Spinal Cord Sensory - MC3.3

Resting potential

-70mV

Depolarization

Na+ in

Repolarization

K+ out

At axon terminal

Ca+ in

At axon terminal

Neurotransmitter out

Refractory Period

during hyperpolarization

Threshold matters

at axon hillock

Synaptic Plasticity

synapses develop and change strength based on the inputs they receive

Synaptic Plasticity is the biological basis of

Learning

Hebbian Principle

Neurons that fire together WIRE together, neurons that are out of sink don’t link. Timing matters!

difference between firing and spatial summation

Spinal Cord

Connects the peripheral sensorymotor system to the brain

Spinal Cord controls the

final common pathway

Nissl Stain

purple are cell bodies

Gray Matter

cell bodies, CNS: Nuclei, PNS: Ganglia, Purple in Nissl

White Matter

Axons, especially myelinated, tracks

Dorsal

toward your back

Ventral

Front / anterior

Dorsal Root

Where sensory into enters the spinal cord

Dorsal horn

Sensory cell synapses and interneuron cell bodies

Dorsal Root Ganglia

Cell bodies of sensory nerves, Just outside S.C.

Sensory Nuerons are Pseudounipolar

Carry sensory information to spinal cord, cell body in dorsal root ganglion, afferent

Modality

Fine touch, vibration

Cell Bodies

dorsal root ganglion

Decussation

crossing the midline happening in the brain stem

Destinations

ipsilateral spinal cord motor pool, contralateral primary somatosensory cortex, fast

Anterolateral System

Anterolateral system modality

Pain, Temperature, crude touch

Anterolateral system cell bodies

dorsal horn

Anterolateral system Decussation

at the level in the spinal cord

Anterolateral system Destinations

contralateral primary somatosensory cortex

Anterolateral system

slow but reliable

Spinocerebellar tracts: spine to cerebellum and involved in error correction

Why sensory information matters

movement accuracy, movement consistency, force adjustments, distance estimation , coordination