Dr Apurba Krishna Chowdhury

The Walking Principal Project-

Locomotion and the nervous system

Normal Locomotor Motion of our Daily Life-

Simple Walking

Nervous system

The system of cells,

tissues, and organs

that regulates the

body's responses to

internal and external internal and external

stimuli.

Parts of Nervous system The nervous system consists of two main parts: the central nervous system and the peripheral

nervous system:

The central nervous system is made up of the brain and spinal cord.

The PNS peripheral nervous system is made up of the nerve fibers that branch off from the

spinal cord and extend to all parts of the body, including the neck and arms, torso, legs, skeletal

muscles and internal organs.

The brain sends messages through the spinal cord and nerves of the peripheral nervous system

to control the movement of the muscles and the function of internal organs.

Parts of Nervous system

NeuronThe basic working unit of the nervous

system is a cell called a neuron. The

human brain contains about 100 billion

neurons. A neuron consists of a cell

body containing the nucleus, and

special extensions called axons and

dendrites.

The peripheral nervous system, or PNS,

consists of the nerves and ganglia

outside of the brain and spinal cord.outside of the brain and spinal cord.

The main function of the PNS is to

connect the central nervous system

(CNS) to the limbs and organs. The

peripheral nervous system is divided

into the somatic nervous system –

receives sensory information from skin,

joints and muscle and the autonomic

nervous system- receives sensory

information below the level of

consciousness

Spinal Locomotion results from intricate dynamic

interactions between a central program in lowerthoraco-lumbar spine and proprio-ceptivefeedback from body in the absence of centralcontrol by brain as in complete spinal cord injuryFollowing Spinal cord injury, the spinal circuitry

Components of spinal locomotion

Following Spinal cord injury, the spinal circuitrybelow the lesion site does not become silentrather it continues to maintain active andfunctional neuronal properties although in amodified manner

Components of spinal locomotion

Centrally generated patterns

The spinal cord executes rhythmical and sequentialactivation of muscles in locomotion.

The central pattern generator (CPG) provides the basiclocomotor rhythm and synergies by integrating commandsfrom various sources that serve to initiate or modulate itsoutput to meet the requirements of the environment.

Components of spinal locomotion

output to meet the requirements of the environment.

CPG within the lumbosacral spinal cord segments representan important component of the total circuitry thatgenerates and controls posture and locomotion.

This spinal circuitry can function independently in theabsence of descending input from the brain to generatestable posture and locomotion and even modulate activityto match changing conditions (e.g., stepping over obstacles).

This capability improve with training (spinal plasticity) andtherefore it is believed that spinal cord has the capability tolearn and memorize.

Sensory feedback

The sensory feedback originates from muscles, joints, tendons and skin

afferents as well as from special senses and dynamically adapts the locomotor pattern of

spinal cord to the requirements of the spinal cord to the requirements of the environment. These afferent sensory

receptors perceive deformation of tissue the amount of pressure (stretch or simply,

placement), direction of movement, speed and velocity at which movement is occurring

The spinal cord processes and interprets proprioception in a manner similar to how our visual system processes information. When we view a painting, the brain interprets the total visual field, as opposed to processing each individual pixel of information independently, and then derives an image. At any instant the spinal

cord receives an ensemble of information from all receptors throughout the body that signals a proprioceptive “image” that represents time and space, and it

computes which neurons to excite next based on the most recently perceived “images.” The importance of the CPG is not simply its ability to generate

repetitive cycles, but also to receive, interpret, and predict the appropriate sequences of actions during any part of the step cycle, i.e., state dependence.

The peripheral input then provides important information from which the probabilities of a given set of neurons being active at any given time can be finely

The peripheral input then provides important information from which the probabilities of a given set of neurons being active at any given time can be finely

tuned to a given situation during a specific phase of a step cycle. Thus, the functional connectivity between mechanoreceptors and specific interneuronalpopulations within the spinal cord varies according to the physiological state.

Even the efficacy of the monosynaptic input from muscle spindles to the motor neuron changes readily from one part of the step cycle to another, according to

whether a subject is running or walking.

Sensory modulation of CPG

The dynamic interactions between Spinal cord and sensory input are ensured by modulating transmission in locomotors pathways in a state- and phase-dependent manner. Proprioceptive inputs

from extensors can, during stance, adjust the timing and amplitude of muscle activities of the limbs to the speed of

locomotion but be silenced during the swing phase of the cycle. locomotion but be silenced during the swing phase of the cycle. Skin afferents participate predominantly in the correction of limb

and foot placement during stance on uneven terrain, but skin stimuli can evoke different types of responses depending on

when they occur within the step cycle. It is important to note that inputs from the hip appear to play a critical role in spinal

locomotion.

Course OverviewThese were the contents of the program and I was

expected to learn about the topics given below.

What I learned

• Memory, Central Anatomy

• Neuron-its parts, Glial Cell, Myelin, demylinization

• Meninges, Peripheral Diseases, Brain Tumors

• Electrical Language for signal

• Action Potential, Neuro-transmittor, Receptors• Action Potential, Neuro-transmittor, Receptors

• Botox

• Perception, Stimulus, Visual Pathway

• Vision and refractive errors

• Hearing, Vestibular function, Cochlea

What I learned

• Neural Tube-formation, defects, pattern

• Telencephalon, Spinal dermatomes

• Brain Stem, Forebrain, Visual Pathway

• Intra Cranial Pressure

• Blood brain perfusion, Strokes• Blood brain perfusion, Strokes

• Voluntary movements

• Posture control

• Cerebellum, learning, memory, Learning

• Homeostasis, hypothalamus, Pitutary

Subject Correlation and Knowledge applicationsWhat I learned what I can apply in routine daily life

• Nervous system organization and divisions

• How neurons work and conduct

• Central nervous system organization and its disorders

• Brian blood supply and injuries

• Perceptions, illusions, visual disorders

• Hearing mechanism and disorders• Hearing mechanism and disorders

• Muscle movement and posture control

• Movement and gait

• Temperature regulation

• Sleep Rhythms

• Amnesia

• Aphasia

• Memory