Cerebral Cortex revision and pathology Flashcards

1
Q

What are the key cortical lobes?

A

Frontal lobe
Temporal lobe
Parietal Lobe
Occipital lobe
Insula

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2
Q

What is the key anatomy of the visual centre?

A

Visual cortices are located in the occipital lobe around the calcarine sulcus which seperates the superior and inferior portions.
The dorsal visual association pathway - goes into the parietal lobe - spatial awareness aka movement and positional information
The ventral visual association pathway goes into the temporal love - object recognitions particularly in complex visual scenes.

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3
Q

What is the primary somatosensory cortex (S1)?

A

Post central gyrus
Topographic map of the body
General sensation from outside world - touch, pain, itch, temp and proprioception

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4
Q

What is the function of the primary motor cortex (M1)?

A

Precentral gyrus
Topographic map
Motor commands originate - corticospinal and corticobulbar tracts.

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5
Q

What is the significant of the premotor cortices?

A

Found in BA6
Control the intenetion of motor activity
Supplementary motor area - internally generated movements - programs complex sequences and aids coordination
Premotor - concerned with responses to external changes - coordination and planning

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6
Q

What is the frontal eye field?

A

BA8
An important premotor cortices
In the prefrontal cortex
Directs eye movement/gaze - choosing where to look

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7
Q

What is Brocas area?

A

BA44 BA45
Predominantly in the left hemisphere.
Associated with language and speech production - choose what to say.
Located in the inferior frontal gyrus

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8
Q

What are the key olfactory regions in the brain?

A

The olfactory bulb, tract, tubercle, pyriform cortex, amygdala and entorhinal cortex
Very evocative in terms of emotion and can influence decision making
Primary olfactory cortex = inferior region of the temporal lobe

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9
Q

What is the limbic lobe?

A

A functional lobe found on the medial surface of the brain - spans the cingulate gyrus, parahippocampal gyrus, uncus.
Also the amygdala, ventral striatum and ventral pallidum.
Plays a role in emotional regulation, addiction and motivation.

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10
Q

What brain regions tend to be affected in major depressive disorder?

A

White matter pathways
Subcallosal cingulate (part of the limbic system) deep brain stimulation treatment - aims to decrease activity in the SCC and increase in surrounding areas experimental for treatment of MDD

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11
Q

What are the typical clinical manifestations of supranuclear palsy?

A

Unsteady gait - esp, going downstairs - worse by vertical gaze palsy
Loss of vertical eye movements
Significant swallowing and speech difficult
Modified hyperextended posture

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12
Q

What are the typical radiological signs of Progressive Supranuclear palsy?

A
  1. Hot cross bun sign - shows selective degeneration of transverse pontocerebellar tracts and median pontine raphe nuclei
  2. Hyperintensity in the lateral border of the putamen -
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13
Q

What brain region tends to be affected in Progressive Supranuclear Palsy?

A

White matter tracts along the dentatorubrothalamic white matter tract.
From the dentate nucleus of the cerebellum, through the superior cerebellar peduncles to the midbrain and then the thalamus.
Potential mild involvement of the frontal lobs.

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14
Q

What disease does this affected brain region collate with?

A

Progressive supranuclear palsy

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15
Q

What pathology does this affected brain region collate to?

A

Corticobasal syndrome
A subgroup of frontotemporal dementia

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16
Q

What pathology does this affected brain region collate to?

A

FTD-ALS
Frontotemporal dementia - amyotrophic lateral sclerosis.

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17
Q

What pathology aligns with these brain region abnormalities?
Prefrontal cortex, insula and anterior temporal lobes, bilaterally

A

Behavioural Variant frontotemporal dementia

18
Q

What pathology aligns with these brain region abnormalities?
Left anteromedial temporal lobe

A

Semantic variant FTD

19
Q

What abnormality aligns with these brain region abnormalities?
Brocas area, left hemisphere

A

Non-fluent/agrammatical variant primary progressive aphasia FTD

20
Q

What are Broadman area based on?

A

Histolgy - may correlate with function
New research using AI identification suggest even more functional areas than 55 BA.

21
Q

What is the basic pattern of how information is transferred to S1?

A

World -> primary sensory neuron (DRG or trigeminal) -> dorsal horn/brainstem -> thalamus -> S1
Should be familiar with the STT, DCML and the Trigeminal lemniscus system.

22
Q

What is the primary auditory cortex?

A

A1 (BA41) - located in superior temporal gyrus - Topographic map of sound frequency - pitch of sound - matches the basilar membrane in the cochlear
Superficial to this is the secondary auditory cortex (BA42/22 also 39/40)- sound localisation, analysis and memory. projections all over the cortex including Brocas and Wernicks area.

23
Q

What is the primary visual cortex?

A

V1 = BA17, located in the occipital cortex.
Topographic map - back to front and upside down.

24
Q

Label the key components of the limbic system.

A

Basal forebrain
Prefrontal cortex
Mammillary body
Amygdala
Rhinal cortex
Hippocampus

25
Q

What part of the cortex is strongly associated with the limbic system?

A

The ventral and medial prefrontal cortex.

26
Q

Why is the hippocampus important?

A

Declarative memory - events and facts
Multi-modal area
Receives information from all relevant areas of cortex - signals to encode these activation patterns as a physical representation of a memory = an engram.
This circuit replays on a retrieval of a memory.
Important in dementia

27
Q

Why is the prefrontal cortex important?

A

Prefronal and cortex and cingulate are the area associations with executive function.
Vulnerable to deterioration
PFC is frequently overgrown (or deficit in GABAergic interneurons or both) in children with Autism.

28
Q

What are the different functional regions of the Prefrontal cortex and why are they important?

A

Dorsolateral PFC - planning
Ventrolateral PFC - restraint
Orbitofrontal - evaluation
Ventromedial - social and affective competency and moral reasoning
Dorsomedial - regulates social impression and emotional regulation

29
Q

What are the two different functional zones of the cingulate gyrus?

A

The anterior cingulate gyrus - assessing consequences
The posterior cingulate gyrus - sense of self-awareness

30
Q

How does a stroke in the PFC lead to disexecutive syndrome?

A

Inability to make appropriate decisions at the appropriate times
Loss of white matter connections from the PFC to other cortical areas and subcortical structures (thalamus, hypothalamus, basal ganglia)
Difficulties in planning, problem solving and task initiation.

31
Q

What is the evolutionary link to the prefrontal cortex and Alzhimers?

A

Humans only mammals with largely developed PFC
And only suffer from dementia.

32
Q

What is meant by the default mode network of the brain?

A

Activity when attention is directed internally e.g. when not focusing on any particular task.

33
Q

What is the dorsal attention network?**

A

Posterior parietal and lateral occipital cortex, also intraparietla sulcus and FEF.
Includes dorsal visual association area - spatial awareness
Bilateral network for holding attention (ignores miscellaneous or background input) and contributes to intellectual capabilities.
Enables to voluntarily focus attention, mainly with a visuospatial focus.

34
Q

How does damage to the dorsal attention network present?**

A

Difficult to swap attention between visual stimuli particularly if there is no visual connection between the stimuli- spatial neglect.
Bilateral damage - unable to perceive that two coloured dots exist - only see one.
Unilateral damage - unable to focus on visual stimuli on the contralateral visual field, aka one side of the visual field is missing.

35
Q

What regions of the brain are affected in unilateral visual neglect?

A

Intraparietal sulcus
Superior parietal lobe
Frontal eye field
Tempopariteal junction
Inferior parietal lobe
Superior temporal gyrus
Ventral frontal cortex
Inferior frontal gyrus
Middle temporal gyrus.

36
Q

What is the key idea of the language networks of the brain?

A

Language processing involves Wernicks (understanding) and Broca’s (production).
Within these semantic categories have different activation patterns - for example unique patterns of activation throughout the parietal, temporal and frontal lobes for people, animals, tools etc.
The same patterns are observed regardless if heard or read - therefore must be language areas (aka meaning of language) rather than auditory/visual areas.

37
Q

What is the basis of cerebral cortex development?

A

Begins in early embryogenesis - proliferation of neural progentors and neural differentiation
Circuit formation and maturation happens way into adulthood (20s/30s) - from birth development can be experience expectant and dependent - as older experiences can influence myelination, synapsis and neurochemical maturation - enables motor connections/cognition to become more efficient.
Tends to become fully fixed within adulthood - may further atrophy as elderly.

38
Q

What is meant by brain development as siring, wiring and firing?

A

Siring - production of neurons, typically at max at 6 months
Wiring - become part of circuits
Firing - circuits become refined, helps with psychological development, other neurons are lost
These circuits extend into adult life.

39
Q

How do different bits of the cortex develop at different rates?

A

Different regions of the brain undergo synaptic pruning at different rates as they mature differently.
Primary cortical areas tend to undergo the least pruning - decline slower and by a lesser extent
Unlike multi-modal association areas which undergo more pruning and increased myelin growth at a faster rate.

40
Q

How does autism link to brain development?

A

Hundreds of genes involved in idiopathic autism.
Mainly genes involves in synaptic development
Or control chromatin and transcriptional regulation - particularly of genes involved in early brain development - abnormal development of PFC in embryogenesis.
Typically leads to overgrowth of PFC