Lecture 13: Higher-Order Cerebral Function Flashcards
What is the neuroanatomical reason behind the presence of handedness?
- highly skilled complex motor tasks are programmed by dominant hemisphere
Where are language centers found in the brain?
predominantly on the left hemisphere
Do language centers vary at all between individuals?
- yes
- left hemisphere is dominant for language in over 95% of right-handers and 60-70% of left handers
- bi-lateral language representation in many left handers
Where is Broca’s Area located? What is its function?
- left lateral side of frontal lobe
- give ability to speak words - motor output
Where is Wernicke’s Area located? What is its function?
- left lateral temporal lobe right below Sylvian/lateral fissure
- speech comprehension, words making sense when speaking
How are Broca’s and Wernicke’s areas connected?
bi-directional arcuate fasciculus
What is the role of the Frontal Lobes during language processing?
- Higher-order motor aspects of speech formation, planning
- Syntax – arrange words/phrases into a language so that it makes sense
What is the role of the supramarginal gyrus and angular gyrus during language processing?
- parietal and temporal lobes
- lexicon (VOCAB)
- writing
What is the role of the visual cortex and visual association cortex during language processing?
reading - visual input goes to occipital lobe, then processed by visual association cortex, then connects with supramarginal gyrus and angular gyrus to help interpret what we are reading
What is the role of the non-dominant hemisphere during language processing?
- affective elements of speech
- can tell tone of voice (happy vs sad)
What is the role of the thalamus and basal ganglia during language processing?
thalamus - relay station for connections
basal ganglia - initiation and execution of movement for speech
What is aphasia?
- impairment of language production or reception or both
- due to physiological or cognitive disruption or both
What are common impairments associated with aphasia as a whole?
- trouble speaking clearly
- trouble understanding speech
- trouble writing clearly
- trouble understanding written words
- trouble remembering words
- trouble remembering object names
Describe characteristics of Broca’s Aphasia
- lose motor output of our speech - very effortful speech
- impaired language production
- aware of deficits
Describe characteristics of Wernicke’s Aphasia
- lose comprehension of speech
- can’t understand what you say to them and talk gibberish because they can’t form correct order of words they want to say
- unaware of deficits
Describe characteristics of Global Aphasia
have both Broca’s and Wernicke’s Aphasia
Define alexia
impairment in reading ability
How might alexia present when alongside Broca’s aphasia?
the patient will have difficulty reading out loud but they can read quietly to themselves
How might alexia present alongside Wernicke’s aphasia?
the patient will talk gibberish when reading out loud and can not understand what they are reading
Define agraphia
impairment in writing ability
How might agraphia present alongside Broca’s aphasia?
writing will be very labored, sparse, break down before finishing word they are trying to write
How might agraphia present alongside Wernicke’s aphasia?
the patient will write something totally off in left field
What is meant by the idea of perception? How does our brain perceive information?
- perceiving is the capacity to transform info from the senses and use it to interact appropriately to the environment
- perception is dictated by past experience, memory, problem solving, etc.
What is body scheme? How does it differ from body image?
- postural model of body
- How my body relates to itself and how my body relates to the rest of the environment and how its experiencing itself within the environment
- body image is just the visual and mental image of one’s body
What is neglect?
- Failure to orient toward, respond to, or report stimuli on the side contralateral to the lesion
- have normal sensory, motor, and visual systems
Damage to which cortical and subcortical regions are most commonly associated with the presence of neglect?
Non-dominant injury -right side of brain which controls left side of body
mostly occurs with right parietal lobe
What are the 2 classification systems for unilateral neglect?
Modality
- sensory
- motor
- representational
Distribution
- Personal
- Spatial
Auditory neglect
- Will not hear anything on one side
- must stand to other side for them to hear you
Visual neglect
- most common
- only see one half of what is in front of them
Tactile neglect
can’t feel one side of body
Motor neglect
unable to generate a movement response to a stimulus even though patient has the muscle strength
Representational neglect
- loss of internally generated images
- ex: At home but can close eyes and visualize classroom and only see one half of it
Personal neglect
Lack of exploration or awareness of contralateral side of body
Peri-personal neglect
neglecting things within arms reach on the one side. Can see outside of arms length
Extra-personal neglect
can see everything in arms reach but can’t see one side out of arms reach
Define asomatognosia. How does it differ from personal neglect?
- impairment of body scheme - lack of awareness of presence of and/or relationship of body parts
- differs from personal because they also lose ownership - will ague that their limb is not theirs
position-in-space disorder
Decreased ability to perceive and interpret spatial concepts
- up, down, in, out, over, under, etc.
Right/Left discrimination
Decreased R/L differentiation with body parts and with following directions
Topographical disorientation
Difficulty perceiving relationships from one location to another in the environment
- read a map
Figure Ground
Inability to distinguish a figure from the background in which it is embedded
- Where’s Waldo
Spatial Relations disorder
Inability to to perceive relationship of one object in space to another object, or to oneself
- obstacle course
Depth and distance perception
Inaccurate judgement of direction, distance and depth
Vertical disorientation/midline disorientation
Cannot identify when body is in the middle
- patient won’t be sitting straight up but they think they are
What are Agnosias?
Decreased ability to recognize stimuli despite intact sensory function
visual agnosias
- Inability to recognize familiar objects despite normal eye function
- ex: Prosopagnosia - can’t recognize familiar faces
Auditory agnosias
- Inability to recognize non-speech sounds or to discriminate between them
- ex: doorbell vs phone ring
Astereognosis
Inability to recognize objects when handling them, despite normal tactile sensations
Agraphesthesia
Inability to recognize symbols when they’re traced on the skin
What is anosognosia?
- Denial or lack of awareness of presence or severity of one’s deficits
- Patient thinks they are fine
What is apraxia? Where is the damage typically associated with this impairment?
- Impairment of voluntary, skilled, well-learned movement w/o deficits in motor, sensory, or coordination
- lesions to dominant (left) frontal or parietal lobes
What is ideomotor apraxia?
- Breakdown between concept (idea) and performance (motor execution)
- can tell every detail on what you need to do but can’t perform it
What is ideational apraxia?
- Failure in the conceptualization of the task
- can’t explain how to do task or do the task
What is the role of the prefrontal cortex best known for?
- executive function
- Planning, decision-making, problem-solving, self-control, and acting with long-term goals in mind
What are the specific regions of the prefrontal cortex?
- dorsolateral prefrontal cortex
- orbitofrontal prefrontal cortex
- ventromedial prefrontal cortex
What is basic function of dorsolateral prefrontal cortex?
Switching attention, working memory, maintaining abstract rules, and inhibiting inappropriate responses
What is basic function of orbitofrontal prefrontal cortex?
DECISION-MAKING
What is basic function of ventromedial prefrontal cortex?
Emotional processing, aids in decision-making, short-term memory (sec to min), self-perception, and social cognition
Where do we find connections to/from the prefrontal cortex?
EVERYWHERE
Cortical
- association cortices
- limbic cortex
Subcortical
- amygdala
- hippocampus
- thalamus (mediodorsal nucleus)
- basal ganglia
How does the frontal lobe contribute to restraint?
- judgement
- foresight
- delaying gratification
- concentration
- inhibiting socially inappropriate responses
How does the frontal lobe contribute to initiative?
- curiosity
- spontaneity
- motivation
- drive
- creativity
- personality
- mental flexibility
How does the frontal lobe contribute to order?
- working memory
- abstract reasoning
- planning
- organization
- sequencing
What are some common symptoms associated with frontal lobe damage?
- disinhibition (silly behavior, crass jokes)
- inappropriate jocularity (laughing at a funeral)
- limited insight
- frontal release signs (palmer reflex, grasp reflex, sucking reflex)
- respond to stimuli at hand, even when not appropriate
