Case 22 Questions 1-15

Question 1

Which of the following statements regarding the limbic system is true?

1. The limbic system is a loop which includes the hippocampus, internal cortex, mamillary bodies and putamen
2. The main function of the limbic system is control of motor activity
3. The entorhinal cortex receives afferent stimulation from the olfactory bulb
4. Damage to Broca’s area leads to a receptive aphasia
5. Limbic system connects to the somatosensory cortex in the precentral gyrus

The correct answer is option a, The limbic system is a loop which includes the hippocampus, internal cortex, mamillary bodies and putamen

The limbic system is a loop which includes the amygdala, hippocampus, thalamus, hypothalamus, and corpus callosum.

The main functions of the limbic system can be remembered by the 5 F’s – feeding (satiety & hunger), forgetting (memory), fighting (emotional response), family (sexual reproduction and maternal instincts) and fornicating (sexual arousal). Motor activity is regulated by the basal ganglia.

Broca’s area is associated with expressive aphasia (speech production deficit)- receptive aphasia is associated with Wernicke’s area. The somatosensory cortex is located in the postcentral gyrus.

Question 2

Which one statement is most true in regards to the basal ganglia?

1. The striatum is composed of the putamen and the globus pallidus
2. The internal capsule travels between globus pallidus and putamen
3. Destruction of the basal ganglia leads to a syndrome characterised by decreased tone in the limbs
4. Dopamine is the major neurotransmitter involved in the nigrostriatal pathway
5. The basal ganglia only communicates with the motor cortex

The correct answer is option d, Dopamine is the major neurotransmitter involved in the nigrostriatal pathway

Dopamine is the major neurotransmitter in the nigrostriatal pathway which connects the substantia nigra pars compacta in the midbrain with striatum in the forebrain – this controls motor movement. The other dopamine pathways are the tuberoinfundibular, mesocortical, mesolimbic.

The internal capsule lies in between the thalamus and globus pallidum/putamen The striatum is composed of the caudate nucleus and the putamen, the internal and external globus pallidus forms the pallidum of the basal ganglia.

Destruction of the basal ganglia leads to Parkinson’s disease, characterised by an increase in tone which presents as rigidity (cogwheel rigidity occurs in PD where a resting tremor is superimposed on increased tone)

Question 3

Which of the following are key features of the neurodegenerative condition affecting the basal ganglia?

1. Uncontrolled movement (chorea)
2. Resting tremor, bradykinesia, rigidity
3. Urinary incontinence, dementia, ataxic gait
4. Altered mental state, nystagmus and ataxic gait
5. Dysdiadochokinesis, intention tremor, hypotonia

The correct answer is option b, Resting tremor, bradykinesia, rigidity

Resting tremor, bradykinesia and rigidity are classic signs of Parkinsonism seen in Parkinsons’ Disease, a neurodegenerative condition affecting the nigrostriatum. Chorea is often seen in Huntington’s disease. Urinary incontinence, dementia and ataxic gait are the triad seen in normal pressure hydrocephalus. Altered mental state, nystagmus and ataxic gait are signs of Wernicke’s Encephalopathy secondary to thiamine deficiency. Dysdiadochokinesis, intention tremor and hypotonia are all signs seen in cerebellar disease (DANISH)

Question 4

Henry Molaison (HM) is a famous patient studied due to the severe anterograde amnesia he developed following surgery in 1953 for epilepsy. Which part of the brain was removed during his surgery?

1. Corpus callosum
2. Optic chiasm
3. Amygdala
4. Bilateral temporal lobes
5. Basal ganglia

The correct answer is option d, Bilateral temporal lobes

The hippocampus, present in the temporal lobe, is the most likely site of a lesion in a patient presenting with anterograde amnesia. HM had portions of both his temporal lobes removed. The corpus callosum allows the two sides of the brain to communicate. The left side of the brain is important for understanding and producing speech – if there is a stimulus on the left side of their vision (perceived by the right hemisphere), a person whose brain cannot communicate between sides will be unable to name the stimulus/object as the language centre in the left hemisphere is not receiving any stimulus.

The optic chiasm is the part of the brain where the optic nerves cross – a lesion here will cause bitemporal hemianopia.

Disruption of the basal ganglia will lead to the motor symptoms of Parkinson’s disease.

Question 5

Which of the following areas in the reticular formation is associated with serotonin release

1. Ventral tegmental area
2. Raphe nucleus
3. Locus coeruleus
4. Pedunculopontine nucleus
5. Edinger-Westphal nucleus

The correct answer is option b, Raphe nucleus

The Raphe nucleus is associated with serotonin release. The ventral tegmental area (VTA) is associated with dopamine, locus coeruleus with noradrenaline and the pedunculopontine nucleus with acetylcholine release. The Edinger-Westphal nucleus is the pre-ganglionic nucleus that innervates the iris sphincter muscle and the ciliary muscle.

Question 6

What is the function of the ascending reticular activating system?

1. Posture and co-ordination
2. Muscles of the axial skeleton
3. Pain and temperature
4. Light touch and pressure
5. Sleep-wake cycle

The correct answer is option e, Sleep-wake cycle

The ascending reticular activating system is a set of connected nuclei in the brainstem that controls the sleep wake cycle. It is also known as the extrathalamic control modulatory system and works as it receives non-specific inputs from all the major sensory systems (somatosensory, proprioceptive, auditory, visual).

There are two main divisions of tracts in the spinal cord – ascending (sensory) and descending (motor). The ascending reticular activating system is not actually part of the ascending tracts of the spinal cord despite its name.

Posture and co-ordination is controlled by the spinocerebellar tracts (remember cerebellar dysfunctions results in DANISH – ataxia and therefore loss of co-ordination of muscle movement is a sign of cerebellar disease). Muscles of the axial skeleton are controlled by the anterior corticospinal tract. Pain and temperature is controlled by the lateral spinothalamic tract. The anterior spinothalamic tract controls light touch and pressure.

Question 7

If a patient had bilateral damage to the medial temporal lobe, which of these aspects of memory would be unaffected?

1. New memory formation
2. Short term memory storage
3. Retrieval of early consolidated memories
4. Retrieval of recent unconsolidated memories
5. Consolidation of memories

The correct answer is option c, Retrieval of early consolidated memories

The medial temporal lobe contains the hippocampus which plays a key role in the formation, storage and consolidation of memories. It is initially involved in memory retrieval but once memories are consolidated they are stored in the cortices and no longer require the hippocampus to aid in their retrieval

Question 8

Which of these statements in regards to the limbic system and its role is FALSE?

1. The amygdala plays a role in modulating the response to fear
2. The hippocampus is more important in forming new memories than retaining long term memories
3. The thalamus relays motor and sensory pathways
4. The parahippocampal gyrus transmits information between the association cortex and the hippocampus
5. The hypothalamus is responsible for vasodilation in the case of low body temperature

The correct answer is option e, The hypothalamus is responsible for vasodilation in the case of low body temperature

The hypothalamus is responsible for homeostasis in the body so co-ordinates thermoregulation. If the body temperature was low the appropriate response would be vasoconstriction.

Question 9

If a lesion occurs in the inferior-temporal cortex, what difficulty is the patient most likely to experience?

1. Colour recognition
2. Spatial awareness
3. Detecting movement
4. Depth perception
5. Facial recognition

The correct answer is option e, Facial recognition

In the 2 stream model of object recognition the pathways can be inferior temporal or parietal; inferior temporal is essentially the ‘what’ pathway and is key in recognising faces, parietal is the ‘where, how’ pathway which helps spatial awareness, movement recognition and to guide movements. The occipital lobe is where visual images are processed and integrated from both hemispheres of the brain and therefore where colour processing and depth perception occurs.

Question 10

A patient presents to the GP with atrophy of the right side of the tongue. Which nerve might be damaged in this case?

1. Right vagus nerve
2. Right hypoglossal nerve
3. Left vagus nerve
4. Right glossopharyngeal nerve
5. Left hypoglossal nerve

The correct answer is option b, Right hypoglossal nerve

Damage to the hypoglossal nerve leads to weakness and atrophy of the ipsilateral side of the tongue

The glossopharyngeal nerve (cranial nerve IX) supplies sensory innervation to the posterior 1/3rd of the tongue

The vagus nerve supplies motor innervation to the palatoglossus (all other intrinsic and extrinsic muscles are supplies by the hypoglossal nerve). The vagus nerve also supplies a small portion of sensory innervation to the posterior 1/3rd of the tongue (via the internal laryngeal nerve)

Question 11

Which of these best describes the transduction of salty taste?

1. Na+ enters through ion channels causing depolarisation of the membrane, voltage gated channels open to let Na+ and Ca2+ through, vesicles of neurotransmitter move towards synapse and are released.
2. Substance binds to cell membrane and activate a G protein, leading to a 2nd messenger system and an influx of Ca2+ triggering the vesicle to release neurotransmitter at the synapse.
3. The G-protein involved in the process is G_olf
4. The signal is transmitted through receptor neurones, sustentacular cells, ensheathing cells
5. The signal ends up in the gustatory cortex in the parietal lobe on the opposite side

The correct answer is option a, Na+ enters through ion channels causing depolarisation of the membrane, voltage gated channels open to let Na+ and Ca2+ through, vesicles of neurotransmitter move towards synapse and are released.

The 1st option is correct and describes the transduction of salt. Acids take the same path.

The 2nd option describes the transduction of bitter, umami and sweet compounds.

The 3rd and 4th option describes the g-protein and the cells involved in the olfactory pathway.

Option 5 is correct but not the best answer here.

Question 12

Which of these is not true about papillae

1. Filiform papillae are minute conical projections – they give a velvety appearance to the tongue and do not contain taste receptors
2. Fungiform papillae are visible as discrete pinheads and are located around the edges of the tongue, these contain a few taste buds
3. The circumvallate papillae form a V shape towards the back of the tongue
4. The sulcus terminalis is the name for the straight line running down the centre of the tongue
5. The sensory neurones coming from the taste receptor are either from the chorda tympani or glossopharyngeal nerve

The correct answer is option d, The sulcus terminalis is the name for the straight line running down the centre of the tongue

Option 4 is the correct answer here, this is not true. The sulcus terminalis is the V shaped groove which separates the oral and pharyngeal parts of the tongue. All of the other points are true.

Question 13

Which of these is best describes the aetiology of Alzheimer’s disease

1. Brain damage due to cardiovascular disease
2. Deposition and accumulation of α-synuclein
3. Accumulation of proteins e.g. tau in frontal and temporal lobes
4. Degeneration of dopaminergic neurones
5. Cortical atrophy and degeneration due to accumulation of neurofibrillary tangles and β-amyloid.

The correct answer is option e, Cortical atrophy and degeneration due to accumulation of neurofibrillary tangles and β-amyloid.

Option 5 describes the aetiology of Alzheimer’s, around 50% of the population with dementia has Alzheimer’s. Around 25% have vascular dementia which is described in option 1, 15% with dementia with Lewy bodies (option 2), <5% with Fronto-temporal dementia (described in 3). Option 4 describes the aetiology of Parkinson’s disease.

Question 14

Which one of these memories would be categorized as a non-declarative memory?

1. You remembering what you had for breakfast this morning
2. You knowing how to brush your teeth
3. Thinking back to when you left school
4. You remembering where you bought your shirt when asked
5. You are living life after an injury but are unable to make memories

The correct answer is option b, You knowing how to brush your teeth

This question shows the differences between the two main types of memory.

Option 2 is an example of non-declarative memory, other examples include being able to ride a bike, driving a car – these involve skills and behaviours, and learning a motor response in association with sensory input.

Option 1, 3 and 4 are examples of declarative memory – facts, events, things you can access and recall.

Option 5 describes anterograde amnesia – going forward from in injury and being unable to form new memories.

Question 15

Which one of these drugs works through being a dopamine precursor?

1. Levodopa
2. Entacapone
3. Selegiline
4. Pergolide
5. Carbidopa

The correct answer is option a, Levodopa

Levodopa is the correct answer here, it is an amino acid precursor of dopamine and a commonly used drug for Parkinson’s.

It is usually combined with carbidopa (option 5) which inhibits its peripheral metabolism. Entacapone reduces the metabolism of levodopa by COMT inhibition, selegiline prevents the breakdown on dopamine by MAO-B inhibition and pergolide is a dopamine receptor agonist. Dopamine can’t be given directly as it cannot cross the blood brain barrier.