Development of Movement Flashcards
What is the effect of a complete spinal cord transection in a cat?
Hing legs walk on treadmill
What is the effect of electrical stimulation of a cut spinal cord, and how does this change when the DRG is severed?
Alternating flexor and extensor activity in each limb - stepping
No change when DRG severed - afferent sensory input not required
What is the effect of grafting leg cord in place of wing cord in a developing chick?
Wings flap alternatively
What is the effect of grafting wing cord in place of leg cord in a developing chick?
Hopping - not walking
Which transcription factor is required for interneuron differentiation and which domain of the spinal cord is it in?
Dbx
In Vo progenitors
What is the effect of a Dbx1 KO in mice?
Unbalanced activity of excitatory central inhibitory neurons - hopping gait
What is the effect of cutting the central commissure of an embryo in vitro?
Fictive locomotor discharges become asynchronous - CINs required for left-right synchrony
Which post-synaptic plasma membrane ion transporter has a high expression level early in development and what is its effect?
NKCC1
Cotransporter - causes net Cl- influx
Which post-synaptic plasma membrane ion transporter has a high expression level in mature neurons and what is its effect?
KCC2
Causes net Cl- efflux
What are the inputs to CPGs?
Brain
Sensory feedback from periphery
What is the role of the basal ganglia?
Select motor program
What is the role of the MLR and DLR?
Command motor activity initiation - via symmetric activation of reticulospinal complex
What is the role of the tectum and hindbrain?
Affect symmetry of reticulospinal system firing - control steering
What is the role of the motor cortex in movement>
Not required for simple locomotion
Involved in visually-guided movement - in complex terrain
What information does the dorsal spinocerebellar tract carry to the cerebellum?
Sensory information of actual limb movements
What information does the ventral spinocerebellar tract carry to the cerebellum?
Afferent inout of state of CPG circuits
What is the role of the cerebellum?
Receives inputs from 2 spinocerebellar tracts
Compares actual against intended limb status - corrective adjustments sent to spinal cord via descending brainstem neurons
What is the role of the midbrain locomotor region (MLR)?
Changes frequency and pattern of locomotor program - increasing stimulation intensity changes CIN activation - left and right limb movements become synchronised
What is the role of 5HT in reticulospinal pathway development?
Causes upregulation of KCC2 - maturation of inhibitory neurotransmission - enables alternating left-right locomotor pattern
What is the role of glutamate in reticulospinal pathway development?
Relays signals from brainstem command centres - important for locomotion initiation and speed control
When do corticospinal tracts arrive in rat lumbar cord and what is the effect of this?
P6
Enables voluntary movements
What is the role of the dopaminergic diencephalospinal tract?
Controls developmental transition in zebrafish swimming behaviour
How do zebrafish swim at 3dpf?
Mainly immobile - occasional long rapid swims
How do zebrafish swim at 4dpf?
Inflate swim bladder - postural control
Increased locomotion
Swims shorter and more frequent
What is the effect of D4R antagonists on 3dpf larvae?
Prevents developmental movement switch
What is the effect of D4R antagonists on 4dpf larvae?
Reverts swimming behaviour to immature form
How do muscles develop?
Start with only pale fast type fibres - change to slow type where needed - give postural support - required for locomotion
