Cortex Flashcards
components of a neuron
- cell body (soma)
- dendrites
- axon
- synapse
examples of glial cells
- astrocytes
- oligodendrocytes
- Schwann cells
oligodendrocytes
*cells responsible for myelination of axons in the CNS
*ONE oligodendrocyte can myelinate MULTIPLE axons from different neurons
schwann cells
*cells responsible for myelination of axons in the PNS
*MULTIPLE schwann cells myelinate a single axon
terms used to describe CNS AXONS BUNDLED TOGETHER
-white matter
-column
-tract
-funiculus
-fasciculus
terms used to describe CNS CELL BODIES GROUPED TOGETHER
-gray matter
-NUCLEI
-cell column
-horn
7 major anatomical components of the CNS
- spinal cord
- medulla
- pons
- midbrain
- cerebellum
- diencephalon
- cerebral hemisphere
components of the diencephalon
- thalamus
- hypothalamus
gray matter
regions of the nervous system populated by large numbers of CELL BODIES (soma)
white matter
regions of the nervous system that have large numbers of AXONS bound together
organization of gray and white matter in the cerebrum (brain)
*gray matter (cell bodies) are on the OUTSIDE
*white matter (axons) are on the INSIDE
note - this is the OPPOSITE in the spinal cord
granular areas of the cortex of the brain
areas designed to process INCOMING INFORMATION
example = sensory areas (visual cortex, auditory cortex, somatosensory cortex)
agranular areas of the cortex of the brain
areas designed to SEND INFORMATION OUT (generally motor information)
example = primary motor cortex
how many layers of the neocortex are there
6 layers
2 types of neurons in the CNS
- projection neurons
- interneurons
neocortex - layer 1
*MOLECULAR layer
*the outer surface of the cortex
*predominantly fiber pathways
neocortex - layers 2 and 4
*GRANULAR layers
*sensory/input
neocortex - layers 3 and 5
*pyramidal layers
*predominantly OUTPUTS
neocortex - layer 6
*polymorphic layer
*mixture of input and output
lobes of the cortex
- frontal
- parietal
- occipital
- temporal
- limbic (not an anatomical lobe, more of a functional lobe)
prominent gyri of the brain
*precentral gyrus - motor (in the frontal lobe)
*postcentral gyrus - sensory (in the parietal lobe)
important sulci of the brain
*central
*calcarine
*lateral
*parietooccipital
*cingulate
internal capsule
serves as the fiber tract of axons that travel in and out of the cerebrum related to underlaying subcortical structures
homunculus organization of somatosensory and motor cortexes
MEDIAL TO LATERAL: feet > legs > torso > arms > hands > face > teeth > tongue
what does the magnification observed in the neural homunculus relate to
*relates to the DISTRIBUTION OF SENSORY RECEPTORS on your skin (feet, hands, and face are big because we have more sensory fibers there)
-think of the 2-point discrimination test
damage to upper motor neurons result in what form of deficit
HYPERreflexia (spasticity)
damage to lower motor neurons results in what type of deficit
HYPOreflexia (flaccidity)
limbic “edge” cortex
portions of the frontal, parietal, and temporal lobes forming the “border cortex” around the diencephalon and brainstem
functions of the limbic system
HOME:
H - homeostasis (hypothalamus)
O - olfaction (olfactory cortex)
M - memory (hippocampal formation)
E - emotion (amygdala)
limbic circuitry - “Papez ciruit”
SUBICULUM -> FORNIX -> MAMMILLARY BODY -> ANTERIOR THALAMIC NUCLEI -> INTERNAL CAPSULE -> CINGULATE -> PARAHIPPOCAMPAL GYRUS -> ENTORHINAL CORTEX & HIPPOCAMPUS
1. fibers arising from subiculum travel in the fornix to the mamillary body
2. the mammillary bodies project to the anterior thalamic nuclei
3. anterior thalamic nucleus projects to the cingulate gyrus via the internal capsule
4. the cingulate gyrus projects to the para-hippocampal gyrus and then anteriorly to the entorhinal cortex and hippocampus
5. entorhinal cortex has bidirectional access to association cortex
limbic system and olfaction
- receptors in the olfactory epithelium project through cribriform plate and synapse on a group of cells in the olfactory bulb
- project back and send inputs primarily to piriform cortex, periamygdaloid cortex, and amygdala
implicit (declarative) vs. explicit memory
*explicit memory is FACTS/EVENTS
*implicit memory is skills, habits, priming, reflexes, and simple classical conditioning
3 pathways of emotions
- emotional memory pathway
- endocrine / autocrine pathway
- olfaction pathways
emotional memory pathway - key structures
*orbitofrontal cortex
*nucleus accumbens
*temporal lobe
endocrine / autocrine pathway of emotion - key structures
*hypothalamus
*brainstem autonomic nuclei
*diffuse systems
olfaction pathway of emotion - key structures
*olfactory structures
*hypothalamus
*thalamus
2 major limbic circuits
- hippocampal circuit
- amygdala circuit
hippocampal circuit of the limbic system - role
*allows you to develop LONG-TERM memories (explicit memory and learning)
damage to the hippocampal circuit of the limbic system results in
ANTEROGRADE AMNESIA (inability to develop NEW memories)
hippocampal circuit of the limbic system - structures
- fornix
- anterior nucleus of the thalamus
- cingulate cortex
amygdala circuit of the limbic system - role
emotional significance of memory and learning
damage to the amygdala circuit of the limbic system results in
impaired ability to RECOGNIZE EMOTIONS
amygdala circuit of the limbic system - structures
- Stria Terminalis
- mediodorsal nucleus of the thalamus
- orbital and medial prefrontal cortex
3 higher order functions of cortex
- executive functions
- spatial processing
- language
region of the cortex responsible for executive functions
*PREFRONTAL CORTEX
-anterior to motor cortex, premotor cortex, and limbic areas
-shares interconnectivity with limbic cortex, amygdala, and hippocampal formations
-receives and sends projections to the mediodorsal nucleus of the thalamus
executive functions of the prefrontal cortex
- restraint - inhibition of inappropriate behaviors
- initiative - motivation to pursue positive or productive activities
- order - the capacity to correctly perform sequencing tasks and a variety of other cognitive operations
2 major pathways of the prefrontal cortex
- dorsolateral - working memory
- ventromedial - impulse control
dominant (usually left) hemisphere functions
- language
- skilled motor formulation
- arithmetic - sequential and analytical calculating skills
- musical ability - sequential and analytical skills in trained musicians
- sense of direction - following a set of written directions in sequence
nondominant (usually right) hemisphere functions
- prosody (emotion conveyed by tone of voice)
- visual-spatial analysis and spatial attention
- arithmetic - ability to correctly line up columns of numbers on the page
- musical ability - in untrained musicians and for complex musical pieces in trained musicians
- sense of direction - finding one’s way by overall sense of spatial direction
spatial processing is largely attributed to which hemisphere
NON-dominant hemisphere (usually the right hemisphere)
general pathway of language
- information arrives at primary auditory cortex on the superior bank of the sylvian fissure
- sounds comprehended as meaningful words are processed in WERNICKE’S AREA
- motor commands to produce sequences of sounds to PRODUCE WORDS or sentences is found in BROCA’S AREA
- heavily connected via the arcuate fasciculus
aphasia
defect in language processing caused by dysfunction of the dominant cerebral hemisphere
Wernicke’s aphasia
fluent but non-sensical
*fluent = YES
*comprehends = NO
*repeats = NO
Broca’s aphasia
*struggles to produce speech, but what they are saying makes sense
*fluent = NO
*comprehends = YES
*repeats = NO
