Paul Broca (1861) presented the patient "Tan" (Leborgne) to argue that speech production depends on the left posterior inferior frontal gyrus. What best described Tan's deficit?

A: He could not understand speech but could speak fluently

B: He had no language ability at all — no production or comprehension

C: He could understand language but could produce almost no speech, limited to the syllable "tan"

D: He had intact speech production but could not read or write

Correct: He could understand language but could produce almost no speech, limited to the syllable "tan"

Tan could comprehend what was said to him and respond appropriately with gesture, yet his only spoken output was "tan" (and occasionally a profanity). Post-mortem examination revealed a large lesion in the left inferior frontal gyrus — now Broca's area (BA 44/45). This dissociation — intact comprehension, severely impaired production — defined Broca's aphasia and was the first strong evidence for language lateralisation and cortical localisation of function.

Wernicke's aphasia results from damage to the posterior superior temporal gyrus. The hallmark symptom pattern is:

A: Non-fluent, effortful speech with good comprehension

B: Fluent speech with intact prosody but severely impaired comprehension and frequent paraphasias

C: Complete mutism with intact reading comprehension

D: Impaired repetition only, with normal spontaneous speech and comprehension

Correct: Fluent speech with intact prosody but severely impaired comprehension and frequent paraphasias

Wernicke's aphasia produces fluent, prosodically normal speech that contains paraphasias (word substitutions: phonemic — "spoot" for "spoon"; semantic — "fork" for "spoon"), neologisms, and sometimes jargon. Comprehension is severely impaired — patients often seem unaware that their output is unintelligible. This contrasts sharply with Broca's aphasia (non-fluent, impaired production, relatively preserved comprehension).

Conduction aphasia — fluent speech, intact comprehension, but severely impaired repetition — is caused by damage to:

A: Broca's area in the left inferior frontal gyrus

B: The arcuate fasciculus, the white-matter tract connecting Wernicke's and Broca's areas

C: The angular gyrus in the left inferior parietal lobule

D: The right hemisphere's homologues of Broca's and Wernicke's areas

Correct: The arcuate fasciculus, the white-matter tract connecting Wernicke's and Broca's areas

Conduction aphasia is a disconnection syndrome. The arcuate fasciculus (and the superior longitudinal fasciculus) connects posterior temporal comprehension regions to frontal production regions. When this pathway is severed, heard language is understood but cannot be directly passed to the articulatory system for repetition — resulting in the characteristic inability to repeat despite fluent spontaneous speech.

True or False: Language is exclusively lateralised to the left hemisphere in all neurologically typical adults.

Answer: False

FALSE. Language is left-lateralised in approximately 95% of right-handers and about 70% of left-handers. The remainder show bilateral or right-hemisphere language dominance. Knecht et al. (2000) used functional transcranial Doppler to show a continuous distribution of lateralisation. Even strongly left-lateralised individuals rely on the right hemisphere for prosody, discourse-level comprehension, and pragmatic inference.

The Wada test (intracarotid sodium amobarbital procedure) is used in pre-surgical assessment to determine:

A: Which hemisphere controls fine motor speech articulation

B: Whether a patient has Broca's or Wernicke's aphasia

C: Which hemisphere is dominant for language and memory before temporal lobe surgery

D: The extent of white-matter damage in the arcuate fasciculus

Correct: Which hemisphere is dominant for language and memory before temporal lobe surgery

The Wada test temporarily anaesthetises one hemisphere via injection into the internal carotid artery, allowing clinicians to determine which hemisphere controls language (and memory) before resective surgery. If language is disrupted when the left side is anaesthetised, the surgeon knows the left hemisphere is dominant and must avoid removing tissue there. It was the gold standard for lateralisation until fMRI language mapping became reliable.

Hickok & Poeppel's (2007) dual-stream model proposes that auditory language processing involves two pathways. Which correctly describes them?

A: Dorsal stream (temporal lobe) for comprehension; ventral stream (frontal lobe) for production

B: Ventral stream (temporal lobe) for mapping sound to meaning; dorsal stream (parietal-frontal) for sensorimotor integration and speech production

C: Left-hemisphere stream for phonology; right-hemisphere stream for semantics

D: Fast stream for spoken words; slow stream for written text

Correct: Ventral stream (temporal lobe) for mapping sound to meaning; dorsal stream (parietal-frontal) for sensorimotor integration and speech production

The ventral stream runs along the superior and middle temporal gyrus and projects to the temporal pole and ventral frontal lobe — it maps sound onto meaning ("what is being said"). The dorsal stream projects from posterior superior temporal cortex to premotor and inferior frontal cortex via the parietal lobe — it maps sounds onto motor articulatory representations and is critical for speech repetition, production, and phonological short-term memory.

Children who suffer early left-hemisphere damage often develop relatively intact language. This is best explained by:

A: The left hemisphere has redundant language areas that take over automatically

B: Language functions reorganise to right-hemisphere homologous regions during the critical period, before full lateralisation is complete

C: Language does not depend on the left hemisphere in children — lateralisation only occurs after age 10

D: Right-hemisphere language processing is identical to left-hemisphere processing at all ages

Correct: Language functions reorganise to right-hemisphere homologous regions during the critical period, before full lateralisation is complete

During the critical period, the brain retains sufficient neuroplasticity for language functions to be "captured" by the right hemisphere when the left is damaged. Plasticity is greatest in infancy and declines with age — consistent with the observation that adults with comparable left-hemisphere lesions show far poorer recovery. This is evidence for both the critical period and neuroplasticity: the same developmental window that makes language acquisition easy also allows functional reorganisation after injury.

Modern neuroimaging has revised the classic Broca/Wernicke model by showing that Broca's area is involved in:

A: Speech production only — it has no role in comprehension

B: A range of language functions including syntactic processing, working memory, phonological rehearsal, and aspects of comprehension

C: Only the motor programming of articulation — semantic and syntactic functions are entirely in temporal regions

D: Written but not spoken language

Correct: A range of language functions including syntactic processing, working memory, phonological rehearsal, and aspects of comprehension

Neuroimaging studies (fMRI, PET) have shown Broca's area (BA 44/45) activates during syntactic processing (even without production), phonological working memory, semantic selection between alternatives, and hierarchical structure building. The clean "Broca = production / Wernicke = comprehension" dichotomy is now understood to be a simplification. Broca's area is better understood as part of the dorsal stream for hierarchical processing.