Biology subjects

Alcami, P.

Publications and source records attributed to Alcami, P..

6 recordsLinked to original sources

bioRxiv2025

Functional interaction of electrical coupling and H-current and its putative impact on inhibitory transmission

The flow of information within neural circuits depends on the communication between neurons, primarily taking place at chemical and electrical synapses. The coexistence of these two modalities of synaptic transmission and their dynamical interaction with voltage-gated membrane conductances enables a rich repertoire of complex functional operations. One such operation, coincidence detection, allows electrically coupled neurons to respond more strongly to simultaneous synaptic inputs than to temporally dispersed ones. Using the mesencephalic trigeminal (MesV) nucleus--a structure composed of large, somatically coupled neurons--as an experimental model, we first demonstrate that electrical coupling strength in the hyperpolarized voltage range is highly time-dependent due to the involvement of the IH current. We then show how this property influences the coincidence detection of hyperpolarizing signals. Specifically, simultaneous hyperpolarizing inputs induce larger membrane potential changes, resulting in stronger IH current activation. This, in turn, shortens the temporal window for coincidence detection. We propose that this phenomenon may be crucial for networks dynamics in circuits of electrically coupled neurons that receive inhibitory synaptic inputs and express the IH current. In particular, molecular layer interneurons (MLIs) of the cerebellar cortex provide an ideal model for studying coincidence detection of inhibitory synaptic inputs, and how this operation is shaped by the voltage-dependent conductances like the IH current, potentially impacting on motor coordination and learning.

neuroscience↗

bioRxiv2025

Canaries differentially modulate solo and overlapping singing during the transition to the breeding season

Songbirds sing different song types depending on the social context. Songs can be categorized into two types based on their timing relative to other birds songs: solo and temporally-over-lapping songs. Overlapping songs have been typically characterized in the breeding season, in which they are associated with an aggressive social context. However, whether both song types occur year long, and whether they show differential modulation of their frequency and properties during the transition between the non-breeding and the breeding season has been rarely studied. Here we investigate, in a group of domesticated canaries (Serinus canaria), the variation of singing in both song types at the transition between the nonbreeding and the breeding season. We found that both song types were present outside the breeding season. Whereas for solo songs, duration and its variability, fraction of time singing and number of songs increased as the breeding season approached, overlapping songs showed opposite trends. Furthermore, both song types were distributed more homogeneously as the daylength increased. Overall, the differential changes of both song types at the seasonal time scale suggest differential underlying mechanisms and functions of these two song types found in a social setting.

animal behavior and cognition↗

bioRxiv2023

Adaptive introgression of a visual preference gene

Visual preferences are important drivers of mate choice and sexual selection, but little is known of how they evolve at the genetic level. Here we take advantage of the diversity of bright warning patterns displayed by Heliconius butterflies, which are also used during mate choice. We show that two Heliconius species have evolved the same visual mating preferences for females with red patterns by exchanging genetic material through hybridization. Extensive behavioral experiments reveal that male preferences are associated with a genomic region of increased admixture between these two species. Variation in neural expression of regucalcin1, located within this introgressed region, correlates with visual preference across populations, and disruption of regucalcin1 with CRISPR/Cas9 impairs courtship towards conspecific females, proving a direct link between gene and behavior. Our results support a role for hybridization during behavioral evolution, and show how visually-guided behaviors contributing to adaptation and speciation are encoded within the genome.

evolutionary biology↗

bioRxiv2023

Mitochondria induce anisotropy and delays in action potential conduction

The internal resistance of axons to ionic current flow affects the speed of action potential propagation. As biological cables, axons contain mitochondria which are necessary to support axonal function with energy supply. Although we would expect mitochondria to increase the internal resistance to current flow, their impact on the conduction velocity of action potentials has remained elusive. To investigate the impact of mitochondria on action potential propagation in the small non-myelinated fibers found in the vertebrate brain, we combined computational modeling and electron microscopy from the axons found in the premotor pathway that controls the production of birdsong with submillisecond precision. Mitochondria occupancy of axonal cross-sections ranged from 5 to 73% (average: 29%) in the [~] 0.2-0.7 m diameter non-myelinated axons connecting song premotor nuclei HVC and RA in canaries. Interestingly, this occupancy depends on axonal diameter: axonal cross-section occupancy by mitochondria was larger in small axons, with an average occupancy of [~]46% for axons with diameters smaller than 300 nm and [~]21% for larger diameters. Computational modeling showed that when the propagating action potential meets a mitochondrion, the conduction velocity decreases and the action potential is delayed by tenths of microseconds to microseconds. This effect is stronger in small axons given their larger cross section mitochondrial occupancy and cumulates delays of tenths of milliseconds along the whole pathway linking HVC and RA. Finally, we modeled the impact of varying densities of mitochondria on action potential propagation along the songbird premotor pathway. In summary, our model shows that axonal mitochondria induce the anisotropic propagation of action potentials, and that this effect cumulates a typical delay in the order of tenths of milliseconds over distances of mms. By partially occupying axoplasm, mitochondria constitute a biological design constraint that delays information processing in the small-diameter unmyelinated axons found in the vertebrate brain.

neuroscience↗

bioRxiv2020

Demographics and Employment of Max-Planck Society's Postdocs

The recently founded Max Planck PostdocNet brings together postdoctoral researchers (or postdocs) from the Max Planck Society (MPS), provides representation for the postdoctoral community across all Max Planck Institutes (MPI) and associated institutes, and advocates for their interests on their behalf. At the 2019 founding meeting, MPS postdocs quickly raised their concerns about their employment situation and their associated social and working conditions. Subsequently, the PostdocNet conducted the first survey targeting exclusively postdoctoral researchers to gather information on their demographics, employment situations and social conditions. This report presents the results of this survey, providing a thorough characterization of the postdoc demographics as well as the working conditions experienced by the postdoctoral community of the MPS. Remarkably, the survey analysis revealed a number of disparities in the access to employment type, wage level and social benefits. These results will guide future and present MPS postdoctoral researchers and their employers at the MPS to thrive for equality and fairness. Moreover, these results should be of help to the MPS to establish, improve and maintain optimal working conditions for MPS postdocs.

scientific communication and education↗

bioRxiv2019

Collective singing dynamics in a competition context drive song plasticity

Singing by songbirds is a complex motor skill learnt during juvenile development or, in open-ended learners, before the onset of the breeding season. Outside of these specific periods, it is believed that birdsong does not change. Challenging this, here we demonstrate that in a seasonal songbird, social interactions during the breeding season induce a novel form of singing plasticity in naturalistic social environments. Using custom-made telemetric backpack technology to monitor song-based communication from freely-behaving canaries, we show that males temporally overlap their songs during aggressive duels. Singing duels induce an unexpected fast plasticity in song length, thereby enhancing singing performance and flexibility of a sexually-selected behavior. Remarkably, dueling canaries sing acoustically-similar songs, suggesting that competition within a specific song acoustic space drives dueling behavior. Overall, our findings reveal a previously unrecognized type of song plasticity different from the well-studied slow song plasticity as an imitation process for display purposes.

animal behavior and cognition↗