Biology subjects

Magyar, D.

Publications and source records attributed to Magyar, D..

4 recordsLinked to original sources

bioRxiv2026

The Amygdalostriatal Transition Area Exhibits Lateral Amygdala-Like Spiking Activity and Tone-Shock Pairing-Induced Plasticity

During Pavlovian fear conditioning, presentation of a conditioned stimulus, such as a tone, together with an unconditioned stimulus, such as an electrical shock, excites neurons in the lateral amygdala (LA). Prevailing models propose that sensory stimulus-evoked activity in the LA is subsequently propagated to its downstream nuclei: the basal amygdala (BA) and central amygdala (CeA). To test this assumption, we performed in vivo electrophysiological recordings in awake, head-fixed male and female mice. We found that tone presentation did not elicit a significant increase in firing in BA or CeA neurons. In contrast, shock presentation evoked similarly robust spiking responses in LA and BA neurons but only a modest increase in CeA neurons. Notably, neurons in the amygdalostriatal transition area (AStria) exhibited LA-like sensory stimulus-evoked responses at both short (<25 ms) and longer (<500 ms) timescales. To examine the role of feedforward inhibition in tone- and shock-evoked activity, we investigated the contribution of parvalbumin interneurons using optogenetics and found that short-latency (<25 ms) spiking in both the LA and AStria was regulated by these inhibitory cells. Finally, LA and AStria neurons exhibited remarkably similar response types, spiking dynamics, and pairing-induced plasticity during repeated tone presentations, subsequent tone-shock pairings, and post-pairing tone presentations. Together, these findings support a model in which the LA and AStria operate in parallel, similarly integrating tone and shock signals during fear conditioning, whereas BA and CeA neurons are not robustly recruited by these sensory stimuli under the conditions tested.

neuroscience↗

bioRxiv2026

Sensory stimulation triggers different spike responses in serotonin and dopamine neurons in the dorsal midbrain tegmentum.

The dorsal midbrain tegmentum, including the dorsal raphe nucleus (DRN) and the ventrolateral periaqueductal gray (vlPAG), contains diverse neuronal populations. Within this region, serotonin (5-HT) and dopamine (DA) neurons are the principal monoaminergic cell types and exert widespread influence on brain circuits. While the role of 5-HT and DA neurons in sensory integration is well established, their stimulus-driven spiking activity remains incompletely characterized. Using silicon probe recordings in mice, we found that >57% of DRN/vlPAG neurons responded to foot shock and mechanical stimulation, whereas <15% showed changes in spiking activity following light or acoustic stimulation. At the population level, similar results were obtained using juxtacellular recordings, a method that allowed post hoc identification of 5-HT and DA neurons. Upon foot shock delivery, 5-HT neurons exhibited heterogeneous responses, including both excitation and inhibition, whereas DA neurons typically increased their firing rates. We found that DA neurons lacking vasoactive intestinal polypeptide (VIP) fired within the first second after foot shocks, while VIP-expressing DA neurons were most active later. Together, our results demonstrate that DRN/vlPAG neurons are most responsive to foot shock and mechanical stimuli. Moreover, 5-HT and DA neurons exhibit distinct patterns of activation following aversive inputs, suggesting that they play different roles in sensory information processing.

neuroscience↗

bioRxiv2024

Metagenomic peek into a corn mummy

Numerous studies have shown that metagenomics has opened a dimension in reading the contents of archaeological remains as time capsules. Corn mummies are ritual objects from ancient Egypt, created by forming human-shaped figures from cereal grains grown in a mixture of water and earth. The aim of our study was to determine whether ancient DNA could be preserved in the mummy, and if so, which organisms it might have originated from. To find answers, we performed metagenomic analyses on samples taken from a corn mummy dating to the second half of the third century BC. Alongside a number of clearly modern contaminants, we identified organisms that cannot be excluded as being of historical origin. Besides considerable amounts of bacterial sequences belonging to the genus Bacillus, Mesobacillus, Metabacillus, Neobacillus, Niallia, Peribacillus and Paenibacillus, we also found traces of plants, animals, and humans. Sequences assigned to the genus Triticum showed the highest similarity to ancient T. turgidum ssp. dicoccum specimens from Egypt and the southern Levant. The fragments identified as of Lepidopteran origin showed the greatest similarity to Sphingidae genomes. Analysis of the human-derived sequences revealed L3 (mtDNA), E, and J (Y chromosome) haplotypes, which are common lineages in Africa today.

bioinformatics↗

bioRxiv2023

Diversity and connectivity of principal neurons in the lateral and basal nuclei of the mouse amygdala

The basolateral amygdala is a non-layered cortical structure playing a role in various cognitive processes. Despite many studies focusing on local information processing within the circuits of the basolateral amygdala, the characteristics of excitatory principal neurons (PNs) are still not fully revealed. Here, we combined neuroanatomical, electrophysiological, and tracing techniques to determine the single-cell features, dendritic and axonal projections of PNs within the lateral (LA) and basal amygdala (BA). Using a mouse reporter line, we found that cholecystokinin (CCK) expression defines two spatially and functionally segregated groups of PNs both in the LA and BA. PNs in CCK-positive (CCK+) areas of the LA (LAa) had small somata and short dendrites which matched their single-cell electrophysiological properties. PNs in CCK-negative (CCK-) areas of the LA (LAp) and all BA had similarly ramified dendrites and single-cell features with some differences. Importantly, the dendritic arbors of PNs were restricted to the subnuclei defined by CCK expression, which corresponded to various extra-amygdalar afferents indicating specific inputs on distinct PN groups. Axonal arborization patterns of PNs within the basolateral amygdala and surrounding areas showed consistency to their soma location. For instance, BA PNs that projected to the medial prefrontal cortex but not to the lateral nucleus of the central amygdala were present in CCK+ areas. In contrast, those BA PNs that projected to the lateral part of the central nucleus were found in the subnucleus lacking CCK. Our study revealed that the basolateral amygdala is composed of functionally different subnuclei with specific inputs and outputs. This structural arrangement may empower the LA and BA to flexibly channel processed information toward their downstream regions, which can be a key requirement for diverse amygdala functions in cognitive operation.

neuroscience↗