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PSYC 304 > CH 7: Mechanisms of Perception > Flashcards

CH 7: Mechanisms of Perception Flashcards

1
Q

List the 3 types of sensory cortex.

A
  1. Primary Sensory cortex
  2. Secondary Sensory cortex
  3. Association cortex
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2
Q

Define PRIMARY SENSORY Cortex

A
  • Receives most input directly from the thalamic relay nuclei of that system
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3
Q

Define SECONDARY SENSORY Cortex

A
  • Receives most input from the primary sensory cortex of the same system
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4
Q

Define ASSOCIATION Cortex

A
  • Receives input from >1 sensory system

- Most input to areas of association cortex comes via areas of secondary system

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5
Q

WRT Sensory System organization, explain what is meant by the term, ‘HIERARCHICAL ORGANIZAITON’

A
  • Organization into a series of levels ranked WRT one another
  • ie) In sensory systems, primary cortex, secondary cortex, & association cortex perform progressively more detailed analyses
  • Sensory structures org in hierarchy based on specificity & complexity of their function
  • Each level of hierarchy receives inputs from lower levels & adds another layer of analysis before passing it up hierarchy
  • The higher the level of damage
  • -> ^specific & complex deficit
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6
Q

WRT Sensory System organization, explain what is meant by the term, ‘FUNCTIONAL SEGREGATION’

A
  • Organization into diff areas, each of which has diff function
  • Each of the 3 levels of cerebral cortex in each sensory system contains functionally distinct areas that specialize in diff kinds of analysis
  • 3 levels of cerebral cortex = primary, secondary & association
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7
Q

WRT Sensory System organization, explain what is meant by the term, ‘PARALLEL PROCESSING’

A
  • Simultaneous analysis of a signal in diff ways by the multiple parallel pathways of a neural network
  • aka info flows through the components over multiple pathways
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8
Q

Summary Model of Sensory System Organization (2)

see Figure 7.1

A
  1. Sensory sys are hierarchical, functionally segregated, & parallel
  2. Sensory sys are characteristic by a division of labour = multiple specialized areas, at multiple levels, interconnected by multiple parallel pathways
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9
Q

Describe the neural mechanisms underlying SOUND LOCALIZATION.

A
  • Sound localization is mediated by the lateral & medial superior olives (but in diff ways)
  • Sound originates to (L) ear
  • -> Sound reaches (L) ear first
  • -> Louder in left ear
  • -> some neurons in MEDIAL superior olives respond to slight diff in TIME OF ARRIVAL of signals
  • -> some neurons in LATERAL superior olives respond to slight diff in AMPLITUDE of sounds
  • Medial & lateral superior olives project to SUPERIOR COLLICULUS & INFERIOR COLLICULUS
  • -> Receives auditory input
  • -> Laid out acc. to map of auditory space
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10
Q

What is the function of SUPERIOR COLLICULI?

A
  • Locating sources of sensory input in space
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11
Q

Describe the effects of AUDITORY CORTEX DAMAGE.

Bilateral vs. unilateral lesions.

A
  • Bilateral lesions
  • -> shock
  • -> complete loss of hearing
  • -> hearing recovers after weeks
  • -> permanent effects = lose ability to localize sounds & impairment of ability to discriminate frequencies
  • Unilateral lesions
  • -> disrupt ability to localize sounds in space contralateral, but not ipsilateral, to the lesion
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12
Q

Describe CONDUCTIVE DEAFNESS.

A
  • Damage to the ossicles
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13
Q

Describe NERVE DEAFNESS.

A
  • Damage to the cochlea or auditory nerve
  • Major cause = loss of hair cell receptors
  • IF only cochlea damage
  • -> Individual has nerve deafness for some frequencies but not others
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14
Q

List 4 types of CUTANEOUS RECEPTORS.

A
  1. Free Nerve Endings
  2. Pacinian Corpuscles
  3. Markel’s Disks
  4. Ruffini Endings
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15
Q

Describe FREE NERVE ENDINGS (3).

A
  • Neuron endings w/ no specialized structures
  • Sensitive to temp changes & pain
  • Simplest cutaneous receptors
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16
Q

Describe PACINIAN CORPUSCLES (3).

A
  • Adapts rapidly
  • Responds to sudden displacements of skin but not to constant pressure
  • Largest & deepest cutaneous receptors = onion-like
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17
Q

Describe MARKEL’S DISKS (2).

A
  • Adapts slowly

- Responds to gradual skin indentation

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18
Q

Describe RUFFINI ENDINGS (2).

A
  • Adapts slowly

- Responds to gradual skin stretch

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19
Q

Explain the functional significance of fast vs. slow receptor adaptation.

A
  • Having receptors that adapt quickly vs. slowly
  • -> Provides info about the dynamic & static qualities of tactual stimuli
  • ie) don’t feel constant pressure of clothes on skin unless focus
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20
Q

Describe how receptors generally function.

A
  • Stimuli applied to skin
  • -> Change chemistry of receptor
  • -> Change permeability of receptor cell membrane to various ions
  • -> Neural signal
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21
Q

List the 2 major somatosensory pathways.

A
  1. Dorsal-Column Medial-Lemniscus System

2. Anterolateral System

22
Q

Describe the Dorsal-Colum Medial-Leminiscus System

A
  • Carries info about touch & proprioception
  • It’s sensory neurons enter spinal cord via dorsal root
  • -> Ascend inspiralaterally in the dorsal columns
  • -> Synapse in dorsal column nuclei of medulla
  • Proprioception = awareness of position & movement of body
23
Q

Describe the Anterolateral System

A
  • Carries info about pain & temp

- see pg 178

24
Q

Name the areas of association cortex that somatosensory signals are sent to, & describe the functional properties of one of those areas.

A
  • Sent to areas of association cortex in prefrontal & posterior parental cortex
  • Posterior parental cortex contains bimodal neurons
  • BIMODAL NEURONS respond to activation of:
    1. Somatosensory stimuli
    2. Visual stimuli
  • Visual & somatosensory receptive fields of each neuron are spatially related
  • ie) if somatosensory receptive fields centred in (L) hand, its visual field is adjacent (L) hand
  • -> If (L) hand moves, visual receptive field of the neuron moves w/ it
25
Q

List the 2 major types of somatosensory AGNOSIA.

A
  1. ASTEREognosia

2. ASOMATognosia

26
Q

Describe Astereognosia

A
  • Inability to recognize objects by touch
27
Q

Describe Asomatognosia

A
  • Failure to recognize parts of one’s own body

- Usually unilateral (only affects (L) side of body)

28
Q

Describe the RUBBER-HAND ILLUSION

A
  • Feeling that an extraneous object (in this case, a rubber hand) is actually part of one’s own body
  • Hide healthy person’s hand from their view via screen
  • Place rubber hand beside real hand but in clear site
  • Stroke both healthy & rubber hand
  • Person thinks rubber hand is their own
  • -> Temp in hidden real hand drops
29
Q

Explain why the 1st reason why the perception of pain is said to be paradoxical.

A
  1. ADAPTIVENESS OF PAIN
    - There’s no stimulus to pain
    - Pain = response to potentially harmful stimulation of any type
    - Pain warns us not to engage in dangerous activities
    - -> important for survival
30
Q

Explain why the 2nd reason why the perception of pain is said to be paradoxical.

A
  1. LACK OF CLEAR CORTICAL REPRESENTATION OF PAIN
    - Pain has no obvious cortical rep
    - Pain stimuli activate many areas of cortex, though none of these areas seem necessary for perception of pain
    - ie) removal of one of those areas isn’t ass w/ change in pain threshold
31
Q

Explain why the 3rd reason why the perception of pain is said to be paradoxical.

A
  1. DESCENDING PAIN CONTROL
    - Pain can be suppressed by cognitive & emotional factors
    - Descending analgesia pathways
  • see pg 183
32
Q

Describe NEUROPATHIC PAIN & when it commonly develops.

A
  • Severe chronic pain in absence of a recognizable pain stimulus
  • Commonly develops after injury
  • -> Injury heals & seems to be no reason for further pain but patient experiences chronic excruciating pain
33
Q

Describe some of the putative neural mechanisms of neuropathic pain.

A
  • Unknown exact mech
  • Somehow caused by pathological changes in NS induced by the original injury
  • -> Caused by abnormal activity in CNS
  • -> Thus cutting nerves from perceived pain location doesn’t bring comfort
34
Q

Describe 2 adaptive roles of the chemical senses.

A
  1. EVALUATION OF POTENTIAL FOODS
    - = ^consumption of E sources & nuts while avoiding toxins
    - ie) in natural environment where food isn’t labelled
  2. REGULATING SOCIAL INTERACTIONS
    - Many sp release pheromones (chemicals)
    - -> influences physiology & behaviour of conspecifics
35
Q

Define OLFACTION

A
  • Smell = response of olfactory sys to airborne chemicals that are drawn by inhalation over receptors in nasal passages
  • see Figure 7.18
36
Q

Describe OLFACTORY MUCOSA.

Where does its output go to?

A
  • Mucous membrane lining upper nasal passages
  • Contains olfactory receptor cells
  • -> Each receptor cell contains only 1 type of receptor protein molecule
  • -> Sends signals to olfactory bulbs
37
Q

Describe OLFACTORY BULBS

Where does its output go to?

A
  • Receives signal sent from olfactory mucosa
  • Its output goes primarily to amygdala & piriform cortex
  • PIRIFORM CORTEX = area of medial temporal cortex adjacent to amygdala
38
Q

Describe OLFACTORY GLOMERULI

A
  • Clusters of axons of olfactory receptors that lie near surface of olfactory bulbs
  • Receives input from 1000s of receptor cells
39
Q

Define GUSTATION

A
  • Taste = response of gustatory system to chemicals in solution in oral cavity
40
Q

Describe TASTE BUDS & how its output is communicated.

A
  • Clusters of taste receptor cells (50-100)
  • On tongue & parts of oral cavity
  • In each bud, only 1 receptor cell (=presynaptic cell) synapses onto neuron carrying signal away from bud
  • -> communication via gap junctions
  • -> send signal to primary & secondary gustatory cortex
41
Q

WRT the Gustatory System, explain what’s meant by BRODLY TUNED.

A
  • Each receptor cell responds to wide range of tastes

- 5-primary component processing theory of tastes implies that each gustatory receptor & neuron is ‘broadly tuned’

42
Q

WRT the Gustatory System, explain what’s meant by NARROWLY TUNED.

A
  • Each receptor cell responds to only 1 taste, or at least to very few of them
  • via ^^^accumulating list of receptor molecules & mechanisms
43
Q

List 2 potential effects of brain damage on the chemical senses.

A
  1. Anosmia

2. Ageusia

44
Q

Describe ANOSMIA

A
  • Inability to SMELL
  • Common cause = blow to head causing brain displacement w/in skull
  • -> Shears olfactory nerve where pass through cribriform plate
  • Less complete deficits in olfaction liked to neurological disorders
  • ie) AD, down syndrome, epilepsy, etc.
45
Q

Describe AGEUSIA

A
  • Inability to TASTE
  • Rare bc sensory signals from mouth are carried via 3 separate pathways
  • Partial ageusia = limited to anterior 2/3 of tongue on 1 side
  • -> after damage to ear on same side
  • -> bc branch of facial nerve that carries gustatory info from anterior 2/3 of tongue passes through the middle ear
46
Q

Describe SELECTIVE ATTENTION

A
  • Ability to focus on a small subset of the multitude of stimuli that are received at any one time
47
Q

Describe the 2 characteristics of Selective Attention.

A
  1. Improves perception of the stimuli in focus

2. Interferes w/ perception of the stimuli not in focus

48
Q

Explain what’s meant by EXOGENOUS vs. ENDOGENOUS Attention.

A

Attention can be focussed in 2 diff ways:

  1. ENDOGENOUS Attention = by internal cognitive processes
    - ie) attention focused on tabletop bc searching for keys
    - Mediated by TOP-DOWN neural mech (from higher to lower levels)
  2. EXOGENOUS Attention = by external cognitive processes
    - ie) attention can be drawn to tabletop bc cat tipped over a lamp
    - Mediated by BOTTOM-UP neural mech (from lower to higher levels)
49
Q

Describe the phenomenon of CHANGE BLINDNESS.

A
  • Difficulty perceiving major changes to unattended-to parts of a visual image when the changes are introduced during brief interruptions in the presentation of the image
  • Occurs bc when we view a scene, we have no memory for parts of the scene that aren’t in focus of our attention
  • see pg 190 for explanation
50
Q

Describe the neural mechanisms of attention (2).

A
  • Selective attention works by strengthening the neural responses to attended-to aspects & weakening the responses to others
  • -> this dual mech = push-pull mechanisms
  • Attention is activated by circuits in prefrontal & parental cortex
  • -> Enhances activity in task-relevant sensory circuits & suppress activity in irrelevant sensory circuits
51
Q

Describe the disorder of attention known as SIMULTANAGNOSIA.

A
  • Difficulty attention to >1 stimulus at a time
  • ie) patient can identify objects in any part of his visual field if they were presented individually
  • -> Thus he isn’t suffering from blindness or other visual field defects
52
Q

Simultanagnosia is usually ass. w/ damage to what part of the brain?

A
  • Bilateral damage to posterior parental cortex

PSYC 304 (18 decks)

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