Lecture 01 - Cerebral Cortex Flashcards Preview

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Flashcards in Lecture 01 - Cerebral Cortex Deck (16):
1

Cerebral Cortex Features

4 lobes:
-frontal, parietal, occipital, temporal
gyri - "ridges" winding around brain
sulci - small grooves that divide the gyri (increase SA)
fissures - deep grooves dividing large regions/lobes
-longitudinal (divide two cerebral hemispheres)
-transverse (separates cerebrum from cerebellum)
-sylvian/lateral (divides temporal from frontal and parietal, deep is the insula)

2

Cerebral gray matter

90% 6 layered neocortex, but layers differ between areas
-pyramidals and stellates are excitatory (glutamate)
-interneurons are inhibitory or use GABA
-there are some more primitive areas not 6 layered
3 layers (paleocortex - olfaction)
4 layers (archicortex - hippocampus)

Brodmann's areas:
17 - primary visual cortex
3,1,2 - primary somatosensory
41,42 - primary auditory

3

various ways to figure out cortical function

1. lesion --> what is the deficit? (dangerous, can affect many different functions)
2. stimulate --> what is the action? (can stimulate multiple locations)
3. Record, what is the activity
4. fMRI --> what/where is activity (increased blood supply)?

4

4 main types of functional regions

1. primary sensory
2. primary motor
3. associate areas
4. limbic (emotional) areas

***many higher order processes no confined to single cortical area (distributed network)

5

Primary sensory cortex

Inputs:
1. visual (occipital)
2. auditory (temporal)
3. vestibular (temporal region deep to auditory and insula)
4. somatosensory (parietal)
5. gustatory (taste - deep to lateral fissure on insula)
6. olfaction (smell) some of this info gets to insula (flavor)
***all go to primary cortex via the primary thalamus (except olfactory - majority goes direct to cortex, piriform cortex )

6

Primary motor cortex

Inputs:
1. LMNs
2. UMNs
3. prefrontal
4. secondary motor
5. posterior parietal cortex
*** plan and execute movement
Layer 5 UMN output to activate LMNs

7

Association cortex

Process raw sensory signals into concepts that can be:
1. remembered
2. used to create new ideas
3. formulated into action via motor outputs

(allows you to attend to ext. stimuli and int. motivation, identify stimulus and its significance, make responses)

8

Unimodal sensory

Part of association cortex
-next to/surrounds primary area (2ndary sensory)
-still focused on that sense
-primary input from primary cortex --> lose primary, lose 2ndary responses (some inpute from thalamus)
-responds best to more complex stimuli

9

Unimodal motor

part of association cortex
Supplementary Motor Cortex (SMA)
-projects to brainstem/spinal cord and acts on LMS and primary motor cortex
-higher threshold and makes more complex motor patterns
-inputs from other cortical areas, including BG and cerebellum via the thalamus
-internally generated selected movement (I think I'll twerk!)

Lateral pre-motor cortex (PMC)
-all the same except receive innervation from posterior parietal cortex
-externally generated movements (reaching/grasping)

10

Multimodal

part of association cortex - the rest
"higher order" - highly developed in humans
-much of thalamic input is pre-processed info
-most inputs from other cortical areas also pre-processed
-subcortical inputs from modulators
***distributed networks for higher cortical function
-what we know derived from effects of lesions, but lots of variability

11

Axon pathways

locally - corticocortical
across to other lobe - via corpus callosum or commissural
down to lower structures - corticofugally

Sup. longitudinal fasciculus - connects cortex of 4 lobes
Inf. longitudinal fasciculus - connects temporal and occipital
uncinate fasciculus - deep to sylvian fissure to connect frontal lobe with rostral temporal lobe
cinglulum - runs with cingulate and parahippocampal gyri

12

Network function

massive inputs to and outputs from each cortical lobe
-many options for one part of cortex to talk to another part
-tons of connections between hemispheres too
-some functions predominate on one side of the brain
-lesion may affect cortical function but many other areas are involved in that function thru interconnections (lesion may cause a loss but is not necessarily where the function is located, due to connections)

13

Speech language pathway

starts in cochlea --> auditory nerve --> cochlear nucleus --> superior olive --> inferior colliculus --> medial geniculate --> primary auditory cortex --> secondary auditory cortical areas --> Wernickes --> Brocas
Also:
1. connections from 2ndary auditory cortical areas to ventral pathway (understanding) along lateral temporal
2. dorsal pathway to articulation centers in frontal cortex
***left side dominant

14

Two streams

Dorsal stream - "where/how"
Ventral stream - "what"
-ventral connected with medial temporal and limbic (long-term memory and emotion)
-influenced by extraretinal factors (attention, working memory, stimulus salience)
-ventral stream provides description but also plays role in judging significance
-disruption of connection between dorsal and ventral may lead to spatial neglect --> TPO junction lesion

15

spatial neglect

patient ignores things in contralateral space, including their own bodies
-primarily occurs with right hemisphere lesions
-right parietal love attending to both left and right hemispace, while left side only attends to right

16

Limbic

limbus = border
-parahippocampal, gyrus, cingulate gyrus, septal area
-all connected by fiver pathway (cingulum)