13 Time Perception Flashcards
1
Q
3 meanings of time
A
- 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
2
Q
subjective time
A
- 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
3
Q
5 influences on time perception
A
- Motivation
- Attention
- sensory change
- novelty
- emotion
4
Q
Role of midbrain dopamine neurons
A
- 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
5
Q
How do dopamine neurons control judgement of time?
A
- 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
6
Q
What is explicit timing?
A
- 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)
7
Q
What is implicit timing?
A
- 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
8
Q
What is the pacemaker-accumulator model
A
- 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
9
Q
Which brain areas are involved in time perception?
A
- Cerebellum
- prefrontal cortex (PFC)
- basal ganglia
10
Q
Cerebellum and time perception
A
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
11
Q
prefrontal cortex and time perception
A
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
12
Q
basal ganglia and time perception
A
- 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
13
Q
coincidence-detection model
A
- 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
14
Q
biological rhythms and timings
A
- 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
15
Q
circadian rhythm
A
- 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)
16
Q
circadian rhythm early development
A
- emerges within first several months after birth
- body temperature rhythms immediately after birth
- sleep-wake rhythm between 3-6 months, consolidation within first year by increased melatonin secretion
- nocturnal sleep coupled with sunset first, then with family bedtime after a few months (environmental factor)
- change in melatonin levels and body temperature (peak in childhood)
17
Q
circadian rhythm in adolescence
A
- rhythmic changes during adolescence
- phase delay in sleep-wake cycle and melatonin dependent on gonadal hormones and environmental factors: social pressure, less parental involvement in bedtime routine
- more sensitive to light exposure at night at age 9-14 (early adolescents) compared to age 11-15 (late adolescents)
- early morning light exposure suppresses melatonin levels, but no age differences
18
Q
circadian rhythm in adulthood
A
- earlier sleeping hours compared to adolescence
- shorter sleep durations
- loss of amplitude in melatonin, cortisol, body temperature
19
Q
interval timing studies with infants
A
- 1-month old infants already show learned pupillary reflex to light, even though no light at expected point in time
- 10-month old infants show same mismatch negativity as adults
- 6-10 month old infants show increased looking time when repeated duration of an event differs
- ability to discriminate changes in duration is proportional to length of standard duration
- infants have primitive sense of time
- cerebral mechanism matures early or/and is functional at early age
20
Q
improvement in time sensitivity during childhood
A
- increase in Weber ratio after 4s
- the lower Weber ratio, the more sensitive to time
- time processing also depends on working memory, attention, and other executive functions like inhibition of motor responses, selective attention, sustained attention
21
Q
explicit time judgement in childhood
A
- explicit time judgement develops between age 3-6
- 3-5-year old children can estimate intervals of events repeatedly experienced but unaware of its time and relevance when they encouter new event
- children can make explicit judgements of time at about 7 years of age
22
Q
implicit time judgement in childhood
A
- earlier maturation of striatum => early timing abilities in infants, implicit time judgements
- longer durational judgements for anger at age 3, no developmental difference between age groups
- emotional states can distort time judgements
- related to early development of striatum and dopaminergic system
23
Q
fMRI studies with children
A
- with increasing age progressive recruitment of later maturing left hemisphere and lateralized fronto-parieto-striato-thalamic networks known to mediate time discrimination in adults
- earlier developing brain regions such as ventromedial prefrontal cortex, limbic and paralimbic areas, and cerebellum subserve fine-temporal processing functions in children and adolescents
- Time processesing from relatively early developed middle frontal limbic and posterior brain regions to fronto-striatal and parietal regions with development
- parallel with increase in attentional capacity with maturation which also affects timing judgment
24
Q
time perception in ADHD
A
- timing deficits in different temporal tasks
- reduced activity in right inferior and dorsolateral prefrontal cortex and anterior cingulate gyrus
- underlining importance of fronto-striatal system’s development in time processing
