The Neural Mechanism Of Automatic And Controlled Process In Time Perception

Time perception is the basis of several abilities of human, e.g. movement, language, music perception. Time perception and the perceived present are in essence the same, the researches are comprise of the limited capacity of perceived present, the threshold of time perception, duration and order perception. Recent years, time perception is limited to the perception of duration within 5 seconds in most of studies, in which the duration is integrated as a unity, and the wholeness and continuity are the critical features of time perception.As the development of cognitive neuroscience, using functional magnetic resonance imaging (fMRI), event-related potentials (ERP), and time perception has been investigated from different dimensions, e.g. explicit & implicit timing, automatic & cognitive controlled timing systems. Several theoretical models were proposed to explain the mechanism of time perception, such as pacemaker-accumulator model, coincidence-detection model, resource allocation model, memory decay model, state-dependent network model, etc. However, the models can't explain results of some studies, such as the neural representations of duration are different under attention and inattention conditions.Based on the related studies in the cognitive neuroscience, the present study hypothesizes time perception is state-dependent, the automatic and controlled process could be researched by operating attention, and time perception is automatic under the inattention condition, whereas it is comprised of automatic and controlled processes under the attention condition. The range-synthetic model of temporal cognition emphasizes the neural representation are different for different range of time, and the process of duration is affected by several factors that are mainly comprised of the physical features of stimuli, cognitive factors, personality traits, etc. Based on this theoretical model, the present study attempts to investigate the neural mechanisms of automatic and controlled process in time perception under different range of time and different modalities, and to develop a theoretical model of time perception.The present study explores the neural mechanisms of automatic and controlled process in time perception using ERP and time-frequency analysis. Study one investigated the neural mechanisms of automatic and controlled process in time percpeiton within 200 ms via experiment 1 to experiment 3. In the experiment 1, the automaticity of auditory time perception was compared with that of visual time perception by employing the cross-modal delayed response paradigm. The standard and deviant stimuli were different durations, and participants were required to identify the durations in the attentional modality. Experiment 2 employed the same experiment paradigm as experiment 1. In order to identify the neural mechanism of controlled process in auditory and visual time perception, the neural activity evoked by time perception under attention condition was compared with inattention condition. In the experiment 3, the cross-modal delayed response paradigm and the S1-S2 matching paradigm were integrated together to investigate the interaction of automatic and controlled processes in time perception. Study two investigated the neural mechanisms of automatic and controlled process in time perception ranged from 1 to 3 seconds. In the experiment 4, the auditory stimuli were presented with regular inter-stimulus interval, and the neural activity evoked by omitted stimulus was investigated to identify whether the rhythms ranged from 1 to 3 seconds could be represented as unities. In the experiment 5, in order to identify whether the controlled process for different duration was different, and whether the neural mechanisms of explicit and implicit timing were different, the participants were required to discriminate the intervals ranged from 200 to 1800 ms, and wait for the response signal. Once the response signal appeared, the participants should respond as quickly and accurately as possible. Study three investigated the neural mechanism of temporal working memory via experiment 6. In the experiment 6, in order to identify the relationship between temporal working memory and Baddeley's working memory model, the participants were required to remember the spatial, temporal and verbal information of the same capital letters of the alphabet, then they should perform the spatial, temporal, verbal 1-back and 2-back task respectively. The findings of these experiments were as follows:1. The automatic process of time perception is based on the sensory memory process; Whereas the controlled process is based on the attention control process, including gaining sensory information, inhibiting sensory information, gaining temporal information, perceptual process for temporal information, and decision making process. Temporal working memory is a new type of working memory that is different from spatial and verbal working memory.2. Automatic processes of time perception for different range of time rely on qualitatively similar mechanisms, and the 0 and a waves take part in the automatic process for different range of time; Whereas there are some differences in the controlled processes for different range of time, and the selective attention for interval inhabits 0 and a wave before about 1000 ms, then inhabits all band of oscillations after about 1000 ms.3. The neural mechanisms are different between auditory and visual automatic process, auditory temporal information is processed relatively automatically; Whereas there are some common neural basis underlying the controlled process of auditory and visual time perception,0 engages in encoding and retrieving temporal information,βand y engage in holding and comparing of temporal information in the working memory.Based on the results of the present study and related studies, the dual-process model of time perception is proposed, the model can explain why the mechanisms of time perception for different range of time is different, and the reason of modality effect of time perception. The model considers that time perception is state-dependent, and time perception is automatic under the inattention condition, whereas it is comprised of automatic and controlled processes under the attention condition. The automatic process of time perception is based on the sensory memory process without control and attention, which relies on sensory process areas. The temporal information can be automatic sensory analyzed, stored and compared. The controlled process of time perception is based on attention control process, including gaining sensory information, inhibiting sensory information, gaining temporal information, perceptual process for temporal information, and decision making process. Their related neural structures can be divided into follow four systems:gain control circuit relies on sensory process area, encoding circuits includes supplementary motor area, striatum, thalamus; working memory circuit comprises of anterior cingulated cortex, prefrontal cortex and posterior parietal cortex; long-term memory circuit comprises of prefrontal cortex, striatum, thalamus and medial temporal lobe.There are some innovations and values in the theory, method, and application of the present study. In the theory, the present study hypothesizes time perception is state-dependent, and proposes dual-process model of time perception to integrate the results from behavior, ERP, electroencephalogram (EEG), fMRI and neuroanatomical studies, therefore, the model can explain the results of the present and the related studies. In the method, the present study first adopts the paradigm in the studies of selective attention and working memory to investigate time perception, and integrates the cross-model delayed response paradigm and S1-S2 matching paradigm together to develop a new experimental paradigm. The present study also uses ERP and time-frequency analysis to obtain some new findings. In the application, the findings and research methods of time perception can be applied into medical science and space flight, e.g. the early diagnosis of Parkinson's disease and evaluation of the treatment effect, as well as measurement and improvement the astronaut's ability of time perception.There are still many problems need to be solved in future study. The inferences of dual-process model of time perception should be tested. In order to develop a better model with higher ecological validity, it is ought to integrate the dual-process model of time perception with other factors, such as the physical features of stimuli, cognitive factors, personality traits and emotional state.