W19- Stroke & Speech Processing

What is a lesion? An area of neural tissue damaged through injury or disease.

What types of brain damage can cause lesions? Stroke, brain tumours, traumatic brain injury, and neurological disease.

What is a stroke? A cerebrovascular accident (CVA) involving disrupted blood supply to the brain.

What are the two major types of stroke? Ischaemic and haemorrhagic.

What causes an ischaemic stroke? Loss of blood supply due to blockage, reducing oxygen and glucose delivery.

What causes a haemorrhagic stroke? Bleeding into brain tissue following vessel rupture.

Which artery is particularly important for language function? The middle cerebral artery (MCA).

What is aphasia? A language disorder caused by brain damage.

What does aphasia literally mean? "Being at a loss for words."

What is expressive aphasia? A language disorder involving impaired speech production.

What is another name for expressive aphasia? Broca's aphasia.

Who first described Broca's aphasia? Paul Broca (1861).

Which patient is associated with Broca's aphasia? Leborgne ("Tan").

What was unusual about Broca's patient? He could comprehend speech but could only say "Tan."

Where is Broca's area located? In the inferior frontal gyrus (BA44/45).

What is receptive aphasia? A disorder involving impaired speech comprehension.

What is another name for receptive aphasia? Wernicke's aphasia.

Who first described Wernicke's aphasia? Carl Wernicke (1874).

What characterises speech in Wernicke's aphasia? Fluent but often meaningless speech with preserved grammar and prosody.

Where is Wernicke's area located? In the posterior superior temporal gyrus.

What is conduction aphasia? A language disorder caused by damage to the arcuate fasciculus.

What is the arcuate fasciculus? A white matter tract connecting Broca's and Wernicke's areas.

What language abilities are relatively preserved in conduction aphasia? Auditory comprehension and fluent speech.

What language abilities are impaired in conduction aphasia? Naming and repetition.

What is DTI? Diffusion Tensor Imaging.

What does DTI measure? Water diffusion within brain tissue.

What can DTI reveal? White matter connectivity and tract integrity.

Why are lesion studies valuable? They provide evidence for causal brain-behaviour relationships.

What is a major limitation of lesion studies? There is no one-to-one relationship between lesion location and symptoms.

Why is diagnosis difficult in aphasia? Symptoms often overlap across aphasia types.

Why are lesion-study samples often heterogeneous? Patients differ in lesion size, location, age, and recovery stage.

What is the main assumption behind lesion studies? If removing a brain area causes loss of behaviour, that area contributes causally to that behaviour.

What happens during the first few weeks after a stroke? Large recovery gains often occur as swelling and inflammation decrease.

What factors influence stroke recovery? Lesion size, lesion location, stroke type, and individual differences.

Which study proposed a model of language recovery after stroke? Saur et al. (2006).

How many aphasia patients were scanned in Saur et al. (2006)? 14 patients.

When were patients scanned in Saur et al. (2006)? Approximately 2 days, 12 days, and 320 days after stroke.

What happened to right IFG activation during recovery in Saur et al. (2006)? It increased dramatically during the subacute stage then decreased later.

What are the three phases of recovery proposed by Saur et al. (2006)? Acute loss of function, subacute up-regulation, and chronic normalisation.

What is disinhibition in stroke recovery? Loss of left IFG suppression causes increased activity in the right IFG.

Which study used TMS to improve picture naming in chronic aphasia? Naeser et al. (2005).

What was the main finding of Naeser et al. (2005)? Low-frequency rTMS over the right IFG improved picture naming in 3 of 4 chronic aphasia patients.