# Neuroplasticity

Psychology I · Psychophysiology · https://tryals.app/learn/psychology-i/neuroplasticity

## The Dynamic Brain

For decades the adult brain was thought to be fixed. It is not. **Neuroplasticity** is the brain's lifelong ability to change its structure and function in response to experience, learning, and injury.

Learning strengthens the synapses that fire together via **long-term potentiation (LTP)**. Conversely, unused connections are removed through **synaptic pruning**, which sculpts an efficient network.

At a larger scale, the cortex can **remap**: when a region is deprived of input, neighboring regions take over its territory. The adult brain also retains **neurogenesis**, the birth of new neurons in the hippocampus, supporting memory.

## Plasticity Across the Lifespan

Plasticity is greatest in early development (**critical** and **sensitive periods**), but it never fully stops. It is the biological basis of learning and recovery.

| Feature | Early Development | Adulthood |
| --- | --- | --- |
| **Rate** | Highest / Peak | Ongoing / Slower |
| **Driver** | Sensory critical periods | Experience & learning |

> **Common pitfall:** Believing neuroplasticity ends in childhood. Plasticity slows down, but the adult brain keeps forming, strengthening, and pruning connections as long as it learns.

## Practice questions

8 of this lesson's 12 practice questions, with answers. The full set is in the app.

### 1. Sort each fact by whether plasticity is greatest early in life or continues into adulthood.

**Answer:**

- Greatest early in development: Dramatic synaptic pruning during childhood and adolescence, Windows in which experience shapes the wiring most decisively
- Continues throughout adulthood: Ongoing strengthening and pruning of connections as you keep learning, Recovery of function after a brain injury in an adult

**Why:** Heavy pruning and critical/sensitive periods peak early; everyday learning and recovery from injury show plasticity continuing into adulthood. Plasticity is greatest early but never fully stops - the lesson's core point.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/sort-each-fact-by-whether-plasticity-is-greatest-early-in-life-or

### 2. Match each concrete example to the plasticity mechanism it illustrates.

**Answer:**

- Practicing piano strengthens the circuits used together → Long-term potentiation
- The teenage brain discards connections it no longer uses → Synaptic pruning
- After an amputation, the map for the missing hand is reassigned → Cortical remapping
- New neurons form in the hippocampus to support new memories → Neurogenesis

**Why:** Strengthening with practice is LTP, discarding unused links is pruning, reassigning a lost limb's map is remapping, and forming new neurons is neurogenesis. Each example embodies one mechanism of plasticity.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/match-each-concrete-example-to-the-plasticity-mechanism-it

### 3. After a limb is amputated, some patients feel touch on the face as though it were coming from the missing hand. What does that reveal about how cortical maps are organised?

A. That the cortical map is fixed at birth and the sensation is a memory of the lost limb.
B. That phantom sensations are psychological rather than neural in origin.
C. That the map is maintained by use and reorganises without it.
D. That the nerves from the face were surgically rerouted to the hand's pathway during the amputation.

**Answer:** C. That the map is maintained by use and reorganises without it.

**Why:** Face and hand are neighbours on the somatosensory strip, and when the hand stops sending signals its territory does not fall silent, the face representation expands into it, so face touch activates cortex the brain still reads as hand. Ramachandran mapped points on patients' faces that reliably produced sensation in specific missing fingers.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/after-a-limb-is-amputated-some-patients-feel-touch-on-the-face-as

### 4. A child with an untreated squint in early childhood can end up with permanently reduced vision in that eye, even though the eye itself is healthy. Why is the timing decisive?

A. Because territory is allocated by competition during a critical period
B. Because the untreated eye deteriorates physically over the same period
C. Because the brain deletes the pathway from the weaker eye entirely
D. Because visual acuity is fixed at birth and cannot be affected by experience

**Answer:** A. Because territory is allocated by competition during a critical period

**Why:** The eye is healthy and the cortex has been reassigned: inputs compete for territory during a developmental window, and the weaker one is outbid. Hubel and Wiesel's cats showed the mechanism, and it is why amblyopia is treated urgently in early childhood and is close to untreatable later.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/a-child-with-an-untreated-squint-in-early-childhood-can-end-up-with

### 5. Select every statement that is TRUE about neuroplasticity.

A. The adult brain cannot form any new connections.
B. Learning a skill changes the brain's structure measurably.
C. Connections that go unused are cleared away as the brain matures.
D. Cortical maps can reorganise after injury or amputation.
E. Plasticity is greatest in childhood but continues throughout life.

**Answer:** A. The adult brain cannot form any new connections.; C. Connections that go unused are cleared away as the brain matures.; E. Plasticity is greatest in childhood but continues throughout life.

**Why:** LTP's strengthening, pruning's removal, and adult hippocampal neurogenesis are true. Plasticity continues into adulthood (it does not end in childhood), and in remapping the neighbors DO extend into the deprived region - so those are false.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/select-every-statement-that-is-true-about-neuroplasticity

### 6. Order the events of cortical remapping after the loss of a limb.

**Answer:**

1. A limb is lost, so its cortical region stops receiving input.
2. That cortical territory falls idle.
3. Neighboring regions gradually extend into the idle territory.
4. The freed cortex is reassigned to nearby body parts.

**Why:** Losing the limb deprives its cortex of input, the territory falls idle, neighbors extend into it, and it is reassigned to nearby parts. This chain is why the cortical map is not fixed but reshapes to use available tissue.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/order-the-events-of-cortical-remapping-after-the-loss-of-a-limb

### 7. Synaptic pruning removes connections that go unused, and a child's brain has far more synapses than an adult's. Why is losing connections a form of development rather than decline?

A. Because pruning affects only the connections between hemispheres, which are not needed after childhood.
B. Because the total number of connections stays constant, with new ones replacing those removed.
C. Because an over-connected network is inefficient and slow.
D. Because the pruned synapses were faulty from the start and never functioned correctly.

**Answer:** C. Because an over-connected network is inefficient and slow.

**Why:** The developing brain overproduces synapses and lets experience select among them, sculptural rather than subtractive, since an everything-to-everything network is expensive, slow and poor at discrimination. Infants discriminate every language's phonemes and by twelve months only their own, which is why the Japanese r/l distinction defeats adult English speakers.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/synaptic-pruning-removes-connections-that-go-unused-and-a-childs

### 8. Because plasticity is greatest early in life, the adult brain cannot form or strengthen any new connections at all.

**Answer:** False

**Why:** False. Plasticity is greatest early but continues throughout adulthood - the adult brain keeps forming, strengthening, and pruning connections (and grows some new neurons). Equating 'greatest early' with 'absent later' is the named pitfall.

Page: https://tryals.app/practice/psychology-i/neuroplasticity/because-plasticity-is-greatest-early-in-life-the-adult-brain-cannot