ICL 2.4: Higher Cortical Functions Flashcards
what are the divisions of the primary cortex?
- motor cortex
- somatosensory cortex
- visual cortex
- auditory cortex
- gustatory cortex
- olfactory cortex
what is the concept of cerebral dominance?
some functions are not equally represented in both hemispheres!
for example, speech is localized to the left hemisphere, in about 95% of the population while the right hemisphere processes spatial concepts, non-speech sounds , tactile and visual relationships better than the left hemisphere
note: cerebral dominance is also related to handedness
what is the WADA test?
this is the test used to determine which functions are in each hemisphere of the brain!
so you inject anesthesia into one hemisphere and look to see which functions are lost –> for 95% of people, speech is in the left hemisphere but you want to make sure before you go in for a surgery
where are higher cortical functions carried out in the brain?
almost all of the higher cortical functions are carried out in association cortex
the greatest increase in brain area from animals to humans is in the association cortex! it’s what makes us human!
70% of neurons within the human central nervous system are in the cerebral cortex and 75% of those are in the association cortex!
what is the association cortex?
it’s the part of the cerebral cortex that does not carry out a primary motor or sensory function but instead interrelates the functions of the primary motor and sensory areas
what are the functional subdivisions of the cortex?
- primary cortex
- unimodal association cortex
- heteromodal association cortex
- supramodal association cortex
what is the function of the primary cortex?
it receives and transfers primarily external sensory and motor stimuli
what is the function of the unimodal association cortex?
an association area that primarily deals with information from one sense modality –> it has cortical-to-cortical connections dedicated to the same modality
unimodal association cortices are adjacent to the primary cortex serving the same modality such as motor, somatosensory, auditory, and visual
for example, the visual association cortex is a unimodal association area that is devoted to the integration of different types of visual information –> it discriminates and categorizes new stimuli, addition meaning and significance by comparing and contrasting them with prior stimuli that have been stored as memories within the association cortex being used
this is how you walk into a candy store and can visually look for the packaging of what you know/remember is your favorite chocolate!
another example is that the auditory cortex allow to to perceive the sound of a bird calling, but auditory association area would allow you to identify what the sound is, and perhaps to identify the bird call as that of a blue jay
what is the function of the heteromodal association cortex? (hint: it has 2 parts)
it’s an association area that manages information from multiple sense modalities; a heteromodal association area also may integrate information from motor areas
- posterior inferior parietal lobe = cross-modal associations and percepts
- prefrontal cortex = sequential associations, order, timing and planning
what is the function of the supramodal association cortex?
aka the orobitofrontal prefrontal cortex which receives and transfers internal sensory information – it’s not directly linked to sensory or motor functions –> it receives projections from the body’s interoceptive functions, including autonomic, visceral, and emotional processes
it influences cognitive processing by receiving, processing, and transferring info about intrinsic body functions to the heteromodal and unimodal association cortices of both hemispheres
it’s involved in emotional state, appetite, and drives, and integration of internal bodily states and sensations with the external world
it also determines which of the many inputs from other brain regions should be attended to at a specific time, and how these inputs are managed in reference to other inputs
what is the specific function of the posterior heteromodal association cortex?
the posterior heteromodal association cortex lies within the posterior inferior parietal lobe
it makes it possible to perceive an association between sensory systems, for example seeing a picture of a boat is associated with the printed word boat and the perception of the sound of the spoken word “boat”.
what is the specific function of the prefrontal heteromodal association complex? (hint: it has 2 functional subdivisions)
the prefrontal heteromodal association complex lies in the frontal lobe and it was one of the last brain structures to develop in the course of evolution –> in humans, it’s more than 1/4 of the entire cerebral cortex!
it controls the execution, order and timing of sequential acts toward a goal
- orbitomedial cortex is involved in sensory processing like taste and olfaction, control of drives, and emotional behavior
- dorsolateral cortex is essential for the planning and execution of complex behaviors, speech and logical reasoning
what is the function of the cortex?
in addition to controlling movement and sensation, the cortex mediates comprehension, cognition, and communication
higher cortical functions are monitored and produced via inputs from and exports to association cortex
what is praxis?
learned motor activity
the corticospinal motor system requires interaction with praxic programs to produce learned skilled movements –> this is largely influenced through cortical association areas of the brain
praxis allows us to:
1. correctly position the limb
- move the limb correctly in space
- orient the limb toward the target of action
- coordinate the timing of movement
- imitate motion
- solve a mechanical problem
- order components of an act
what is gnosis?
the ability of the brain to recognize previously learned information such as objects, persons, or places collected from our senses
sensory input from visual, auditory, and tactile and other sensory systems interact to allow perception of stimuli –> disorders of perception or recognition are referred to as agnosias
visual perception includes apperceptive and associative functions
what is apperceptive visual perception?
ability to see, describe and recognize an object
what is associative visual perception?
awareness of the significance, meaning or use of an object
what are the subcomponents of speech and language?
- fluency
- reading
- writing
- repeating
- comprehension
- expression
- naming
what are the major structures involved in language?
- Broca’s area
- Wernicke’s area
- angular gyrus
- arcuate fasciculus
what is the function of Broca’s area?
expression; producing language
it controls motor functions involved with speech production
it’s in charge of grammatical details and the correct order of words that makes the speech fluent
damage to this zone leads to disorders of speech in terms of fluency, difficulties in using prepositions, adverbs, and conjunctions –> patients can understand words but struggle to put them together in speech
what is the function of Wernicke’s area?
comprehension of speech
what is the function of the angular gyrus?
reading and writing
what is the function of the arcuate fasciculus?
it’s the fibers that connects Broca’s and Wernicke’s area
it’s responsible for repetition
what is the pathway that is taken in the brain in the production of speech?
this is the path taken by impulses when a person identifies a visual object:
information travels from the lateral geniculate nucleus in the thalamus to the primary visual cortex, to higher order visual critical areas, and to the angular gyrus
information then travels from Wernicke area to Broca area via the arcuate fasciculus
Broca area processes the information into a detailed and coordinated pattern for vocalization and then projects the pattern via a speech articulation area in the insula to the motor cortex, which initiates the appropriate movements of the lips, tongue, and larynx to produce speech
what are visuospatial skills?
the ability to identify visual and spatial relationships amongst objects
so if something is wrong with a patient’s visuospatial skills, they will frequently gets lost (environmental agnosia), cannot read maps (topographagnosia), recognize familiar faces (prosopagnosia), or has other visual problems related to processing
you can test this by asking the patient to draw a cube, draw a clock with the numbers on it or draw overlapping pentagons
what is cognition?
one of the 3 fundamental aspects of intellect
it’s manipulation of knowledge –> the ability to compare, use, and combine knowledge to produce new information
ex. “If you place 18 books on 2 shelves such that twice as many books are on one shelf as the other, how many books go on each shelf?”
ex. interpretation of idioms and sayings or describing differences/similarities
“What does it mean when it is said that people in glass houses shouldn’t throw stones?”
“How are an apple and an orange similar?”
what is intellect?
intellect comprises thinking, relating and judging
intellect is associated with cortical brain function (as opposed to subcortical)
what are the three fundamental aspects of intellect?
- fund of knowledge/memory
long-term storage of info through large networks of neurons in the association cortex
- cognition
ability to compare, use, and combine knowledge to produce new information. This also involves memory
- executive function/control
ability to control mental processing
what are some examples of executive functions?
one of the 3 fundamental aspects of intellect
- reasoning and abstraction
- planning and initiating of activity
- monitoring and shaping of behavior to ensure adaptive actions
- inhibiting maladaptive behavior
- prioritizing and sequencing actions
- attention
- problem solving
- coordinating motor and sensory functions into goal-directed behavior
sequences are related to what part of the brain?
dorsal lateral frontal lobe
inability to maintain sequences most often indicates dorsal lateral frontal lobe dysfunction
so if you ask someone to draw a line with alternating square and triangle within it and they can’t, this would indicate impaired frontal lobe function
what is executive control?
one of the 3 fundamental aspects of intellect that is responsible for monitoring and control of verbal and/or physical activities
- foresight
- planning
- ability to predict consequences of behavior
- attention
- mental adaptability
drive is related to what part of the brain? what is drive?
frontal lobe
drive is the motivation or ability to carry out activities
midline frontal dysfunction results in decreased motivation and apathy
what are the two types of long term memory?
- explicit
2. implicit
what is explicit memory?
a type of long term memory
it is associated with awareness and is dependent on the hippocampus and other parts of the medial temporal lobes
it allows one to retain knowledge - this is like your traditional memory of facts and stuff
what is implicit memory?
a type of long term memory that is important for training reflexive motor or perceptual skills
three subtypes:
1. priming = facilitation of the recognition of words or objects by prior exposure to them
- procedural memory = skills and habits, which, once acquired, become unconscious and automatic
- associative learning = classical and operant conditioning
what are the 3 types of memory?
- immediate/working: < 10 min.
- short-term: 1 hour
- long-term: Years
memory is the processing, storage and retrieval of information
what was the case of Henry Gustav Molaison?
the doctors removed this guys temporal lobes for a seizure procedure and he lost all of his short term memory but all of his long term memory was fine
removal of the hippocampus in the medial temporal lobes leads to marked memory deficits
long-term memory for events that occurred prior to surgery is maintained, but anterograde amnesia can ensue – short-term memory is intact, but one cannot commit new events to long-term memory or learn new motor tasks
the temporal lobe, in particular the hippocampus, is critical in the formation of long-term declarative memories and for the conversion of short-term to long-term memories
how do you test immediate recall and what part of the brain controls it?
probably mediated by auditory association cortex
you can test it with digit span like say a phone number and have them repeat it back 3 minutes later
immediate recall is severely affected with confusional states or delirium
what part of the brain controls short term memory?
deep temporal lobe
encoding of new memories probably localizes to the hippocampus
for example, asking patient to register and retain 5 words for 3-10 min. of distraction, then testing recall
what is long term potentiation?
long term potentiation is a process triggered by calcium accumulation in post-synaptic neurons after high frequency stimulation – it is believed to play an active role in LTM formation
long-term memories are stored in the association cortex
storage of complex multi-modality memories and long term memories are likely stored in the association cortex
once established, LTM can be recalled by many associations. For example, the memory of a vivid scene can be evoked by a sound or smell associated with the scene
how can you improve retrieval?
retrieval improves with prompting in subcortical disease states, but not for those with cortical problems (Alzheimer’s disease)
