CH 6 - Hemispheres - contralateral

Part 1:

• Lateralization: Different functions are more dominant in one hemisphere than the other.

  • Left: Logical, calculating, linguistic

    • Broca's and Wernicke's areas

  • Right side of the body, right visual field, faces, visual motos skills

    •   Left damage:

      • Pessimistic

      • Overly emotional

      • Overly noticing of even nonserious problems

  • Right: Emotional, holistic, intuitive

  • Faces, visual motor tasks

  • Left side of the body, left visual field

    • Right damage:

      • Optimistic

      • Unemotional

      • Oblivious to serious injury and disability (anosognosia)

• Localization: Specific functions are located in specific brain regions.

• Localized v Lateralization: *memorize the diseases

  • Selective Amnesia: Selective memory loss

  • Apperceptive agnosia: Vision intact, impaired recognition of shapes/forms

    • Basic disruption in perceiving patterns

    • Lose the ability to take the basic visual info and form a pattern

    • Able to perceive only small, local aspects of stimuli

    • Nonverbal, tactile, and motion cues can facilitate recognition

• Associative agnosia: Vision intact; shapes/forms intact; impaired object recognition “unable to put labels“

  • Percept is correct, but the deeper association with the "label" is severed

  • No non-verbal recognition or motion facilitation

  • Results from damage to the ventral stream of the brain, the occipitotemporal stream

  • Scope of the deficit varies

• Dyscalculia: Cant do simple calculations

• Alexia: Cannot read

• Agraphia: Cant write

• Broca's aphasia: Cant produce language

• Wernicke's aphasia: Cant comprehend language

PART 2: Decussation: crossing of nerve fibers from one side of the central nervous system to the other, most prominently seen in structures like the pyramidal decussation where about 85–90% of corticospinal fibers cross in the lower medulla

• Areas of Decussation

  • Corpus Callosum - Cerebral hemispheres (bridge between hemispheres)

  • Optic chiasm - vision

  • Superior olivary complex - audition

  • Spinal cord - sensory and motor

• Inter-hemisphere communication

  • Bridge of 200 mil fibers

  • Served in split-brain patient

• Optic Chiasm

  • Left visual field info to right visual cortex

  • Right visual field info to left visual cortex

• Auditory Pathways

  • A bunch of subcortical areas

  • Decussation in the superior olivary complex after cochlear nucleus (NOT complete decussation)

    

Spinal Cord

• Pain and temperature

• Touch and vibration

• Motor output

• Multiple points of decussation for different sensory and motor pathways

  

PART 3 - Split-brain patients

Severed corpus callosum

Can tell us about:

Information transfer: Visual, Verbal, Tactile

Spoon shown in left side field → patient doens’t know what they saw but are able to identify it on a group of different objects

Cup shown in the right side field → Patient is able to recognize what they saw

Present word “Devil” on the left hermisphere, patient is able to recognize is bad and able to sy the word is “devil”. But when it is onthe right hemisphere they know the word is bad but dont know what the word is

• Gazzaniga’s split brain patient

Emotion:

• Gazzaniga and LeDoux (1978)

  • Present emotionally charged word to left hemisphere

Motor coordination

• Kurt Goldstein (1930’s)

  • Alien hand phenomenon: middle-aged woman would try to strangle herself with her left hand (right hemisphere: more emotional?)but her right hand would fight back, autopsy revealed CC lesion (as if someone else had control of her hand)