Neuro Lecture 4
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Neuro Lecture 4
The Cerebral Cortex and Hemispheric Specialization
What are some characteristics that are "uniquely human"?
Fractionated hand movement
What are the vertical axes of the cerebral cortex dedicated to?
Individual sensory modalities that are considered to be the functional unit of the cortex.
What are the 3 phylogenic categories based on horizontal organization?
What is Archicortex?
2 cell layers
What is Paleocortex?
3 cell layers
What is Neocortex?
6 cell layers
Most of frontal, parietal, temporal, and occipital cortex
The horizontal axis has 3 _____ and _____ layers
Input and Output
What are types of cerebral cortex areas?
What do specialized areas do?
Form the control centers for specific functional systems (primary projection regions)
What are association areas for?
Responsible for integrating input from specialized areas
What are the 3 types of white matter?
Describe Interhemispheric white matter
Connect functionally related areas from two hemispheres
Largest fiber bundle in the nervous system
: Corpus Callosum, Anterior and Posterior Commissures
Describe Intrahemispheric white matter
Project anterior-posteriorly connecting functionally relates areas within the same hemisphere
Describe Projection Fibers
Corticopetal (fibers from outside into the cerebral cortex)
Corticofugal (cortex to downstream targets)
What characteristics does the left hemisphere contain?
What characteristics does the right hemisphere contain?
What is Aphasia?
Disorder of language
What is Apraxia?
Difficulty performing learned skilled movements
What is Agnosia?
Inability to know (recognize) familiar objects/sounds
What are the primary clinical aspects of the cerebral cortex?
Psychiatric disorders (e.g. Schizophrenia)
Impairment in the execution of speech and often occurs without a disorder of language (lesion of craial nerves or other motor areas)
Speech and hearing are not a requisite for what?
Language development in left hemisphere
What are some other synonyms for Broca's aphasia?
Nonfluent, motor, productive, expressive or anterior aphasia
What functionally happens to cause Broca's aphasia?
Pattern for sounds and for the structure of language are not passed on to the motor cortex
How can Broca's aphasia present?
Speech is not fluent
Language production ranges from nearly complete muteness to slowed, deliberate speech
Use only key words
Generally aware of errors
Reading and writing (like speech) is abnormal
Almost always with Right hemiparesis and homonymous hemianopsia (due to anatomy)
What are some synonyms for Wernicke's aphasia?
Fluent, sensory, receptive, or posterior aphasia
What functionally happens to cause Wernicke's aphasia?
Words reacing the auditory cortex fail to activate Wernicke's area and are not comprehended.
How can Wernicke's Aphasia present?
Deficit in comprehension
Speech is fluent
Language is normal in rate, rhythm, and melody
May use wrong words
Add additional syllables to words or words with phrases
Neologisms (made up words)
Press of speech (excessive language)
Generally unaware of impairment
Inabillity to repeat words/phrases
Severe reading and writing disabilities
What joins Broca's and Wernicke's areas?
What is Global Aphasia?
Combination of both productive and receptive aphasia with a complete loss of the ability to comprehend spoken or written language, as well as express language verbally or orthographically
Describe signs of Conduction Aphasia
Damage to arcuate fasciculus
Fluent with many paraphasic errors
Comprehension is good
Impaired ability to repeat
Reading aloud impaired but silent reading is good
Inability to perform previously learned movements in the absence of weakness, sensory loss, or impairment of language comprehension
Name 3 types of apraxias:
Kintec (Motor) apraxia
Define Ideomotor Apraxia
Inability to perform complex motor tasks despite awareness of the intended task
Can perform many complex tasks automatically but cannot carryout the same tasks on command
Define Ideational Apraxia
Inability to carry out sequences of acts, althought individual movements can be made correctly
What causes Ideomotor apraxias?
Due to a lesion of the supramarginal gyrus in the dominant hemisphere
What causes Ideational apraxias?
Due to lesion of the parietal lobe in the dominant hemisphere or the corpus callosum
Define Kinetic (Motor) Apraxia
Inability to perform fine learned movements in the absence of weakness or sensory loss.
What causes Kinetic Apraxia?
Due to bilateral lesion (disease) of the frontal lobes
Process of knowing or comprehension involving comparison of current sensory data with past experience
Failure to recognize stimuli when appropriate sensory systems function properly
Name 3 types of agnosias
Define Visual Agnosia
Failure to recognize objects visually in the absence of impairment of visual acuity or cognition
What can cause visual agnosia?
Due to bilateral lesion of temporal aspect of visual unimodal association areas
What is Prosopagnosia?
Agnosia of familiar faces
Define Tactile Agnosia
Inability to recognize objects by touch when tactile and proprioceptive sensations remain intact
What can cause tactile agnosia?
Due to lesion of supramarginal gyrus
Define auditory agnosia
Failure to recognize specific sounds, including speech, music, and familiar noises with intact hearing
What can cause auditory agnosia?
Due tobilateral lesions of osterior part of the superior temporal gyrus
disruption of abillity to read (acquired and congenital, respectively)
Inability to write
What can cause Neglect Syndrome?
Usually caused by a lesion of the parietal lobe in the non-dominant (spatial) hemisphere (right)
Can be associated with hemianopsia
Define Seizure Disorders
Produced by the failure of surround inhibition leading to synchronized discharge of a group of cortical columns
Define petite mal
Produced by the synchronized discharge of a "small" number of cortical columns.
Define grand mal
Produceed by the synchronized discharge of both hemispheres
What are some of the anatomical changes in Schizophrenia?
Some patients exhibit enlarged lateral ventricles, enlarged third ventricles and widening of sulci