4. Localization of cognitive brain functions

• Franz Joseph Gall 1758-1828

• = brain is organ of mind. All mental functions emanate from the brain

• brain composed of particular organ each resposible for a mental faculty

• external form of cranium refelcts the internal organization

• used mid 19th century

• 
  

• Jean Pierre Flourens 1794-1867

• animal experimentalist

• demonstrated specific involvement of

  • cerebral hemispheres in perception and judgement

  • cerebelleum in movement

  • brainstem in vital cardiovascular functions and respiration

Aphasia

Left frontal lobe / Broca

Paul Broca studied the speech-impaired patient Leborgne ("Tan") and discovered a lesion in the left frontal lobe(gyrus), leading to the identification of Broca’s area and the first strong evidence for functional localization in the brain.

A language disability affects the ability to understand or produce meaningful language (e.g., aphasia), while a speech disability affects the physical act of speaking (e.g., dysarthria or stuttering), involving articulation, voice, or fluency.

It is a classical model that describes how language is processed in the brain through a network of specialized regions:

• Wernicke’s area: comprehension of spoken and written language.

• Broca’s area: speech production and grammar.

• Arcuate fasciculus: a fiber tract that connects Wernicke’s and Broca’s areas, enabling repetition and integration of speech.

• Geschwind’s contribution: added the role of angular and supramarginal gyri in reading and writing.

They identified the motor cortex by electrically stimulating the dog’s cerebral cortex and causing specific muscle movements, proving that motor control is localized in distinct brain areas.

Jackson proposed hierarchical brain organization and described motor seizures, while Ferrier mapped motor and sensory cortical areas in monkeys, advancing the concept of brain localization.

Gage’s frontal lobe injury caused major personality changes, providing early evidence that the frontal cortex is crucial for personality, decision-making, and social behavior.

Penfield is known for mapping the motor and sensory cortex via electrical stimulation during awake brain surgery, developing the cortical homunculus, and pioneering techniques to treat epilepsy.

Harlow documented Gage’s recovery and behavioral changes, providing early evidence that frontal lobe injuries can affect personality, emotion, and social behavior, helping link brain areas to cognitive functions.

• Damage of higher-order cognitive functioning

• disinhibition

• failure to plan

• Dysexecutive syndrome

It means cognitive disorders often arise from disrupted connections between brain areas (disconnection syndromes), not just damage to a single localized brain region, because brain functions depend on networks, not isolated spots.

After surgical removal of his medial temporal lobes (including the hippocampus), H.M. developed severe anterograde amnesia, showing the hippocampus is essential for forming new long-term memories, while procedural memory remained intact.

1. Amnesic patients can recall old but not new information

2. Amnesic patients can learn skilled movements

She showed that the hippocampus and medial temporal lobe are essential for forming new declarative memories, demonstrated by her work with patient H.M., and highlighted the distinction between declarative and non-declarative memory.

• The FFA is a brain region in the temporal lobe specialized for facial recognition and is highly active when viewing faces, playing a key role in identifying and interpreting facial features.

• Part of the ventral visual stream

= network phenomena that is the result of coordinated activity between multiple brain areas