Biology subjects

Ambroggi, F.

Publications and source records attributed to Ambroggi, F..

4 recordsLinked to original sources

bioRxiv2024

Basolateral amygdala population coding of a cued reward seeking state depends on orbitofrontal cortex

Basolateral amygdala (BLA) neuronal responses to conditioned stimuli are closely linked to the expression of conditioned behavior. An area of increasing interest is how the dynamics of BLA neurons relate to evolving behavior. Here, we recorded the activity of individual BLA neurons across the acquisition and extinction of conditioned reward seeking and employed population-level analyses to assess ongoing neural dynamics. We found that, with training, sustained cue-evoked activity emerged that discriminated between the CS+ and CS-and correlated with conditioned responding. This sustained population activity continued until reward receipt and rapidly extinguished along with conditioned behavior during extinction. To assess the contribution of orbitofrontal cortex (OFC), a major reciprocal partner to BLA, to this component of BLA neural activity, we inactivated OFC while recording in BLA and found blunted sustained cue-evoked activity in BLA that accompanied reduced reward seeking. Optogenetic disruption of BLA activity and OFC terminals in BLA also reduced reward seeking. Our data suggest that sustained cue-driven activity in BLA, which in part depends on OFC input, underlies conditioned reward-seek-ing states.

neuroscience↗

bioRxiv2021

Two distinct neuronal populations in the rat parafascicular nucleus oppositely encode the engagement in stimulus-driven reward-seeking

The thalamus is a phylogenetically well-preserved structure. Known to densely contact cortical regions, its role in the transmission of sensory information to the striatal complex has been widely reconsidered in recent years. The parafascicular of the thalamus (Pf) has been implicated the orientation of attention towards salient sensory stimuli. In a stimulus-driven reward seeking task, we sought to characterize the electrophysiological activity of Pf neurons in rats. We observed a predominance of excitatory responses over inhibitory responses for all events of the task. Neurons responded more strongly to the stimulus compared to lever-pressing and collecting reward, confirming the strong involvement of the Pf in sensory information processing. The use of long sessions allowed us to compare neuronal responses to stimuli when the animal engaged in action or when it did not. We distinguished two populations of neurons responding in an opposite way: MOTIV+ neurons responded more intensively to stimuli followed by a behavioral response than those that did not. Conversely, MOTIV-neurons responded more strongly when the stimulus was ignored by the animal. In addition, MOTIV-neurons excitations appeared at a shorter latency after the stimulus than MOTIV+ neurons. Through this encoding, Pf could perform an early selection of environmental stimuli transmitted to the striatum according to motivational level. HIGHLIGHTSO_LIPf neurons respond to reward-predicting stimuli and reward-related actions C_LIO_LIMOTIV+ Pf neurons were more active to stimuli evoking reward-seeking C_LIO_LIMOTIV- Pf neurons were more active to stimuli ignored by the animal C_LIO_LIStimuli-evoked excitations latencies were shorter in MOTIV- than MOTIV+ neurons C_LI

neuroscience↗

bioRxiv2020

Optimal Binning of Peri-Event Time Histograms Using Akaike Information Criterion

Peri-event time histograms (PETH) are widely used to study correlations between experimental events and neuronal firing. The accuracy of firing rate estimate using a PETH depends on the choice of binsize. We show that the optimal binsize for a PETH depends on factors such as the number of trials and the temporal dynamics of the firing rate. These factors argue against the use of a one-size-fits-all binsize when making PETHs for an inhomogeneous population of neurons. Here we propose a binsize selection method by adapting the Akaike Information Criterion (AIC). Simulations show that optimal binsizes estimated by AIC closely match the optimal binsizes using mean squared error (MSE). Furthermore, using real data, we find that optimal binning improves detection of responses and their dynamics. Together our analysis strongly supports optimal binning of PETHs and proposes a computationally efficient method for this optimization based on AIC approach to model selection.

neuroscience↗

bioRxiv2020

Microstructural meal pattern analysis reveals that nicotine is a potent anti-anorectic drug despite producing long-term anorexigenic effects

Nicotine consumption in both human and animal studies has been strongly associated with changes in feeding-related behaviors and metabolism. The current dogma is that chronic nicotine decreases food intake and increases metabolism, leading to lower body weight. However, the effect of acute nicotine intake on feeding is unclear. The present study employed microstructural and macrostructural behavioral analyses to elucidate changes in feeding behavior in animals that intravenously self-administered nicotine. At the microstructural level (seconds to minutes), nicotine increased feeding and drinking behavior during the first 5 minutes after nicotine self-administration. This effect was also observed in animals that passively received nicotine, but the effect was not observed in animals that self-administered saline or passively received saline. At the macrostructural level (hours to days), nicotine decreased body weight gain, decreased feeding, and was associated with increases in feeding and body weight gain during abstinence. These results suggest that nicotine first produces anti-anorectic effects before producing long-term anorexigenic effects. These results challenge the notion that nicotine is an anorexigenic drug and paradoxically suggest that the anorexigenic effects of nicotine may be a long-term consequence of acute anti-anorectic effects of nicotine.

physiology↗