chapter 4 Cerebral Specialization and Aging Flashcards
what is Lateralization
refers to functions assifned to one hemisphere or the other
what are the functions of lateralization
localization- specific functions in different lobes of each hemisphere
-Dominance-a hemisphere having dominance for certain functions (priority)
comparison of the left to right hemisphere
the left
- weighs more
- longer in adults
- lateral fissure is longer and better defined
- temporal pole is more distinguished
- parietal operculum is larger and deeper
- ventricle is larger
- visual cortex vells are larger
- pyramidal tract is larger/thicker
common functions of both hemispheres (equal)
- Olfaction
- Vision (17, primary visual cortex; 18/19, visual association areas)
- Audition (41, primary audiroty cortex; 42/37 and 22, auditory association areas)
- Somesthesia(3/1/2 primary sensory cortex; 5/7 sensory association areas)
- Stereogenesis/ability to name via touch(5/7)
- Voluntary motor movement (4 primary motor cortex-gross motor movement)
- Executive functions (prefrontal cortex, 38% of brain is in the frontal cortex)
- 96% of descending fibers decussate at brain stem, resulting in contralateral innervations
special functions of the right hemisphere
-spatial itegration/discrimination (disorder= visual agnosia)
-nonverbal ideation (creativity;disorder affects artistic skills)
-facial discrimination (disorder is propagnosia-can recognize by voice not face)
-tonal discrimination (disorder is dysmusia)
metalinguistic ability (disorder -maks like faces-affects humor, body language, and cues difficulty interpretting others faces)
-language comprehension/ production (only 2-5% have right language center- very little language on right side of the brain)
special functions of the left hemisphere
- eye/ hand coordination, especially for writing with the right hand(exners area 8/9)
- language comprehension (disorder-wernickes aphasia, area 22)
- language production (disorder- Broca’s aphasia, area 44/45)
- speech programming (disorder-apraxia of speech, area 44/45)
- wernicke’s area connects to broca’s area via arcuate fasciculus (damage - conduction aphasia)
- angular gyrus(39) and supramarginal gyrus (40) damage-learning disability
- word recall disorder-anomia
- writing disorder- dysgraphia
- reading disorder-dyslexia
- math disorder- dyscalculia
evidence for left hemisphere dominance
- even the vast majority of left handers have left hemisphere dominance for language
- 92% of fetuses tend to use right thumb when sucking supporting genetic predisposition
- most perple are right ear, hand, arm,leg dominant.
gender differences
- males tend to have more white matter and csf -than females( move faster, have a faster impulse sending)
- males tend to have larger parietal lobes and a larger amygdala
- males appear better at spatial tasks
- serotonin levels are 52% higher im men-makes them calm
- females tend to have more gray matter, larger frontal cortex and limbic lobe-smarter more decision making and more emotional
- females and homosexual men tend to have smaller hypothalamic cells
- females appear better at verbal tasks
- emotional memories stimulate the right amygdala in men and the left in women.
ARC- after the age of 30
brain mass shrinks by .25%
ARC- by age 80
7% of brain mass has been lost
ARC-neocortex (outer 1/2-1 inch of the brain)
- does not fully function till 3-4 years of age
- results in poor memories prior to this
ARC- cell loss
- occurs with age
- primarily in frontal, temporal, and occipital lobes
ARC-telomeres (tips of chromosomes)
help with cell repair- up to a certai npoint
ARC- arterial plaque, neuritic plaque, and neurofibrillary tangles
increase with age, and the last two are seen in parkinson patients
ARC-alcohol
apears to damage younger brains more than older brains, affects the frontal cortex and the hippocampus
