STUDY GUIDE: FINAL EXAM, NEUROBIOLOGY, FALL 2011
1. Types of motor systems (Dr.Ayers lecture)
a. myogenic control (insect flight)
i. synchronous (burst of motor neuron action potentials per wing beat) vs
asynchronous (no relationship between motor neuron action potentials and
ii. wing movements are caused by alternating discharge in dorso-ventral muscles
and longitudinal muscles
iii. stretch is the stimulus that causes muscle contraction
b. single phase oscillator (crustacean neurogenic heartbeat)
i. muscle contractions force blood out of arteries
ii. motor program consists of:
1. regular bursts where all motor neurons discharge together
2. motor neuron bursts are constant in duration
iii. central pattern generator in the cardiac ganglion consists of small cells that are
endogenous bursters (see intrinsic membrane properties slide in my lecture)
c. two phase symmetric oscillator (lobster swimmerets- paired appendages under abdomen)
i. motor program consists of:
1. power stroke
2. return stroke
ii. when swimmeret beating frequency increases the:
1. amplitude of swimmeret beating increases (positive relationship)
2. number of active motor neurons increases
a. motor neurons are recruited in order of their size
3. discharge frequency of individual motor neurons increases
d. walking movements underlying locomotion (general principles)
i. three phase step cycle:
1. early swing phase when the leg is flexed and protracted
a. leg muscles = flexors
2. late swing phase when the leg is extended and protracted until it contacts the ground
a. leg muscles = early extensors
b. combination of early and late swing is always constant in duration
3. stance phase when the leg bears weight against gravity and provides propulsive force by
retracting the leg
a. leg muscles – late extensors
b. stance phase duration varies with walking speed
2. Types of movement
i. examples- knee jerk (monosynaptic) and pain withdrawal circuits
b. rhythmic movements (central pattern generators)
i. definition: groups of neurons that can generate a rhythmic output without
ii. be able to identify known intrinsic membrane properties they may exhibit iii. describe the model of a basic CPG
1. insect metamorphosis- ecdysis behavior
a. differentiate function and motor output of pre-ecdysis vs ecdysis
i. pre-ecdysis-loosen the old cuticle▯ muscles contract
and relax synchronously in all segments of the
abdomen every 5-10 seconds
ii. ecdysis- frees animal from old cuticle▯uses the same
muscles, but contracts in a wave towards the front
from segment to segment
b. what neuropeptide initiates this behavior? how does affect
i. Neuropeptide- release of CCAP starts the patterns
ii. Neuronal firing- longerAPs, with a lower threshold
2. lobster stomatogastric ganglion- what behavior does this control?
a. different neuromodulators elicit different firing patterns in
different neurons in the circuit- why?
i. 3. rhythmically firing spinal cord interneurons- if given a voltage trace
recording, be able to identify:
i. the neurotransmitter
ii. where the voltage is underlied byAMPA, NMDA or Ca - 2+
activated-K channel opening
c. voluntary movements
i. location and topographical arrangement (homunculus) of primary motor cortex
ii. role of the cerebellum
3. General principles
a. be able to identify the specific receptor for different external stimuli- are there internal
internal sensory stimuli-Temperature, blood sugar, pressure & CO Muscle 2,nsion
& joint position (proprioception)
b. understand the basic attributes of sensory systems and be able to describe them
specifically for the sensory systems we covered in lecture (encoding of intensity and
i. modality- what sense is this?
ii. Intensity- how strong is it? (represented byAP frequency▯amount of
iii. Duration- concept of sensory adaptation
iv. Location- where is it processed and encoded (cortical and subcortical)
c. what subcortical structure is the relay center for sensory stimuli? what sensory modality
does not relay into the thalamus first?
ii. Olfaction does not relay into the thalamus first (smell)
d. concept of receptive fields
i. what is the advantage of large vs small receptive fields
1. in a large receptive field two stimuli are perceived as a single point
because they are in the same receptive field, only one signal is sent to the
brain vs. small ▯ two stimuli are perceived as separate and two signals
are sent to brain
ii. how does lateral inhibition increase sensory discrimination?
1. Pathway closest to stimulus inhibits close by pathways, to enhance
perception of stimulus
a. mechanoreceptors in the skin i. you should know nociceptors and pacinian corpuscles
1. nociceptors- free nerve endings that detect painful stimuli
2. pacinian corpuscles- sensitive to pressure on skin
b. proprioceptors in muscles- stretch receptors
i. be able to differentiate rapidly-adapting vs slow-adapting stretch receptors
c. what is the “homunculus” and how does it topographically represent the body?
a. understand the properties of sound (frequency or pitch and amplitude or loudness)
i. how are both encoded in the auditory system?
1. Frequency of air-pressure waves codes for pitch (what you hear)
2. Amplitude of air-pressure waves codes for loudness or intensity
b. conduction pathway for sound traveling to hair cells
c. in the cochlea
i. differentiate basilar vs tectorial membrane
ii. what is function of the vestibular system? what sensory receptors do they have?
iii. describe how hair cells are mechanically-gated
1. what is the kinocilium?
2. what ion channels depolarize hair cells?
3. how does this lead to sensory coding of sounds?
iv. fluids of the cochlea (endolymph vs perilymph)
1. compare their location in relation to the hair cells
2. how does their potassium concentration differ?
3. what structure maintains the endolymph?
v. tonotopical organization of hair cells on the basilar membrane
1. how does this relate to sound frequency?
d. sound localization
i. nuclei and structures in the CNS
1. where does sound from both ears converge?
2. how do our pinna contribute to sound localization?
ii. interaural time (phase) differences vs intensity differences
1. what brain structure computes each and where are they located?
2. which work best for low vs high frequency sounds?
3. concept of “delay lines” and “coincidence detectors”
e. cortical structures for sound processing
i. how is sound frequency represented in the primary auditory cortex?
1. differentiateA1 vsA2 areas (what are phonemes?)
2. differentiate Wernicke’s vs Broca’s area
a. lesions in each lead to what kind of deficit?
b. how do their locations relate to brain lobes?
c. Wernicke’s area considered a true association area
i. it is activated by what different kinds of stimuli?
ii. audiovisual binding- what is the McGurk effect and what does it illustrate about
f. hearing loss
i. what are some common causes?
ii. conduction vs sensorineural hearing loss
1. how can a tuning fork differentiate between the two types? 2. what are their different treatments?
a. properties of light
i. waves of energy- higher energy are shorter wavelength
ii. what are the limits of the human visual system?
1. what wavelengths underlie white light?
2. what wavelengths underlie a single color?
b. functions and structures of the eye
i. how are objects focused on the retina?
1. how are objects represented on the retina?
2. what is the path of light vs the path of phototransduction?
3. optic tracts and visual field
a. nasal regions decussate so left visual field in right optic tract, etc
ii. neurocircuitry of the retina
1. what is the direct pathway?
a. which cell types show graded potentials vs action potentials?
b. What are the 2 “sign inversions” make visual processing less
2. horizontal and amacrine cells affect interactions at which synapses?
a. do they show graded or action potentials?