Long-Term Potentiation Phenomenon Quiz

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Questions and Answers

What is the famous phenomenon described in the text?

Long-term potentiation (LTP)

What frequency tetanus induces the phenomenon of LTP as mentioned in the text?

100 Hz

What would low frequency tetanus of 1 Hz induce at synapses?

Long-term depression (LTD)

What would happen if activity-dependent potentiation continued without the existence of LTD as per the text?

Synaptic saturation Signup and view all the answers

Which stimulus frequency range induces long-term depression (LTD) at synapses?

1 Hz Signup and view all the answers

What is the graph mapping the effects of different stimulus frequencies on synapse strength referred to as in the text?

Modification curve Signup and view all the answers

What integrates the separated inputs into binocular representations in layers 2, 3, and 5 of V1?

Intracortical connections Signup and view all the answers

How can segregation in ocular dominance columns of layer 4 be initiated?

By Hebbian plasticity Signup and view all the answers

Who hypothesized that the activity of neurons plays a critical role in the development of ocular dominance territories?

David Willshaw Signup and view all the answers

Which laboratory showed that retinal neurons produce spontaneous activity?

Lamberto Maffei's laboratory, Italy Signup and view all the answers

What did Carla Shatz's laboratory reveal using calcium imaging?

Waves of activity passing across the retina Signup and view all the answers

Where can waves of activity passing through the retina be recorded?

In a dish with a calcium imaging dye Signup and view all the answers

What impact does raising animals in the dark have on Hebbian synaptic plasticity in the primary visual cortex?

Decreases LTD and increases LTP Signup and view all the answers

How does low frequency stimulation affect synaptic plasticity in dark-reared animals compared to those raised under normal lighting?

Produces more LTD Signup and view all the answers

At what frequency does higher frequency stimulation induce more LTP in animals raised in the dark?

40 Hz Signup and view all the answers

What is the expected impact of dark exposure on visual function following monocular deprivation in adult animals?

Decrease visual deficits attributed to monocular deprivation Signup and view all the answers

What was the major visual deficit observed in kittens that underwent monocular deprivation through the critical period according to Donald Mitchell's laboratory?

Significant visual deficits akin to almost complete blindness through the deprived eye Signup and view all the answers

What is a key difference between the visual acuity of the deprived eye and the open eye in kittens following monocular deprivation?

The deprived eye exhibits significant deficits akin to almost complete blindness Signup and view all the answers

What is a key factor in determining the opening and closing of the critical period?

Cortical inhibition Signup and view all the answers

What happens to vision limited to the deprived eye in animals?

It never recovers Signup and view all the answers

What does the text imply about the recovery of visual experience post-critical period?

There is no functional recovery Signup and view all the answers

What do monocularly deprived kittens demonstrate after about a week of opening their previously closed eye?

Normal binocular vision Signup and view all the answers

In the context of visual cortical critical periods, what varies from one species to another?

Time and longevity of the critical period Signup and view all the answers

What has research by Mark Bear and Takao Hensch focused on regarding critical periods?

Determinants of critical period opening and closing Signup and view all the answers

What term is used to describe the period during which defining plasticity is permitted?

Critical period Signup and view all the answers

In the context of the text, what does the term 'critical period' refer to?

A specific stage of postnatal development Signup and view all the answers

What is the consequence of monocular deprivation in five-week-old kittens?

Ocular dominance shift in layer 2/3 neurons Signup and view all the answers

Why is the attachment formed during a critical period described as unbreakable in the text?

Because it persists even if the provider changes roles Signup and view all the answers

What is one area where the concept of the critical period has had influence, as mentioned in the text?

Education Signup and view all the answers

What would be the result of a reverse suture of the opposite eye after monocular deprivation in kittens?

Equivalent shift in the opposite direction Signup and view all the answers

Study Notes

LTP and LTD

LTP (Long-term Potentiation) is a form of synaptic plasticity that can last for at least an hour, and is induced by high-frequency tetanus (100 Hz) in one pathway.
LTD (Long-term Depression) is the reverse phenomenon, also a form of synaptic plasticity, induced by low-frequency tetanus (1 Hz) in the same pathway.
Both LTP and LTD can be observed longitudinally at the same synapses.
A modification curve shows the effects of different stimulus frequencies on the strength of synapses, with low frequencies inducing LTD and higher frequencies inducing LTP.

Critical Period

The concept of a critical period refers to a brief window during which defining plasticity is permitted, and has been influential in education, psychology, psychiatry, and neuroscience.
The critical period is relevant to the effects of visual experience in deprivation on the neocortex of mammals.
In kittens, the effects of monocular deprivation are highly reversible if the deprivation occurs during an early critical period.

Visual Cortex and Ocular Dominance

In the visual cortex, intracortical connections integrate separated inputs into binocular representations in layers 2, 3, and 5.
Ocular dominance columns in layer 4 can arise from activity within the nervous system, rather than genetic programming.
Spontaneous activity in retinal neurons can lead to waves of activity that pass across the retina, influencing the development of ocular dominance territories in the brain.

Dark-Rearing and Visual Function

Dark-reared animals have altered inhibition and a shifted modification threshold, leading to reduced LTD and increased LTP in response to different stimulus frequencies.
The expectation is that dark exposure could reduce the impact of monocular deprivation or recover lost visual function in adult animals.

Visual Acuity and Critical Period

Kittens that underwent monocular deprivation during the critical period retain major visual deficits long after the eye is open.
Visual acuity can be tested independently through each eye, and monocularly deprived kittens show normal binocular vision a week or so after the eye is open post-critical period.
However, vision limited to the deprived eye never recovers, and the animals remain functionally blind through this eye.

Species Variation in Critical Period

The visual cortical critical period varies in time and longevity from one species to another, with closure of the critical period occurring around 8-9 weeks, months, or years depending on the species.
Cortical inhibition is a key determinant of both the opening and the closing of the critical period.

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