Biology subjects

Panichello, M. F.

Publications and source records attributed to Panichello, M. F..

4 recordsLinked to original sources

bioRxiv2023

Cue-specific neuronal ensembles span intermittent rate coding of working memory

Persistent, memorandum-specific neuronal spiking activity has long been hypothesized to underlie working memory. However, emerging evidence suggests a possible role for activity-silent synaptic mechanisms. This issue remains controversial because evidence for either view has largely depended on datasets that fail to capture single-trial population dynamics or on indirect measures of neuronal spiking. We addressed this by examining the dynamics of mnemonic information on single trials obtained from large, local populations of prefrontal neurons recorded simultaneously in monkeys performing a working memory task. We show that mnemonic information does not persist in the spiking activity of prefrontal neurons, but instead alternates between On and Off periods during memory delays. At the level of single neurons, Off periods are driven by a coordinated loss of selectivity for memoranda and a return of firing rates to baseline levels. Further exploiting the large-scale recordings, we asked whether the functional connectivity among large neuronal ensembles depended on information held in working memory. We show that mnemonic information is available in the pattern of ensemble connectivity during the memory delay in both On and Off periods of neuronal activity. Intermittent epochs of memoranda-specific spiking therefore coexist with activity-silent mechanisms to span memory delays.

neuroscience↗

bioRxiv2020

Behavioral and neural fusion of expectation with sensation

Humans perceive expected stimuli faster and more accurately. However, the mechanism behind the integration of expectations with sensory information during perception remains unclear. We investigated the hypothesis that such integration depends on fusion -- the weighted averaging of different cues informative about stimulus identity. We first trained participants to map a range of tones onto faces spanning a male-female continuum via associative learning. These two features served as expectation and sensory cues to sex, respectively. We then tested specific predictions about the consequences of fusion by manipulating the congruence of these cues in psychophysical and fMRI experiments. Behavioral judgments and patterns of neural activity in auditory association regions revealed fusion of sensory and expectation cues, providing evidence for a precise computational account of how expectations influence perception.

neuroscience↗

bioRxiv2020

Selective control of working memory in prefrontal, parietal, and visual cortex

Cognitive control guides behavior by controlling what, where, and how information is represented in the brain. Previous work has shown parietal and prefrontal cortex direct attention, which controls the representation of external sensory stimuli1,2. However, the neural mechanisms controlling the selection of representations held in mind, in working memory, are unknown. To address this, we trained two monkeys to switch between two tasks, requiring them to either select an item from a set of items held in working memory or attend to one stimulus from a set of visual stimuli. Simultaneous neural recordings in prefrontal, parietal, and visual cortex found prefrontal cortex played a primary role in selecting an item from working memory, representing selection before parietal and visual cortex. Surprisingly, a common population representation in prefrontal cortex encoded selection of an item in working memory and attention to an external stimulus, suggesting prefrontal cortex may act as a domain-general controller. Selection acted on memory representations in two ways. First, selection improved the accuracy of memory reports by enhancing the selected items representation in prefrontal and parietal cortex. Second, selection transformed memory representations in a task-dependent manner. Before selection, when both items were relevant to the task, the identity of each item was represented in an independent subspace of neural activity. After selection, the representation of only the selected item was transformed into a new subspace that was used to guide the animals behavioral report. Together, our results provide insight into how prefrontal cortex controls working memory representations, selectively enhancing and transforming them to support behavior.

neuroscience↗

bioRxiv2018

Error-correcting dynamics in visual working memory

Working memory is critical to cognition, decoupling behavior from the immediate world. Yet, it is imperfect; internal noise introduces errors into memory representations (1, 2). Such errors accumulate over time (3-5) and increase with the number of items simultaneously held in working memory (6-10). Here, we show that error-correcting attractor dynamics mitigate the impact of noise on working memory. These dynamics pull memories towards a few stable representations in mnemonic space, inducing a bias in memory representations but reducing the effect of noise. Model-based and model-free analyses show attractor dynamics account for the frequency, bias, and precision of working memory reports in both humans and monkeys. Furthermore, attractor dynamics were optimized to the context; they adapted to the statistics of the environment, such that memories drifted towards contextually-predicted values. Our results suggest attractor dynamics mediate errors in working memory by counteracting noise and integrating contextual information into memories.

neuroscience↗