NN2 repeat Flashcards
What are the two main outcomes of neurotransmission involving glutamate and GABA?
Glutamate results in excitation, while GABA results in inhibition.
What determines whether a neurotransmitter is excitatory or inhibitory?
The type of neurotransmitter and the receptor it binds to determine whether it is excitatory or inhibitory.
How do ionotropic and metabotropic receptors differ in neurotransmitter response?
Ionotropic receptors respond directly to neurotransmitter binding by opening ion channels, while metabotropic receptors trigger intracellular signaling cascades.
What is a “quanta” in neurotransmission?
A quanta refers to the release of neurotransmitter from a single vesicle.
Name one strategy to increase quantal release in neurons.
Extensive innervation, as seen in Purkinje cells, or the presence of a large presynapse like the Calyx of Held.
What is synaptic integration?
It is the summation of postsynaptic membrane potentials from multiple synaptic inputs.
How does inhibition influence spontaneously active neurons?
Inhibition can sculpt the discharge patterns of these neurons by suppressing certain action potentials.
What are the two types of inhibitory neurons in the neocortex mentioned in the document?
Low-threshold spiking (LTS) cells and fast-spiking (FS) cells.
What neurotransmitter do both LTS and FS cells release?
GABA.
What is the role of climbing fibers in the cerebellar network?
They regulate the low discharge of Purkinje cell complex spikes through extensive synaptic contacts.
Define sensory transduction.
It is the conversion of a physical stimulus into a change in membrane potential.
What are the four key events in sensation?
- Stimulation of the sensory receptor.
- Transduction of the stimulus.
- Generation of nerve impulses.
- Integration of sensory input.
What is the difference between general and special senses?
General senses include touch, pressure, temperature, pain, and proprioception, while special senses include smell, taste, vision, hearing, and balance.
What is lateral inhibition, and how does it help in sensory perception?
Lateral inhibition exaggerates differences in stimulus intensity between adjacent neurons, improving localization.
What principle is used to estimate stimulus location in sensory systems?
Topographic mapping, such as somatotopy in the somatosensory system.
What is the relationship between the distance of a synapse and its influence on a neuron’s trigger zone?
The influence of a synapse decreases as the distance to the neuron’s trigger zone increases.
What are the two main types of synaptic contacts in neurons?
Axosomatic (axon to soma) and axodendritic (axon to dendrite).
What does the term “network architecture” refer to in neuroscience?
It refers to the arrangement of excitatory and inhibitory neurons and their physiological properties, such as firing patterns
What are the primary functions of sensory systems?
Sensory systems detect signals and discriminate aspects of sensory input, such as modality (what is it), intensity (how much of it), location, and duration.
What is the function of sensory receptors?
Sensory receptors detect specific stimuli and perform transduction, converting physical stimuli into electrochemical signals.
How does adaptation affect sensory coding?
Adaptation reduces the frequency of action potentials during sustained stimuli, modulating the perception of intensity.
What is a receptive field (RF)?
An RF is the region of sensory space where stimulation changes the firing rate of a neuron.
How does the brain identify the modality of a sensory input?
Through labeled lines, where specific neural pathways are dedicated to particular sensory modalities.
What neurotransmitter is released by granule cells and inferior olivary cells in the cerebellar network?
Glutamate.
What is the role of Purkinje cells in the cerebellum?
They integrate inputs from parallel and climbing fibers and regulate motor coordination.
How do parallel fibers influence Purkinje cells?
Parallel fibers, originating from granule cells, contact Purkinje cells to generate high-frequency simple spikes.
What is the role of climbing fibers in motor learning?
Climbing fibers mediate complex spikes in Purkinje cells, essential for motor learning and timing.
What is the significance of LTD (long-term depression) in Purkinje cells?
LTD at parallel fiber-Purkinje cell synapses decreases Purkinje cell activity, disinhibiting the interposed nucleus for motor learning.
How do mechanoreceptors and nociceptors differ in function?
Mechanoreceptors detect physical deformation, while nociceptors respond to painful stimuli.
What is the principle of topographic mapping in sensory systems?
Points close together on the sensory surface are represented close together in the brain, such as somatotopy in the somatosensory system.
What is the function of lateral inhibition in sensory systems?
It sharpens sensory perception by exaggerating differences in stimulus intensity between adjacent neurons.
What is the difference between graded potentials and action potentials?
Graded potentials vary in amplitude and are not propagated, while action potentials have a fixed amplitude and are propagated along the neuron.
What is feedforward inhibition in neural networks?
Feedforward inhibition occurs when an excitatory neuron activates an inhibitory interneuron, which then suppresses the activity of a downstream neuron. This mechanism ensures precise timing and prevents overexcitation.
What is the primary role of feedforward inhibition in neural circuits?
It enhances signal precision by limiting the duration of excitatory signals and shaping the timing of action potentials in target neurons.
How does feedback inhibition function in neural networks?
Feedback inhibition involves an excitatory neuron activating an inhibitory interneuron, which then inhibits the original excitatory neuron or its neighbours, creating a regulatory loop.
What is the main purpose of feedback inhibition?
Feedback inhibition maintains homeostasis in the network by preventing runaway excitation and stabilizing neuronal activity.
How do feedforward and feedback inhibition differ in their timing and control?
Feedforward inhibition occurs early in the signal pathway, acting as a filter for incoming signals, while feedback inhibition occurs later, regulating ongoing activity within the network.
What is the significance of convergence in feedforward inhibition?
Convergence ensures that multiple excitatory inputs can collectively activate inhibitory neurons, providing robust suppression of downstream targets.
How does divergence influence feedback inhibition?
Divergence allows a single inhibitory neuron to suppress multiple excitatory targets, amplifying the inhibitory signal across the network.
How do inhibitory interneurons sculpt excitatory neuron firing patterns in feedback loops?
Inhibitory interneurons selectively suppress spontaneous or excessive excitatory neuron activity, creating rhythmic or patterned firing in the network.
What is the role of feedforward and feedback inhibition in sensory processing?
Feedforward inhibition enhances signal specificity and prevents overstimulation, while feedback inhibition regulates gain control and adapts network responses to sustained inputs.
How does the balance of excitation and inhibition affect network function?
Proper balance ensures optimal signal transmission and prevents pathological states like epilepsy (overexcitation) or hypoactivity (overinhibition).
