circuits of CNS

Question 1

what are Central Pattern Generators?

Answer 1

neural circuits that produce rhythmic motor output

Question 2

what is a Local Circuit?

Answer 2

arrangement of neurons and their synaptic connections within local brain region

Question 3

Define microcircuits.

Answer 3

finer arrangements of neurons and synapses w/in local circuits

Question 4

what are the 3 elements of local circuits?

Answer 4

• input axons
• interneurons
• projection/output neurons

Question 5

what neurons function in local processing?

Answer 5

• interneurons or intrinsic neurons whose axonal connections remain within the local circuit

Question 6

how do neurons in local circuits operate?

Answer 6

these neurons operate in parallel w/ one another and info from each circuit is mutually shared while continually influencing its neighbors.

(in a highly interactive, simultaneously interdependent, expansive networks)

Question 7

A single motor neuron & muscle cells it synapses on are collectively called _______.

Answer 7

motor unit

Question 8

_________ innervate main force generating muscle fibers.

Answer 8

alpha motor neurons

Question 9

_________innervate only fibers of muscle spindles.

Answer 9

gamma motor neurons

Question 10

what generates rhythms?

Answer 10

combination of intrinsic pacemaker properties and synaptic interconnections

Question 11

how to achieve coordination among various limbs?

Answer 11

sets of central pattern generators must be interconnected

Question 12

what is reciprocal innervation?

Answer 12

it increases effectiveness of stretch reflex by minimizing antagonistic forces of antagonist muscles.

Question 13

sound localization along vertical plane depends on what?

Answer 13

distinctive shape of external ear (pinna)

Question 14

how to accurately determine sound along horizontal plane (horizontal direction)?

Answer 14

• two ears needed wherein cochlea of each ear will process the sounds and then sounds will be compared by neurons w/in CNS

Question 15

Interaural intensity difference measures what?

Answer 15

sounds that are high in frequency (~2 to 20 kHz)

Question 16

What does the NS use IOT measure low frequencies?

Answer 16

interaural time-delay map, using info from both ears together

Question 17

how does the brain measure interaural timing?

Answer 17

neural delay lines and coincidence detectors

Question 18

Do neurons in cochlear nuclei receive info from both ears?

Answer 18

No. Neurons in each nuclei receive input from only the ear on one side.

Question 19

What neurons receive abundant input from both ears?

Answer 19

medial superior olivary nucleus

Question 20

what do the axonal length of delay lines and their conduction velocity determine?

Answer 20

how long it takes for activated APs to go from cochlear nucleus to presynaptic terminals onto the MSO neuron.

Question 21

What is the 1st place where APs from both ears converge?

Answer 21

superior olivary nucleus

Question 22

how does the brain organize sensory input and motor output?

Answer 22

brain organizes these functions spatially by use of maps.

Question 23

Main force-generating muscle fibers

Answer 23

extrafusal fibers

Question 24

Muscle spindles

Answer 24

intrafusal muscle fibers

Question 25

group of motor neurons innervating a muscle

Answer 25

motor neuron pool

Question 26

Example of monosynaptic/myotatic reflex

Answer 26

knee jerk reflex

Question 27

What neuron will be stimulated in knee jerk reflex?

Answer 27

primary sensory afferent, which convey their info through Group Ia axons.

Question 28

Monosynaptic communication

Answer 28

Direct communication b/w sensory and motor neurons

Question 29

Why is the reflex relaxation of the antagonist muscle in the knee jerk reflex considered polysynaptic?

Answer 29

it is considered polysynaptic b/c IOT achieve inhibition, branches of group Ia sensory axons synapse w/ inter neurons that inhibit alpha motor neurons of antagonist muscle of quadriceps, resulting in relaxation of semitendinosus muscles.

Question 30

Sensitive to tension w/in a tendon & respond to the force generated by muscle rather than to muscle length

Answer 30

golgi tendon organ

Question 31

Example of polysynaptic inverse myotatic reflex

Answer 31

Golgi tendon reflex

Question 32

Axons present in golgi tendon organ

Answer 32

group Ib axons

Question 33

axons present in muscle spindles/intrafusal muscles

Answer 33

group Ia axons and group II axons

Question 34

What group of axons are involved in polysynaptic flexor reflex?

Answer 34

group A delta axons

Question 35

What axons does a noxious stimulus activate?

Answer 35

group A delta axons

Question 36

How is flexor reflex different from simple stretch reflex?

Answer 36

flexor reflexes coordinate movement of entire limbs and even pairs of limbs Ex. During noxious stimuli

Question 37

Central pattern generators in SC CAN CREATE COMPLEX

Answer 37

motor program even WITHOUT SENSORY FEEDBACK

Question 38

What is a motor program?

Answer 38

Set of structured muscle commands determined by NS before a movement begins

Question 39

What makes the visual thalamus?

Answer 39

primary visual cortex

Question 40

interneurons facilitate sensory-motor communication

Answer 40

polysynaptic reflex ex. golgi tendon, flexor

Question 41

CPGs in spinal cord take advantage in:

Answer 41

- sensory feedback - interconnections among spinal segments - interactions with brainstem control centers

Question 42

is phantom limb a psychological problem?

Answer 42

NO but sensations originate from SC and brain

Question 43

brain's ability to reorganize itself by forming new neural connections

Answer 43

plasticity

Question 44

coincidence detection

Answer 44

axons from both right & left cochlear nuclei converge and synapse onto a series of neurons in MSO nucleus

Question 45

neurons from MSO nucleus and higher CNS centers receive input from: both ears? one ear only?

Answer 45

both ears

Question 46

a positive feedback circuit found in respiratory center also helps maintain consciousness, muscular coordination, & normal breathing

Answer 46

reverberation

Question 47

circuit in which neurons or poos process same info simultaneously found in reflex arcs

Answer 47

parallel-after discharge

Question 48

continuous firing after stimulus has stopped

Answer 48

after discharge

Question 49

a circuit in which neurons or pools work sequentially

Answer 49

serial processing

Question 50

convergence circuit

Answer 50

provides input to a single neuron from multiple sources

Question 51

divergence circuit

Answer 51

spreads stimulation to multiple neurons or neuronal pools in CNS

Question 52

interneurons are organized into functional groups

Answer 52

neuronal pools (responsible for broad range of neural functions)