Cerebral Cortex II

Question 1

cells can be grouped by:

Answer 1

• morphology
• projections
• location
• electrophysiological properties (function)
• neurotransmitters produced
• protein markers they express

Question 2

layers of the cortex

Answer 2

I: Molecular layer
II: External granule layer
III: External pyramidal layer
IV: Internal granule layer
V:  Internal pyramidal layer
VI: Polymorphic layer

granular = small
pyramidal = large

Question 3

agranular cortex is dominated by _________ cells

Answer 3

agranular cortex is dominated by LARGE PYRAMIDAL cells

Question 4

granular cortex is dominated by ________ cells

Answer 4

granular cortex is dominated by SMALL cells

Question 5

cortex functions

Answer 5

• integrates all sensory modalities
• plans/executes all motor activity, speech, and volitional action
• enables abstract thought, emotion, creativity
• controls attention :: modulates its own activity and focus

Question 6

thalamic sensory and relay nuclei —> what cortical layer?

Answer 6

layer IV (internal granule)

Question 7

input from intrathalamic nuclei —> what cortical layer?

Answer 7

layer VI (polymorphic)

Question 8

intracortical input —> what cortical input?

Answer 8

layers II/III (external granule/pyramidal)

Question 9

cortical layers that receive input

Answer 9

II/III: external granule/pyramidal
--intracortical input
IV: internal granule
---thalamic sensory/relay nuclei
VI: polymorphic
---thalamic nuclei

Question 10

cortical layers that have outputs

Answer 10

III: external pyramidal layer
---other cortical areas
V: internal pyramidal layer
---striatum, brainstem, spinal cord
VI: polymorphic
---thalamus

Question 11

cortical layer III has output to __________

Answer 11

cortical layer III has output to OTHER CORTICAL AREAS

Question 12

cortical layer V has output to __________

Answer 12

cortical layer V has output to STRIATUM, BRAINSTEM, SPINAL CORD

Question 13

cortical layer VI has output to __________

Answer 13

cortical layer VI has output to THALAMUS

Question 14

association fibers

Answer 14

intracortical white matter tracts

-stay within same hemisphere

Main:

• superior longitudinal fasciculus
• cingulum
• amygdalofugal pathway

Question 15

commissural fibers

Answer 15

intracortical white matter tracts

-project from 1 hemisphere to the other

Main:

• corpus callosum
• anterior commissure

Question 16

corpus callosum

Answer 16

• type of commissural fiber
• massive intracortical white matter tract
• contains 200-250 million axons

Question 17

anterior commissure

Answer 17

• type of commissural fiber
• connects the temporal lobes
• 1/10 size of corpus callosum

Question 18

superior longitudinal fasciculus

Answer 18

• a main association fiber
• connects frontal with posterior
• contains ARCUATE fasciculus: connects brain regions involved in generation/comprehension of language

Question 19

arcuate fasciculus

Answer 19

• within the superior longitudinal fasciculus (association fibers)
• connects brain regions involved in generation/comprehension of language

Question 20

cingulum

Answer 20

• a main association fiber
• forms nearly a complete circle
• from cingulate to parahippocampal gyrus

Question 21

amydalofugal pathway

Answer 21

• a main association fiber

- connects amygdala with thalamus, hypothalamus, basal forebrain, brain stem, septal nuclei, nucleus accumbens

Question 22

cortical columns are ______

Answer 22

cortical columns are MICROCIRCUITS

-many connections with other neurons in same column (and within columns)

Question 23

cortical columns process sensory input _________

Answer 23

cortical columns process sensory input TOPOGRAPHICALLY

-area of visual field corresponds to region in cortex

Question 24

T/F there is a larger cortical region for peripheral vision than the center

Answer 24

FALSE: even though it is a smaller area of our visual field, the center takes up a larger area in the cortex

Question 25

direction-sensitive neurons

Answer 25

- type of functional organization - some neurons only become active when light moves across the visual field in a certain direction - due to the connections that each neuron makes with nearby neurons, and the excitatory/inhibitory nature of those connections -converge with other neurons to integrate info into more complex things (recognize familiar faces/scenes/threats) "columnar microcircuits work together to engender cellular behavior"

Question 26

fusiform gyrus

Answer 26

- activated during facial recognition | - higher order cortical center

Question 27

how do they map specific higher order regions?

Answer 27

- fMRI (functional MRI) - measures oxygen poor blood - --theoretically, the area that is active will be using oxygen

Question 28

prosopagnosia

Answer 28

- "face blindness" | - disruption of circuits in fusiform gyrus

Question 29

what happens if you stimulate the fusiform gyrus with an electric current?

Answer 29

- prosopagnosia (face blindness) | - "face metamorphosed"

Question 30

tools to identify cortical activity

Answer 30

- fMRI - single cell recording (rare) - EEG

Question 31

single cell recording

Answer 31

- very rare - depth electrodes placed in the cortex - allows for monitoring of firing rate of individual neurons in response to discrete stimuli

Question 32

EEG

Answer 32

electroencephalogram -records electrical activity thru skull/scalp - as neurons are activated, they create small electrical potentials which can be measured trans-cranially - detects a signal within a few millimeters