cerebral cortex and higher cog function Flashcards
highest cortical neuron density
human cerebral cortex
most of the human cortex is composed of… how many layers does it have?
neocortex- 6 layers
What does the paleo cortex compose of?
4 or 5 layers; subiculum (tightly aorund hippocampus)
What is the archicortex?
3 layers; hippocampus
What are the 6 layers of the human neocortex?
I- Molecular layer: Input from brainstem- alertness
II- External granular layer: Intracortical association pathways
III- Small pyramidal cell layer: To opposite cortex (via corpus callosum)
IV- Internal granular layer: Input from sensory systems
V- Large pyramidal cell layer: Output to motor systems (basal ganglia, brainstem, and spinal cord)
VI- Fusiform layer: Output to thalamus
3 main functionos of the frontal lobe
- thought, personality, conscience
- planning complex voluntary movements
- execution of complex volunary movement
functions of parietal lobe
primary and secondary somatosensory processing for awareness of body position
functions of temporal lobe
memory and auditory processing
functions of limbic lobe
behavior, emotion, memory, regulation of hypothalamus, olfaction
functions of occipital lobe
visual signal processing and visual memory storage
thalamocortical system
key to higher corticl function
What do lesions to the tlaamocortical system cause?
decrease function of associated cortex
function of thalamus and location
key central relay
looks like a loaf of bread in the middle of the brain
sensory pathways of the thalamus ____ and the motor pathways ___ through the thalamus.
ascend
descend
What are the 2 key thalamic motor circuits and what do they do?
putamen circuit- premotor and supplemental motor cortex project to putamen and then back to motor cortex (for EXECUTION of voluntary movement)
caudate circuit- movements occur as a result of a sequence of thoughts, cuadate receives prefrontal cortical input (association areas) which allows cognitive control of motor activity
What would a lesions to the dorsal media do?
changes in personality, thoughts, drive, and conscience
what does the primary motor area do?
signals to voluntary muscle to control discrete muscle movement
what does the supplementary and secondary premotor area do?
complex ‘patterns’ of motor activity
what does the primary sensory area do?
detect specific sensations (visual, auditroy, somatic)
what does the secondary sensory area do?
analyze ‘meaning’ of sensory input
- shape, size, texture
- color, light, intensity, motion
- tone, pitch, frequency of sound
association areas simulataneously recevies and analyzes signals from many motor and sensory cortical areas. What does the parieto-occipitotemporal portion control?
nexus of somatic, visual, and auditory areas; maps body position and spatial awareness
association areas simulataneously recevies and analyzes signals from many motor and sensory cortical areas. What does the prefrontal control?
planning complex movements and highest order thought
association areas simulataneously recevies and analyzes signals from many motor and sensory cortical areas. What does the limbic do?
involved in behavior, emotions and motivation
What effect would a frontal lobotmy have on a person?
apathy and disjointed thoguhts; decreased spontaneity, decreased self awareness, and decreased self control
lethargy, emotional blunting, and deminished intellect
what hemisphere contains Broca’s and Wernicke’s?
dominant hemisphere (LEFT)
What is Broca’s responsible for?
the form words, language
What is Wernicke’s for?
language comprehension
What connect thte two hemispheres for the brain?
corpus callosum
lesions of Wernicke’s
no control of right motor cortex
What is neglect syndrome?
left sided visual/spatila input fails to reach Wernicke’s area
What is the anterior commissure?
storage and access to emotional memory (amygdala and related structures)
Mechanism of ‘tjhinking’ and elaboraiton is unknown but what is a possible explanation?
result of specific pattern of neuronal activity simultaneously in many cortical areas
What 2 things does speech involve?
- formation in the min of thought to be expressed and the choice of words - Wernicke’s
- motor control of vocalization and the act of vocalization- Broca’s
Where is speech always conducted in the brain?
dominant cerebral hemisphere (L)
In Wernicke’s- what is the angular gyrus?
primary/secondary visual areas, word interpretation
What is the arcuate fasicuclus in the Wernicke’s?
output tract to Broca’s area
What is the arcuate fasciculus in Broca’s area?
pathway from Wernicke’s area
Aphasia
communcation disorders resulting from lesions in the dominant hemisphere
Broca’s aphasia
inability to articulate speech
- ‘motor’ aphasia
- comprehension often spared
Wernicke’s aphasia
inability to understand the written/spoken word
- ‘sensory’ aphasia
- very debilitating
What do non-dominant lesions cause?
loss of music appreciation, aprosodia (loss of meaning of intonation and inflection), inability to interpret ‘body language’, loss of spatial awareness
How was the auditory pathway clinically tested?
by repetition “repeat after me”
Auditory pathway
- Primary auditory and interpretive areas- Recognize the sound as a word
- Interpret the word and thoughts the word expresses in Wernicke area
- Form thoughts and words that convey meaningful response
- Arcuate fasciculus transmits word/thought to Broca’s area
- Broca’s area- Motor commands produced to form words
- Motor command projected to centers that control speech muscles
visual pathway
- Visual input received in primary visual area
- Visual information processed in angular gyrus of the parietal-temporal-occipital association cortex
- Visual input fully interpreted and word/thoughts formed in Wernicke’s area
- Arcuate fasciculus transmits word/thought to Broca’s area
- Broca’s area- Motor commands produced to form words
- Motor command projected to centers that control speech muscles
what are two types of imaging that show communication areas in the brain?
fMRI & PET
What is global aphasia?
complete loss of ability to comprehend language and commnicate is caused by severe lesions to Wernicke’s area that extend into the angular gyrus, temporal lobe, and superior parietal cortex
What does global aphasia often result from?
massive cerebrovascular accidents (CVA) involving the middle cerebral artery
