MCB 462 Exam 2 Study Guide Questions With
Complete Solutions
How can different neuromodulators and their receptors cause different CPG outputs? -
ANSWER different CPGs may differ from each other in having different receptors to the
neuromodulators. Thus, different neuromodulators can cause different patterns of
output
-basically, different neuromodulator inputs can change CPG output patterns,
modulating the coordination states in CPGs
What are AMPA/kainate receptors neuromodulators responsible for? - ANSWER
mediating phasic EPSPs (spikes of the burst)
What are NMDA receptors neuromodulators responsible for? - ANSWER mediate
plateau potentials (the plateau of the burst)
-bursts are initiated by AMPA and NMDA receptors; NMDA receptors initiate the plateau
potentials on which spike bursts are sustained; plateau potentials are terminated by
I(K,Ca) as the AHPs (after-hyperpolarizations) summate
What are 5-HT (serotonin) receptors neuromodulators responsible for? - ANSWER
-reduces I(K,Ca)
-decreases after-hyperpolarizations, increasing spike frequency in burst
-increases plateau potentials, prolonging burst duration
-has effects on phase lag between segments
How can descending inputs from the brain cause different CPG outputs in the spinal
cord? - ANSWER descending inputs from the brain can virtually rewire CPGs by
inhibiting some synaptic paths and permitting others to function
-this is metastable coordination: the CPG can produce different output patterns when it
receives descending input which can "rewire" the excitatory and inhibitory circuitry of
the CPG
Describe locomotion in the lamprey with respect to behavior - ANSWER a lamprey
swims through water by generating a mechanical wave that ravels along its body,
creating an undulating motion; the lamprey locomotes forwards by an antero-posterior
(head-to-tail) traveling wave caused by alternating muscle contracture on each side;
backward locomotion results from a posterio-anterior (tail-to-head) traveling wave of
alternating muscle activation
, -also selective co-activation of the dorsal and ventral muscle bundles allows dorsal or
ventral bending in addition to the lateral bending of the swim
Describe locomotion in the lamprey with respect to strucuture of the elemental CPG -
ANSWER the lamprey CPG is built around a half-cell
-glutamatergic neurons excite all CPG elements on their own side
-glycinergic neurons inhibit all CPG elements on the opposite side
-motor neurons activate muscle groups on the same side
Describe locomotion in the lamprey with respect to the function of the CPG - ANSWER
basically, the main function of the lamprey CPG is to produce alternating activity
between the left and right side of the body segment, so that, for instance, when the
segment's left muscle bundle is activated and contracted, then the right muscle bundle
is inhibited and relaxed, and vice-versa
-this allows for the local bend formation in the lamprey body that is seen in its undulatory
motion pattern
-alternating activity between the left and right side of the body is integral part of the
motor pattern in swimming, as well as walking, and is made possible by CPGs
Describe locomotion in the lamprey with respect to coupling within the chain of CPGs
and the resulting effect on locomotory pattern - ANSWER -100 segments in the lamprey
spinal cord; phase lag between segments is 1%
-the spread of excitation from segment to segment and the phase lag between segments
are due to the connections with the chain of CPGs
-inhibitory interneruons project both contralaterally and caudally up to 30 segments and
sometimes rostrally
-excitatory interneruons project ipsilaterally and either rostrally or caudally for at least 5
segments
Describe locomotion in the lamprey with respect to the role of serotonin - ANSWER
-reduced I(K,Ca), resulting in decreased after-hyperpolarization, increasing spike
frequency in burst, and increased plateau potentials, prolonging burst duration > this
affects the phase lag between segments
Complete Solutions
How can different neuromodulators and their receptors cause different CPG outputs? -
ANSWER different CPGs may differ from each other in having different receptors to the
neuromodulators. Thus, different neuromodulators can cause different patterns of
output
-basically, different neuromodulator inputs can change CPG output patterns,
modulating the coordination states in CPGs
What are AMPA/kainate receptors neuromodulators responsible for? - ANSWER
mediating phasic EPSPs (spikes of the burst)
What are NMDA receptors neuromodulators responsible for? - ANSWER mediate
plateau potentials (the plateau of the burst)
-bursts are initiated by AMPA and NMDA receptors; NMDA receptors initiate the plateau
potentials on which spike bursts are sustained; plateau potentials are terminated by
I(K,Ca) as the AHPs (after-hyperpolarizations) summate
What are 5-HT (serotonin) receptors neuromodulators responsible for? - ANSWER
-reduces I(K,Ca)
-decreases after-hyperpolarizations, increasing spike frequency in burst
-increases plateau potentials, prolonging burst duration
-has effects on phase lag between segments
How can descending inputs from the brain cause different CPG outputs in the spinal
cord? - ANSWER descending inputs from the brain can virtually rewire CPGs by
inhibiting some synaptic paths and permitting others to function
-this is metastable coordination: the CPG can produce different output patterns when it
receives descending input which can "rewire" the excitatory and inhibitory circuitry of
the CPG
Describe locomotion in the lamprey with respect to behavior - ANSWER a lamprey
swims through water by generating a mechanical wave that ravels along its body,
creating an undulating motion; the lamprey locomotes forwards by an antero-posterior
(head-to-tail) traveling wave caused by alternating muscle contracture on each side;
backward locomotion results from a posterio-anterior (tail-to-head) traveling wave of
alternating muscle activation
, -also selective co-activation of the dorsal and ventral muscle bundles allows dorsal or
ventral bending in addition to the lateral bending of the swim
Describe locomotion in the lamprey with respect to strucuture of the elemental CPG -
ANSWER the lamprey CPG is built around a half-cell
-glutamatergic neurons excite all CPG elements on their own side
-glycinergic neurons inhibit all CPG elements on the opposite side
-motor neurons activate muscle groups on the same side
Describe locomotion in the lamprey with respect to the function of the CPG - ANSWER
basically, the main function of the lamprey CPG is to produce alternating activity
between the left and right side of the body segment, so that, for instance, when the
segment's left muscle bundle is activated and contracted, then the right muscle bundle
is inhibited and relaxed, and vice-versa
-this allows for the local bend formation in the lamprey body that is seen in its undulatory
motion pattern
-alternating activity between the left and right side of the body is integral part of the
motor pattern in swimming, as well as walking, and is made possible by CPGs
Describe locomotion in the lamprey with respect to coupling within the chain of CPGs
and the resulting effect on locomotory pattern - ANSWER -100 segments in the lamprey
spinal cord; phase lag between segments is 1%
-the spread of excitation from segment to segment and the phase lag between segments
are due to the connections with the chain of CPGs
-inhibitory interneruons project both contralaterally and caudally up to 30 segments and
sometimes rostrally
-excitatory interneruons project ipsilaterally and either rostrally or caudally for at least 5
segments
Describe locomotion in the lamprey with respect to the role of serotonin - ANSWER
-reduced I(K,Ca), resulting in decreased after-hyperpolarization, increasing spike
frequency in burst, and increased plateau potentials, prolonging burst duration > this
affects the phase lag between segments
