Session 8 L1: Cerebral Cortex Flashcards Preview

Nervous System And Neuropsychiatry > Session 8 L1: Cerebral Cortex > Flashcards

Flashcards in Session 8 L1: Cerebral Cortex Deck (28)
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1
Q

What is the fine structure of the cerebral cortex?

A
  • Arranged as 6 layers fo cell bodies and dendrites
  • Most outputs from the cortex are the axons of pyramidal neurones
  • Most inputs are from the thalamus and other cortical areas. An important population of inputs arise from the reticular formatting, maintaining cortical activation (consciousness)
  • Interneurons connect inputs and outputs in a complex way, giving rise to behaviour, emotion, memory etc.
  • Information is processed in the complex synaptic network found between input and output.
2
Q

What are the functions of Frontal Lobe?

A
  • Motor
  • Expression of Speech (Broca’s)
  • Behavioural Regulation/Judgement
  • Cognition
  • Eye movements
  • Continence
3
Q

How does damage to the Frontal Cortex affect Eye movements?

A
  • Contain frontal eye fields
  • Damage can cause problems with conjugate gaze and other eye movement disturbances (diplopia without other cortical features suggests more brainstem/cranial nerve problem)
4
Q

What are the functions of parietal lobes?

A
  • Sensory
  • Comprehension of speech (Wernicke’s)
  • Body image and awareness of external environment
  • Calculation and writing
  • Visual pathways projecting through white matter
5
Q

What can damage to the parietal lobe cause?

A
  • Neglect. Visual fields are normal however patients forget half the world exist most likely the left. Patients will eat half their meal for example on one side (left)
  • Can affect calculation ability
  • Visual field defects are superior optic radiations run. Damage can cause contralateral inferior homonymous quandrantopia
  • Receptive dypahsia
  • Contralateral anaesthesia
6
Q

What are the functions of Temporal Lobe?

A
  • Hearing
  • Olfaction (olfactory cortex)
  • Memory
  • Emotion
  • Visual pathways projecting through white matter
7
Q

What are the features of damage to Temporal Lobe?

A
  • Auditory hallucinations may be a feature of temporal lobe lesions
  • Olfactory hallucinations or other issues with smell
  • Hippocampus is crucial structure for consolidating declarative memories. Damage may lead to amnesia (but theres 2 hippocampus)
  • Some pathologies can leads to triggering of memories leading to de ja vu feeling
  • Can cause some psychiatric disorders
  • Damage can cause a contralateral superior homonymous quadrantanopia due to affecting the inferior optic radiation
8
Q

What is Cerebral dominance?

A

Some functions are represented more prominently in one hemisphere

  • In 95% of people, the left hemisphere is dominant for language and mathematical/logical functions
  • In 95% of people the right hemisphere is dominant for body image, visuospatial awareness, emotion and musical ability
9
Q

What is the function of the Corpus Callosum when it comes to cerebral dominance?

A
  • Corpus callosum allows the two hemispheres to communicate with one another, meaning we can be thought of as average of two hemispheres
  • Destruction of the corpus callosum can cause conditions such as alien hand syndrome and subtle effects on language processing
10
Q

What is Broca’s area and what can damage to the area lead to?

A
  • Found in inferior lateral frontal lobe involved in production of speech.
  • Sits near to mouth/pharynx area of primary motor cortex
  • Damage can cause staccato speech, where the patient still understands what’s being said to them so Expressive Aphasia
11
Q

What is Wernicke’s area and what can damage to the area lead to?

A
  • Found at the parieto-temporal junction
  • Sits near to primary auditory cortex in the temporal lobe
  • Responsible for the comprehension of speech
  • Damage can cause fluent nonsensical speech where the patient does not appear to understand what is being said to them (Receptive Dysphasia)
12
Q

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

A

-Connected by arcuate fascicles so damage to this white matter pathway cause cause inability to repeat heard words

13
Q

What is the effect of a Middle cerebral infarct on speech?

A

-Can cause a dense/global aphasia where both areas are destroyed leading to virtually no verbal language function

14
Q

What is the pathway for repeating a heard word?

A
  • Auditory cortex hears the word and transmit to Wernicke’s area
  • Wernicke’s area interprets the word and sends it to Broca’s area
  • Broca’s area transmits the impulses to the motor cortex to form muscular movements
  • This allows the words to be spoken
15
Q

What is the pathway for speaking a written word?

A
  • Visual cortex sees the word and transmits the impulses to Wernicke’s area
  • Wernicke’s area interprets the impulse and transmits the impulses to Broca’s area
  • Broca’s area transmits the impulses to the motor cortex
  • This allows the formation of sound from the mouth
16
Q

What is the pathway for speaking a thought?

A
  • Impulses form many parts of the brain are transmitted to Wernicke’s area
  • Impulses are transmitted from Wernicke’s area to Broca’s area
  • Broca’s area interprets these impulses and sends them to the motor cortex to allow the sound to be made by effecting muscle movements
17
Q

What are the 2 types of memory?

A

Declarative

Non-declarative memory

18
Q

What is declarative memory?

A

Explicit facts which tends to be stored in cerebral cortex

19
Q

What is non-declarative memory?

A

Implicit, motor skills and emotions and tends to be stored in subcortical structures (e.g. basal ganglia) and cerebellum

20
Q

What is short term memory?

A

-Stored for seconds to minutes as reverberation or echo in cortical circuits

21
Q

What is long term memory?

A

-Stored for very long period in the cerebral cortex, cerebellum etc. (up to a lifetime) following consolidation

22
Q

What is consolidation of memories?

A

-Converting short term memories into long term memories

23
Q

What is are the factors influencing consolidation of memory?

A
  • Emotional context
  • Rehearsal
  • Association
24
Q

Which part of the brain is involved in consolidating declarative memory?

A

Hippocampus

25
Q

Where is the hippocampus found?

A

-Sits deep in the temporal lobe in the medial edge

26
Q

What is the role of the hippocampus?

A

-Oscillator facilitating consolidation of memories in the cortex via its output pathways (primarily the fornix to mammillary bodies to thalamus to cortex)

27
Q

Where are the inputs to Hippocampus?

A

Has multimodal inputs from many brain systems

  • Visual
  • Auditory
  • Somatosensory
  • Limbic

Good at association stimuli

28
Q

Describe long term potentiation

A
  • Changes in glutamate receptors in synapses leading to synaptic strengthening
  • New physical connections can also form between neurones to further strengthen connections (axonal sprouting)