Our Senses Depth Perception Requires the use of

Our Senses

Depth Perception • Requires the use of both eyes (binocular vision). • Uses Pre-learned information from the brain.

Optical Illusions • Depend on our previous interactions with how things look. • Some “tricks” illusions utilize: – Can use shadows and light. – Can use perspective and context. – Can use patterns and familiar shapes. – Can use missing details.

Our sense of touch • What we detect: – Pressure – Pain – Temperature (heat and cold) – Proprioception • (our consciousness of space and our body moving in it – includes balance)

Touch Receptors • Different touch receptors detect different sensations. (heat, cold, constant pressure, pain) – page 57 in text. • The number of receptors and the size of the fields vary in different areas of the body. • Are most densely packed in the fingertips and lips. • Least densely spaced in the back and legs.

Receptors • Types: – Touch – Photoreceptors (rods and cones) – Hearing – Taste – Smell – “stretch” – tell brain how much muscles are contracted or streched. • Located on the ends of sensory neurons

Neuron types • Sensory neurons – send information to the brain. • Motor neurons – send information back from the brain telling the body to move. • Neurons carry electrical signals back and forth. • Constant communication happens between our senses and our motor neurons.

3 main parts of a neuron • Cell body – center of operation, contains nucleus. • Dendrites – branches which receive incoming information. • Axon – a long thin extension of the cell that passes the “message” along to other neurons. It actually carries an electrical charge!

Between neurons • Synapse – the tiny space between the axon of one neuron and the dendrite of the next. • When an electrical impulse reaches the end of an axon (away), the axon releases neurotransmitters (chemicals) that communicate with the next dendrite.

Neurotransmitters • Many types – Acetylcholine – Dopamine – Adrenaline (norepinephrine) – Serotonin – Endorphins (gives the runner “high” people experience during increased physical stress – also released when eating chocolate!)

Brain development • • By 3 weeks a fetus has the brain budding. By 5 weeks it has divided into 3 main regions. Newborn is ¼ the size of an adult brain. Much is still not known about the way pathways in the brain are used and reinforced.