10- Critical period

Question 1

Any kind of phase-sensitive learning (occurring at a particular age or life stage) that is rapid and appears independent of the consequence of behaviour is known as…

Answer 1

Imprinting

Question 2

What is the critical period window of geese imprinting on the first object they see after hatching?

Answer 2

13—16 hours after hatching

Question 2

What is this describing?

Form strong and exclusive attachments to particular types of objects/animals after relatively brief exposure early in life

Answer 2

Filial Imprinting

-genetic (goslings following the first moving object at the time of imprinting after birth)

Question 2

stamping in describes?

Answer 2

Filial imprinting

(Lorenz)

Question 2

Lorenz demonstrated imprinting behaviours of geese soon after hatching by dividing eggs laid by graylag goose into which two groups?

Answer 2

Hatched by mother goose

Hatched by Lorenz in incubator

Question 3

Which group of baby geese imprinted on first moving stimulus within what Lorenz called a “critical period” (13—16 hours after hatching)

Answer 3

Incubator-hatched geese

Question 3

When does imprinting happen in young birds?

Answer 3

Some imprinting occurs after hatching

Imprinting is more consistently achieved in all animals 13-16hrs after hatching

A bird which is more than a day old will not imprint (no following behaviour)

Question 3

Imprinting led to the notion that there are … in the development of brain and behaviour?

Answer 3

critical periods

Question 4

A period during the early life of an animal when some property develops rapidly, and is most susceptible to alteration by the environment is know as?

Answer 4

A Critical period

Question 5

Order these developmental functions after birth:
3 waves of learning during the critical period

Motor/ language
Sensory
Higher cognition

Answer 5

Birth:
Sensory
Motor/ language (never completely closes maintaining plasticity)
Higher cognition

Question 6

Critical periods for cortical regions devoted to vision and other senses open at birth, infancy or childhood, then close tightly?

Answer 6

infancy

Question 7

Critical periods for language and higher cognition open earlier or later thanbirth, infancy and never entirely close?

Answer 7

open later

Question 8

The … is a definite portion of an animal’s life devoted to shaping the neural connections

Answer 8

critical period

Question 9

The longer the lifespan the longer the…

Answer 9

the critical period is

Question 9

Critical Periods and the visual system:
Researchers experimented on the critical period to describe the period during which ocular (eye) dominance can be disrupted by monocular deprivation.

What were the results for critical period on vision?

Answer 9

Critical period is not a single entity – particular to: different visual functions,
different brain regions
depending on the visual history of the animal
(different time windows where they are most sensitive)

Question 10

Critical Periods and monocular deprivation:
3 week old kitten (not same effects at a year old)

Researchers classified cells primary visual cortex in terms of the balance of input they received from each eye

What happens when one eye is closed during the critical periods of visual development?

Answer 10

neurons in primary visual cortex stop responding to input from that eye and start responding to input from the other eye

almost all neurons respond to the open eye only
Big shift in eye preference to the eye which was deprived (different to binocular deprivation the effects are not as bad)

Question 11

General principles of critical periods:

The visual system is plastic between eye opening and ?

More severe visual deprivations have larger effects

Answer 11

puberty

Question 12

General principles of critical periods:

Higher levels of the visual system have … critical periods and different properties have different critical periods.

Answer 12

later

Question 13

General principles of critical periods:

Critical periods for … and recovery may be different

Answer 13

disruption

Question 14

General principles of critical periods:

Critical periods depend on the … of visual experiences

Answer 14

history

Question 15

Visual system is plastic between eye opening and puberty:

Effects of monocular deprivation in different species suggest critical period starts after … and ends around …?

Answer 15

eye opening, puberty

Question 16

When you deprive an eye early, you produce a shift in response in the cortex, yet if you deprive later on in life you do not. What is the reason for this?

Answer 16

Because the window for disruption is closed meaning you cant disrupt it any further

Question 17

What is the critical period for monocular deprivation in:
Cats
Hamsters
Humans

Answer 17

Question 18

More severe visual deprivations have a larger effect:

The severity of the deficit in visual acuity depends upon which 2 things?

Answer 18

the length of monocular deprivation
and
the time during the critical period

Question 19

Monocular deprivation (in cats) has very little effect in the Retina and LGN. Explain why higher levels of the visual system have later critical periods

Answer 19

Responses of cells in primary visual cortex (V1) are dominated by open eye and cannot be driven by closed eye after long deprivation In higher visual areas (e.g. inferotemporal cortex), early critical period and later more protracted period of development and plasticity

Question 20

Which stream of visual functions may be more vulnerable to disruption than "what" stream functions during development?

Answer 20

Dorsal

Question 21

Different properties have different critical periods: Effects of monocular deprivation at different ages on the balance of visual sensitivity between the two eyes in macaque monkeys If you introduce monocular deprivation before 3 months of age, what is impaired?

Answer 21

dark adapted light sensitivity before 3 months of age

Question 22

If you introduce monocular deprivation before 6 months of age, what is impaired?

Answer 22

light adapted light sensitivity before 6 months of age

Question 23

If you introduce monocular deprivation before 20 months of age, what is impaired?

Answer 23

Contrast sensitivity before 20 months of age

Question 24

Critical period for M magnocellular axons innervating cortex ends before critical period for ... axons?

Answer 24

parvocellular (P) axons Monocular deprivation reduces extent of LGN axons (width of ODC) innervating visual cortex Layer 4Cα (M) dominated by axons from left eye that was open first (reduced innervation from right eye) Layer 4Cβ (P) dominated by axons from right eye that was opened second (reduced innervation from left eye) Critical period for M axons innervating cortex ends before critical period for P axons

Question 25

Different properties have different critical periods: There are different critical periods for the development of the parvocellular (P) pathway and magnocellular (M) pathways At 3 weeks kittens were introduced to monocular deprivation, producing a big change in the structural preference for eye of input Researchers then opened the eye that had been closed from right to left at 3 weeks of age What is this called?

Answer 25

Reverse deprivation/ reverse suture in the macaque

Question 26

Critical periods depend on the history of visual experiences: Rearing an animal in what setting delays both the start and end of the critical period?

Answer 26

in the dark History of visual experiences (e.g. no exposure to light during early development) shifts the critical period to a later age

Question 27

Researchers found that dark-reared cats are more, less or equally less plastic than light-reared cats at 5-6 weeks of age?

Answer 27

Less Equally plastic at 8-9 weeks, and more plastic at 12-20 weeks Light sensitivity in dark-reared cats is reduced but then they show a peak sensitivity, pushing the critical window of disruption back in time

Question 28

Critical periods for, development, disruption and recovery may be different:

Answer 28

Critical period for disruption of acuity may last longer than its initial period of development Strabismus and anisometropia change the critical period in humans (like dark rearing) The critical period for disruption in strabismus and anisometropia different from deprivation The critical period for recovering visual acuity is hugely different to its development and disruption

Question 29

What is the critical period for patients with Cataract (deprivation)?

Answer 29

6 weeks- 10 years The critical period for recovering visual acuity is hugely different to its development and disruption

Question 30

Which 2 eye developmental disorders have unknown critical period starting point but can last up until 6-8 years?

Answer 30

Strabismus Anisometropia

Question 31

Different techniques have been used to reopen juvenile-like critical periods of heightened brain plasticity in adult brains such as?

Answer 31

Pharmacological drugs Dark exposure Environmental Enrichment

Question 32

Reopening critical periods in an adult brain is thought to work by removing structural and functional brakes on brain plasticity. Functional Break Structural changes

Answer 32

Functional Break: Human neural connections are monitored by excitatory neurons, by inhibiting these responses (reducing firing, communication with synapse) Once optimised for the environment, you get a balance between excitatory and inhibition when adulthood is reached Structural changes: connectivity between new neurons (neuron nets keep it in place and stop communicating with other neurons)

Question 33

Summary:

Answer 33

The notion that animals imprint on the first animal that moves after birth led to the concept of a critical period Critical periods refers to a period in time when brain and behaviour develop and learn Without the appropriate stimulus during a "critical period", it may be difficult, or impossible, to develop some functions later in life The longer an animal lives the longer the critical periods during development devoted to shaping neural connections Monocular deprivation used extensively in the visual brain to understand the principles governing the opening, duration and closure of critical periods

Question 34

Summary: important card Any description of a critical period must define the visual property, previous visual history, and type of visual deprivation Four principles that are generally true:

Answer 34

1-The longer a lifespan, the longer a critical period 2-Visual system is plastic between eye opening and puberty 3-Critical period for disruption of a property lasts longer than the initial period of development 4-Recovery of a visual property can be obtained after the critical period for disruption has ended