Somatosensation +pain
What are the three main types of neurons in the nervous system, and which type is responsible for sensing touch, pain, and temperature?
Sensory, motor, and interneurons; sensory neurons detect touch, pain, and temperature.
What is the difference between open-loop and closed-loop motor control?
Open-loop control executes rapid, ballistic movements without feedback, while closed-loop uses sensory feedback for accuracy (like smooth, guided motions).
What is the function of the ossicles in the middle ear?
To amplify and transmit vibrations from the eardrum to the oval window of the cochlea.
Which sense relies on chemoreceptors, and where are these receptors located?
Taste and smell; taste receptors are in taste buds on the tongue, smell receptors in the olfactory epithelium of the nasal cavity.
What is neurogenic chronic pain, and how does it alter the spinal cord?
Pain from abnormal neuron signaling; substance P uptake and sympathetic overactivity remodel spinal neurons, making light touch feel painful.
How can sensory neurons encode the intensity of a stimulus even though action potentials are “all or none”?
By increasing firing frequency, recruiting more neurons, and using range fractionation (different thresholds).
Describe the role of the pyramidal and extrapyramidal systems in movement control.
Pyramidal (corticospinal) system controls voluntary, fine movement; extrapyramidal (basal ganglia + cerebellum) modulates coordination and posture.
Describe how the bending of hair cells in the cochlea leads to hearing.
Sound waves bend stereocilia, opening ion channels → depolarization → glutamate release → auditory nerve activation.
What happens in the retina when light hits photoreceptors?
Light activates rhodopsin, causing retinal to change shape → transducin activation → PDE activation → cGMP breakdown → Na⁺ channels close → hyperpolarization.
What is synesthesia, and what does it reveal about sensory processing?
It’s a condition where one sense triggers another (e.g., hearing colors); shows cross-activation between sensory cortical areas.
This type of somatosensory receptor is slowly adapting and detects pressure and texture.
merkel disc
Contrast the movement symptoms of Parkinson’s and Huntington’s disease, and describe the brain areas involved.
Parkinson’s (slow, stiff movements due to loss of dopamine in substantia nigra → basal ganglia); Huntington’s (excess, dance-like movements due to degeneration of caudate and putamen).
Compare frequency coding and place coding for pitch perception.
Low frequencies use frequency coding (firing rate matches sound frequency); high frequencies use place coding (location on basilar membrane).
person who can see still objects clearly but cannot perceive motion (e.g., liquid appearing frozen) likely has…
akinetsopia
Why is pain considered both a sensory and an emotional experience, and which brain regions correspond to each aspect?
Pain has a sensory component processed in the somatosensory cortex (intensity, location) and an emotional component processed in the anterior cingulate cortex (ACC) (unpleasantness, distress).
Explain the Gate Control Theory of pain and provide one real-life example of how it works.
Non-painful input (A-beta fiber activation) can “close the gate” in the spinal cord, inhibiting pain transmission; for example, rubbing a stubbed toe reduces pain.
Explain how mirror neurons in the premotor cortex contribute to both learning and empathy.
Mirror neurons fire when performing or observing an action, allowing imitation learning and emotional understanding of others’ actions.
Explain how the brain determines the direction of a sound using the superior olives.
Medial superior olive compares timing differences (latency) for low-frequency sounds; lateral superior olive compares loudness (intensity) for high-frequency sounds.
What are the three cell types in the LGN and how do they differ in function? (Parvocellular, Magnocellular, Koniocellular)
Parvocellular (P-cells): Small cell bodies, small receptive fields, process fine detail and color.
Magnocellular (M-cells): Large cells, large receptive fields, detect motion and broad outlines.
Koniocellular (K-cells): Very small cells in thin layers between P & M layers, carry miscellaneous/non-P-non-M visual info (e.g., some color pathways, low-acuity signals).
Describe how the motor cortex and cerebellum cooperate during complex, learned movements such as playing an instrument.
The motor cortex initiates voluntary commands, while the cerebellum refines timing, precision, and coordination through inhibitory control (Purkinje cells). With practice, these circuits strengthen, allowing smoother, automated movements.
A patient reports feeling pain in a missing limb after an amputation. Explain the neural mechanism behind this phenomenon.
Phantom limb pain results from cortical reorganization — the somatosensory cortex region for the missing limb becomes activated by nearby inputs.
Compare nicotinic and muscarinic acetylcholine receptors in terms of location, receptor type, and function.
Nicotinic receptors are ionotropic, excitatory, and found at the neuromuscular junction and autonomic ganglia; muscarinic receptors are metabotropic, slower, and found in the CNS and parasympathetic targets, where they can be excitatory or inhibitory.*
What would be the auditory consequence of damage to one primary auditory cortex versus damage to the cochlea in one ear?
Auditory cortex damage reduces sound processing and localization but doesn’t cause complete deafness (bilateral input), while cochlear damage causes total deafness in that ear.
Trace the complete pathway that visual information takes from the retina all the way to higher-order processing areas. Include what happens after the primary visual cortex (V1) and describe the functions of the two major pathways beyond it.
Visual information travels from the retina → optic nerve → optic chiasm → optic tract → lateral geniculate nucleus (LGN) of the thalamus → optic radiations → primary visual cortex (V1, occipital lobe).
From V1, information splits into two main processing streams:
The dorsal stream ("where/how" pathway): V1 → V2 → V5 (MT) → posterior parietal cortex, which processes motion, spatial orientation, and visually guided action.
The ventral stream ("what" pathway): V1 → V2 → V4 → inferior temporal cortex, which processes color, form, and object recognition.
Explain why receptive fields of rods lead to higher sensitivity but lower acuity compared to cones.
Many rods converge onto one ganglion cell → Summation boosts sensitivity → But detail is lost (low acuity). Cones have 1:1 ratio → Sharp detail.