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Medicine year 2 semester 2 > Case 22- Physiology and Pathology > Flashcards

Case 22- Physiology and Pathology Flashcards

1
Q

Components of cognition

A

Navigate, Speak, Write, Plan, Think, Compare, Value, Judge, Decide and Remember. It is not reflex, simple sensation or simple movement.

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2
Q

Assessing cognitive function- the Mental state examination:

A
  • The Mini Mental State Exam
  • Addenbrooke’s Cognition Examination
  • Montreal Cognitive Assessment (MoCA)
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3
Q

What’s assessed in the mental status exam

A

Assessment if the cerebral cortex and cognitive function:

1) Orientation
2) Attention
3) Language
4) Memory
5) Visuospatial
6) Executive function

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4
Q

Examining Attention, Language, Memory, Spatial and Perceptual

A

1) Attention (right hemisphere)= Observe patient. Orientation to person, place and time. Check for neglect and extinction.
2) Language= Wernicke and Broca’s area. Fluency, comprehension. Naming, repetition, writing, praxis.
3) Memory= Amygdala, Hippocampus and Parahippocampus. Ask them to remember 3 words (lemon, key, ball) and then wait 5 minutes and repeat it. Remembering past public and personal events
4) Spatial and Perceptual= Parietal lobe. 3D perception. Agraphesthesia and Astereognosis. Colour/Faces

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5
Q

Specific and non-specific cognitive tests

A

The MMSE, ACE-R and MoCA are very sensitive to cognitive problems but they are not specific about what the problem may be. More specialised tests should then be pursued such as brain scans or specific tests of frontal lobe function.

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6
Q

Specialised neuropsychological tests- the Rey figure

A

Suspect frontal lobe deficits? Differential diagnosis with movement disorder. Copying a complex drawing from memory
• Dyspraxia: deficits in carrying out purposive or skilled acts, such as drawing
• Memory problems
• Organizing thoughts, sequences

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7
Q

Assessing cognitive function and brain structure: Specialised tests?

A
  • Specialised neuropsychological test batteries
  • Brain imaging- structural MRI, diffusion MRI, functional MRI, PET scanning
  • Angiography
  • EEG/MEG
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8
Q

Location of cognitive function:

A

Distinct cerebral lobes perform distinct functions but many functions are not strictly located:
• Executive function, motor control, attention= Frontal lobe
• Multimodal sensory integration and spatial orientation (spatial and abstract reasoning)= Parietal lobe
• Hearing, memory, perceptual organisation, emotions= Temporal lobe
• Visual perception= Occipital lobe

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9
Q

Effects of brain damage on cognitive function

A
  • General deterioration in brain function E.g. Degenerative, will affect a set of areas, trickier to localize
  • Differential impact, but localised to a particular region or lobe E.g. ‘Frontal lobe syndrome’
  • Highly specific effects in certain locations E.g. Stroke, tumour, some can be easier to localise & diagnose
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10
Q

Effects of blockage to the ACA (anterior cerebral artery)

A

The ACA feeds the medial surface of the frontal lobe and parietal lobe. An infarction (block) causes a weakness in the opposite leg and shoulder and personality problems (medial frontal damage).

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11
Q

Effects of blockage to the PCA (posterior cerebral artery)

A

The PCA feeds the occipital lobe, temporal lobe, the thalamus and the hippocampus. Infarctions in the PCA cause visual disturbances, Achromatopsia, Akinetopsia (cant see motion) and memory changes.

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12
Q

Blockage to the MCA (middle cerebral artery)

A

The MCA feeds the frontal lobe, lateral surface of the temporal and parietal lobes, the internal capsule and the putamen. Infarction in the MCA causes weakness in hand, arm and face. Aphasia (impaired language) and neglect.

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13
Q

Degenerative disorders- Dementia

A
  • Alzheimers Dementia – Tau tangles and amyloid plaques pathology
  • Lewy body pathology – can involve more of visual system, dopaminergic system abnormalities (movement, value-based decision making)
  • Fronto-temporal dementia – can affect language system
  • Vascular dementia – cardio-vascular events (mini-strokes) evident on MRI scans, affecting cognition in areas where they are evident (thalamus – memory; cortex)
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14
Q

Effect of damage to the primary visual cortex

A

Damage to the primary visual cortex on one side causes blindness in the opposite visual field (hemianopia).

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15
Q

Object recognition requires the ventral or inferior visual stream:

A
  • In Inferior-Temporal (IT) cortex, subgroups of neurons are highly selective for faces
  • The ventral visual pathway integrates a lot of visual information (color, head orientation) to achieve complex object perception and recognition
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16
Q

What happens when the left striate and extra striate cortex are destroyed

A

The patient is blind in the contralateral visual space.

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17
Q

Blindsight

A
  • When you can judge orientation, colour of line and objects you cant see
  • Blindsight is mediated outside the primary thalamo-striate cortex visual pathway within the direct thalamo-extrastriate
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18
Q

Deficits in object recognition

A

Visual object agnosia- inability to recognise objects by vision with preserved ability to recognise them by other senses. Can copy a drawing but doesn’t recognise original or copy
Prosopagnosia: Face blindness

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19
Q

Cognitive assessment in primary care

A
  • Abbreviated mental test score (AMTS)
  • General practitioner assessment of cognition (GPCOG)
  • Mini-cog
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20
Q

Cognitive assessment in memory clinics

A
  • Addenbrookes cognitive examination- III
  • Montreal cognitive assessment (MoCA)
  • Mini mental state examination (MMSE)
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21
Q

Differentials for Parkinson’s disease

A
  • Essential tremor
  • Drug-induced parkinsonism
  • Other degenerative parkinsonian syndromes- Dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration
  • Alzheimer’s and multiple cerebral infarction
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22
Q

Clinical features of Parkinson’s

A

• Bradykinesia- slow movement
• Tremor- rest, postural
• Rigidity= cog-wheel, lead-pipe
• Postural instability- late feature
• Early features- loss of sense of smell, REM sleep behaviour disorder, constipation, depression and anxiety
Late complications- bladder and blood pressure problems, psychosis and dementia

23
Q

Pathology of dopamine in PD

A
  • Degeneration of dopaminergic (DA) neurones in the nigrostriatal tract
  • Decreased DA neurotransmission in the striatum via D2 receptors
  • Dysfunction in inhibitory striatal output
  • Loss of dopamine in the striatum results in a Dopamine/ACh imbalance- the pharmacological aim is to normalise this dysfunction by increasing dopamine neurotransmission in the striatum
24
Q

L-DOPA and Carbidopa (peripheral acting decarboxylase inhibitor)

A

L-DOPA is not converted to dopamine in the periphery, more is transported into the brain where it is converted to dopamine. Improved therapeutics. It increases dopamine synthesis

25
Q

Forms of MAO

A

MAO- intraneuronal enzyme responsible for the metabolism of dopamine. It exists in two isoforms MAO-A and MAO-B. Dopamine is mainly metabolised by MAO-B.

26
Q

MAO inhibitors (MAOI’s)

A
  • Blocks intraneural metabolism of dopamine
  • Increases the dopamine content of vesicles
  • Increases dopamine transmission
  • Selegiline, rasagiline
27
Q

Structures in the Basal ganglia

A
  • Can be divided into Corpus striatum and Amygdala
  • The Corpus striatum can be divided into the Neostriatum (striatum) and Paleostriatum
  • The Paleostriatum contains the Globus pallidus
  • The Neostriatum contains the caudate nucleus and Putamen, they are functionally linked
  • Together the Putamen and Globus pallidus for the Lentiform nucleus, this is an anatomical link
28
Q

Role of Basal ganglia (muscle)

A

Involved in the control of movement, posture and muscle tone

29
Q

The three main structures of the Basal ganglia

A

The caudate nucleus, the Putamen and the Globus pallidus

30
Q

Caudate nucleus

A

Forms the lateral wall of the lateral ventricle, its body follows the curve of the lateral ventricle. The tail of the caudate nucleus forms the roof of the inferior horn of the lateral ventricle. The caudate nucleus is medial to the internal capsule

31
Q

Putamen

A

Lateral to the internal capsule. The putamen and caudate limb are separated by the anterior limb of the internal capsule. There are connection fibres which pass between the internal capsule to connect the putamen and caudate nucleus

32
Q

The Globus pallidus and Nucleus accumbens

A

Globus pallidus- found on the inner surface of the putamen. Has two parts the Globus Pallidus Internus and externus
Nucleus accumbens- the head of the caudate nucleus and putamen are continuous with each other and form the Nucleus accumbens. The Nucleus accumbens is the pleasure centre of the brain

33
Q

Basal ganglia- associated structures

A
  • Substantia nigra- region in the midbrain, made up of two anatomically and functionally distinct portion the Pars compacta and the Pars reticulata. Allows for the fascilitation of movement but also involved in learning, drug addiction and emotion
  • Subthalamic nucleus- ventral to the thalamus, causes suppression of unwanted movements. Against the border of the internal capsule and has connections to the globus pallidus and the substantia nigra. Important in control of movement through the indirect and hyperdirect pathways. Involved in emotion, decision making and attention
34
Q

The internal capsule

A

A subcortical structure, contains a concentration of white matter project fibres which convey information to and from the cortex. Fibres to and from the cerebral cortex have a radial distribution, this is the corona radiata. Deeper in the hemisphere the fibres are more concentrated these are the internal capsule. It has a high concentration of motor and sensory projection fibres.

35
Q

Divisions of the internal capsule and blood supply

A

The interior capsule can be divided into the anterior limb, Genu, Posterior limb and the Retrolenticular part.

The lenticulostriate arteries arise from the middle cerebral artery. These arteries supply the internal capsule and the nuclei associated with the basal ganglia.

36
Q

Functions of the limbic system

A

Emotions, Motivational behaviour, Homeostatic function, Motivational states (desire to do something), Learning and memory

37
Q

Divisions of the limbic system

A

The limbic system has cortical and subcortical structures and there is variation on what structures are considered part of the limbic system.

38
Q

Limbic system and memory

A

1) There are strong connections between the limbic system and the Hypothalamus which is essential for adaptive behaviour. We can learn new responses based on previous experiences and memories
2) Allows us to adjust our personal and social responses based on previous experiences.
3) Provides the basis for instinctive and emotional aspects of behaviour and memory.
4) Influences the expression of emotional states by motor behaviour i.e. facial expressions or limb gestures (due to connections between limbic system and basal ganglia.
5) Allows for autonomic responses i.e. blushing or crying through connections to the hypothalamus The feeling and reacting brain

39
Q

Limbic lobe

A
  • Cortical regions of the limbic system
  • Not a true lobe- spans the frontal, parietal and temporal lobe
  • Around the corpus collosum, following the lateral ventricles
  • Ring of cortex on medial surface of brain
  • Spans the frontal, parietal and temporal lobes
40
Q

Prominent components of the limbic system

A
  • Cingulate gyrus- above the corpus collosum
  • Parahippocampal gyrus- within the medial temporal lobe
  • Hippocampal complex
  • Septal area
41
Q

Key structures of the limbic system- Hippo with a hat

A
  • Hippocampal formation (Hippo)
  • H – Hypothalamus
  • A – Amygdala (key subcortical structure)
  • T – Thalamus (anterior and mediodorsal nuclei)
42
Q

How does information go to the limbic system

A

Information to the limbic system is either directly to the Amygdala or indirectly to the Hippocampal formation via the enterinal cortex

43
Q

Other structures which are often included in the limbic system

A
  • Reticular formation
  • Nucleus accumbens (basal ganglia)
  • Prefrontal cortex (orbitofrontal cortex)
  • Septal nuclei in forebrain
44
Q

Hippocampal formation

A
  • ‘Seahorse’
  • Infolding of the temporal lobe into the lateral ventricle
  • Hippocampal formation: Hippocampus, Dentate gyrus, Subiculum, Parahippocampal gyrus
  • Receives input from the inferior temporal cortex via the entorhinal cortex of the temporal lobe. Also receives input via the fornix, principal output pathway is via the fornix and projections via the enterhinal cortex to the association areas of the neocortex
  • The Hippocampus is medial to the inferior horn of the lateral ventricle. Projections to the basal ganglia allow for motor response based on memory
  • The Hippocampus is divided into four sections, CA1-4
45
Q

Function of the Hippocampal formation

A
  • Memory formation- involved in short term memory and the consolidation of memory. However, the storage of memory is in the association and primary cortices not the medial temporal lobe.
  • Also involved in spatial navigation and orientation
46
Q

Fornix connections

A

1) Goes Hippocampus -> Crus of fornix -> body of fornix -> column of Fornix then terminate in the Mammillary bodies of the Hypothalamus.
2) The Mamillary bodies then project to the Thalamus, Brain stem, Hippocampus and nucleus accumbens.
3) The body of the fornix passes beneath the corpus callosum. The Hippocampal commissure allows information to be shared between the two half’s of the brain

47
Q

Fornix

A
  • Main output pathway from the hippocampus
  • The fornix links the Hippocampus to the mamillary bodies of the Hypothalamus
  • White matter structure which arches over the ventricular system
  • Curves under the corpus callosum
  • Joined at the hippocampal commissure
  • Divides into two columns
  • At the anterior commissure it divides into precommissural and post commissural fornix to reach the various structures
  • Majority of fibres terminate in the mammillary bodies
  • Axons from the hippocampus leave via the fornix
48
Q

Alzheimer’s disease- Hippocampus

A
  • Atrophy of the hippocampal formation
  • Amnesia for relatively recent events and inability to learn new information – loss of episodic memory.
  • Enlarged lateral ventricles and atrophy of the cortical gyri and hippocampus
49
Q

Hypothalamus connections

A
  • Most ventral part of diencephalon
  • Collection of nuclei with a variety of different functions
  • Found beneath the thalamus- forms the floor and part of the lateral wall of the third ventricle, below the Hypothalamic sulcus. Anteriorly is the anterior commisure
  • Hypothalamic sulcus - transition between thalamus and hypothalamus
  • Forms the floor and part of the lateral wall of the third ventricle
  • Mammillary bodies – posterior portion of the hypothalamus, contains the hypothalamic mamillary nuclei
50
Q

Hypothalamus structure

A
  • Function- regulates the physiological function of survival, consumption of fluid and food, temperature control, sleep-wake cycle, regulation of Homeostasis. Regulates emotional and behavioural patterns through links with the limbic system, the ability to learn new responses based on previous experiences
  • 2 H’s- Homeostasis and Hormones
  • Connected to pituitary gland via the infundibulum
51
Q

Hypothalamus structure

A
  • Collection of nuclei
  • Continuous with pituitary gland via infundibulum and the Hypophyseal stalk
  • Columns of the fornix cut through the Hyothalamus
  • The mamillary bodies are either side
  • Divided into zones
  • Nucleus which plays a key role in memory and connects to the structures of the limbic system is the medial nucleus found in the mammillary (posterior) region.
  • Connections between the limbic system and the Hypothalamus are important for adapting behaviour, the ability to learn new responses to situations based of previous experiences from memories
52
Q

Amygdala

A
  • Almond-shaped structure
  • In the temporal pole between the inferior horn of the lateral ventricle and the lentiform nucleus
  • Connected to Nucleus accumbens (in the basal ganglia) which allows the motor response
  • Found anterior to the inferior horn of the lateral ventricle & tail of caudate nucleus in temporal lobe
  • Emotional centre of the brain
  • Primarily associated with emotion of fear
  • Has connections to: Septal area, Hypothalamus, Thalamic nuclei, Several brainstem and forebrain structures
53
Q

Thalamus

A

Forms the lateral wall of the third ventricle with the hypothalamus, contains numerous nuclei. Lateral to the thalamus is the posterior limb of the internal capsule. Associated with sensory information, things you can see, hear, taste and touch. Why oursensory information has links with memory

54
Q

Septal nuclei

A
  • Rostral to the anterior commissure
  • Plays a role in pleasurable behaviours
  • Damage to this area causes extreme displeasure or rage
  • Afferents to the septal area come from the amygdala, hippocampus, olfactory tract and brainstem

Medicine year 2 semester 2 (47 decks)

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