Chapter 8: Sensorimotor System Flashcards
sensory vs motor pathways
sensory pathways are afferent (go to the brain)
motor pathways are efferent (come from the brain)
where does a motor sequence start and stop?
starts in the cortex and terminates in muscle fibres of the PNS
what is the purpose of the premotor cortex?
organizes movement sequences
what is the purpose of the prefrontal cortex?
plans movements
what is the purpose of the motor cortex?
outer strip of the brain that includes a map of the body and produces specific movements
part of a feedback loop with the basal ganglia
what kind of neurons are located in the motor cortex?
upper motor neurons
what do the caudate nucleus and putamen form?
form the walls of ventricles and the striatum
what is the purpose of the striatum?
habitual movements
what is the purpose of the globus pallidus?
processes how much force is needed (volume control)
what causes Parkinson’s disease?
a loss of dopaminergic neurons in the substantia nigra
what are some common symptoms of Parkinson’s disease?
hyperkinetic (unwanted) movements, hypokinetic symptoms (inability to move), resting tremor
what are the symptoms of Huntington’s disease?
erratic functioning, cognitive and motor decline
what is MPTP?
a neurotoxin used to model Parkinson’s disease in rodent models. rapidly kills dopaminergic neurons in the substantia nigra (within 24 hours)
what does dysfunction in the basil ganglia sometimes lead to?
obsessive-compulsive behaviours
how to axons of upper motor neurons descend to the brainstem?
via the internal capsule
what do the corticobulbar tracts control?
movement of the head, face, mouth
what do the corticospinal tracts control?
arms, legs, other parts of the body
what is the purpose of the cerebellum in movement sequences?
timing and flow, and accuracy and error correction
where do the corticobulbar tracts synapse?
lower motor neurons in the brainstem (cranial nerves and face and neck muscles)
what is the function of the lateral corticospinal tract?
moves limbs and digits
what is the function of the anterior corticospinal tract?
moves muscles at the body’s midline
what occurs on the anterior root of the spinal cord?
motor signals travel down it and exit on different parts of the spinal cord
what is the purpose of the posterior root of the spinal cord?
receives sensory signals that travel up to the brain
what is responsible for the exteroceptive sense?
the skin
what are some examples of exteroceptive senses?
feeling things on the skin, temperature changes, damage to the skin
what is the proprioceptive sense?
where your limbs are in space
what are interoceptive senses?
has to do with the autonomic nervous system (organs, blood pressure, etc)
what are merkel receptors?
touch receptors that are close to the surface of the skin and are all over the body
what are ruffini corpuscles?
corpuscles that are located low down in the skin and respond to stretching of the skin
what are pacinian corpuscles?
layered and filled with fluid, respond to deep vibrations of the skin
what are free nerve endings?
pain receptors close to the surface of the skin and respond to pain and temperature changes
what are the procedure for determining the two-point threshold?
slowly bring two points closer together until the person only feels one point (sensitivity threshold)
the lower the threshold, the more sensitive the body part is
what do highly sensitive areas contain?
a higher density of merkel receptors
what are CT mechanoreceptors?
receptors wrapped around the roots of fine hairs and respond to their movement
what are the three general categories of pain?
nociceptive
inflammatory
neuropathic
nociceptive pain
sharp pain against the skin and temperature changes
inflammatory pain
response to red, inflamed skin
neuropathic pain
lingering pain after the initial injury
what are the two dimensions of pain?
affective and discriminative
affective dimension of pain
the emotional aspect; typically negative/emotionally upsetting
discriminative dimension of pain
where the pain is coming from
where is pain processed?
in the pain matrix
which structures make up the pain matrix?
parietal (somatosensory), prefrontal (decision making), limbic (emotional quality)
traditional theory of pain
sensation of pain is explained in purely physiological terms
what are the issues associated with the traditional theory of pain?
can’t explain why placebos work for some people and can’t explain how people continue playing a sport after being injured without feeling the pain
