Exam #4 Flashcards
What percent of your body weight does skin account for?
16%
Discrimination touch
- Perception of pressure, vibration, and texture
- Mediated by 4 different categories of mechanoreceptors in the skin
Pain and temperature
Free nerve endings
Proprioception
Registration of tension and stress in muscles and joints
Rapidly adapting (RA)
Respond to changes in stimulation, but do not continue to respond to constant stimulation
Slowly adapting (SA)
Respond to constant stimulation
Punctate
Small receptive fields with distinct boundaries
Diffuse
Large receptive fields with non-distinct boundaries
4 receptor types enervated by nerve fibers
- Merkel disks
- Meissner corpuscles
- Ruffini ending
- Pacinian corpuscles
Merkel disks
Constant source of stimulation over a small area (shallow)
ex: carrying a pebble
Meissner corpuscles
Respond best to active touch, involved in detailed object exploration (shallow)
Ruffini ending
Constant stimulation over a larger area, also detects skin stretch (deep)
Pacinian corpuscles
Extremely sensitive over a large receptive field (deepest)
ex: blow gently on the palm of your hand
How do receptors work? (2 steps)
- Mechanical stimulus (ex: pressure) deforms receptors’ membrane
- This starts a cascade of events that ultimately results in an AP
3 primary types of proprioceptors
- Muscle spindles
- Golgi tendon organs
- Joint receptors
Muscle spindles
Mechanoreceptors that detect changes in muscle fiber length (stretch) and velocity (speed of stretch), maintains intended limb movement position, direction, and velocity
Golgi-tendon organs
In skeletal muscle near insertion of tendon, detects changes in muscle tension (ex: force), not good at detecting muscle length changes
Joint receptors
Detect change in force and rotation applied to joint, joint movement angle
Peripheral sensory apparatus (in vestibular system)
- Semicircular canals and otolithic organ
- Detects and relays info about head orientation and head angular and linear acceleration to brain
- Orients head with respect to gravity
Central processing system
Processes info in conjunction with other sensory inputs for position and movement of head in space
Motor output system
- Generates compensatory eye movements and compensatory body movements during head and postural adjustments
- Sense of orientation
- Detection of linear and angular acceleration
Semicircular canals
Detects rotational movements by using hair cells to sense fluid displacements
Otolithic organ
Detects linear acceleration and head orientation, otoconia crystals (little rocks) stimulate hair cells in canals
Gate control theory of pain
Pain is actively suppressed in emergency situations by messages sent from brain to Dorsal Horn, pain continues when emergency is over
Referred pain
Pain that feels as if it is coming from some part of the body other than the part being stimulated
Haptics
Active touch, interaction of proprioceptive and mechanoreceptive info (ex: allows up to determine Braille)
Mastication
Chewing, aids in digestion, promotes release of taste stimulants
5 basic taste sensations
- Sweet- sugars, some AAs
- Salty- metal ions (inorganic salts)
- Sour- hydrogen ions (acids)
- Bitter- alkaloids
- Umami- AA glutamate (MSG)
Labeled-line hypothesis (specificity)
Single taste cells respond selectively
Ageusia
Complete loss of sense of taste
Selective aguesia
Loss of specific taste sense
Hypogeusia
Diminished taste sensitivity
Hypergeusia
Enhanced taste sensitivity
Dysgeusia
Distortion in taste perception
What is the cross fiber hypothesis analogous to?
- It is a population code for taste
- Analogous to trichromatic theory
Anosmia
Inability to smell odors
Presbyosmia
Normal loss of odor sensitivity with age
Brain mechanisms of olfaction (4)
- Bio-mechanical properties of nose
- Olfactory epithelium
- Olfactory bulb
- Olfactory cortex
Bio-mechanical properties of the nose
- Warms and humidifies air
- Cleans debris (nose hairs)
- Controlled by nasal cycle
Olfactory epithelium
Contains receptor neurons that detect odors, picks up odors, binds, and sends to brain
Olfactory coding
Odors are coded using a population code
- 10 million olfactory receptor neurons
- 1,000 distinct receptor proteins
Olfactory bulb
Collects and encodes odor signals from neurons, send processed odor signal to cortex
Olfactory cortex
Complex processing of odors, interactions with other sense and brain systems
What part of brain does smelling activate?
Center of brain-subcortical levels
Pheromones
Chemical signal released to outside of body of producer that effects physiology or behavior of a receiving individual of the “same” species
Lee-Boot Effect
When female mice are housed together their estrous cycles stop
Whitten Effect
When above females are exposed to males, their estrous cycles re-start in synchrony
Vandenbergh Effect
The acceleration of puberty onset in a female rodent cause by exposure to a male
Bruce Effect
When a recently impregnated mouse encounters a male other than the one with which she mated, the pregnancy will terminate
VNO organ
Contains receptor sites to detect pheromones, its effects on behavior may bypass conscious processing
Mentalists’ approach
Nothing really exists outside the mind
Materialists’ approach
There is only matter, conscious states are physical brain states, unity of conscious experience and the brain, consciousness consists entirely of computational processes
Epiphenomentalism
Consciousness is an illusion
Panpsychism
Everything is conscious
Dualism
Conscious experience distinct from brain activity, our experience cannot be reduced to brain activity
Mysterian
Consciousness is a complete mystery
Definition of consciousness
States of awareness of the outside world and of one’s own mental processes, thoughts, feelings, and perceptions
Functions of consciousness (2)
- Monitoring mental events (introspection)
2. Control: allows us to formulate and reach goals
External sensory perception
Awareness of sights, sounds, tastes, and touch in the environment
Internal sensory perception
- Ability to internally experience sensory info from a remembered event
- Create sensory representations of events we’ve never experienced
- Mental imagery
Abstract awareness
- Abstract ideas (freedom)
- Emotions
- Symbols we use to represent big ideas
Awareness of self
-Aware of yourself as an individual, of thoughts & feelings, observe your experiences from the “outside”
Hard problem of C: phenomenal consciousness
- Where do feelings come from
- We can talk about the function of pain and the brain states involved, but why does it hurt?
Hard problem of C: functionalist problem
We do not know what its exact function is
Hard problem of C: materialist problem
We do not know what it is made of
Hard problem of C: experimental problem
We cannot measure it directly
Easy problem of C
What are the neural correlates of consciousness?
-Are there specific neurons, brain areas, and/or neural processes that correlate with conscious awareness
Psychophysics
How to relate mind and matter
*First definition of psychology
Investigation of conscious processes in the modes of connection peculiar to them (Wundt 1874)
Structuralism tasks of psychology (3)
- Analyze mind to its basic elements and describe consciousness
- Discover laws that govern the combo of elements to larger wholes in the mind
- Discover the physiological brain events that correspond to psychological elements
How did psychology change in the 20th century?
Psychologists avoided consciousness, it became a taboo
Visual neglect
Failure to acknowledge objects in the field contralateral to lesion
Balint Syndrome
Field of attention which is limited to one object at a time (simultanagnosia)
Blindsight
Ability of certain patients to perform above chance on visual tasks but report that they cannot see (ex: patient DB)
Key assumption for neural correlates of consciousness (NCC)
Many different brain areas are involved in the NCC
Key problem of NCC
The distinction between what is necessary and what is sufficient for consciousness
Ways to measure NCC (2)
- EEG: measure potential differences
- TMS: use a brief change in magnetic field to disrupt neural activity, can create & disturb perception
Which neurons follow physical stimulation and which neurons follow perceptual awareness?
- High level areas care more about perception
- Lower level areas care more about physical stimulation
Subliminal perception
Notion that brief exposure to sub-threshold stimuli can influence awareness
What is not in NCC?
Most of the brain processes. We are not aware of most things that our brain does (zombie agents)
Functional significance of unconscious mechanisms (3)
- Efficient and rapid
- Can operate simultaneously
- Operate in the absence of consciousness
Function of consciousness
- Awareness is important during learning (eg: self reflection)
- Less important when the task is well-learned
What can spiritual experiences (SEs) occur in conjunction with?
Temporal lobe epilepsy (TLE)
Stimulation of what part of brain resulted in out-of-body experience?
Temoroparietal junction (TPJ)
Passive senses in additional senses (3)
- Biological compass
- Pheromones
- Electroperception
Active senses in additional senses (2)
- Electric fish
2. Biological sonar
Map navigation
Know where in the world you are
Compass navigation
Only know North or South directions
Passive electroreception
Detecting fields from external sources
Active electroreception
Detecting perturbations to fish’s own field
Ampullae of Lorenzini
Special sensing organs called electroreceptors that form jelly-filled pores, can be used to sense Earth’s magnetic field while shark is in motion
Doppler shift
- Low frequency echo for receding object
- High frequency echo for approaching object
