Higher Cortical Functions Flashcards
What does the thalamus do?
Thalamus acts as a gatekeeper for things going in and out of the cerebral cortex.
Thalamus also keeps the brain alive because information goes through it to get into the cerebral cortex.
What does the mapping effect of the thalamus refer to?
Cortical effects can be mapped onto areas in the thalamus
What are intracortical connections?
Connections within the cortex which is the primary way of the brain functioning.
How do interhemispheric connections communicate?
Via the corpus collosum
How is the brain organised physiologically?
In 6 laminae (6 layers):
I, II, and II are intracortical association fibers
IV is where incoming sensory fibers terminate
V, and VI is where output fibers leave the cortex (V goes to the brain and VI to the thalamus)
How do the output fibers in lamina V and VI act?
They are primarily stimulatory and produce mostly glutamate (an excitatory neurotransmitter)
What kind of cells are present in lamina V and VI and what neurotransmitter do they produce and what do they do?
Pyramidal cells (in V) and fusiform cells (in VI)
These output fibers are excitatory so they produce glutamate. Some cells produce GABA which is inhibitory but much more rare than glutamate
What kind of cells are present in lamina IV?
Incoming sensory fibers. They have short interneurons which produce either glutamate (exc.) or GABA (inh.)
How are fibers from I, II, and III lamina different to everywhere else?
They are more branched and interconnective whereas the rest are long and not very connected.
What are primary areas of the brain?
First recognition of external stimuli exist here. The rest of the brain makes sense of these areas.
What is the premotor area?
Secondary motor area which controls primary area.
Where is an image made in the brain?
In a secondary visual area. Primary visual area receives undeciphered visual stimuli
What can be said about the size of primary areas of the brain?
They are proportionally very small compared to the total size of the brain
What are primary cortical regions?
Point of first contact for Motor and Sensory systems in cortex.
Motor:
Origin of motor tracts which decussate at medulla and descend spinal cord to efferent motor neuron. They have a discrete connection with specific effectors.
Sensory:
Termination of sensory tracts from specific sensory organs. Visual, auditory, somatic
How are different regions of the cortex mapped to the function?
Where we have neurons for a specific location the more neurons we have for them in the brain in that particular region of the cortex. (Homunculi)
What do secondary cortical regions do?
They are regions of control which are located proximal to primary areas and they begin to make sense out of signals to/from the primary areas.
These areas provide complex patterns of motor activity in motor neurons. They interpret meaning. (Eg. Auditory siren = run, Visual lines continue to form shape recognition)
Do we get a full picture from secondary visual areas?
No, only the meaning of primary stimuli. It is the first level of integration of a signal.
What are association areas?
Areas in which complex activities take place and higher order functions are done. (Eg. Word formation, Behaviour, emotions, motivation, etc)
What area is responsible for word formationa and where is it located?
Broca’s area which is located in the center area directly posterior to the frontal lobe.
What area is responsible for behaviour, emotions, and motivation?
Limbic association area
Which area is responsible for language comprehension and intelligence?
Wernicke’s area
Where do higher order/accessory areas sit?
In between secondary areas
What is the prefrontal cortex responsible for?
Planning complex movements and elaboration of thoughts
What area is associated with spatial coordinates of body and surrounding?
An accessory area in the parietal lobe that receives input from visual, auditory, and vestibular location of the brain.
What do association cortices do?
Produce association between sensory inputs and motor behaviour.
Also has the ability to form memories.
What are the 3 major divisions of the association cortex?
Parieto-occipito-temporal AA (involved in polysensory integration and language)
Prefrontal AA (Executive functions, motor planning, attention, working memory)
Limbic AA (memory, emotion, motivation)
Where does the Parieto-occipito-temporal Association Area sit?
Sits in a triangle between hearing, somatosensation, and balance location which gives image of the world.
This area allows interpretation of language and gives interpretive meaning.
This area also gives spatial coordinates from visual and somatosensory input and continuous analysis of spatial orientation.
Produces initial processing of visual language.
Naming objects area coordinates names learnt
Language comprehension area (Wernicke’s area)
What does prefrontal association area do?
Controls behaviour, in front of primary motor cortex and secondary motor cortex.
What does the limbic association area do?
It is located right above limbic system and is responsible for emotional drive, memory, and motivation
What happens to movement planning and language processing if the parieto-occipito-temporal association area is damaged?
Failure to plan movements on opposite side of the body
Loss of names
Loss of ability to comprehend language
Which part of the parieto-occipito-temporal association area is responsible for language comprehension?
Angular gyrus area
What does the prefrontal association area do?
Calling forth information and using it to obtain a goal (motor and non-motor thinking)
Plan/consider consequences of actions performed
Concerted thinking ing a logical sequence
Working memory (analysing thoughts as they occur)
Elaboration of thought (Correlate divergent info, control one’s abilities and ensuring behaviour is culturally appropriate)
What happens if the prefrontal cortex is damaged?
Causes an inability to keep track of simultaneous bits of information, and creates easy distraction.
Loss of complex problem-solving, ability to perform sequential tasks, learn parallel tasks, morals/social appropriateness, and purpose.
What happens if the limbic association cortex is damaged or obstructed with a lesion?
Difficulties with abstract reasoning, judgement, and mood
Losing ability to integrate behaviour with mood
What parts of the brain does communication involve?
Sensory integration (audiovisual)
Formation of thoughts (choice of words)
Motor control of vocalization (vocalization)
Formation of word, thought and choice of words is function of Wernicke’s area (comprehension area).
Broca’s area controls the motor coordination required for speech.
What does Wernicke’s area do?
General interpretive area (integrates comprehensive interpretive function, integrates auditory/visual/somatic AAs, complex patterns involving many modalities)
Language-based intellectual functions (Integrates sense to form thoughts (word choice) and feeds directly to Broca’s area)
Everything feeds into Wernicke’s area where it is integrated and then action is achieved by Broca’s area.
How does Wernicke’s area feed into Broca’s area?
Directly through arcuate fasciculus
`What is the pathway for auditory communication?
Primary auditory area recognition of sound as a word.
Interpretation of the word and the the thought that the word expresses in Wernicke’s area.
Formation of the word that expresses a thought to respond.
Transmission via arcuate fasciculus to Broca’s area.
Activation of motor programs in Broca’s area for control of word formation. (here the complex patterns required to express the though are formed)
Transmission of signals to motor cortex to control speech muscles.
What is the pathway for visual communication?
Input from primary visual area
Processing visual information on parietal-temporal-occipital association cortex (angular gyrus region)
Wernicke’s area completely interprets visual input
Broca’s area creates motor formation of the word
Motor cortex creates the necessary movements for the words to be expressed.
What is hemispheric dominance?
1 hemisphere is larger than the other.
In some people Wernicke’s area can be as much as 50% larger in the dominant hemisphere.
Which hemisphere is commonly more dominant?
95% of population has a dominant left hemisphere.
What happens in non-dominant hemisphere of the brain?
Non-dominant side related to other forms of sensory intelligence (music, sensory feelings)
Where is language function localized in the brain?
Language function is lateralized as well as other functions of the brain
Is hemispheric dominance acquired or congenital?
In neonates Wernicke’s area can be as much as 50% larger in dominant hemisphere
What higher functions are lateralized to left side in most people?
Language (and signing)
Reading
Mathematical/analytical
Music (musicians) [For non-musicians its on the right!]
What higher functions are lateralized to right side in most people?
Body image
Complex spatial tasks
Non-verbal ideation (
Music (non-musicians)
