# Language in the Brain

Languages I · Introduction to Linguistics · https://tryals.app/learn/languages-i/language-in-the-brain

## Evidence from Damage

Early brain science relied on damage to understand language.

In 1861, **Paul Broca** described a patient who understood speech but could not produce it. Broca linked this to left frontal damage. In 1874, **Carl Wernicke** described fluent speech with poor comprehension, linked to temporal damage.

| | Broca's aphasia | Wernicke's aphasia |
|---|---|---|
| Fluency | Halting | Fluent |
| Content | Meaningful words | Semantically empty |
| Comprehension | Good | Poor |
| Awareness | Aware | Unaware |

In **conduction aphasia**, speech and comprehension remain intact, but repetition fails.

### Lateralisation

Language is left-lateralised in **95%** of right-handers and **70%** of left-handers. The classic source for these numbers is the **Wada test**, which anaesthetises one hemisphere.

### Beyond the Classical Model

The classic model is oversimplified:

- Damage in Broca's patients extended well beyond Broca's area.
- Language relies on broad, distributed networks rather than two isolated centres.
- Broca's patients struggle to understand complex syntax.

### The Critical Period

First-language acquisition declines with age. The case of **Genie**, isolated until age thirteen, showed vocabulary growth without normal syntax. Studies of deaf individuals learning sign language at different ages confirm this decline.

> **Common pitfall:** Broca and Wernicke areas are not simple functional modules for production and comprehension. The actual neural processing relies on wide networks.

## Practice questions

8 of this lesson's 13 practice questions, with answers. The full set is in the app.

### 1. A patient produces fluent, well-formed sentences that convey almost nothing, comprehends poorly, and appears unaware of any difficulty. Which aphasia is this, and what makes the diagnosis quick?

A. Conduction aphasia, fluent speech combined with severely impaired comprehension
B. Global aphasia, severe comprehension deficits coupled with effortless speech
C. Wernicke's aphasia, fluency plus poor comprehension and lack of awareness
D. Broca's aphasia, intact grammatical structure alongside poor comprehension

**Answer:** C. Wernicke's aphasia, fluency plus poor comprehension and lack of awareness

**Why:** **Wernicke's.** Fluency separates it from Broca's at once, and the combination with poor comprehension and absent awareness completes it. Conduction aphasia, the first option, spares comprehension and impairs repetition specifically.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/a-patient-produces-fluent-well-formed-sentences-that-convey-almost

### 2. The classical model mapped production to Broca's area and comprehension to Wernicke's area, but modern findings show Broca's patients struggle with complex syntax. What does this distinction reveal about how syntax is processed?

A. Syntax and comprehension are governed entirely by temporal cortexes
B. Broca's area is dedicated exclusively to decoding grammatical rules
C. Syntactic processing relies on broader distributed neural networks
D. Syntactic deficits only emerge when both classical centres are damaged

**Answer:** C. Syntactic processing relies on broader distributed neural networks

**Why:** Syntax is not an isolated motor skill confined to one centre; it integrates across wider networks during both production and interpretation. Assuming a neat anatomical split between comprehension and production overlooks how grammatical structure underpins both faculties.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/the-classical-model-mapped-production-to-brocas-area-and

### 3. Language is left-lateralised in about 95 per cent of right-handers.

**Answer:** True

**Why:** **True**, and the left-handed figure of roughly 70 per cent is the useful companion. Left-handedness shifts the probability without reversing it, which is why handedness alone is a poor guide to an individual patient and the Wada test was used before surgery.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/language-is-left-lateralised-in-about-95-per-cent-of-right-handers

### 4. Arrange these kinds of evidence from the strongest to the weakest for showing that a region is NECESSARY for language.

**Answer:**

1. A lasting deficit after damage to the region
2. A temporary deficit under direct stimulation
3. Activation of the region during a language task
4. Correlation between the region's size and language ability

**Why:** Only the first two show that removing or disrupting the region breaks the function. Activation shows a region **participates**, which is much weaker, a region can light up during a task without being required for it, and a size correlation is weaker again. Confusing engagement with necessity is the most common misreading of imaging results.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/arrange-these-kinds-of-evidence-from-the-strongest-to-the-weakest-for

### 5. Sort each source of evidence about language in the brain by whether it is LESION-based or NON-LESION.

**Answer:**

- Lesion evidence: Broca's 1861 patient, Conduction aphasia after damage to a connecting tract, Recovery patterns after stroke
- Non-lesion evidence: Functional imaging during sentence reading, The Wada test before surgery, Event-related potentials to anomalous words

**Why:** The distinction matters because the two kinds of evidence answer different questions. A lesion shows what is **necessary**; imaging shows what is **engaged**, which is a much weaker claim, a region can activate during a task without being required for it.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/sort-each-source-of-evidence-about-language-in-the-brain-by-whether

### 6. In roughly what percentage of left-handers is language left-lateralised?

**Answer:** 70 (within ±8)

**Why:** **About 70 per cent.** The remaining left-handers divide between right-lateralised and bilateral representation. The figure is worth remembering as a corrective: the popular idea that left-handers have "reversed" brains is wrong, most of them are organised like everyone else.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/in-roughly-what-percentage-of-left-handers-is-language

### 7. Complete the account of the aphasias.

**Answer:** Damage to the left inferior frontal gyrus produces **Broca's** aphasia, whose speech is halting and **agrammatic**. Damage further back in the temporal lobe produces **Wernicke's** aphasia, whose speech is fluent but empty and whose **comprehension** is poor.

**Why:** Anchoring each to its lesion site rather than to a function is deliberate. The aphasias are named after where the damage is, and treating the names as labels for mental modules is exactly the error the last section of the lesson warns about.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/complete-the-account-of-the-aphasias

### 8. A brain region that activates during a language task has been shown to be necessary for it.

**Answer:** False

**Why:** **False**, and this is the most common misreading of imaging results. Activation shows a region participates; only impairment after damage, or after temporary disruption, shows it is required. The two methods are complementary precisely because they answer different questions.

Page: https://tryals.app/practice/languages-i/language-in-the-brain/a-brain-region-that-activates-during-a-language-task-has-been-shown