6-10 Flashcards
Explain the function of sensory nerves (1)
- Carry information from the body’s peripheral sensors into the nervous system for the purpose of both perception and motor coordination
- Are also known as afferent neurons
What sensory properties does our skin have? (6)
- Pain
- Pleasure
- Touch
- Itching
- Heat
- Vibration
What are somatic receptors and give 3 examples of somatic receptors.
- A subgroup of sensory receptors involved in different sensory perception.
- Located in the skin, muscle bones, and joints
EXAMPLES
Mechanoreceptors - touch and proprioception
Nociceptors - pain
Thermoreceptors - temperature
Receptor potential from short mechanoreceptors spread ______ from the _________ region to the ________ pole.
This action (does/does not) require an action potential
passively; sensory; synaptic; does not
Receptor potential from long mechanoreceptors can generate _________ and gives information about _______ and ______ of the original stimulus.
Action potentials; duration or intensity
Describe the course of action potential frequency in slowly and rapidly adapting receptors. What is receptor MRO1? What receptor is MRO2?
Slow adapting receptors
- Weak stretch produces a series of action potential
- MRO1
Fast adapting receptors
- Action potential frequency declines over time during long stretch (receptro potential is not maintained)
- MRO2
What kind of signals are recorded during intracellular recording? (2)
Afferent nerve: retrograde signals
Efferent nerve: anterograde signals
Explain the process to dissect a crayfish, leaving only the superficial extensors on the crayfish for experimentation.
- Remove head
- Remove ventral part of the shell by cutting close to ventral surface
- Remove deep-flexore muscles with hand
- Attach a thread to the tail
How can we obtain a high signal-to-noise ratio when performing extracellular recording?
- Getting the best possible recording (high signal)
- Decreasing the noise reaching the electrode (low noise)
- Electronically removing noise that reaches the amplifier (filtering)
What are muscle receptor organs?
- Stretch-sensitive proprioceptors that help track the positioning of body parts
- Broader category: somatic receptors
What are the functions of exteroceptors? (3)
Touch, temperature, pain
What is the function of enteroceptors? (1)
Regulation of internal processes
- Respiration
- Thirst
- Hunger
- blood pressure
What is neuroplasticity?
The ability of neurons and neuronal networks to change or adapt de to experience
E.g.
- Learning a new ability
- Neuronal damage/dysfunction
- Information acquisition
- Environmental influence
What are two types of plasticity?
Functional plasticity: transfer functions from an impaired region to unaffected areas
Structural plasticity: alter physical structure in response to the process of learning
What types of learning are there? (2)
- Associative learning
- Behavioural change by formation of associations between events or two stimuli
- Classical conditioning (involuntary)
- Operant conditioning (voluntary) - Non-associative learning
- Behavioural change due to experience with particular stimuli
- Habituation (negative memory)
- Sensitization ( positive memory)
Why are Aplysias used as animal models in electrophysiology? (5)
- Short life span (~ 1 year)
- Simple nervous system
- Large nerve cell bodies (largest reaches up to 1mm)
- Little variation (consistent location of individual neurons between groups)
- Capable for various behaviours and simple learning
What is short-term habituation and its mechanism?
Habituation is a process that causes the animal to become less responsive to repeated occurrences of a stimulus.
- Occurs due to activity-dependent presynaptic depression of synaptic transmission
- Quantal release of glutamate decreases from the presynaptic terminals of sensory neurons
What are three falsified theories of habituation and how are they proven false?
- Muscle fatigue
- Reflex response remained constant throughout when strong stimulus applied - Motor synapse fault
- Stimulation of motor neuron after habituation of Aplysia elicited nonhabituated response - Skin sensitivity
- Blocking of signals to the sensory neuron when Aplysia is habituated yields recovery despite skin being stimulated even when nerve block occurred.
What are 5 examples of bad trials during the habituation experiment?
- Natural movements or reflexes
- Responses to water movement, such as shaking a table, or reactions to shadows
- You touched a different part of the siphon/body
- Double pump (siphon/gill)
- Variations in the intensity or speed of touching the siphon, whether too strong, too weak, very fast, or very slow.
What are some good notes to take during an Aplysia experiment? (4)
- If aplysia inks
- If aplysia is non-responsive
- If an aplysia laid eggs
- If you missed a trial, had a problem, any other issues
Explain the pathway of neuronal signals in a reflex response
- Sensory signals
- Only signal that is affected stimulus and have a graded receptor potential in this pathway - Motor signals
- Uses graded synaptic potential - Muscle signals
- Uses graded synaptic potential
What can affect the extent of sensitization in aplysias? (3)
- Age of the animal
- Intensity of the stimulus
- Frequency of the exposure of the stimulus
What type of cellular receptros are associated with serotonin binding? (2)
- Channel linked
- ion channels - GPCR
Explain the pathway for short- and long-term sensitization
Short-term
1. Noxious stimulus to tail
2. Release of serotonin in through serotonergic modulatory neurons
3. Stimulated GCPR activated for cascade effect through effectors (e.g. cAMP)
- Actiaved PKA prevents outflow of K+ and helps influx of Ca+2
Long-term
4. PKA enters nucleus and activates CREB (promoter)
5. CREB recruite other transcription proteins to transcript target gene
6. Transcribed gene causes synaptic plasticity
7. Ubiquitinhydrogolase increase cAMP in sennory presynaptic
What is the defining contributor to short-term and long-term sensitization.
Short-term: serotonin upreguulates cAMP and PKA in sensory nerve terminal for more glutamate release.
Long-term: Requires new nuclear gene expression and protein synthesis. Caused by repeated activation of serotonergic modulatory neurons.
What differs from LTP and LTD?
LTP - long-term increase in synaptic strength through insertion of additional AMPA receptors
LTD - long-term decrease in synaptic strength through internalization of AMPA receptors
What type and dosage of current is injected to Aplysia when delivering an electrical stimulus during the sensitization experiment?
- 60-100mA
- DC current
How large should the sample size be for a standard scientific experiment and why? (3)
- A standard scientific experiment should have at least 3 samples per group
- Ensures statistical reliability of experiment
- Control for differences in experimental outcomes
a. Differences in animal physiology
b. Variations in experimental procedure
c. Setup configurations
How can we calculate for the change in response over time in a habituation and sensitization experiment?
|Initial Response Time - Final Response Time|/Initial Response Time *100
(Increase in response = Initial<Final; Decrease in response = Final<Initial)