Biology subjects

Shintaki, R.

Publications and source records attributed to Shintaki, R..

4 recordsLinked to original sources

bioRxiv2022

Subjectivity of time perception alters choice preference for future rewards through fronto-striatal value signal dynamics

Our preference for a reward depends on the time of delay for its delivery. Here we show that changes in the external environment can manipulate the perceived duration of time, which alters the formation of the choice preference through value signals in the cortical and subcortical brain regions. Humans anticipated a real liquid reward delayed by tens of seconds, during which colors of visually presented panels gradually changed. The color-change delay was perceived as shorter than a control color-constant delay. Interestingly, participants with greater perceptual bias of the delay showed stronger preference for rewards with the color-change delay. The ventrolateral prefrontal cortex (vlPFC) and ventral striatum (VS) showed dynamic neural signatures of value components that were modulated by subjectively perceived duration. Crucially, these effects were specifically observed while a future reward was anticipated, and moreover, the vlPFC activity was weaker in participants with greater bias in the duration perception. These results demonstrate that subjective time experience leads to biased choice preference of delayed rewards, which is regulated by dynamic value signals of future rewards and accurate perception of the external world in the vlPFC-VS systems.

neuroscience↗

bioRxiv2022

An excitatory-inhibitory fronto-cerebellar loop resolves the Stroop effect

The Stroop effect is a well-known behavioral phenomenon in humans that refers to robust interference between language and color information. Although this effect has long been studied, it remains unclear when the interference occurs and how it is resolved in the brain. By manipulating the verbality of stimulus perception and response generation, here we show that the Stroop effect occurs during perception of color-word stimuli and is resolved by a cross-hemispheric, excitatory-inhibitory functional loop involving the lateral prefrontal cortex and cerebellum. Humans performed a Stroop task and a control task in which the stimulus did not contain verbal information, and made a response either vocally or manually. The resolution of Stroop interference involved the lateral prefrontal cortex in the left hemisphere and the cerebellum in the right hemisphere, independently of whether the response was made vocally or manually. In contrast, such cross-hemispheric lateralization was absent during the non-verbal control task. Moreover, the prefrontal cortex amplified cerebellar activity, whereas the cerebellum suppressed prefrontal activity, and these effects were enhanced during interference resolution. These results suggest that this fronto-cerebellar loop involving language and cognitive systems regulates goal-relevant information to resolve the interference occurring during simultaneous perception of a word and color.

neuroscience↗

bioRxiv2021

Perceptual uncertainty alternates top-down and bottom-up fronto-temporal network signaling during response inhibition

Response inhibition is a primary executive control function that allows the withholding of inappropriate responses, and requires appropriate perception of the external environment to achieve a behavioral goal. It remains unclear, however, how response inhibition is achieved when goal-relevant information involves perceptual uncertainty. Twenty-six human participants of both sexes performed a go/no-go task where visually presented random-dot motion stimuli involved perceptual uncertainties. The right inferior frontal cortex (rIFC) was involved in response inhibition, and the middle temporal (MT) region showed greater activity when dot motions involved less uncertainty. A neocortical temporal region in the superior temporal sulcus (STS) specifically showed greater activity during response inhibition in more perceptually certain trials. In this STS region, activity was greater when response inhibition was successful than when it failed. Directional effective connectivity analysis revealed that in more coherent trials, the MT and STS regions showed enhanced connectivity to the rIFC, whereas in less coherent trials, the signal direction was reversed. These results suggest that a reversible fronto-temporal functional network guides response inhibition under perceptual uncertainty, and in this network, perceptual information in the MT is converted to control information in the rIFC via STS, enabling achievement of response inhibition. Significance statementResponse inhibition refers to withholding inappropriate behavior and is an important for achieving goals. Often, however, decision must be made based on limited environmental evidence. We showed that successful response inhibition is guided by a neocortical temporal region that plays a hub role in converting perceived information coded in a posterior temporal region to control information coded in the prefrontal cortex. Interestingly, when a perceived stimulus becomes more uncertain, the prefrontal cortex supplements stimulus encoding in the temporal regions. Our results highlight fronto-temporal mechanisms of response inhibition in which conversion of stimulus-control information is regulated based on the uncertainty of environmental evidence.

neuroscience↗

bioRxiv2021

Anticipatory dynamics in the human brain guide foraging for primary rewards

Deciding whether to wait for a future reward is crucial for acquiring rewards in an uncertain world and involves anticipating future reward attainment. While seeking for a reward in natural environments, behavioral agents constantly face a trade-off between staying in their current environment or leaving it. It remains unclear, however, how humans make continuous decisions in such situations. Here we show that anticipatory brain activity in the anterior prefrontal cortex (aPFC) and hippocampus underpins continuous stay-leave decision making. Human participants awaited for real liquid rewards available after tens of seconds, and continuous decision was tracked by monitoring dynamic patterns of brain activity. Participants stopped waiting more frequently and sooner after they experienced longer delays and received smaller rewards. When dynamic activity reflecting the anticipation of a future reward was enhanced in the aPFC, participants remained in their current environment, but when this activity diminished, they left the environment for a new one. The anticipatory activity in the aPFC and hippocampus was associated with distinct decision strategies; aPFC activity was enhanced in participants adopting a leave strategy, whereas those remaining stationary showed enhanced activity in the hippocampus. Our results suggest that fronto-hippocampal anticipatory dynamics underlie continuous decision making while anticipating a future reward.

neuroscience↗