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Pulecchi, F.

Publications and source records attributed to Pulecchi, F..

3 recordsLinked to original sources

Individual strategies for ignoring irrelevant information are reflected in distinct neural signatures during temporal attention.

Attentional functions enable the nervous system to regulate incoming information, selecting what is behaviorally relevant while filtering out distractions. To investigate attentional control in rats, we developed a paradigm in which animals are required to ignore an irrelevant tactile stimulus (a vibration) and categorize the relevant one as weak or strong. Stimuli were separated in time but delivered to the same set of vibrissae, making this a temporal rather than spatial attention task. In the first task version, the irrelevant stimulus was presented first and the relevant second. Across animals, we observed substantial variability in how this task was learned and performed, consistent with emerging work showing that learning unfolds along idiosyncratic trajectories rather than converging on a single behavioral solution. While the irrelevant stimulus typically exerted an attractive bias on judgments, some rats progressively reduced this influence and achieved near-complete suppression, transitioning from a proficient to an expert stage of performance. Other animals, however, adopted alternative stable strategies and did not exhibit comparable levels of attentional filtering. To probe behavioral flexibility, we designed a version of the task in which the relevant stimulus could appear in either temporal position. Under these conditions, rats generally struggled to flexibly allocate attention across time, again with substantial variability across individuals. Importantly, behavioral analyses indicate that this variability is not random but reflects a small number of reproducible strategy classes, characterized by distinct patterns of sensitivity to stimulus order. These findings suggest that attentional control in this task does not rely on a single canonical algorithm, but instead emerges from a constrained set of alternative solutions. Electrophysiological recordings from a limited number of animals revealed neural correlates consistent with these behavioral differences. In expert animals performing the original task, neuronal populations in motor cortex showed differential encoding of the irrelevant and relevant stimuli. In a proficient animal implanted in both vS1 and M1/M2, outcome-dependent modulation was prominent in vS1, whereas M1/M2 transformed sensory inputs into categorical representations with partial suppression of the irrelevant stimulus. Local field potential analyses further indicated that effective task performance was associated with increased high gamma synchronization between vS1 and M1/M2, alongside low-beta modulation consistent with top-down interactions. Taken together, these results suggest that learning to ignore irrelevant information reshapes interactions between sensory and motor cortices, but that this process unfolds heterogeneously across individuals. Rather than reflecting a single mechanism of attentional control, the data support a framework in which multiple, identifiable strategies coexist within a shared task structure, underscoring the importance of individual differences in understanding the neural basis of attention.

neuroscience↗

The sensory code within sense of time

Sensory experiences are accompanied by the perception of the passage of time; a cell phone vibration, for instance, is sensed as brief or long. The neuronal mechanisms underlying the perception of elapsed time remain unknown1. Recent work agrees on a role for cortical processing networks2,3, however the causal function of sensory cortex in time perception has not yet been specified. We hypothesize that the mechanisms for time perception are embedded within primary sensory cortex and are thus governed by the basic rules of sensory coding. By recording and optogenetically modulating neuronal activity in rat vibrissal somatosensory cortex, we find that the percept of stimulus duration is dilated and compressed by optogenetic excitation and inhibition, respectively, during stimulus delivery. A second set of rats judged the intensity of tactile stimuli; here, optogenetic excitation amplified the intensity percept, demonstrating sensory cortex to be the common gateway to both time and stimulus feature processing. The coding algorithms for sensory features are well established4-10. Guided by these algorithms, we formulated a 3-stage model beginning with the membrane currents evoked by vibrissal and optogenetic drive and culminating in the representation of perceived time; this model successfully replicated rats choices. Our finding that stimulus coding is intrinsic to sense of time disagrees with dedicated pacemaker-accumulator operation models11-13, where sensory input acts only to trigger the onset and offset of the timekeeping process. Time perception is thus as deeply intermeshed within the sensory processing pathway as is the sense of touch itself14,15 and can now be treated through the computational language of sensory coding. The model presented here readily generalizes to humans14,16 and opens up new approaches to understanding the time misperception at the core of numerous neurological conditions17,18.

neuroscience↗

A sensory integration account for time perception

The connection between stimulus perception and time perception remains unknown. The present study combines human and rat psychophysics with sensory cortical neuronal firing to construct a computational model for the percept of elapsed time embedded within sense of touch. When subjects judged the duration of a vibration applied to the fingertip (human) or whiskers (rat), increasing stimulus mean speed led to increasing perceived duration. Symmetrically, increasing vibration duration led to increasing perceived intensity. We modeled spike trains from vibrissal somatosensory cortex as input to dual leaky integrators - an intensity integrator with short time constant and a duration integrator with long time constant - generating neurometric functions that replicated the actual psychophysical functions of rats. Returning to human psychophysics, we then confirmed specific predictions of the dual leaky integrator model. This study offers a framework, based on sensory coding and subsequent accumulation of sensory drive, to account for how a feeling of the passage of time accompanies the tactile sensory experience.

neuroscience↗