Summary #2 lateralization of function
Hemispheres are separate except for commissures
- Corpus callosum
- Anterior/posterior commissure
The separate hemispheres have separate functions. lateralization of function
Theory of cerebral dominance
Left hemisphere; dominant & right hemisphere; minor
Function of hemispheres is contralateral, except for: taste, smell
Auditory signals go to both hemispheres, but the contralateral connection is strongest.
Most strongly lateralized function language PRODUCTION
Lateralized functions:
- Right; general pattern & form left; details &
meaning
- Right; emotions vs. left; factual/rational
How they found out.
- Left hemisphere injury more ipsilateral effects
- When solving exercises about a 3-dimensional figure
the right hemisphere is more active.
- Right lesion difficulty in emotional processing
- Dichotic melody test left ear is superior
Why lateralization evolutionary theories
o Analytic-synthetic theory of cerebral asymmetry
= left; analytic/logic/abstracting/computer-like & right;
synthetic/organizes/processes/whole picture information
No empirical evidence, vague
o Motor theory of cerebral asymmetry
The left hemisphere was specialized in fine motor movements later important for
language. Aphasia hand in hand with motor deficiency
No explanation for the lateralization
o Linguistic theory of cerebral asymmetry
The left hemisphere is purely linguistic. Only theory in which language is the primary
factor in lateralization
No empirical basis
Advantage of lateralization
- All neurons are concentrated + efficient
- Lateralization of connected functions (e.g., fine motor skills and language+efficient)
- 2 control areas can lead to competition (speech area in both hemispheres= stutter)
Handedness and lateralization
Right handed people have a 95% chance of having the speech center located in the left
hemisphere
Left handed people have a 75% chance of having a speech center in the LH.
Hemispheres are separate except for commissures
- Corpus callosum
- Anterior/posterior commissure
The separate hemispheres have separate functions. lateralization of function
Theory of cerebral dominance
Left hemisphere; dominant & right hemisphere; minor
Function of hemispheres is contralateral, except for: taste, smell
Auditory signals go to both hemispheres, but the contralateral connection is strongest.
Most strongly lateralized function language PRODUCTION
Lateralized functions:
- Right; general pattern & form left; details &
meaning
- Right; emotions vs. left; factual/rational
How they found out.
- Left hemisphere injury more ipsilateral effects
- When solving exercises about a 3-dimensional figure
the right hemisphere is more active.
- Right lesion difficulty in emotional processing
- Dichotic melody test left ear is superior
Why lateralization evolutionary theories
o Analytic-synthetic theory of cerebral asymmetry
= left; analytic/logic/abstracting/computer-like & right;
synthetic/organizes/processes/whole picture information
No empirical evidence, vague
o Motor theory of cerebral asymmetry
The left hemisphere was specialized in fine motor movements later important for
language. Aphasia hand in hand with motor deficiency
No explanation for the lateralization
o Linguistic theory of cerebral asymmetry
The left hemisphere is purely linguistic. Only theory in which language is the primary
factor in lateralization
No empirical basis
Advantage of lateralization
- All neurons are concentrated + efficient
- Lateralization of connected functions (e.g., fine motor skills and language+efficient)
- 2 control areas can lead to competition (speech area in both hemispheres= stutter)
Handedness and lateralization
Right handed people have a 95% chance of having the speech center located in the left
hemisphere
Left handed people have a 75% chance of having a speech center in the LH.
