Biology subjects

Tufo, C.

Publications and source records attributed to Tufo, C..

3 recordsLinked to original sources

bioRxiv2024

Functional maturation and experience-dependent plasticity in adult-born olfactory bulb dopaminergic neurons

Continued integration of new neurons persists in only a few areas of the adult mouse brain. In the olfactory bulb (OB), immature adult-born neurons respond differently to olfactory stimuli compared to their more mature counterparts, and have heightened levels of activity-dependent plasticity. These distinct functional features are thought to bestow unique properties onto existing circuitry. OB interneurons, including those generated through adult neurogenesis, consist of a set of highly distinct subtypes. However, we do not currently know the different cell-type-specific mechanisms underlying their functional development and plastic potential. Here, we specifically characterised electrophysiological maturation and experience-dependent plasticity in a single, defined subtype of adult-born OB neuron: dopaminergic cells. We selectively live-labelled both adult-born and resident dopaminergic cells, and targeted them for whole-cell patch-clamp recordings in acute mouse OB slices. Surprisingly, we found that from the time - at [~]1 month of cell age - that live adult-born dopaminergic neurons could first be reliably identified, they already possessed almost fully mature intrinsic firing properties. We saw significant maturation only in increased spontaneous activity and decreased medium afterhyperpolarisation amplitude. Nor were adult-born dopaminergic cells especially plastic. In response to brief sensory deprivation via unilateral naris occlusion we observed no maturation-specific plastic alterations in intrinsic properties, although we did see deprivation-associated increases in spike speed and amplitude across all adult-born and resident neurons. Our results not only show that adult-born OB dopaminergic cells rapidly functionally resemble their pre-existing counterparts, but also underscore the importance of subtype identity when describing neuronal maturation and plasticity.

neuroscience↗

bioRxiv2024

Brain responses to predictable structure in auditory sequences: From complex regular patterns to tone repetition

In classical studies of auditory pattern learning, neuronal responses exhibit repetition suppression, where sequences of repeated tones show a reduced evoked response. This may be due in part to adaptation, but is also hypothesized to indicate suppression of expected stimuli. Repetition suppression is thought to form a building block of regularity learning, and is the paradigmatic example of predictive coding in humans and other animals. However, stimuli with more complex patterns appear to show the opposite effect. Predictable regular (REG) patterns distributed over a range of frequencies show a strongly enhanced sustained brain response compared to frequency-matched random (RAND) sequences, sitting at odds with the usual reduced evoked responses to predictable stimuli. A limiting factor in reconciling these findings is that they are obtained using different stimuli and analysis methods. This human EEG study (N=20) brings together auditory sequence predictability and repetition in a single paradigm, based on rapidly unfolding tone pip patterns, incorporating sequences consisting of exactly repeating tones at a single frequency, alongside REG and RAND of varying complexity. We demonstrate that regularity is associated with increased sustained responses, offset responses, tone locked responses and cycle-locked responses. We further show that both repetition suppression and repetition enhancement occur over different timescales, and that sustained brain responses to simple repetition show qualitatively different effects than to more complex regularities during automatic tracking of stimulus statistics. Our results indicate a system for automatic monitoring of predictability in the auditory environment, which is distinct from, but concurrent with, repetition suppression. NEW & NOTEWORTHYWe investigate how human brain response patterns evolve as auditory patterns become progressively simplified, focusing on the impact of sequence structure on various aspects of EEG responses, both evoked and induced. By contrasting EEG responses across different phases of the stimulus--onset, sustained, and offset--we uncover the interplay between repetition suppression and predictability. This approach allows us to discern how the brain processes and adapts to changing regularities in sensory input.

neuroscience↗

bioRxiv2017

Myosin II activity is required for structural plasticity at the axon initial segment

In neurons, axons possess a molecularly defined and highly organised proximal region - the axon initial segment (AIS) - that is a key regulator of both electrical excitability and cellular polarity. Despite existing as a large, dense structure with specialised cytoskeletal architecture, the AIS is surprisingly plastic, with sustained alterations in neuronal activity bringing about significant alterations to its position, length or molecular composition. However, although the upstream activity-dependent signalling pathways that lead to such plasticity have begun to be elucidated, the downstream mechanisms that produce structural changes at the AIS are completely unknown. Here, we use dissociated cultures of rat hippocampus to show that two forms of AIS plasticity in dentate granule cells - long-term relocation, and more rapid shortening - are completely blocked by treatment with blebbistatin, a potent and selective myosin II ATPase inhibitor. These data establish a link between myosin II and AIS function, and suggest that myosin IIs primary role at the structure may be to effect activity-dependent morphological alterations.

neuroscience↗