Neural control of locomotion

Neural Control Of Locomotion
- PRIYANKA.PARATE
NEURO MPTH,PUNE

Introduction
• Human locomotion (gait cycle) is not only the cycle of
mechanical events but also controlled by nervous system.
• As child grows up and his nervous system gets matured,
locomotion pattern also changes from reflexive
gestational movements to matured adult gait cycle
(bipedal plantigrade gait pattern).
• Different structures of nervous system plays different
important role in locomotion these include-
1. Central pattern generator
2. Peripheral receptors and afferents.

3. Brainstem locomotor regions.
4. Cerebellum
5. Basal ganglia
6. Cerebral cortex

1. Central Pattern Generators
 CPGs refer to grouping of neurons or neural
circuits that can generate co-ordinated
movements autonomously.
Reflexive movements of human fetus start at 8
week of gestation.
It has been observed that infants with total loss
of cerebral cortex development(anencephaly)
also has co-ordinated leg movements, which

indicates presence of same mechanism at spinal
level, generating the movements known as CPG.
CPGs can gnerate co-ordinating movement
even in absence of afferent inputs but if afferent
neurons are intact, it gives different outputs as
per requirement of speed.
For eg- walking, running its activity constantly
changes as per inputs.

 Command neurons are the neurons which pick
up the preferred sensory input for a specific
phase and initiate CPGs.
Though this is been seen in intact spinal cord
but not true for cord injury at higher levels or
loss of efferents from cortex and hence biased
for humans.
The possible description is quadripedal
locomotion requires co-ordinated movements for
all four limbs.

 Bipedal requires more of balance i.e equilibrium
As equilibrium is largely a supraspinal function.
Humans have got efferent pathways more as
compared to any other animal substituting the
CPGs.

PERIPHRAL RECEPTORS AND
AFFERENTS

2. Peripheral Receptors and Afferents.
 Generation of locomotion depends on sensory
inputs, the most important input is from muscle.
For a co-ordinated smooth bipedal locomotion,
constant monitoring of muscle length and tension
is required.
This is done by muscle spindles and golgi tendon
organs which are sensitive to length/ tension.

 Muscle spindles is supplied by gamma motor
neurons which determines sensitivity of muscle
stretch i.e changes its sensitivity as per
requirement of movement.
This helps in dynamic changes in muscle length
during hhuman locomotion.
Thus acting as a feedforward mechanism along
with feedback.

 Golgi tendon organs are contraction sensitive
mechano receptors innervated by I b fibers.
GTOs constantly alters the force output of
different muscles as per requirement, as in
stance phase flexors are inhibited.

3.Brain Stem Locomotor Regions
 Brainstem has got three important locomotor
region-
1) Mesencephalic locomotor region-
 Receives afferents from basal ganglia, limbic
system and sensorimotor cortex and connects to
spinal circuitry via reticulo spinal tract.
 It is important for relay between cortical limbic
drives and CPGs.

2) Pontine locomotor regions-
 Present just below mesencephalic locomotor
region (MLR), may extend till upper cervical spinal
cord.
 These regions are responsible for postural tone
and changes firing within MLR.
3) Subthalamic locomotor regions-
 Necessary for modulation of locomotion pattern.
Studies have been done mainly on animals, which

Shows loss of ability to avoid obstacles in absence
of this region.
4) Reticular formation region-
 network of circuit, located at brainstem from
midbrain to medulla.
Function- temporal and spatial co-ordination of
movement.

4. Cerebellum
 Important function for smooth execution of
voluntary movements.
Some regions of cerebellar cortex are active
before movement and preset the body for intented
movement.
The cerebellum receives somatotopically
organized inputs from cerebral cortex, brainstem
nuclei such as vestibular nuclei.

 Also from dorso ventral spinothalamic tracts
both the tracts gives this similar information.

5. Basal Ganglia
 Functions- play an important role in initiation
and termination of movement.
Processes sensory stimuli and determine which
stimuli will be used by the CNS to impact
movement.
It not only integrate sensory information, but
also attach situational or emotional significance
to it.

6. Cerebral Cortex
 Functions- Motor planning
- Visuomotor co-ordination
- Cognitive aspects of motor control.
 Cortical neurons often are activated before
movement onset and typically fire phasically
during locomotion.
For eg- equilibrium, bipedal gait, anticipatory
muscle action, and bodily responses need

higher organisation are done by cerebral cortex.
 Cerebral cortex makes a motor planning by
integrating sensory information from neurons
within functionally acting cortical cells.
By long loop trans cortical reflex pathways it can
modulate and shape, simple spinal reflexes.
This shaping is vitally important for anticipatory
reactions.

Neural control of locomotion

More Related Content

What's hot (20)

Similar to Neural control of locomotion (20)

Recently uploaded (20)

Neural control of locomotion