Untitled Flashcards Set

Sensation- refers to the act of our sensory systems to detect environmental stimuli

Perception- the CNS and what our brain is telling us to make sense of that sensory information

Types of sensation and perception

Sensory system                                             physical stimuli

Olfactory (smell)                                           odorants (airborne chemicals)

Somatosensory (touch, heat, pain)           pressure or damage to the skin

Gustatory (taste)                                           chemicals (typically in food)

Auditory (hearing)                                        sound waves

Visual (sight)                                                  light (photons)

Sensory receptor cells

• Specialized cells that converts into neural impulses

Sensory transduction

• The process of converting a form of stimuli into a neural impulse that our brain can read

Sensory Homunculus

• Has different sections for different areas that receive sensory stimuli

The limits of our senses

Threshold: the amount of sensory to detect things

• We need a certain amount of things for the sensor to give a response

Absolute threshold- the smallest amount of stimulus that people can detect

Difference threshold

-how much change and amount of change is required to feel stimulus, notice a difference in stimuli

Sensory sensitivity depends on:

• Experience, expectations, and consequences for failure

Signal detection theory- the response to a signal depends in an individuals ability to differentiate between signal and noise

Sensory adaptation

Repeated stimulation of a sensory cell lads to a reduces response

When a stimulus isn't harmful or dangerous your body tends to tune it out more

Ex. Typing in lecture, weird smell in train

Processing sensory info

1. Bottom up processing is taking individual observations, pieces of environmental stimuli and constructing into neural impulses

Bottom up processing

Physical stimuli-> neural impulses sent to CNS-> perception

1. Top-down processing - involves experience and memory and is helped to map out future stimuli, using mental representation that’s already in your brain, precedent

Top-down processing

Previously acquired knowledge -> perception

Perception usually involves both

Top-down examples

• Optical illusion

• A perceptual set is the readiness to interpret a certain stimuli in a certain way 

The senses

Technically there are more than 5 senses

• Nervous system is composed of different sensory systems

• Touch can be broken down!

Kinesthetic (body movement)

Vestibular (head's position, movement)

Can be further divided into thermoception and nociception

The chemical senses

• Olfactory sense (smell)

KEY WORDS: odorants- airborne chemicals that are detected as odours

                        Olfactory receptor neurons- sensory receptor cells that convert chemical signals from the odorants into neural impulses that go to the brain

• Gustatory sense (taste)

The Papillae- the bumps on your tongue,

Taste buds- those are the sensory receptors that convert chemical signals from food into neural impulses that go to brain

1. Sugar

2. Salt

3. Bitter

4. Salt

5. Umami- msg

   • Sensory receptors designed to detect chemical

   • If enough attach to the nerves then the brain will perceive it as a specific type of smell

Eating is more than taste and smell

• Not just about the chemical being detected

• The sense of touch is a big part of how we experience food

• Difference of textures

The development

• Smell Developed at birth

• Taste is too

• Humans are well developed with these sense as they are essential for survival, an infant are helpless, so a nose can help distinguish between safe and unsafe food

Individual differences in taste and smell

• Women are more sensitive to odours than men

• Taste is a variable in individuals, some are more sensitive than others

• "super tasters" more common in women, highly sensitive to tastes, good at detecting differences in taste

Taste disorders

Ageusia- cant taste

Anosmia- cant smell

Hyposmia- less smell

Reflex epilepsy- a seizure after specific odour

Migraine headaches- specific odours can trigger migraines

Disorders may implicate dysfunction in the brain, sensory receptors, or both

Tactile or cutaneous senses

A combination of skin senses including:

• Pressure

• Touch

• Temperature

• Pain

Different somatosensory receptors

• Free nerve endings- surface of the skin, easily accessible, touch , pressure

• Function: detect touch, pressure, pain and temperature

• Meissner's corpuscles, located in fingertips, lips, palms, info about touch

• Function: convert information about sensitive touch

• Markels's - surface of the skin

• Converts info about light to moderate pressure against skin

• Ruffini's end -organs, deep in the skin

• Function: registers heavy pressure, movement of joints

• Pacinian corpuscles- deep in skin

• Function: respond to vibrations and heavy pressure

Steps to perceive touch

1. Finger touches, senses it and sends it to spinal cord then brain

Two pathways of pain

-fast pathways- sharp, localized pain, myelinated, should be registered faster

Slow pathways- more dull burning pain

Development- at birth, the ability of it stimuli is developed with learning

Individual differences- women have a lower threshold of detecting pain than men

People have different reaction to pain based on their sensitivity

Disorders of tactile senses

Chronic pain

• Endorphins that have pain relieving properties

• Drugs mimic body's relief system

• Gate control theory and touch sensations can help alleviate acute pain

No pain (familial dysautonomia)

Phantom limb sensations

Auditory sense

Sound waves

Frequency

Amplitude

How ears hear

1. Sound wave enters ear

2. Waves hit eardrum

3. Waves pass into the middle ear, contains three smallest bones in body

4. Stapes hits the oval window, causes wave to form

5. Fluid detects the basilar membrane, bending hair cells

6. As hairs move, impulses are created and sent to the brain

Strabismus- lack of coordination movement of both eyes affect 2-4 percent of population

Amblyopia- loss of visual abilities in one eye

Other senses: vestibular and kinesthetic

Kinesthetic- receptor cells in your muscles tell the brain when we are moving and where are body parts are

Vestibular- close to our sense of hearing, the movement of fluid tell us if we are standing up or moving

How the eye works

• Light enters the eye

• Muscles in the iris adjust pupil size to control amount of light allowed

• Muscles change shape of lens to bring object to focus

• The lens focuses light on retina, multi layered sheet of nerve cells

• Photoreceptors (receptors for vision called rods and cones) located in retina

There are two classes of photoreceptors (rods and cones) which convert light waves to impulse

Retina

rods

• Detects light

• Used for night vision

• Not as acute as cones

• Many more rods than cones

Cones

• Used for central and colour vision

• Very clear

• Fovea (centre of retina) contains all cones

• Not as many cones

Visual fields

• The optic nerve carries messages from each eye (visual field) to the visual cortex (occipital lobe)

Visual pathway

• The optic nerve contains the axons of 1 million ganglion cells that exit the eye via the blind spot and project to the thalamus

• From the thalamus, neurons project to visual cortex

"what" pathways

• Helps us determine the identity of an object

• Visual agnosia- damage to the "what" pathways

• Prosopagnosia- a form of visual agnosia where people cant recognize faces

"where" pathway

Hemi-neglect

• Damage to the "where" pathway: people ignore one side of their visual field

• People with damage to the right side of their "where" pathways neglect the left side of their visual field

Gestalt (top-down processing) laws

1. Proximity: objects that are physically close together are grouped together

(the figure below, we see 3 groups of six, instead of 18 separate hearts)

1. Similarity: similar objects are grouped together

(the same colours are grouped together)

1. Continuity: objects that continue a pattern are grouped together

2. Closure: we fill in small gasp in objects so that they are perceived as whole objects

3. Figure ground: the tendency to see one part of the picture as the figure and the other one as the background

Visual field impairment

• Strabismus- lack of coordination in both eyes

• Amblyopia- loss of visual abilities in a weaker eye

Other senses

• Kinesthetic- receptor cells in your muscles tell your brain when we are moving and where our body parts are

• Vestibular- located in the semicircular canals of our inner ears; fluid movement tells us if we are standing or swaying