Week 5 Lecture Flashcards
What in contralateral control?
The left side of the brain control the right side of your body and vice verse. This is the case for almost everything except smell.
If you are right handed, which side of your brain is more dominant (normally)?
Left brain
What noticeable role is the left brain dominant in controlling?
language
What do both sides of the brain communicate through
The corpus callosum
What is front/back labelled as (tummy/back)?
ventral and dorsal
What is the front of fact to the bottom of feet labelled as?
rostral/anterior to caudal/posterior
Top of brain to bottom in terms of labels?
dorsal ventral
Is rostral at the front or back?
front
Which side of the brain has an enlargement of the planum temporal (Wernicke’s area)?
left hand side
parts of the thalamus are larger on which side?
The left hand side
What is white matter?
axons, connections
What is grey matter?
where the cell bodies are located
describe the parts of the corpus callosum from front to back
- genu
- body
- splenium
Which types of the grain is the genu associated with?
the prefrontal cortex
What are 3 aspects of homotopic connections?
- structures present in the same place in both hemispheres
- fibres connecting corresponding areas of the two hemispheres
- functional homotopy: connectivity between brain areas
What does homotopic?
Starts at the same area and goes to the same area on the opposite hemisphere
What are 2 aspects of heterotopic connections?
- structures with different locations in both hemispheres
2. fibres linking different areas of the two hemispheres
In primates, all callosal connections start and finish at:
the same layer of the neocortex
In a normal corpus callosum, , how would one big light bar which are in both eyes, what will the firing neurons be doing?
firing in synchrony. In a severed corpus callosum, these firing neurons are non-synchronised
What information does the anterior commissure transmit?
- olfactory pathway
- pain sensation
- connects temporal regions
What information does the habenular commissure transmit?
-pineal gland
What information does the posterior commissure transmit?
- pupillary light reflect
- pineal gland
What was found in the severing of the corpus callosum in cats, cutting the optic chiasm and blindfolding one eye to restrict the visual information to one hemisphere?
The learning of the food task was only learned to one hemisphere. They only had to operate by chance.
What were the 3 main findings in the Myers and Sperry cat experiment, restricting information to one side?
- the cat forebrain can act as 2 separate forebrains, capable of independent learning
- the corpus callosum function is to carry information between hemispheres
- the best strategy for studying the corpus callosum is to limit information to a single hemisphere
Who is a human callosotomy/commissurotomy given to?
people with life threatening cases of epilepsy (few side effects)
What happens is the genu is spared in cutting the corpus collosum?
tranfer of higher order semantic info is spared
What happens is the splenium is spared in the cutting of corpus callosum? (back)
tactile but not visual identification is disrupted
What happens if the posterior portion (including splenium) is spared?
lesions disrupt transfer of visual, tactile, and auditory information
which side of the brain is better for emotion usually?
right side
In the video with the severed corpus callosum patient, when the word is presented to his right brain, what can he do?
draw it with his left hand with his eyes closed, however, he does not know why he drew it
If stimulus is given on the left side, and theres a partial corpus callosum (split at the back), what will the patient say?
they will say “i have a picture but can’t say it… two fighters in a ring, hemlets….knights?”
If a stimulus is shown on the left hand side and there is a complete corpus callosum split, what will the patient say?
I didn’t see anything (the speech centre didn’t see anything)
If there is a spoon presented on the left side and an apple on the right, what will the person say they saw with a complete corpus callosum split?
they will say apple because it is on their language side
If you ask the patient to pick up with their left hand the word you see (and there’s key on the left and ring of the right) and their corpus callosum is severed, what will happen?
They will say ring but pick up the key and not know why they did that.
What will happen if an object is presented to the left hemisphere, by touching and viewing in RIGHT visual field: (in severed corpus)
- could pick out object with right hand
- could name correct object
- could not pick out the right object with the left hand
Object presented to the right hemisphere (by touching with left hand or viewing in LEFT VISUAL FIELD):
- could pick out correct object with left hand
- claimed nothing had been presented
- could not pick right object with right hand
Can split brain patients simultaneously direct each of their hemispheres to separate visual fields?
no
Can split brain patients use either hemisphere to direct attention to positions in either left or right visual field?
yes
Which hemisphere is better at recognising self, and which hemisphere is superior to recognising familiar faces?
- left hemisphere
2. right hemisphere
in a letter priming task, which hemisphere is not as good at recognising compatible letters?
left
Which hemisphere is better for aspects of visuospatial processing tasks (eg mental rotation, drawing, block patterns)
right hemisphere
if the corpus callosum is severed and a picture is shown in their left visual field what will they say they see?
nothing. But, if you ask what goes on it, they will draw it. However, they still won’t be able to say it
If presented with pan and water in their left visual field and asked what happens when the words are related?
The left hemisphere hemisphere finds the task trivial, and the right cannot perform the task
What is the Wada test? (sodium amytal test)
administered prior to neurosurgery to determine which side is dominant for speech lateralisation.
How does the wada test work? (sodium amytal test)
anesthetises the ipsilateral hemisphere and allows the abilities of the contralateral hemisphere to be assessed. When injection is on the dominant speech side, the patient is totally mute for am minute or two.
What is the dichotic listening test?
information coming through one ear, told to pay attention to one side, determines which side is important by which side does better
If told to listen to melodies, which hemisphere does better?
The right hemisphere
What is the third way to do brain imaging to test lateralisation?
brain imaging (how much is lighting up)
What is the language system in the brain often called?
the left perisylvian language system (surrounding the Sylvian fissure)
Which area is more dominant for language comprehension?
wernickes area
Which area is responsible mostly for language production?
The Broca’s area
What does anomia mean?
difficulty finding words
What is dysarthia?
difficulty to control muscles used in speech
What is apraxia?
impairment of motor planning and programming of speech articulation
What is aphasia?
deficit in language comprehension or production
What is Broca’s aphasia?
started with the patient called Leborgne (called “tan”) could only say one word. after he died, they found huge damage in Broca’s area.
What are some speech problems which Broca’s aphasia is also known as?
- anterior
- non-fluent
- expressive
- agrammatic
What is Wernicke’s aphasia
speech comprehension problems. not just damage to Wernicke’s area, but also connections to it
Is there a left/right split between brain logic and creativity?
no
Is cerebral lateralisation exclusive to humans?
no, all animals
how long ago does evolution suggest lateralisation has been around for?
425 million years ago
does evolution suggest that handedness evolved in response to tool use?
no, it does not suggest that
birds and lateralisation:
- eyes are lateralised
- better at categorisation
- visual inputs almost completely lateralised
nonhuman primates and lateralisation?
- similarly lateralised anatomical asymmetries as humans
- left hemisphere dominant for gestural communication
- split brain monkeys show similar interactions to humans in tasks
What is the motor theory?
motor theory says that the left hemisphere is specialised for fine motor movement, of which speech is one eample
What are 2 lines of theories which support the motor theory?
- lesions disrupt facial movements even when not related to speech
- disruptions are positively correlated with the degree of aphasia
What is one problem with the motor theory?
it does not suggest why motor function became lateralised in the first place
What is the linguistic theory?
the primary function of the left hemisphere is language (deaf people sign language ability is lost with left hemisphere damage)
What is the analytic synthetic theory?
suggests there are two fundamentally different modes of think. analytic mode (left) and synthetic mode (right). According to this theory, the left hemisphere is more logical and the right makes more synthetic judgements overall
What is mostly used for narrow sharply focused thinking?
left hemisphere
Which side of the brain is predominant for broad thinking?
right hemisphere
