Biology subjects

Zippo, A. G.

Publications and source records attributed to Zippo, A. G..

4 recordsLinked to original sources

bioRxiv2022

Look-up and look-down neurons in the mouse visual thalamus during freely moving exploration

The traditional view that visuomotor integration is a property of higher brain centres has recently been challenged by the discovery in head-fixed rodents that locomotion increases neuronal activity throughout the early visual system (including the retina). Any appreciation of the importance of this behavioural modulation of visual inputs must encompass a comprehensive understanding of the range of behaviours engaged by this mechanism. This information is unavailable from head-fixed preparations in which head and body postures are fundamentally constrained and dissociated from their natural coupling with visual experience. We addressed this deficit by recording spiking activity from the primary visual thalamus during freely moving exploration, while simultaneously applying frame-by-frame quantification of postures and movements to robust 3D reconstructions of head and body. We found that postures associated with the animal looking up/down affected activity in >50% neurons. The extent of this effect was comparable to that induced by locomotion. Moreover, the two effects were largely independent and jointly modulated neuronal activity. Thus, while most units were excited by locomotion, some expressed highest firing when the animal was looking up ("look up" neurons) while others when the animal was looking down ("look-down" neurons). These results were observed in the dark, thus representing a genuine behavioural modulation, and were amplified in a lit arena. These findings define the influence of natural exploratory behaviour on activity in the early visual system and reveal the importance of up/down postures in gating neuronal activity in the primary visual thalamus.

neuroscience↗

bioRxiv2019

Chronic pain alters microvascular architectural organization of somatosensory cortex

Chronic pain (CP) represents a complex pathology profoundly involving both neural and glial compartments of the central nervous system. While most CP studies have also investigated the macroscopic brain vascular system, its microstructural architecture still remains largely unexplored. Further, the adaptive modifications of the vascular microstructure as consequence of diseases or pathological insults, did not receive adequate attention. Here we show microtomographic signs of diffuse and conspicuous microvascular neogenesis in somatosensory cortex of CP animal models already peaking at 15 days from the model instantiation. Progressive fading of this microvessel neogenesis then ensued in the next six months yet maintaining higher vascular density with a preserved small fraction of them. Due to the important consequences on the neuron-glial-vessel arrangements and on the resulting metabolic and functional disorders of the local networks, novel additional scenarios of CP are thus conceivable with profound consequences of potential future CP diagnostic and therapeutic appraisals.

neuroscience↗

bioRxiv2019

Removal of behavioural and electrophysiological signs of chronic pain by in vivo microsections of rat somatosensory cortex with parallel X-ray microbeams

Chronic pain (CP) is a condition characterized by a wide spectrum of clinical signs and symptoms, missing a sound modelling at the neuronal network scale. Recently, we presented a general theory showing common electrophysiological traits in different CP rat models, i.e. a collapse of relevant functional connectivity network properties, such as modularity, in the somatosensory thalamo-cortical (TC) network. In this work, we preliminary investigated by an in silico accurate simulator of the six-layer mammalian cortical networks that evidenced the crucial collapse of network modularity in CP simulated conditions and the consequent reduction of network adaptive processes. On this track, in studies on CP experimental animals affected by sciatic nerve multiple ligature (Bennett-Xie model), by synchrotron-generated X-ray microbeam (MB) irradiations (7 parallel beams, 100um width), we targeted in vivo the CP involved hindlimb somatosensory projection cortex that, because of the doses radiation (360 Gy, peak at each beam), non-invasively produced fast and precise tissue destruction along the 7 beam projections. These parcellated the cortical tissue and restored the cortical network statistics related to modularity and information processing efficiency as evidenced from post irradiation in vivo electrophysiological recordings. In addition, by MB treatment there was an ensuing removal of behavioral signs of allodynia and hyperalgesia accompanied by recovered normal gait schemes yet preserving the normal sensory thresholds of the experimental rats up to three months after the MB irradiation. Finally, novel and unprecedented therapeutic appraisals for CP are devised. Significance StatementChronic pain (CP) is an excruciating condition with severe effects on patients life. Apart from many clinical and experimental studies no current theory on CP is generally accepted. Recently, we proposed a general theory of CP in experimental animals as characterized by strong alteration of the connections among neurons in different brain regions. We show here on in silico simulations that specific connectivity changes in the somatosensory cortex recover the lost functional integrity. Concurrently, in experimental animals, we re-modulated, in vivo, some anatomical connections of the somatosensory cortex by extremely thin synchrotron generated X-ray microbeam irradiations. The resulting behavioral and electrophysiological signs of CP disappeared yet maintaining normal sensory responses. No adverse or pathological effects on blank animals were observable.

neuroscience↗

bioRxiv2016

Alternating dynamics of segregation and integration in human brain functional networks during working-memory task

Brain functional networks show high variability in short time windows but mechanisms governing these transient dynamics still remain unknown. In this work we studied the temporal evolution of functional brain networks involved in a working memory task while recording high-density electroencephalography in human normal subjects. We found that functional brain networks showed an initial phase characterized by an increase of the functional segregation index followed by a second phase where the functional segregation fell down and the functional integration prevailed. Notably, wrong trials were associated with different sequences of the segregation-integration profile and measures of network centrality and modularity were able to catch crucial aspects of the oscillatory network dynamics. Additionally, computational investigations further supported the experimental results. The brain functional organization may respond to the information processing demand of a working memory task following a 2-step atomic scheme wherein segregation and integration alternately dominate the functional configurations.

neuroscience↗