Introduction to Sensation The Basics

Streams of info coming in from different senses interact. Translation of info from outside the nervous system into neural activity. Streams of info coming in from different senses interact. Reality of sensation differs from person to person.

Which do you prefer? Return

Sensory Interaction Return

What is this image? Don’t take the sensory process for granted! Your visual system had to detect the light reflected off the screen and translate (or transduce) the light energy into neural activity the brain could interpret. Your brain doesn’t interpret raw physical energy. Our sensory systems are so efficient we are rarely aware of the process.

Sensation & Perception The process through which the senses are given meaning Sensation Info about the world is gathered from forms of energy Sound, light, heat, physical pressure.

Sensory Systems Auditory/Visual/Gustatory/Olfactory/Tactile/Proprioceptive Systems Humans rely primarily on vision/hearing/skin sensations to gather info about the world Humans rely less on smell & taste to gather info about the world

Sensory System Process Energy contains info about the world Accessory structure modifies energy Receptor cells transduces energy into a neural response Sensory nerves transfer coded activity to the CNS Thalamus processes and relays the neural response Cerebral cortex receives input and produces the sensation & perception Return

Example Accessory Structures Lens of the Eye Pinna of the Ear Return

Receptor Cells in the Sensory Systems Respond to changes in energy Constant levels of stimulation result in adaptation Transduction is the process of converting incoming energy into neural activity. Return

Examples of Sensory Adaptation Visual dark adaptation Turning off the lights Smell (good or bad) adaptation Walking into someone’s house Temperature (not too extreme) adaptation Adjusting to the temperature outside Return

Coding of Sensory Information Coding is the process of translating the physical properties of a stimulus into a pattern of neural activity that specifically identifies those properties. Think about action potential.

Types of Sensory Coding Temporal Coding TIMING patterns of a nerve firing. The more INTENSE the energy, the faster the neuron fires Spatial Coding Involves the location of firing neurons relative to their neighbors. Allows us to know where sensations are coming from.

Doctrine of Specific Nerve Energies Stimulation of a particular sensory nerve codes for that sense no matter HOW the stimulation takes place 1. With your eyes closed, press on your eyeball…gently! 2. Ever get hit by something on the ear/side of your head? Return