610 Pre-req Knowledge (part ii)

Broca’s area and inferior frontal lobe

Syntax, phonological encoding, connection with motor planning

Superior and middle temporal lobe

Semantics, syntax

Inferior parietal lobe

Semantics, reading/spelling

Wernicke’s area and posterior superior temporal lobe

Auditory processing, word selection, lexical access

Issues with Broca’s area and inferior frontal lobe lead to

Non fluency, motor deficits, phonological encoding issues

Where were the lesions causing syntactic deficits in the brain?

Left frontal and superior temporal lesions

Where were the lesions causing lexical deficits in the brain?

Left parieto-temporal lesions

Where were the lesions causing phonological deficits in the brain?

Left frontal and parietal lesions

Where does the perisylvian region receive blood supply?

From the middle cerebral artery

What is the most common cause of aphasia?

A stroke of the left middle cerebral artery (LMCA)

What effects are associated with damage to left perisylvian and/or extrasylvian damage?

Disruption of the left lateralized language network

What is extrasylvian region?

The area around the perisylvian region that plays a supporting role in language

What aphasia is caused by damage to the extrasylvian region?

Transcortical aphasia

What is the perisylvian region?

The area around the Sylvian Fissure

What is a stroke?

An acute series of rapidly developing clinical signs of focal or global disturbance of cerebral function with symptoms lasting 24 hours or longer or leading to death with no apparent cause other than of vascular origin (impairment in blood supply)

What are the two types of stroke?

1. Hemorrhage (bleeding or rupture of a blood vessel leading to cell death)

2. Ischemia (occlusion or blockage of a blood vessel causing cell death)

If symptoms last longer than 24 hours, what would that be? Less than 24 hours?

Stroke, transient ischemic attack

What is the cascade of events during a stroke?

Reduced blood flow (hypoperfusion) → reduced electrical activity → release of glutamate (neurotransmitter), excess causes cell death → death of neuron (necrosis) → triggers (post-synaptic) release of Na+, CA+ → further release of glutamate (post-synaptic) → death of post-synaptic neuron (necrosis) → transneural degeneration (atrophy of neighboring cells → diaschisis (reduced function of remotely connected cells), resolves as blood flow improves leading to improvements in aphasia

What is the etiology of primary progressive aphasia?

Atrophy (neural degeneration) of the left Perisylvian regions