Neurophysiology Quiz Questions Flashcards
A person with normal vision except for anomalous trichromacy (red-green colour-blindness): A. sees blue as grey. B. sees red and green as grey. C. has blurry vision. D. sees purple as grey. E. sees yellow as blue.
Answer: sees purple as grey.
With normal vision, purple is red and blue together without green, whereas grey is red, green and blue all together. If your red and green sense is the same, then there is no distinction between purple and grey for you.
In transducing mechanical energy into a neural signal, the cochlear hair cells:
A. utilise ligand-gated channels near the apical border of the cell.
B. employ stereocilia that allow a single hair cell to combine the sound signals from the two ears.
C. utilise an influx of cations to depolarise the hair cell.
D. receive a chemical signal from the tectorial membrane.
E. have the same response to a forwards deflection of the stereocilia as to a backwards deflection.
Answer: utilise an influx of cations to depolarise the hair cell.
In this case K+ will be the major cation contributor because of the high concentration of K+ in endolymph and the big driving potential.
During normal voluntary muscle contraction (alpha and gamma co-activation):
A. intrafusal muscle fibres shorten while extrafusal fibres do not.
B. gamma motor neurons activate the alpha motor neurons.
C. extrafusal fibres provide most of the contractile force.
D. extrafusal muscle fibres shorten while intrafusal fibres do not.
E. contraction of the intrafusal muscle fibres weakens the stretch reflex.
Answer: extrafusal fibres provide most of the contractile force.
Intrafusal fibres regulate the spindle activity.
N1 and N2: post-synaptic action potential
N2: post-synaptic action potentia
N2 and N3: no post-synaptic action potential
Which of the following is the most likely conclusion?
A. N1 is sub-threshold excitatory, N2 is supra-threshold excitatory, N3 is inhibitory.
B. N1 is inhibitory, N2 is supra-threshold excitatory, N3 is sub-threshold excitatory.
C. N1 is sub-threshold excitatory, N2 is sub-threshold excitatory, N3 is inhibitory.
D. N1 is inhibitory, N2 is sub-threshold excitatory, N3 is sub-threshold excitatory.
E. N1 is supra-threshold excitatory, N2 is sub-threshold excitatory, N3 is inhibitory.
Answer: N1 is sub-threshold excitatory, N2 is supra-threshold excitatory, N3 is inhibitory.
In the myotatic reflex:
A. the intrafusal muscle fibres contract due to 1B activity.
B. the extrafusal muscle fibres relax due to 1A activity.
C. the extrafusal muscle fibres contract due to 1A activity.
D. the 1B afferents increase their firing rate in response to increased muscle length.
E. the 1A afferents increase their firing rate in response to increased muscle tension.
Answer: the extrafusal muscle fibres contract due to 1A activity.
This is the reflex contraction.
Which of the following sensory parameters are topographically organised in their primary sensory cortex?
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Answer: B
Topographically means ‘map-like’ and generally these parameters will be organised like that in the periphery and in the primary sensory cortex.
Golgi tendon organs:
A. respond primarily to muscle length.
B. are in parallel with intrafusal muscle fibres.
C. are rapidly adapting receptors.
D. are in series with extrafusal muscle fibres.
E. cause mono-synaptic excitation of alpha motoneurons.
Answer: are in series with extrafusal muscle fibres.
The force of the muscle is transmitted through the tendon, and detected by the Golgi tendon organ.
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A. An ice cube pressed gently against the skin.
B. The sharp edge of a knife pressed firmly against the skin.
C. A flat piece of plastic pressed gently against the skin.
D. A candle flame held near the skin.
E. The blunt end of a pencil pressed firmly against the skin.
Answer: An ice cube pressed gently against the skin.
An ice cube pressed gently against the skin would explain the cold and tactile afferent activity.
Which ONE of the following statements about motor pathways is CORRECT?
A. The extrapyramidal tracts are predominantly involved in control of limb muscles.
B. The extrapyramidal tracts synapse onto spinal motor neurons.
C. The corticospinal tract originates mainly in the basal ganglia.
D. The corticospinal tract carries afferent information.
E. The corticospinal tract crosses the midline.
Answer: The corticospinal tract crosses the midline.
Most fibres cross in the medulla, and so give rise to motor cortex controlling the contralateral side of the body.
When preparing to reach down and pick up a bag, which brain area would be the final motor area to be activated before the movement begins? A. basal ganglia B. primary motor cortex C. pre-motor area D. cerebellum E. supplementary motor area
Answer: primary motor cortex
The primary motor cortex directly innervates spinal motor neurons and spinal cord interneurons that drive the motor neurons.
Reflexes:
A. require only an integrator and an effector.
B. must involve a proprioceptive afferent such as a Golgi tendon afferent.
C. can be used to keep a limb in position.
D. must take less than 10ms otherwise they are not involuntary.
E. are not signalled to the cortex.
Answer: can be used to keep a limb in position.
Reflexes are best at simple tasks. The myotatic reflex helps hold a limb in position.
Choose the CORRECT statement about the retina.
A. Rod photoreceptors outnumber cone photoreceptors throughout the retina except at the fovea.
B. Stimulus location is coded by the type of photoreceptor activated.
C. Stimulus colour is coded by the activity of rod photoreceptors.
D. Increased light intensity causes increased transmitter release from photoreceptors.
E. Rod photoreceptor activity is unaffected by a change in the intensity of a coloured stimulus.
Answer: Rod photoreceptors outnumber cone photoreceptors throughout the retina except at the fovea.
Cone density is low except at the fovea.
With regard to spinal motor neurons:
A. Alpha motor neurons synapse onto spindle afferent neurons.
B. The activity of an alpha motor neuron can be influenced by descending cortical input.
C. A motor unit is composed of an alpha motor neuron and a single muscle fibre.
D. A motor unit may be composed of more than one alpha motor neuron.
E. A single action potential in a single alpha motor neuron does not cause muscle contraction.
Answer: The activity of an alpha motor neuron can be influenced by descending cortical input.
This is correct and necessary otherwise our muscles wouldn’t be much use to us.
When a neuron adapts to a stimulus, this means that it:
A. becomes more selective for the properties of that stimulus.
B. changes its morphology to accommodate the stimulus.
C. becomes sensitised to the stimulus.
D. generates action potentials at a lower rate.
E. generates stronger action potentials.
Answer: generates action potentials at a lower rate.
The response rate decreases over time, even though the stimulus is steady.
Which ONE of the following statements about the photoreceptors of the retina is CORRECT?
A. Both rods and cones are found in the centre of the visual field.
B. The highest density of photoreceptors in the eye is at the optic disc.
C. In the peripheral retina, rods are more common than cones.
D. There are more cones than rods in the retina.
E. There are three types of rod photoreceptors and one type of cone photoreceptor.
Answer: In the peripheral retina, rods are more common than cones.
