Block 5: Cortical Functions, Cerebrum Flashcards
What does series processing refer to and how is it different than parallel processing?
- Series processing occurs when a stimulus activates a first order neuron which then activates a second order neuron which activates a third order neuron –> labelled line theory
- Parallel processing involves signal divergence where inputs from one receptor go to two or more second order neurons
Define divergence and convergence.
Divergence: signal input from one receptor cell goes to two or more second order neurons
Convergence: inputs from two cells synapse on one postsynaptic cell
Besides series and parallel processing, how else can sensory pathways be modulated?
Descending pathway information
How does a hyperpolarization in a photoreceptor cell become depolarization in a ganglion cell?
It all depends on the bipolar cell actions. Some bipolar cells do not change their response from a PR (off response). Other bipolar cells actually flip the signal to become an on response; this is typically done through amacrine cells providing an inhibition of a inhibition –> excitation!
What are the three visual cortex areas and what do they encode for?
- Ocular dominance columns: depth perception
- Orientation columns: edge –> motion
- “Blob” cells: color perception
What is strabismus and what does it result in infants under the age of 6 months old and young children?
- Strabismis = muscle imbalance that results in misalignment of visual axes within the two eyes
Under 6 months old, infants with strabismus develop diplopia (double vision).
In younger children, suppression of the weaker eye visual field occurs and results in amblyopia.
Define cortical achroma.
Cortical achroma = cannot see color and cannot identify things (ventral stream lesion)
Define ideomotor apraxia.
Ideomotor apraxia = cannot execute movements that are dependent on sight (dorsal stream lesion); loss of gestures (waving goodbye) and using tools
Define orofacial apraxia.
Inability to make specific facial movements
Define ideational apraxia.
Inability to perform sequential actions (socks before shoes; associated with frontal cortex too)
Define prosopangnosia.
Prosopagnosia = inability to recognize faces (caused by a bilateral lesion of inferior temporal cortex)
Define visual agnosia.
Visual agnosia = inability to recognize an object by sight (caused by damage to unimodal visual cortex)
Define astereognosia.
Astereognosia = inability to recognize an object by touch alone (caused by damage to unimodal somatosensory cortex)
Define associative visual agnosia.
Associative visual agnosia = can identify objects, but not name them (damage to posterior parietal cortex)
Define finger agnosia.
Finger agnosia = inability to identify their fingers (damage to angular gyrus of dominant parietal cortex)
What agnosias signify Gerstmann syndrome and where is the lesion located?
finger agnosia, acalculia, agraphia, and right-left confusion
- Lesion in lateral parietal lobe
What is the primary language pathway?
- Input from primary auditory and visual cortices
- Gerschwind’s territory (recognition, labelling items)
- Wernicke’s area (language comprehension)
- Arcuate fasiculus
- Broca’s area (language generation)
- Primary motor cortex (stimulate voluntary muscles that control speech - CN IX, X, XII)
What are the stages of speech production?
- Airstream from lungs (diaphragm - phrenic nerve)
- Vibration of vocal cords
- Filtering vocal tract - formation of vowels
- Produce speech sounds (consonants)
Define receptive aphasia and where in the language pathway there is a deficit.
Receptive aphasia = patient is unable to comprehend written and spoken language
Deficit in Wernicke’s area
Define conductive aphasia and where in the language pathway there is a deficit.
Conductive aphasia = good comprehension and able to produce speech with lots of pauses and gaps; commonly detected as a problem in comprehension though
Deficit in arcuate fasiculus
Define expressive aphasia and where in the language pathway there is a deficit.
Expressive aphasia = patient has a difficult time generating speech, no problems with comprehension; have impaired verbal and oral expression and an inability to organize speech
Deficit in Broca’s area
Define global aphasia and where in the language pathway there is a deficit.
Global aphasia = patients have problems generating and comprehending speech; does not have a distinct pattern, impacts entire pathway
What speech deficits would be expected in a patient that has a lesion in Gerschwind’s area?
Inability to come up with words; on the tip of their tongue
What is spatial neglect and what cerebral hemisphere does it affect and its specific location?
Spatial neglect = failure to acknowledge half of the world
Occurs in the non-dominant cerebral hemisphere; posterior parietal cortex
Occurs in ~50% of right-hemisphere strokes
Results as a lack of attention paid to half of the visual field: right hemi –> left visual field; left hemi –> both right and left visual fields
