Tritonia Swimming Behavior Flashcards
__________________ integrate intrinsic (combine natural), synaptic and network properties during the production of rhymtical activity.
Central pattern generators
What is a classical example of a rhythmical swimming movement?
The Tritonia sea slug swims by making a series of alternating ventral and dorsal interactions.
What is an oscillator?
A device for generating oscillatory (move back and forth) electrical currents or voltage by nonmechanical means
What are the four bilaterally symmetric groups of premotor interneurons that Tritonia swimming oscillator has been localized?
DSI (dorsal swim interneuron)
VSIa (ventral swim interneuron)
VSIb
C2
What are the interneurons that are in between the DSI, VSIa, and VSIb?
Hint: Located in the anterior region of sea slug
Cerebral cells (C2)
True or False: When these four groups of neurons (DSI, VSIa, and VSIb, C2) (w/ their inherent membrane properties and molecular receptors) are precisely connected, a coordinated firing pattern occurs.
True
What do DSI controls?
Controls contractions of the dorsal muscles
What do the VSI controlled?
Control contraction of the ventral muscle
True or False: C2 is not necessary for the circuit to function.
False
When DSI neuron is firing the VSI (do/do not) at all. The sea slug (contracts/ relax) its dorsal muscle.
Do not
Contracting
Both VSI ________ and DSI do not ________. The sea slug is contracting its ventral muscles.
Fire together; fire at all
DSI and VSi are firing alternatively. What would happen to the animal’s behavior if they fire together?
The sea slug will not swim
Where in the simple circuit can it cause oscillations?
How does this simplified circuit predict the firing pattern of neurons?
Hint: There are 5-time units in the cycle.
- A sensory stimulus causes the DSI interneuron to fire a burst of AP
- DSI interneuron excite C2 and C2 beings firing AP
- After the C2 neuron fire
I. C2 inhibits DSI and DSI stops firing
ii. C2 strongly excites VSI-A and VSI A starts firing
iii. C2 excites VSI B and VSI B starts firing
4. After the VSI’s start firing, VSIb strongly inhibits C2 and turns off
5. After C2 turns off
I. C2 no longer inhibits DSI and DSI starts firing slowly
ii. C2 no longer excites VSI A and VSI A stops firing
iii. C2 no longer excites VSI B and VSI B stops firing
1. After the VSI’s stop firing, the VSI no longer inhibits DSI and DSI starts firing more rapidly. The cycle repeats itself.
What are a few differences between the real circuit and a simple circuit?
(1) There are delays in the circuit.
Characteristics of the network are the presence of mainly chemical synapse with very different times.
If the circuit only has interneuron interaction the delay will be based on:
how many time units
how many interneuron
(2) The excitatory connection can be strong or weak
(3) Synapses can be multi-type
(E-I) Exciting and then inhibiting with a delay
(E-I-E) Exciting then inhibiting then exciting
(I-E) Inhibiting and then exciting
Many of these synapses produce multiple PSP
Thus, the synapse from C2 onto DSI cause an E(excitation) followed by I (Inhibition)
(4) DSI in the real circuit excites itself
How many components is in this multiple type synapse?
Also, How do we know that the synapse is multicomponent?
This is a 2 component of multiple types. One will synapse on the motor neuron and the other on the interneurons. One synapse is excitatory and the other is inhibitory.
Place electrode onto the neuron
If postsynaptic become excitatory or inhibitory then the presynaptic is multiple type
The real circuit has an advantage over the simplified circuit. The normal circuit causes _______ firing rates for all _________ groups. Therefore _________ powerful and oscillates slower than the simpler circuit.
Larger ; 3 neuronal ; more
What would happen when an excitatory neuromodulator is added to VSIb?
Hint: useful to stop movement, when the slug escaped from the starfish (preaditors)
The firing rates of VSI b and other neurons in the circuit don’t change much but the circuit as a whole oscillates slower and then the animal will swim slower
What would happen is a “fast pacemaker” is added to DSI?
The firing rates of a cell decrease
the oscillation does speed up but only very slightly.
4 cycle instead of 3 cycles
