The association cortices and complex brain functions

Question 1

Who first suggested hierarchical organisation of the cortex

Answer 1

• Dr John Hughlings Jackson

Question 2

What is the association cortex?

Answer 2

• Higher order integration

Question 3

Hierarchical organisation of sensory systems

Answer 3

Receptors -> Thalamic relay nuclei -> Primary sensory cortex -> Secondary sensory cortex -> Association cortex

Question 4

Types of association areas

Answer 4

• Unimodal association areas(single modality)

- Multimodal association areas(>1 modality)

Question 5

Initial stage of processing in the association cortex

Answer 5

• primary sensory area

Question 6

Final stage of processing in the association cortex

Answer 6

• primary motor area

Question 7

Three main multimodal association areas

Answer 7

1. Posterior association area (perception, language)
2. Temporal association area (emotion, memory)
3. Prefrontal association area (executive functions - planning/goal setting)

Question 8

Where does evidence for the presence of primary, secondary and tertiary sensory and motor cortices come from

Answer 8

• Evidence comes from observing humans with selective injuries to the cortex resulting from trauma, tumour, stroke, or surgery for underlying neurological disorder, experimental studies with monkeys, and imaging techniques for localising brain function during cognitive tasks

Question 9

What are agnosias

Answer 9

• Disorders of high-level sensory analysis

Question 10

What are apraxias

Answer 10

• Disorders of high-level motor co-ordination

Question 11

What are aphasias

Answer 11

• Disorders in communicating and using symbols

Question 12

Prosopagnosia

Answer 12

• neurological disorder characterized by the inability to recognize faces

Question 13

Visual agnosia

Answer 13

• a condition in which a person can see but cannot recognize or interpret visual information, due to a disorder in the parietal lobes

Question 14

Anosognosia

Answer 14

• is a deficit of self-awareness, a condition in which a person with some disability seems unaware of its existence.

Question 15

What can disruption of the prefrontal association area result in

Answer 15

• Personality changes
• Impairment of long term planning and judgement
• Impairment of working memory

Question 16

Where does information converge to in modal areas

Answer 16

• Info converges from unimodal to multimodal areas

Question 17

What do connections between cortical areas represent

Answer 17

• Stages of information processing

- At each stage, progressively more abstract information is extracted from the sensory stimulus

Question 18

What is apperceptive agnosia

Answer 18

• Features are not perceived

Question 19

What is associative agnosia

Answer 19

• Features are perceived but they do not make sense

Question 20

In which system is the sequence of information processing reversed

Answer 20

• Motor system

Question 21

Effect of frontal cortex firing

Answer 21

• Individual neurons fire for a range of related behaviours(not specific motor responses)
• Movements and complex actions result from patterns of firing of large networks of neurons in the frontal lobe

Question 22

What does the premotor cortex generate

Answer 22

• Generates motor programs and the neurons are active during preparation of movement

Question 23

Effect of motor cortex firing

Answer 23

• Neurons mainly fire to produce movements in particular directions around specific joints

Question 24

Language process

Answer 24

• Language comes into brain through visual and auditory systems
• Motor system produces speech, writing
• Processing between sensory and motor systems; essence of language

Question 25

What is aphasia

Answer 25

• Partial or complete loss of language abilities following brain damage, often without the loss of cognitive faculties or the ability to move the muscles used in speech

Question 26

What is the wada procedure

Answer 26

• Barbiturate is injected into one hemisphere through the left or right internal carotid artery
• If the right carotid is injected, the right side of the brain is inhibited and cannot communicate with the left side.
• The effect shuts down any language and or memory function in that hemisphere in order to evaluate the other hemisphere (“half of the brain”).
• An EEG recording at the same time confirms that the injected side of the brain is inactive as a neurologist performs a neurological examination.
• The neurologist engages the patient in a series of language and memory related tests

Question 27

What is broca’s motor non-fluent aphasia

Answer 27

Individuals with Broca’s aphasia have trouble speaking fluently but their comprehension can be relatively preserved. This type of aphasia is also known as non-fluent or expressive aphasia

Question 28

What is wernicke’s aphasia

Answer 28

• Wernicke’s aphasia, also known as receptive aphasia, sensory aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language
• Patients with Wernicke’s aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities, and effortless speech output

Question 29

Method for split brain studies

Answer 29

• To reach the corpus callosum, a portion of the skull is removed and the cerebral hemispheres are retracted
• The hemispheres may retain some communication via the brain stem or smaller commissures, but most of the communication between the cerebral hemispheres is lost
• The two hemispheres can initiate conflicting behaviours eg alien hand syndrome