Class 21 - Nervous System pt. 3 Flashcards
Neural integration
The ability to process, store, and recall information and use it to make decisions.
Chemical synapses allow for decision-making but synaptic delay makes info travel slower
2 types of postsynaptic potentials produced by neurotransmitters
- Excitatory postsynaptic potential (EPSP) - Voltage change from the RMP toward threshold (usually Na+ into cell)
- Inhibitory postsynaptic potential (IPSP) - Voltage becomes more negative than it is at rest (Cl- entry or K+ exit)
____ determine the kind of postsynaptic potential a neurotransmitter activates
Receptors in the postsynaptic membrane
Summation
The process of adding up postsynaptic potentials and responding to their net effect, whether it be excitatory or inhibitory
Occurs in the trigger zone
Two ways EPSPs can be added to reach threshold
- Temporal summation - A single synapse generates EPSPs so quickly that each is generated before the previous one fades
Allow EPSPs to add up and reach threshold - Spatial summation - EPSPs from several different synapses add up to threshold at an axon hillock
An example of facilitation, where one neuron enhances the effect of another
Presynaptic facilitation
When one presynaptic neuron enhances another. Increases
Presynaptic inhibition
When one presynaptic neuron suppresses another one
Reduces or halts unwanted transmission
Neural coding
Converting stimulus information into meaningful pattern of action potentials
Labeled line code
Mechanisms for transmitting qualitative info of the ** type of stimulus**.
Communicated based on which neurons fire (e.g. optic nerve firing interpreted as “light”)
Two ways quantitative info is encoded in the nervous system
Info about the ** intensity of a stimulus**
- Weak stimuli only activate “low threshold” neurons
- Strong stimuli also activate less sensitive “high threshold” neurons through recruitment
Weak stimuli cause neurons to fire action potentials at a slower rate, strong stimuli cause higher firing frequency
Neural pools, discharge zone, and facilitated zone
Functional groups of neurons. Each pool consists of thousands of interneurons concerned with a particular bodily function.
Discharge zone - Zone where the input neuron can act alone to make postsynaptic neurons fire
Facilitated zone - Zone where input neuron makes fewer, less powerful synapses. Can only stimulate targets with the assistance of other input neurons
Diverging vs. converging neural circuits
- Diverging circuit - One nerve fiber branches and synapses with several postsynaptic cells
- Converting circuit - Input from many different nerve fibers is funneled to one neuron/neural pool
Reverberating vs. parallel after-discharge neural circuits
Reverberating - Neurons stimulate each other in linear sequence but one or more of later cells restimulates the first cell to start the process over (e.g. breathing)
Parallel after-discharge - Input neuron diverges to stimulate several chains of neurons, and neurons chains converge on one or few output neurons with varying delays
After-discharge = continued firing after stimulus stops
Serial processing
Neurons and neural pool relay info along a pathway in a relatively simple linear fashion
Can only process one flow of info at a time; multitasking between similar activities doesn’t exist,
Parallel processing
Info is transmitted along diverging circuits through different pathways that act on it simultaneously, for different purposes
E.g. visual and auditory systems fire the same nerves
