Biological Approach – Brain and Behaviour: Localization of Function

Twenty question-and-answer flashcards covering key definitions, case studies (Broca, Wernicke, Penfield, Lashley, Sperry & Gazzaniga), and evolving views on localization of brain functions.

What does the theory of localization of function propose?

Specific psychological functions are controlled by specific, identifiable areas of the brain.

How is strict localization defined?

A one-to-one correspondence between a mental function and a particular brain area, implying every function can be clearly mapped.

What is weak localization?

One brain area is primarily responsible for a function, but other regions can also perform or share that function.

What are widely distributed functions?

Psychological functions that cannot be tied to any single location in the brain.

Which two speech disorders provided the earliest evidence for strict localization?

Broca’s aphasia and Wernicke’s aphasia.

Who was the famous patient ‘Tan’ and what deficit did he demonstrate?

Paul Broca’s patient who could only utter the syllable “Tan,” demonstrating loss of articulated speech (Broca’s aphasia).

Where is Broca’s area located, and what is its function?

Posterior inferior frontal gyrus of the left hemisphere; production of articulate speech.

Where is Wernicke’s area located, and what function does it serve?

Left temporal lobe; comprehension of spoken and written language.

What is the hallmark of Wernicke’s aphasia?

Impaired language comprehension with fluent but often nonsensical speech.

Which technique did Wilder Penfield use to map cortical function?

Electrical stimulation of the cortex in awake patients during surgery.

What is the cortical homunculus?

A visual map showing how much cortical area is devoted to each part of the body for motor or sensory functions.

What was Karl Lashley’s research method for studying memory localization?

Induced lesions in rat cortices after maze-learning to observe memory deficits.

State Lashley’s principle of mass action.

Memory performance depends on the total amount of cortex destroyed, not the lesion’s location.

Define equipotentiality as concluded by Lashley.

Any intact cortical area can assume functions of a damaged area when necessary.

Overall, what did Lashley’s findings suggest about memory?

Memory is widely distributed across the cortex rather than strictly localized.

What was the main aim of Sperry & Gazzaniga’s split-brain studies?

To examine how the two hemispheres function independently after severing the corpus callosum.

Why could split-brain patients not verbally name objects shown to the left visual field?

The image reached the right hemisphere, but language centers are localized in the left hemisphere, preventing verbal description.

Which hand successfully grasped a spoon seen in the left visual field and why?

The left hand; it is controlled by the right hemisphere that received the visual information.

What do split-brain results indicate about language localization?

Language production and comprehension are lateralized (weakly localized) in the left hemisphere.

How has the concept of localization evolved in modern neuroscience?

Absolute (‘strict’) localization has been replaced by the view that functions are relatively localized, with significant inter-region cooperation and plasticity.