Cerebral cortex I Flashcards
What is another name for the Rolandic fissure?
Central sulcus
What’s another name for the Sylvian fissure?
Lateral sulcus
What brain area sits just superior to the corpus callosum?
Cingulate gyrus
What is the very general function of the cortex?
Analyzes, plans, initiates responses
What part of the brain adjusts the cortex’s level of responsiveness?
Reticular system
Name the 3 types of cortex.
- Neocortex
- Archicortex
- Paleocortex
How many layers is the neocortex?
6 (most of cortex)
(not as important) Where would you find the archicortex?
What about the paleocortex?
- Hippocampus
- Telencephalic base, olfactory
About how many neurons are in the brain?
What % in cortex?
- 86 billion
- 19%
What % of cells in the cortex are pyramidal vs. nonpyramidal
80% pyramidal, 20% nonpyramidal
Describe cortical pyramidal cells.
- Contain a long apical dendrite and a basal dendrite
- Axons will leave the cortex
- Have dendritic spines
What NT is the main one associated w/pyramidal cells?
Nonpyramidal cells?
- Glutamate (excitatory)
- GABA (inhibitory)
When are dendritic spines modified?
During learning/unlearning
Describe cortical nonpyramidal cells.
- Various shapes
- Axons don’t leave cortex
- Like “interneurons” of the cortex
Name the 2 areas found throughout the 6 layers of the cerebral cortex that we should be aware of (and describe the typical cell size found in each layer).
- Agranular area (large pyramidal cells)
- Granular area (small neurons)
What’s another name for the granular layer of the cortex?
Koniocortex
Afferent axons tend to come into (upper or lower?) cortical areas.
upper
Typically, would you find pyramidal and nonpyramidal cells in deeper or more superficial layers?
- Pyramidal cells: deeper
- Nonpyramidal cells: superficial
How are cells of the cortex arrange/grouped together (structure)?
In columns
What’s the function of the corpus callosum?
Projects from cortical area to mirror image (+ other areas). Tends to hookup L and R hemispheres
The genu of the corpus callosum connects the ____________.
Frontal lobes
The anterior body of the corpus callosum connects the ____________.
Frontal lobes
The posterior body of the corpus callosum connects the ____________.
Parietal lobes
The splenium of the corpus callosum connects the ____________.
Occipital and temporal lobes
What’s the function of the anterior commissure?
Interconnects temporal lobes and components of the olfactory system
What’s another name for association bundles?
Fasciculi
What are fasciculi?
- Corticocortical connections in the *same hemisphere
- None are discrete point-to-point
- Fibers travel in both directions, leaving and entering
(can be dissected out)
Define agnosia.
Inability to interpret sensations and hence to recognize things.
Define aphasia.
An impairment of language, affecting the production or comprehension of speech and the ability to read or write.
Define alexia.
Inability to see words or read.
Define agraphia.
Loss of ability to communicate through writing.
Define acalculia.
Loss of ability to perform simple math calculations.
What are neocortical areas?
Specialized cortical areas for specific functions (sensory, motor, association, limbic)
- Injury to area would give “specific” deficit
Primary neocortical areas can be described as “direct links to the world.” Describe their main inputs/outputs.
- Inputs: thalamic nuclei
- Outputs: brainstem and sc
Describe primary neocortical area body maps.
Precise but distorted
What primary neocortical area is Brodmann’s area #4?
In what part of the brain structure would you find it?
Primary motor area
- Precentral gyrus
What primary neocortical area is Brodmann’s area #3,1,2?
In what part of the brain structure would you find it?
Primary somatosensory area
- Postcentral gyrus
What primary neocortical area is Brodmann’s area #41?
In what part of the brain structure would you find it?
Primary auditory area
- Transverse temporal gyrus
What primary neocortical area is Brodmann’s area #17?
In what part of the brain structure would you find it?
Primary visual area
- Calcarine fissure
Describe what a unimodal association area is, compared to a neocortical area. Where are they spatially w/r/t neocortical areas?
- More complex response functions
- Same fcn but less precise
- Adjacent to primary cortical areas
Injury to a unimodal association area can cause _________.
Agnosia- inability to interpret sensations and hence to recognize things.
(E.g. see a comb but have no idea what it is until using other sensory modalities)
Name the 2 unimodal association areas associated w/primary motor area.
- Premotor area (larger groups of mm. in activity)
- supplementary motor area (postures and bilateral mm.)
Describe what a multimodal association area is, compared to a neocortical area.
- High level intellectual functions
- Send *converging inputs
- May respond to multiple stimuli
Injury to a multimodal association area may cause ________ or ________.
- Apraxia (motor; can’t perform certain physical tasks)
- Neglect (sensory; unaware of part of body)
Name the 3 main multimodal association areas.
- Parietal-occipital-temporal region
- Prefrontal area
- Limbic area
What are the basic functions of the prefrontal cortex?
Executive functions of the brain – Planning, insight, foresight and basic aspects of personality.
Where does the P-O-T region receive input from?
- Surrounding sensory areas
- Pulvinar nuc of thalamus
Injury to the right inferior parietal lobule of the P-O-T region can cause _____________. (contralateral or ipislateral?)
contralateral neglect
Injury to the left parietal area of the P-O-T region can cause __________.
an apraxia
What are the functions of the dorsolateral PFC?
Working memory, attention, and logical aspects of problem solving
What are the functions of the ventromedial PFC?
Extensive limbic connections; emotional aspects of planning and decisions
What is the basic function of the limbic areas?
Emotional and “drive” related behaviors
Name the gyri found in descending order, starting directly below the thalamus (while moving slightly posteriorly as well).
- Uncus
- Hippocampal gyrus
- Parahippocampal gyrus
- Fusiform gyrus
- Inferior temporal gyrus
Explain where on the cortex you’d find the limbic area.
- Ring all the way around the middle deep cortex (above the CC) that includes the cingulate gyrus
- Anterior portion of temporal lobe
Almost all cortical areas receive commissural fibers from the corpus callosum. What’s the main exception that we should be aware of, and what does it connect?
- Anterior commissure, connecting the temporal lobes
What type of injury typically leads to a disconnection syndrome?
What syndrome did we discuss in class?
White matter dmg at CC or ant. commissure
- Alexia w/o agraphia
What is the major symptom of alexia w/o agraphia?
- Can write but cannot read
What type of CVA could lead to alexia w/o agraphia? Explain…
- *L occipital CVA
Wernicke’s area and Broca’s area can still communicate w/each other (R side of brain), but contralateral visual input from CC can’t cross to other side, so cannot really read, although can still write and understand speech.
What would a man think about another man w/a wide face?
He must be competent as fuck
What # layer of the cortex is typically input? What about typically output?
4, 5
Define apraxia.
Inability to perform particular purposive action
