Association Cortices

Question 1

How does the cortex develop?

Answer 1

Inside-out cortical development

neurons migrate towards the cortical plate with the help of radial glial cells = radial glial migration

migration is achieved through the action of cytoskeletal microtubules resulting in the formation of 6 cortical layers of the cerebellum

Question 2

Brain Tissue Histology:
How many layers in the following:

• allocortex
• mesocortex
• neocortex

Answer 2

• 3/4 layers (olfactory system and
  hippocampus)
• 3 layers (paralimbic region connecting
  the limbic system to higher neocortical
  areas)
• 6 layers (90% of the brain)

***histology

Question 3

Brain Tissue Connections:
Role of the following layers:

• Layer IV
• Layers III & V

Answer 3

• Layer IV = input
• Layers III & V = output

(generally)

areas of the brain collecting sensory information would have a thicker layer IV as there would be more inputs

motor cortex would have thicker output layers

Question 4

Brodmann identified 52 separate areas of the brain based on

Answer 4

the histology and architecture of the brain in these different areas

Question 5

Nervous System Circuitry:

Answer 5

insert slide

Question 6

Anatomy of the Brain:

Answer 6

insert diagrams
insert slide

Question 7

What is the function of the primary cortex?

Answer 7

Deals with unprocessed information from the body/retina

Question 8

What is the function of the secondary association cortex?

Answer 8

integration of information of other parts of the brain

Question 9

Association Cortex Areas:

Answer 9

insert flowchart

Question 10

Parallel Processing in the Brain: Sensorimotor Integration:

Answer 10

• perceptual mechanisms generate a
  sensory representation of the external
  world and individual in it
• cognitive processes decide on course
  of action
• motor plan relayed to action systems
  to implement

Question 11

What is the dorsal stream in the cortex?

Answer 11

the dorsal stream from occipital to parietal cortex is concerned with:

• location
• motion
• action

(Where/How)

Question 12

What is the ventral stream in the cortex?

Answer 12

The ventral stream from occipital to temporal cortex is concerned with:

• object identity
• conscious perception

(What)

Question 13

Dorsal and Ventral Streams in the Cortex:

Answer 13

insert diagram

Question 14

Which Brodmann Area is assigned to the primary motor cortex?

Answer 14

Area 4

Question 15

Which Brodmann Area is assigned to the premotor/supplementary motor area?

Answer 15

Area 6

Question 16

Which Brodmann Area is assigned to the posterior parietal cortex?

Answer 16

Areas 5 & 7

Question 17

Temporo-parieto-occipital region:

Answer 17

integration of information where temporal, parietal and occipital lobes meet

higher cognitive areas in this area, where all information comes together

shorter connections, faster, less likely to have damage to information

Question 18

The Binding Problem:

Answer 18

• Lashley’s epipotential theory: every
  neuron in the CNS has the potential to
  perform every function -> not true
  because loss of some parts of brain
  function can not be recovered
• Grandmother cell hypothesis = only
  one cell in CNS for a function,
  grandmother cell will know everything
  to do with your grandmother, if it is
  damaged, you will lose the knowledge
  of your grandmother

Question 19

Cortical Plasticity:

Answer 19

• adult brain has a low incidence of
  regeneration
• some degree of plasticity in the
  somatosensory cortex located in the
  postcentral gyrus
• when fingers are amputated there are
  changes in that cortical area to reflect
  the missing digits now responding to
  stimulations from adjacent skin areas
• cortical plasticity diminishes with age

Question 20

How does fMRI work?

Answer 20

• brain has no energy stores and
  requires glucose
• glucose needs to be transported to the
  brain and causes arterioles to dilate
• signal characteristics of oxy and deoxy
  haemoglobin indirectly measures local
  neuronal activity based on this
  vascular response
• poor spatial and temporal resolution

Question 21

What is conduction aphasia?

Answer 21

lesion of the arcuate fasciculus
inability to repair but preserved comprehension and fluency

Question 22

Broca’s Area:

Answer 22

• frontal lobe
• posterior inferior frontal gyrus
• superior branch of left middle cerebral
  artery
• non-fluent (makes sense but cant find
  words) dysphasia (expressive
  dysphasia)

Question 23

Wernicke’s Area:

Answer 23

• temporal lobe
• posterior third of superior temporal
  gyrus
• inferior branch of left middle cerebral
  artery
• fluent (but nonsensical)
  dysphasia (receptive dysphasia)

Question 24

Which white matter tract links brocas and wernickes area?

Answer 24

Arcuate Fasciculus

important for repetition

Question 25

Language Areas:

Answer 25

insert diagram

Question 26

Alexia without agraphia:

Answer 26

• pure word blindness
• lesion of splenium (posterior corpus
  callosum)
• dominant occipital lobe lesion
• disconnection of visual cortex from
  Wernicke’s area
• inability to read = alexia
• name colours = colour anomia
• cant read, but can identify colours,
  objects etc

Question 27

What is the Wada test?

Answer 27

• establishes language and memory
  lateralisation in each hemisphere
• injection of barbiturate into one
  carotid artery, monitored with EEG
• if you infuse the dominant
  hemisphere, language ability is
  significantly impaired

Question 28

Gerstmanns Syndrome:

Answer 28

• dominant lobe parietal lobe damage
• supplied by middle cerebral artery
• finger agnosia
• left-right confusion
• dysgraphia
• dyscalculia

Question 29

Visual Neglect:

Answer 29

• non-dominant hemisphere
• failure to acknowledge or be aware of
  items on the contralesional side

Question 30

Aprosody:

Answer 30

• non-dominant hemisphere damage
• intonation of speech is altered

Question 31

Prosopagnosia:

Answer 31

• non dominant hemisphere (fusiform
  gyrus) damage
• facial blindness

Question 32

Gnosis

Answer 32

knowledge

Question 33

Anosognosia

Answer 33

lack of insight (unaware of deficit, not denial )

Question 34

Agnosia:

Answer 34

• unable to recognise and idenitfy
  objects, people or sounds using one or
  more of their senses despite othewise
  normally functioning senses
• apperceptive - failure in recognition
  due to perception deficits
• associative - failure in recognition
  despite no deficit in perception eg
  math colours but can not name or
  identify objects