Spinal cord circuits Flashcards
What is divergence in relation to sensory neurons?
When a neuron transmits information to two or more cells and these neurons follow a similar pattern. Required for high spatial resolution e.g. cones and bipolar cells in retina.
What is convergence in relation to sensory neurons?
When multiple neuronal signals converge onto a neuron. High divergence required to detect weak signals e.g. rods and bipolar cells in retina and for complex or multiple functions e.g. vestibulo-ocular reflex.
What are sensory receptors?
neurons specialized in the transduction of energy generated by external stimuli.
What allows for sensory discrimination within a modality i.e. touch?
Mechanosensory receptors detect specific sensory information within a modality
How do receptive fields aid sensory discrimination?
They allow for spatial discrimination
How can we determine spatial distrubtion?
the two-point discrimination test allows researcher to assess spatial sensitivity discrimination. E.g. more dense receptive fields in the fingers than on the arm
How can firing rate aid sensory discrimination?
Firing frequency of sensory receptors can discriminate within receptor e.g. difference of temperature within cold receptor and warm receptors. Firing rate peaks appears peak in the middle of sensory detection (check slide)
What stimulus discrimination relies on anatomical and functional differences to analyse sensory information in the mammalian nervous system?
Mechanosensory receptors
Spatial distribution of receptors
Windows of response sensitivity (firing rate)
How does the brain extract information about specific features of an object (e.g. space, edge)?
Lateral inhibition - interneurons can inhibit activation of lateral neurons to narrow spread of activity
Spinal cord basic organisation
sensory neurons synapse onto inter/motor neurons in the grey matter in the spinal cord
What is the three neuron relay system?
The ascending pathway for sensory information
What route does mechanosensory information ascend?
The dorsal column
Pain and information ascending route?
anterolateral pathway
What is the motor system
the muscles and neurons
Relexes for proprioceptive sensory input
Muscles spindles - negative feedback regulation of muscle length
Golgi tendon organs - negative feedback of muscle tension
