Time Flashcards

1
Q

Humans are sensitive to the day/night time and 24-hour cycle. Name an example:

A

waking up just before your alarm goes off and not just because of the sun:
jetlag

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2
Q

Name an example of Period Timing:

A

Circadian rhythms.

Question: is the cyclical behaviour really controlled by time per
se? Or is it controlled by stimuli that are always present at that
particular time?

Wheel running in the rat (described in Carlson):

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2
Q

What is the term used to describe learning to respond at a particular time of day?

A

Period Timing

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3
Q

How does a stimulus cue of light on and light off periods affect rats exercise activity?

A

Rats increased their exercise activity between the light off periods (nocturnal) even when the timings of the light off were shifted from 8am-8pm to 4pm and midnight.

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3
Q

What is the term used to describe learning to respond after a particular interval of time?

A

Interval Timing

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3
Q

Stimuli of light acts as a ? synchronising the internal clock.

A

Zeitgeber

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3
Q

(Roberts, 1965). found Cockroaches increased activity at which time of day when removing visual cues cycle that drifted until increased activity started?

A

Dusk
15 hours before dusk (cycle slightly less than 24 hours).

This is evidence for some sort of intrinsic clock in animals’ heads
(but not that accurate) Without the light stimuli, time drifts.

Restoring visual cues produced a gradual shift back to correct
time.

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4
Q

Is the apparent internal 24-hour clock the result of environmental experience or is it innate?

Bolles & Stokes (1965) studied rats who were born and reared under either 19, 24 or 29-hour light/dark cycles. Then fed at a regular point in their own particular cycle and food delivery is signaled a few hours before by a change in lighting.
Change in lighting before food was given.

What were the findings?

A

Rats on the 24-hour cycle learned to anticipate food

But rats that were trained on the 19 or 29-hour light/dark cycles didn’t:
Showing no anticipatory response of food, even becoming less active

Conclusion:
Not the product of experience, suggests innate

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4
Q

What happens when rats are presented with constant dim light when no light cues are available? Will their rates of exercise change?

A

Findings suggest 24-hour clock activity:
They maintained their exercising behaviour on an approximately
25-hour cycle
The exercise got a little later each day (active period was drifting)

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5
Q

Evidence for a physiological system that could provide this 24-hour clock:

Which brain structure is thought to be involved in animals’ 24-hour clock cycle?

A

The suprachiasmatic nucleus (SCN) of the hypothalamus.

The metabolic rate in the SCN varies as a function of the day-night cycle.

Lesions (damage) of the SCN:
Abolish the Circadian Regularity of foraging and sleeping in the rat. Receives direct and indirect inputs from the visual system, which could keep circadian rhythms entrained with the real day-night cycle.

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5
Q

Disruption in circadian rhythms can be responsible for physical illness Who is more susceptible to heart disease, diabetes, infections and even cancer?

A

shift workers

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5
Q

Which type of timing to rats do during conditioning?

A

Interval Timing
eg. pairing tone (20sec) and food
but instead of looking at responding for the entire duration of the tone, you look to see how it is distributed during the timing intervals

Results: rats response to the food coming gets stronger as the tone intervals proceed
If tone stimulus keeps going, animals will show a peak of expectation, then lose interest and stop responding

Conclusions:
shows that they know at what time period after the tone the food will come

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5
Q

More recent work suggests every cell in the body has a circadian rhythm, which are all under the control of which brain region?

This can dictate e.g. circadian variation in
sensitivity of tumours to chemotherapy.

A

the SCN.

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6
Q

In Alzheimer’s disease the phenomenon of sundowning refers to:

A

The worsening of symptoms in afternoon/evening

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6
Q

Church & Gibbon, 1982:
Rats in lit chamber. Occasionally houselight went off, for a 0.8, 4.0
or 7.2 sec (the CS). When the lights went on again a lever was
presented for five seconds. If the rat pressed the lever after a
4-sec CS it got food, otherwise it did not. Then tested with a
range of stimulus durations (0.8 - 7.2 secs).

After how many seconds were the rats most likely to make a response?

A

Rats were more likely to make a response after 4 seconds of darkness(where food is rewarded)
compared to shorter/ longer periods of darkness

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6
Q

Sleep and circadian rhythm disruption is also associated with several types of mental illness, such as:

A

depression, schizophrenia, bipolar illness.

6
Q

Church & Gibbon, 1982:
Rats in lit chamber. Occasionally houselight went off, for a 0.8, 4.0
or 7.2 sec (the CS). When the lights went on again a lever was
presented for five seconds. If the rat pressed the lever after a
4-sec CS it got food, otherwise it did not. Then tested with a
range of stimulus durations of 2, 4, 8 seconds.

The graph curves on responses to the stimulus durations where much tighter if the food happened after what time duration?
What is this due to?

A

(smaller) 2 seconds

Weber’s Law. The just noticeable difference:

when you change a stimulus is proportional to the initial intensity/ magnitude of the changed stimulus.

Hence in absolute terms small amounts judged more accurately
than large amounts.

7
Q

Church & Gibbon, 1982:
Rats in lit chamber. Occasionally houselight went off, for a 0.8, 4.0
or 7.2 sec (the CS). When the lights went on again a lever was
presented for five seconds. If the rat pressed the lever after a
4-sec CS it got food, otherwise it did not. Then tested with a
range of stimulus durations of 2, 4, 8 seconds.

What did What is Weber’s Law show?

A

reaches half maximum at
~ 50% of duration in each case

Responding rate drops by half when stimulus duration is dropped by half

7
Q

What is Weber’s Law: Scalar property of timing?

A
8
Q

SCALAR TIMING THEORY
Gibbon, Church & Meck, (1984)

Fill in this model which predicts performance:

A
9
Q

SCALAR TIMING THEORY
Gibbon, Church & Meck, (1984)

Explain this model which predicts performance:

A
10
Q

What is the role of the pacemaker in the SCALAR TIMING THEORY
Gibbon, Church & Meck, (1984)?

A

Pacemaker emits pulses at a roughly constant rate t
(there is random variation).

11
Q

During the SCALAR TIMING THEORY, when a stimulus is presented, a switch is operated, and the pulses are allowed to be transfered and accumulate in which next section?

A

The working memory

12
Q

During the SCALAR TIMING THEORY, the storing of the duration of the stimulus (light) which predicts food deliverance is stored in which section?

A

Reference memory (5sec)

-however, this memory is not completely accurate (5.1sec)
-some memory distortion

Represented by K, a number that is close to 1:
If K = 1 the memory is accurate;
If K < 1 a smaller number of pulses is stored;
If K > 1 a greater number is stored.

error is proportional to duration scalar again

13
Q

During the SCALAR TIMING THEORY, when the reinforcement occurs, pulses stop accumulating; another switch allows the number of pulses in working memory (N * t) to be stored in which next section?

A

Reference memory

14
Q

During the SCALAR TIMING THEORY, stored value used in reference memory to decide whether or not to respond on the next trial.

On each trial the animal compares the number of pulses in working memory (N * t) with a random value drawn from those stored in reference memory Nmx.

Which component is key for this process?

A

If the values are close, then the animal responds.

14
Q

What is going on here?

A

The animal uses ONE of the values in reference memory to decide when to respond.

Smaller numbers closer together = now its time to respond

14
Q

What are problems with the SCALAR TIMING THEORY?

A

1) No physiological evidence for a pacemaker

Alternatives have been proposed:
(i) Instead of a pacemaker, it has been proposed that timing
could be achieved by a series of oscillators, each of which has
two states, on or off. If each oscillator switches after a different
period of time, then the entire pattern of activation could be
used to determine the exact time.

(ii) Another solution that has been proposed is the
Behavioural theory of timing
When the animal gets a reward, this stimulates behaviour.
The animal moves across an invariant series of behavioural
classes in between reinforcements. A pulse from an internal
pacemaker will change the behaviour from one class to
another. The behaviour that is occurring when the next
reinforcer occurs becomes a signal for that reinforcer.

2) Conditioning and timing supposedly occur at the same time,
and yet are controlled by completely different learning
mechanisms.

15
Q

Which theory has been proposed in light of the limitations of the SCALAR TIMING THEORY?

A

Behavioural theory of timing

15
Q

What is an alternative model for the SCALAR TIMING THEORY?

A

Some theories of timing try and explain conditioning; e.g.,
Gibbon & Balsam (1977).

They calculate rate of reinforcement during stimulus, and rate of reinforcement absence of stimulus. Instead of correlation!

15
Q

Which theory cannot explain basic phenomena, like blocking.

A

SCALAR TIMING THEORY

16
Q

What type of model assumes the stimulus is assumed to change over the course of its presentation, and this allows the animal to learn about when a reinforcer occurs “stimulus trace”?

A

Real Time Models