Biology subjects

Fernandez, L. M. J.

Publications and source records attributed to Fernandez, L. M. J..

3 recordsLinked to original sources

bioRxiv2026

A Conserved Locus Coeruleus fMRI Signature of Brain-State Transitions across Sleep, Anesthesia, and Wakefulness

Neuromodulatory systems dynamically reconfigure large-scale brain networks to support adaptation across behavioral and cognitive states. The locus coeruleus (LC), which broadcasts noradrenaline throughout the forebrain, is a central regulator of arousal and state-dependent dynamics. However, how LC activity manifests in brain-wide organization across physiological contexts, and how it biases fMRI connectivity, remains poorly understood. Using an optogenetically informed cross-species framework, we identify a transient LC-derived spatiotemporal pattern of brain activity accompanying brain-state transitions under progressively naturalistic conditions: controlled LC stimulation and endogenous LC fluctuations in anesthetized mice, sleep-wake transitions in rodents and humans, and resting-state activity in awake humans. This LC-derived signature is conserved across species and contexts, leaving a robust and detectable imprint on the BOLD signal. Critically, the prevalence of LC events systematically biases functional connectivity metrics in human fMRI. These findings establish LC activity as a mechanistically interpretable source of variability in resting-state measurements, with direct implications for the interpretation of fMRI biomarkers in arousal-related disorders.

neuroscience↗

bioRxiv2022

Autophagy in parvalbumin interneurons is required for inhibitory transmission and memory via regulation of synaptic proteostasis

With the emerging role of the autophagic machinery in healthy brain development and aging, there is a pressing need to better characterize its functions in different neuronal populations, providing cellular insight into autophagy-related brain diseases. Here, we generated and characterized mice with conditional ablation of atg5 in GABAergic neurons expressing parvalbumin (PV-atg5KO), mostly comprising fast-spiking interneurons, as well as Purkinje cells in the cerebellum. Using light-sheet microscopy to image PV neurons throughout the brain, we reveal that autophagy is required for the sustenance of Purkinje cells but not of PV-interneurons. Yet, proteomic analysis showed that autophagy deficiency in cortical and hippocampal PV-interneurons alters the proteostasis of key synaptic proteins, as well as the surface expression of glutamate receptor subunits. Consistently, hippocampal autophagy-deficient PV-interneurons exhibit reduced inhibitory neurotransmission and PV-atg5KO mice display excitation-inhibition imbalance in the hippocampus and memory deficits. Our findings demonstrate a neuronal type-specific vulnerability to autophagy deficiency, while also identifying PV-interneurons as cellular substrates where autophagy is required for memory.

neuroscience↗

bioRxiv2019

A thalamic reticular circuit for head direction cell tuning and spatial navigation

To navigate in space, an animal must refer to sensory cues to orient and move. Circuit and synaptic mechanisms that integrate cues with internal head-direction (HD) signals remain, however, unclear. We identify an excitatory synaptic projection from the presubiculum (PreS) and the multisensory-associative retrosplenial cortex (RSC) to the anterodorsal thalamic reticular nucleus (TRN), so far classically implied in gating sensory information flow. In vitro, projections to TRN involved AMPA/NMDA-type glutamate receptors that initiated TRN cell burst discharge and feedforward inhibition of anterior thalamic nuclei. In vivo, chemogenetic anterodorsal TRN inhibition modulated PreS/RSC-induced anterior thalamic firing dynamics, broadened the tuning of thalamic HD cells, and led to preferential use of allo-over egocentric search strategies in the Morris water maze. TRN-dependent thalamic inhibition is thus an integral part of limbic navigational circuits wherein it coordinates external sensory and internal HD signals to regulate the choice of search strategies during spatial navigation.

neuroscience↗