Biology subjects

Cerminara, N. L.

Publications and source records attributed to Cerminara, N. L..

5 recordsLinked to original sources

bioRxiv2025

Cerebellar involvement in self-timing

The cerebellum is well-established in sub-second motor timing, but its role in supra-second interval timing remains unclear. Here, we investigate how cerebellar output influences time estimation over longer timescales. Rats performed an interval timing task, estimating time based on an auditory cue, while chemogenetic inhibition of the lateral cerebellar nucleus assessed its role in both predictable (externally cued) and unpredictable (internally cued) timing conditions. Cerebellar inhibition produced bidirectional effects: delayed action initiation in predictable trials and premature responses in unpredictable trials. Despite slowed movement, overall task success rates remained unchanged, suggesting a specific impairment in temporal estimation rather than motor execution. These findings demonstrate that the cerebellum integrates motor and cognitive processes for supra-second timing, with differential effects on externally guided and self-generated timing. Our results provide evidence that the lateral cerebellum contributes to supra-second interval timing, supporting its role in adaptive behavior across extended timescales.

neuroscience↗

bioRxiv2020

A Purkinje cell model that simulates complex spikes

Purkinje cells are the principal neurons of the cerebellar cortex. One of their distinguishing features is that they fire two distinct types of action potential, called simple and complex spikes, which interact with one another. Simple spikes are stereotypical action potentials that are elicited at high, but variable, rates (0 - 100 Hz) and have a consistent waveform. Complex spikes are composed of an initial action potential followed by a burst of lower amplitude spikelets. Complex spikes occur at comparatively low rates (~ 1 Hz) and have a variable waveform. Although they are critical to cerebellar operation a simple model that describes the complex spike waveform is lacking. Here, a novel single-compartment model of Purkinje cell electrodynamics is presented. The simpler version of this model, with two active conductances and a leak channel, can simulate the features typical of complex spikes recorded in vitro. If calcium dynamics are also included, the model can capture the pause in simple spike activity that occurs after complex spike events. Together, these models provide an insight into the mechanisms behind complex spike spikelet generation, waveform variability and their interactions with simple spike activity.

neuroscience↗

bioRxiv2020

Sensory and motor electrophysiological mapping of the cerebellum in humans.

Damage to the cerebellum during posterior fossa surgery can lead to ataxia and in paediatric cases, the risk of cerebellar mutism syndrome. Animal electrophysiological and human imaging studies have shown compartmentalisation of sensorimotor and cognitive functions within the cerebellum. In the present study, electrophysiological monitoring of sensory and motor pathways was carried out to assess the location of limb sensorimotor representation within the human cerebellum, as a potential approach for real time assessment of neurophysiological integrity to reduce the incidence of cerebellar surgical morbidities. Thirteen adult and paediatric patients undergoing posterior fossa surgery were recruited. For sensory mapping (n=8), electrical stimulation was applied to the median nerves, the posterior tibial nerves, or proximal and distal limb muscles and evoked field potential responses were sought on the cerebellar surface. For motor mapping (n=5), electrical stimulation was applied to the surface of the cerebellum and evoked EMG responses were sought in facial and limb muscles. Evoked potentials on the cerebellar surface were found in two patients (25% of cases). In one patient, the evoked response was located on the surface of the right inferior posterior cerebellum in response to stimulation of the right leg. In the second patient, stimulation of the extensor digitorum muscle in the left forearm evoked a response on the surface of the left inferior posterior lobe. In the motor mapping cases no evoked EMG responses could be found. Intraoperative electrophysiological mapping, therefore, indicates it is possible to record evoked potentials on the surface of the human cerebellum in response to peripheral stimulation.

neuroscience↗

bioRxiv2020

Action-based organization and function of cerebellar cortical microcircuits

The cerebellum is the largest sensorimotor structure in the brain, but its mode of operation is not well understood. However, a fundamental organizational feature of the cerebellar cortex is division into elongated zones, defined by their inputs from specific parts of the inferior olive and Purkinje cell output to cerebellar and vestibular nuclei. Little is known about how the pattern of neuronal activity in zones, and their functional microcircuit subdivisions, microzones, is related to behaviour in awake animals. Here, we studied the organization of microzones within the C3 zone and their activity during a skilled forelimb reaching task in cats. Neurons in different parts of the C3 zone, functionally determined by receptive field characteristics, differed in their patterns of activity during movement. Our results suggest that the cerebellar C3 zone is organized and operates within an action-based frame of reference, with different microcircuits within the zone controlling specific muscle synergies.

neuroscience↗

bioRxiv2020

Pre-movement changes in sensorimotor beta oscillations predict motor adaptation drive.

Beta frequency oscillations in scalp electroencephalography (EEG) recordings over the primary motor cortex have been associated with the preparation and execution of voluntary movements. Here, we test whether changes in beta frequency are related to the preparation of adapted movements in human, and whether such effects generalise to other species (cat). Eleven healthy adult humans performed a joystick visuomotor adaptation task. Beta (15-25Hz) scalp EEG signals recorded over the motor cortex during a pre-movement preparatory phase were, on average, significantly reduced in amplitude during early adaptation trials compared to baseline or late adaptation trials (p=0.01). The changes in beta were not related to measurements of reaction time or duration of the reach. We also recorded LFP activity within the primary motor cortex of three cats during a prism visuomotor adaptation task. Analysis of these signals revealed similar reductions in motor cortical LFP beta frequencies during early adaptation. This effect was also present when controlling for any influence of the reaction time and reaching duration. Overall, the results are consistent with a reduction in pre-movement beta oscillations predicting an increase in adaptive drive in upcoming task performance when motor errors are largest in magnitude and the rate of adaptation is greatest.

neuroscience↗