SENSING

Understanding sensory-motor integration

ORGANIZATION OF SENSORY SYSTEMS

• Sensori-motor integration• External senses• Localize/Detect and monitor change• Tuned…sense modes• Less sensitive to unchanging stimuli

The Visual System

Tracing the ccts of vision

The organ of vision

The eye is like an SLR camera

Like a camera

• Lens • Iris• photoreceptors

The lens

Like a camera

• Upside-down and inverted

Control of eye movement also critical

Eye movement

Pursuit/tracking

Saccades

vergence

Sensitivity and Limitations of the visual system

The Iris

• Controls light exposure

Visual field and retino-topic organization

The retina-photoreceptive tissue

More on the retina

Receptive fields and Coding

RODS- dark/low illuminationsensitive to movementperipheral vision

CONES- High illuminationsensitive to colorfoveal vision

ROD CONE DISTRIBUTION

FOVEA

FOVEA and optic disc/blind spot

Coding in cones

Foveal acuity

NOTE:

• Light passes through ganglion cell layer, and bipolar cell layer before striking photoreceptors ( light transparent).

• Activation of photoreceptor activats cct in reverse direction.

Sensory convergence

Retina ganglion cell axons coalesce

…and leave eye chamber to form the optic nerve

From retina to cortex

Partial decussation at optic chiasm

Decussation-crossing over

Not as simple as left and right eye

Decussation of visual field info

VENTRAL STREAM

• Object Recognition– Visual agnosias– Prosopagnosia– anosagnosia

• Dorsal Sream-

• WHERE/ CONTEXT/SPACE

– Balints– Movement agnosia– Visual Sensory neglect

Visual hemilateral neglect

• Hearing• Sound • The Structure of Ear • The Pathway from Ear to Cortex • The Neural Coding of Sound

• Pitch • Loudness • Location • Feature Detection • How Does Our Auditory System Develop? • Taste and Smell: A Briefer Look • Taste • Smell