13 Time Perception Flashcards
3 meanings of time
- natural time: concept of time as medium or dimension
- clock time: quantifiable units
- subjective time: subjective feeling of both the passage of time and how much time has passed
subjective time
- construct by the brain
- organs and brain don’t aspire to represent objective outside world
- allows us to feel natural and clock time
- subjective experience is influenced by biology
- subjective time governed by underlying physiological processes
5 influences on time perception
- Motivation
- Attention
- sensory change
- novelty
- emotion
Role of midbrain dopamine neurons
- essential for voluntary movement, reward processing, working memory
- encode reward prediction error (reinforcement learning)
- DA neurons respond less at times when rewards and reward-predicting cues are more expected (receive temporal information)
- manipulating DAergic system disrupts timing behavior (may directly modulate timing)
- dopaminergic neurons control temporal judgements on a time scale of seconds
How do dopamine neurons control judgement of time?
- pharmacogenetic suppression of dopamine neurons decreased behavioral sensitivity to time
- dopamine neurons encoded information about trial-to-trial variability in time estimates
- transient activation or inhibition of dopamine neurons influences time estimation
- activation of DA neurons slows down time estimation
What is explicit timing?
- estimate of stimulus duration or interstimulus interval
- perceptual discrimination of timing: decide whether one stimulus/ISI duration is shorter or longer than another
- motor timing: represent timed duration/ISI with sustained, delayed, or periodic motor act (e.g. paced finger tapping task)
What is implicit timing?
- regular temporal pattern of sensory stimuli or motor responses can be used to achieve non-temporal task goals
- e.g., velocity parameters of an approaching vehicle can be used to estimate when it will reach a certain location
What is the pacemaker-accumulator model
- model of duration estimation based on internal clock model
- stimulus triggers accumulator to start counting pulses emitted by internal pacemaker
- pulse tally is passed into working memory for comparison with previously stored pulse tally
- response according to comparison
- attentional switch: the less attention paid, the fewer pulses accounted for by accumulator -> underestimation of time
- neurophysiologists seek more neurally plausible model
Which brain areas are involved in time perception?
- Cerebellum
- prefrontal cortex (PFC)
- basal ganglia
Cerebellum and time perception
comparison between patients with Parkinson and cerebellar/cortical lesions:
- increased motor timing variability and impairments in accuracy in explicit timing in cerebellar patients
- supramodal role for cerebellum in timing
- TMS evidence supports results while suggesting putative functional specialization of lateral and medial regions for auditory and visual time representations
- deficits in implicit timings in cerebellar patients as well
- lesions to lateral regions of cerebellum cause motor timing deficits
prefrontal cortex and time perception
hazard function
- probability of event occurring rises with increasing time it’s not occurring
- increase in subjective sense of temporal expectation (faster RTs)
- lesions to right PFC lead to loss of RT benefit of long fore-periods
- right PFC has feedback role to update temporal predictions
basal ganglia and time perception
- less important than cerebellum in making temporal predictions (PD patients no difficulty in implicit timing)
- PD patients show deficits in explicit timing (perceptual and motor timings)
- impairments correlate with disease severity
migrations effect - off medication, PD patients overestimated pre-learned short durations and underestimated long ones
- both estimates tended to migrate towards central common value
- motor and perceptual timing tasks activate lateral (putamen) and medial regions (caudate and globus pallidus), however most often activated with variety of anatomically discrete cortical regions
coincidence-detection model
- basal ganglia might monitor activity of functionally integrated network
- activation of thalamo-corticalstriatal circuits (BG, PFC and posterior parietal cortex)
- BG signals patterns of activity in working memory
- timing based on coincidental activation of different neural populations
- timing circuit is continuous-event, cognitive controlled timing system requiring attention
- probably not limited to temporal processing
biological rhythms and timings
- infradian rhythm: >24h, e.g. menstrual cycle, seasonal hormonal changes like testosterone
- circadian rhythm: 24h, e.g. sleep-wake cycle
- ultradian rhythm: <24h, e.g. sleep stages
- interval timing: seconds to minutes/hours, e.g. decision making, time estimation
- ms timing: >1s, e.g. speech, motor control
circadian rhythm
- center: suprachiasmatic nucleus (SCN) in hypothalamus: regulates neuronal activity, body temperature, sleep-wake-cycle, hormonal signals
- set by genetic and environmental factors (e.g. light, social cues, meal time, work schedule)
