Week 5: Brain Lateralisation Flashcards
What is hemispheric lateralisation?
Is a contralateral system meaning that the left brain controls the right side of the body and the right brain controls the left side of the body
Doesn’t apply to smell
Dominant side tends to be opposite side to handedness
What are the structural asymmetries between hemispheres?
RH = enlargement of the anterior portion, mostly smaller dendrites
LH = enlargement of planum temporal (Wernicke’s Area), parts of the thalamus are larger, mostly larger dendrites
What are the 3 parts of the corpus callosum?
Genu: prefrontal cortex
Body: pre-motor & primary motor cortex
Splenium: primary somatosensory cortex
What is the corpus callosum?
connects hemispheres for the transfer of information between them
What is the homotopic connection of the CC?
Structures present in the same locale in both hemispheres that have fibres connecting those corresponding areas
What is the heterotopic connection of the CC?
Structures with different locations in each hemisphere with fibres linking different areas of the 2 hemispheres
What do all primate callosal connections have in common?
start and finish at same layer of neocortex
What are the other commisures?
Anterior: Olfactory pathway, pain sensation, connects temporal regions
Habenular: pineal gland, epithalamus
Posterior: pupillary light reflex, pineal gland epithalamus
What conclusions were draw from the Myers & Sperry split-brain experiment?
Cat forebrain has ability to act as 2 separate forebrains
Function of CC is to carry info between hemispheres
Best way to study CC function is to limit info in single hemisphere
RELATIVE DOMINANCE
Vision?
LH = Words, Letters
RH = Faces, Geometric patterns, emotional expression
RELATIVE DOMINANCE
Audition?
LH = Language sounds
RH = non-language sounds, music
RELATIVE DOMINANCE
Touch?
LH = X
RH = tactile patterns, Braille
RELATIVE DOMINANCE
Movement?
LH = complex & ipsilateral movement
RH = movement in spatial patterns
RELATIVE DOMINANCE
Memory?
LH = verbal, finding meaning in memories
RH = non-verbal, perceptual aspects
RELATIVE DOMINANCE
Language?
LH = speech, reading, writing, arithmetic
RH = emotional content
RELATIVE DOMINANCE
Spatial ability?
LH = X
RH = Mental rotation of shapes, geometry, direction, distance
In split-brain testing, what happens when object is presented to Left hemisphere? (RVF)
touching with right hand or viewing in RVF
Could pick out correct object with right hand
Could name correct object
Could not pick out right object with left hand
In split-brain testing, what happens when object is presented to right hemisphere (LVF)?
touching with left hand or viewing in LVF
could pick out correct object with left hand
claimed nothing about being present
could not pick out right object with right hand
What is the RH specialised for?
Mental rotation, spatial matching, mirror-image task
Better able to draw/match 3D figure
Superior block design performance
Spatial Processing
What are the 4 language deficits?
Anomia - finding words
Dysarthria - controlling muscles use in speech
Apraxia - impairment of motor planning & programming of speech articulation
Aphasia - deficit in language comprehension or production (any disorder involving language)
What are the 2 language areas?
Broca’s Area - Speech
Wernicke’s Area - Understanding Language
Both are connected by arcuate fasciculus
What is Broca’s aphasia?
Speech problems; often non-fluent or agrammatic
What is Wernicke’s aphasia?
Speech comprehension problems; difficulty understanding speech
What is the left brain vs right brain myth?
Although some neural functions rely on one hemisphere more than the other for some functions, there is no evidence that people use one hemisphere more than the other
True or False:
Cerebral lateralisation and handedness is exclusive to humans.
False.
What are the 3 theories of hemispheric specialisation?
Motor theory
Linguistic theory
Analytic-Synthetic Theory
What is the motor theory?
Posits that left is specialised for fine motor movement
What is the linguistic theory?
Based on the idea that primary function of LH is language; slightly more popular than previous theory
What is the analytic-synthetic theory?
Suggests there are 2 fundamentally different mode of thinking; analytic on the left and synthetic on the right
LH = logical, sequential, analytic RH = immediate, overall synthetic judgements
Vagueness of the theory makes it difficult to test empirically
