S8) Higher Cortical Function

Question 1

Information is processed in the complex synaptic network found between inputs and outputs.

Describe the fine structure of the cortex in terms of inputs and outputs

Answer 1

• Most inputs are from the thalamus and other cortical areas (reticular formation)
• Most outputs are from pyramidal cells and project to widespread areas
• interneurones connect the input and output

Question 2

Identify 6 functions of the frontal lobe

Answer 2

• Motor
• Expression of speech (usually left hemisphere) Brocas area
• Behavioural regulation / judgement
• Cognition
• Eye movements
• Continence (medial)

Question 3

How might one test the higher cognitive ability of the frontal lobe?

Answer 3

Ask a patient to count down in 7s from 100

Question 4

Identify 5 functions of the parietal lobe

Answer 4

• Sensory
• Comprehension of speech (usually left hemisphere) Wernickes area
• Body image → absent can cause neglect
• Awareness of external environment (attention)
• Calculation and writing

Question 5

What is hemispatial neglect?

Answer 5

• Hemispatial neglect is a neuropsychological condition occurring due to damage to one hemisphere of the brain
• There is a deficit in attention to/awareness of one side of the visual field and the patient is unable to process and perceive stimuli on one side of the body or environment

Question 6

Identify 4 functions of the temporal lobe

Answer 6

• Hearing
• Olfaction
• Memory
• Emotion

Question 7

In terms of cerebral dominance, state which form of processing is over-represented in the different cerebral hemispheres (in 95% of people)

Answer 7

• Left: sequential processing
• Right: ‘whole picture’ processing

Question 8

Sequential processing is dominant in the left hemisphere.

Which two functions does this include?

Answer 8

• Language
• Mathematics/logic

Question 9

Whole picture processing is dominant in the right hemisphere.

Which four functions does this include?

Answer 9

• Body image
• Visuospatial awareness
• Emotion
• Music

Question 10

Language pathways are primarily found in the left hemisphere.

In light of this, what is Broca’s area and what does it do?

Answer 10

Broca’s area (inferolateral frontal lobe) – production of speech

→ sits near primary motor cortex

Question 11

Language pathways are primarily found in the left hemisphere.

In light of this, what is Wernicke’s area and what does it do?

Answer 11

Wernicke’s area (superior temporal lobe) – interpretation of language

→ close to primary auditory complex

Question 12

How are Broca’s area and Wernicke’s area connected?

Answer 12

Broca’s area and Wernicke’s area are connected to each other via the arcuate fasciculus

area of white matter

Question 13

Describe the pathway for repeating a heard word

Answer 13

Cochlea → auditory cortex → Wernicke’s area → arcuate fasciculus → Broca’s area → motor cortex

Question 14

Describe the pathway for speaking a written word

Answer 14

Eyes → visual cortex → Wernicke’s area → arcuate fasciculus → Broca’s area → motor cortex

Question 15

Describe the pathway for speaking a thought

Answer 15

All over the brain → Wernicke’s → arcuate fasciculus → Broca’s area → motor cortex

Question 16

What is Wernicke’s aphasia (aka receptive aphasia)?

Answer 16

Wernicke’s aphasia is form of aphasia wherein the ability to grasp the meaning of spoken words and sentences is impaired, while the ease of producing connected speech is not very affected

‘fluent gibberish’

Question 17

What is Broca’s aphasia (aka expressive aphasia)?

Answer 17

- Broca’s aphasia is a form of aphasia wherein a patient has trouble speaking fluently but their comprehension can be relatively preserved

• Patients have difficulty producing grammatical sentences and their speech is limited mainly to short utterances of less than four words
• they can comprehend what is being said to them

Question 18

What types of memory are there?

Answer 18

• Declarative – explicit, facts
• Non declarative – implicit, motor skills and emotions

Question 19

Where in the brain is memory stored?

Answer 19

• Declarative – cerebral cortex
• Non declarative – cerebellum

Question 20

How are memories stored?

Answer 20

Short term memory (seconds to minutes) becomes long term memory (up to a lifetime) when it is consolidated, depending upon emotional context, rehearsal and (emotional) association

Question 21

Which part of the brain is responsible for memory consolidation?

Answer 21

The hippocampus is crucial for consolidating declarative memories

sits deep in the temporal lobe

→ oscillator (facilitates consolidation of memories in cortex via output pathways)

Question 22

how many layers is the cerebral cortex made up of

Answer 22

6

Question 23

what are the three output fibres that arise from the cortex

Answer 23

→ projection fibres going down brainstem cord

→ commissural between hemispheres

→ association connecting regions in the cortex together

Question 24

what does damage in the parietal lobe cause with vision

Answer 24

contralateral inferior homonymous quadrantanopia

Question 25

in some situations, the corpus callousum can be cut to prevent epileptic outburst spread to other hemisphere. What are some side effects of this?

Answer 25

→ alien hand: left and right hands do opposing actions

→ 2 hemispheres can give different answers

Question 26

what artery can cause damage to both Broca and wernickes area

Answer 26

→ infarction of large middle cerebral artery

→ can result in no verbal function

Question 27

where does explicit memory get stored

Answer 27

cerebral cortex

Question 28

where does implicit memory get stored

Answer 28

subcortical structures (basal ganglia)

cerebellum

Question 29

what is long term potentiation

Answer 29

→ key molecular mechanism of memory consolidation

→ causes changes in glutamate receptors strengthening synapses

→ new physical connections form between neurones