaching objects. Similar phenomenological models have been used to describe either the firing rate or the membrane potential of neurons responsible for visually-guided collision avoidance in other animals. In goldfish, the{kappa} model has been proposed to describe the Mauthner cell, an identified neuron involved in startle escape responses. In the vinegar fly, a third model was developed for the giant fiber neuron, which trigger last resort escapes immediately before an impending collision. One key property of these models is their prediction that peak neuronal responses occur a fixed delay after the simulated approaching object reaches a threshold angular size on the retina. This prediction is valid for simulated objects approaching at a constant speed. We tested whether it remains valid when approaching objects accelerate. After characterizing and comparing the models responses to accelerating and constant speed stimuli, we find that the prediction holds true for the{kappa} and the giant fiber model, but not for the{eta} model. These results suggest that acceleration in the approach trajectory of an object may help distinguish and further constrain the neuronal computations required for collision avoidance in grasshoppers, fish, and vinegar flies.

neuroscience↗

bioRxiv2022

Convergent escape behavior from distinct visual processing of impending collision in fish and grasshoppers

In animal species ranging from invertebrate to mammals, visually guided escape behaviors have been studied using looming stimuli, the two-dimensional expanding projection on a screen of an object approaching on a collision course at constant speed. The peak firing rate or membrane potential of neurons responding to looming stimuli often tracks a fixed threshold angular size of the approaching stimulus that contributes to the triggering of escape behaviors. To study whether this result holds more generally, we designed stimuli that simulate acceleration or deceleration over the course of object approach on a collision course. Under these conditions, we found that collision detecting neurons in grasshoppers were sensitive to acceleration whereas the triggering of escape behaviors was less so. In contrast, neurons in goldfish identified indirectly through the characteristic features of the escape behaviors they trigger, showed little sensitivity to acceleration. This closely mirrored a broader lack of sensitivity to acceleration of the goldfish escape behavior. Thus, although the sensory coding of simulated colliding stimuli with non-zero acceleration likely differs in grasshoppers and goldfish, the triggering of escape behaviors converges towards similar characteristics. Approaching stimuli with non-zero acceleration may help refine our understanding of neural computations underlying escape behaviors in a broad range of animal species. Key pointsO_LIA companion manuscript showed that two mathematical models of collision-detecting neurons in grasshoppers and goldfish make distinct predictions for their responses to simulated objects approaching on a collision course with non-zero acceleration. C_LIO_LITesting these experimental predictions showed that grasshopper neurons are sensitive to acceleration while goldfish neurons are not, in agreement with the distinct models proposed previously in these species using constant velocity approaches. C_LIO_LIBoth the escape behaviors of grasshopper and goldfish were insensitive to acceleration suggesting a further transformation downstream in grasshopper motor circuits that matches the computation observed in the goldfish Mauthner cell. C_LIO_LIThus, in spite of different sensory processing in the two species, escape behaviors converge towards similar solutions. C_LIO_LIThe use of object acceleration during approach on a collision course may help better understand the neural computations implemented for collision avoidance in a broad range of species. C_LI

neuroscience↗

bioRxiv2019

Cell-type specific epigenetic links to schizophrenia risk in brain

The importance of cell-type specific epigenetic variation of non-coding regions in neuropsychiatric disorders is increasingly appreciated, yet data from disease brains are conspicuously lacking. We generated cell-type specific whole-genome methylomes (N=95) and transcriptomes (N=89) from neurons and oligodendrocytes from brains of schizophrenia and matched controls. The methylomes of these two cell-types are highly distinct, with the majority of differential DNA methylation occurring in non-coding regions. DNA methylation difference between control and schizophrenia brains is subtle compared to cell-type difference, yet robust against permuted data and validated in targeted deep-sequencing analyses. Differential DNA methylation between control and schizophrenia tends to occur in cell-type differentially methylated sites, highlighting the significance of cell-type specific epigenetic dysregulation in a complex neuropsychiatric disorder. Our resource provides novel and comprehensive methylome and transcriptome data from distinct cell populations from schizophrenia brains, further revealing reduced cell-type epigenetic distinction in schizophrenia.

genomics↗

bioRxiv2019

Accelerated evolution of oligodendrocytes in human brain

Recent discussions of human brain evolution have largely focused on increased neuron numbers and changes in their connectivity and expression. However, it is increasingly appreciated that oligodendrocytes play important roles in cognitive function and disease. Whether both cell-types follow similar or distinctive evolutionary trajectories is not known. We examined the transcriptomes of neurons and oligodendrocytes in the frontal cortex of humans, chimpanzees, and rhesus macaques. We identified human-specific trajectories of gene expression in neurons and oligodendrocytes and show that both cell-types exhibit human-specific upregulation. Moreover, oligodendrocytes have undergone accelerated gene expression evolution in the human lineage compared to neurons. The signature of acceleration is enriched for cell type-specific expression alterations in schizophrenia. These results underscore the importance of oligodendrocytes in human brain evolution.

evolutionary biology↗

bioRxiv2018

Evolutionarily developed connections compromised in schizophrenia

The genetic basis and uniquely human character of schizophrenia has led to the notion of human brain evolution to have resulted in vulnerability to the disorder. We examined schizophrenia-related changes in brain connectivity in the context of evolutionary changes in human brain wiring by comparing in-vivo neuroimaging data from humans, chimpanzees and macaque monkeys. We find that evolutionary changes in human connectome organization overlap with the pattern of schizophrenia-related changes in brain connectivity, with connections evolutionary enhanced in the human brain showing significantly more involvement in schizophrenia pathology than connections shared between humans and non-human primates (effects shown in three independent patient-control datasets). Our findings suggest that the evolution of brain wiring in support of complex brain function in humans may have come at the cost of an increased vulnerability to brain dysfunction in disease.

neuroscience↗