23A Cerebral Cortex

Question 1

Cerebral cortex develops as outpocketings of

Answer 1

Prosencephalon

Question 2

Up until 6 mos, the cerebral cortex is smooth or…

Answer 2

Lissencephalic

Question 3

By birth at nine months, the cerebral cortex is said to be Gyrencephalic or…

Answer 3

coverd with gyri and sulci

Question 4

Three types of cortex have been defined based on histology

Answer 4

1) Allocortex- 3 layers
2) Isocortex- 6 layered
3) Mesocortex- 3-5 layers

Question 5

Archicortex formed from which pallium

Answer 5

medial

Question 6

Paleocortex formed from which pallium

Answer 6

lateral

Question 7

Neocortex formed from which pallium?

Answer 7

Dorsal {Pallium

Question 8

How many cortical layers are there?

Answer 8

6

Question 9

Layer 1 is called

Answer 9

molecular layer

Question 10

Layers 2,3 called

Answer 10

superficual pyramidal layer

Question 11

Layer 4 called?

Answer 11

Granular layer

Question 12

Layer 5 called?

Answer 12

Deep pyramidal cell layer

Question 13

Layer 6 called

Answer 13

polymorphic layer

Question 14

Supragranular layer

Answer 14

layers 1-3, because 4 = granular,

This makes 5-6 subgranular

Question 15

Pyramidal vs non-pyramidal

Answer 15

pyramidal- pear shaped soma and a single dominant apical dendrite. Send axons deep to the white matter and are projection neurons. Project locally and to other areas. Excitatory. Glutamate as transmitter

non-pyramidal- mostly GABAergic neurone which are local only,,,only project into a local area of cortex. Typically multipolar or bipolar

Question 16

Spiny vs Aspiny

Answer 16

pyramidal = spiny

non-pyramidal- sparsely spiny

Question 17

What is a spiny stellate cell

Answer 17

found in layer 4 of primary sensory cortex. Mostly subtypes of pyramidal cells but only project locally. Called non-yramidal

Question 18

Main input to most cortical neurons is from

Answer 18

other cortical neurons

Question 19

What is the main extrinsic input to cortex?

Answer 19

Thalamus

Question 20

What are the two types of Thalamic input?

Answer 20

Specific- from thalamic nuclei that project into a single cortical area and concerns a single modality such as VL (motor cortex neuron), VPL (somatosensory cortex neuron)

Non-specific- comes from thalamic nuclei that integrate information from many sources. This input is important for general brain states and arousal.

Question 21

Specific thalamic nuclei generally project to what layer of the cortex?

Answer 21

Layer 4

Question 22

Non-specific thalamic afferents generally project to what cortical layer

Answer 22

Layer 1

Question 23

Pyramidal cells in what layers are the main source or cortico-cortical connections>

Answer 23

II and III… Association fibers and callosal projections….some also project to the striatum which surprisingly is still a part of the telencephalon

Question 24

Association Fibers?

Answer 24

Pyramidal cells which project ipsilaterally (local and long distance)

Question 25

Callosal projections

Answer 25

pyramidal cells which project contralaterally, via the corpus callosum

Question 26

Layer V pyramidal neurons are what

Answer 26

The main output neurons of the cortex

Question 27

Layer VI pyramidal neurons are what

Answer 27

They project primarily to the Thalamus

Question 28

The Thalamocortical feedback loop is the basis for several thalamocortical thythms observed in EEG....important in regulation of sleep-wake cycle, consciousness, and several pathologic conditions

Answer 28

ok

Question 29

Since most inputs to pyramidal cells come from other pyramidal cells, this system of mutual excitation wold lead to an unstable network if not for less numerous non-pyramidal inhibitory neurons. (80% pyramidal and excitatory, 20% non pyramidal)

Answer 29

ok

Question 30

A central belief regarding cortical function is that the cortex is composed of repeated modules called cortical columns.

Answer 30

ok

Question 31

Macrocolumn=

Answer 31

all of the cells allied together for a particular function. The idea is that a macrocolumn is the basic functional unit.

Question 32

The basic idea is that all of the pyramidal cell members of a developmental mini-column are ancestors of a single precursor cell in the ventricular zone of the embryonic cerebral vesicles

Answer 32

ok

Question 33

What is association cortex

Answer 33

Cortex that is not primary motor or sensory...all 6 layers very obvious...called homotypic

Question 34

Non-asssocaition areas where cortex layers are less obvious are called

Answer 34

heterotypic

Question 35

Which layer of cortex is virtually absent from Primary Motor cortex?

Answer 35

Granular layer...thus motor cortex is referred to as agranular

Question 36

Which layer is very large?

Answer 36

Layer V is very large in motor cortex because it has large pyramidal cells to project to spinal cord and subcortical motor centers

Question 37

Primary Sensory cortex

Answer 37

Large granular layer

Question 38

Primary Motor Cortex = what Brodmans areas

Answer 38

4

Question 39

Primary somatosensory cortex is brodmann's area number what?

Answer 39

3, 1, 2

Question 40

Primary visual cortex is brodman number

Answer 40

17

Question 41

Primary auditory complex brodmann area

Answer 41

41,42

Question 42

Brodmans area 6?

Answer 42

Premotor cortex- unimodal association area

Question 43

Brodman area 5,7

Answer 43

unimodal association areas for somatesthesias

Question 44

General layout of a somatosensory and motor homunculus?

Answer 44

Medial --> Lateral Lower limb, trunk, shoulder, arm, hand, neck, head, mouth, throat Basically, lower limb in the mid-sagital area and upper limb on the lateral surface of the pre- or post-central gyri. Can be used to localize strokes since the middle cerebral artery supplies the putside of the cortex while the anterior cerebral artery supplies the mid-sagital area

Question 45

Parietal association cortex is important for

Answer 45

attention to the physical world

Question 46

Temporal association complex is important for

Answer 46

naming things

Question 47

Prefrontal cortex acts as the overall executive for behavior

Answer 47

ok

Question 48

Occipital association cortex is concerned with?

Answer 48

Visual system

Question 49

If the parietal cortex is damaged in the dominant hemisphere (left side for right handers and usually left handers as well) what occurs?

Answer 49

Patients suffer from language disorders (aphasias)

Question 50

What occurs with non-dominant parietal damage?

Answer 50

sensory neglect...pts ignore sensory experiences on the half of the body contralateral to the injury. this the non-dominant parietal association cortex is necessary for attention to the internal and external environment

Question 51

Temporal association cortex important for

Answer 51

recognizing and naming objects

Question 52

Pre-frontal association cortex

Answer 52

Largest component of the cortex. Important for determining personality and our sense of self

Question 53

What are teh two components of the Pre-frontal cortex?

Answer 53

Dorsolateral- working memory and planning behaviors | orbitofrontal- aggression and emotions

Question 54

PFC allows us to choose between actions. Mnemonic RIO stands for what

Answer 54

Restraint Initiative Order