Phineas Gage & Split Brain

phineas gage

accident occurred in 1848 and survived additional 12 years

damaged

3 places: small wound under left cheekbone where tamping iron entered, another located in orbital bone in base of skull behind orbit of eye, largest wound at top of skull, where iron exited, never healed

laterisation

the idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations

epileptic patients

have corpus callosum cut to reduces seizures in the brain. loves largest unaffected, seizures reduced. affected abilities related to naming objects in left visual field

investigation

Sperry and Gazzaniga (1967) were the first to investigate hemispheric laterisation with split brain patients. aim was to examine extent to which two hemispheres are specialised for certain functions. findings were that lef is dominant in speech and language and right is dominant is visual-motor tasks.

broca’s aphasia

• Location:

  Left frontal lobe.

• Symptoms:

  • Speech Production: Slow, broken, and halting speech (non-fluent).

  • Comprehension: Generally good; they can understand language.

  • Awareness: Patients are often aware of their errors, leading to frustration.

  • Syntax: Poor grammar; struggle to produce full sentences (telegraphic speech).

Wernicke’s aphasia

• Location: Left temporal lobe.

• Symptoms:

  • Speech Production: Fluent, rapid speech that lacks meaning, uses incorrect words (paraphasias), and makes up words (neologisms).

  • Comprehension: Poor; difficulty understanding spoken and written language.

  • Awareness: Patients are often unaware of their mistakes (anosognosia).

  • Structure: Often uses proper grammar, but the content makes no sense.