Biology subjects

Prat-Ortega, G.

Publications and source records attributed to Prat-Ortega, G..

2 recordsLinked to original sources

bioRxiv2024

Episodic recruitment of attractor dynamics in frontal cortex reveals distinct mechanisms for forgetting and lack of cognitive control in short-term memory

Short-term memory (STM) is prone to failure, especially during prolonged memory maintenance or under limited cognitive control. Despite predictive mechanistic frameworks based on persistent neural activity and attractor states, a direct assessment of network dynamics during multifactorial STM failure is still missing. We addressed this in a delayed-response task where mice maintained a prospective response during a long variable delay. Mice behavior episodically switched between a task-engaged state described by an attractor model, and a task-disengaged state purely determined by previous choices. During task engagement, the anterolateral motor cortex (ALM) showed delay persistent activity stably encoding correct choices, whereas the encoding reversed during the delay in error trials. In contrast, in task-disengaged phases ALM showed no clear traces of attractor dynamics and instead exhibited enhanced synchrony at [~] 4-5Hz. Thus, ALM switches between distinct error-generating dynamics: in control-capable trials, transitions between memory attractors cause forgetting errors, whereas non-memory errors are caused by the dissociation of ALM during the mnemonic period reflecting the lack of cognitive control.

neuroscience↗

bioRxiv2020

Flexible categorization in perceptual decision making

Perceptual decisions require the brain to make categorical choices based on accumulated sensory evidence. The underlying computations have been studied using either phenomenological drift diffusion models or neurobiological network models exhibiting winner-take-all attractor dynamics. Although both classes of models can account for a large body of experimental data, it remains unclear to what extent their dynamics are qualitatively equivalent. Here we show that, unlike the drift diffusion model, the attractor model can operate in different integration regimes: an increase in the stimulus fluctuations or the stimulus duration promotes transitions between decision-states leading to a crossover between weighting mostly early evidence (primacy regime) to weighting late evidence (recency regime). Between these two limiting cases, we found a novel regime, which we name flexible categorization, in which fluctuations are strong enough to reverse initial categorizations, but only if they are incorrect. This asymmetry in the reversing probability results in a non-monotonic psychometric curve, a novel and distinctive feature of the attractor model. Finally, we show psychophysical evidence for the crossover between integration regimes predicted by the attractor model and for the relevance of this new regime. Our findings point to correcting transitions as an important yet overlooked feature of perceptual decision making.

neuroscience↗