Sensory Signal Processing

Information

Sensation Perception

Attributes of a Stimulus

1. Modality

2. Location

3. Timing

4. Intensity

Sensory Modality Is Determined by the Stimulus Energy

The same cause, such as electricity, can simultaneously affect all sensory

organs, since they are all sensitive to it; and yet, every sensory nerve

reacts to it differently; one nerve perceives it as light, another hears its

sound, another one smells it; another tastes the electricity, and another

one feels it as pain and shock. One nerve perceives a luminous picture

through mechanical irritation, another one hears it as buzzing, another

one senses it as pain. . .. . . Sensation is not the conduction of a quality or

state of external bodies to consciousness, but the conduction of a quality

or state of our nerves to consciousness, excited by an external cause.

Johannes Müller 1826 Handbuch der Physiologie des Menschen für Vorlesungen, 2nd Ed., translated by Edwin Clarke and Charles Donald O'Malley:

Modality Is Encoded by a Labeled Line Code –

•Stimulus transduction

•Receptor specificity

•Stimulus threshold

The Spatial Distribution of Sensory Neurons Activated by a Stimulus Conveys Information About the Stimulus

Location

Weber’s Law of “Just Noticeable Difference”

Sensory thresholds

Stimulus intensity is encoded by frequency of AP

Sensory Systems Have a Common Plan

Somatic Sensory Signal Processing

Somatic Sensory Receptors

Excitation of sensory nerve

Types of nerve fiber - Principle of Connectional Specificity

Dermatomes

Trigeminal nerve

Central Pathway

Thalamus

Sensory Cortex

Thalamocortical projection

Integration of tactile information by Cortex

The columnar organization of cortical neurons

Each region of the somatic sensory cortex receives inputs from primarily one type of receptor.

Two Point Discrimination

Two Point Discrimination

Shape and Size Sensation

Spatial and Temporal Summation

Vibration Sense

Pain Signal Processing

Types of Pain

Pain Perception

Pain Pathway

Dual Pathways for Transmission of Pain Signals into the Central Nervous System

Nociceptive Components of the Thalamus and Cortex

Gate control theory

Pain Modulation

The Placebo Effect

Sensitization

Visceral Pain

Phantom Limbs and Phantom Pain

Energy channels

Chakra or Energy center

Memory of pain beyond present life

Rangeetha L. Balsuriya 20Y/FPresenting symptom

– Pain in abdomen, back and chest x 7months admitted 5 times in the hospital without relief

Examination: Normal except scoliosisInvestigation: X-Spine – Lumbar scoliosis

– MRI spine, IVP, Biochemistry, Urine Normal

Diagnosis: Somatoform Pain disorder

Treatment:• Stopped all analgesic• Relaxation therapy • Interferential therapy• Placebo analgesia• Transient relief of pain with any new

mode of treatment• Planed to start Hypnotic regression to

see any childhood psychogenic trauma causing present problem