Week 2 - Perception, Attention & Consciousness

Question 1

Sense organs:

Visual
Vestibular
Auditory 
Olfactory
Tactile
Gustatory

Answer 1

Sense organs:

Visual - seeing -eyes
Vestibular - balance - ears
Auditory - hearing -ears
Olfactory - smell - nose
Tactile - touch - skin
Gustatory - taste - tongue

Question 2

3 shared characteristics across senses

Answer 2

Transduction
Adaptation
Sense & perceive

Question 3

Transduction

Answer 3

Transforming the physical energy caused by a stimulus into electrical signals that are sent to the brain for further information processing

Question 4

Adaptation

Answer 4

The decreasing response of sense organs cause by exposure to a continuous level of stimulation
Slow & quick adaptation
No adaptation for high intensity stimulation

Question 5

Sense & perceive

Answer 5

Information that the brain must process following transduction are sensations
Perceptions are the meaningful experiences that result after brain processes the sensations

Question 6

What Is attention

Answer 6

Narrowing of the senses (Aristotle)
One from many thoughts / objects taking vivid possession of the mind (James)
Filter / bottleneck - owing to limited capacity perceptual system (broadbent)
Providing priority - semantic priming
Response preparation/ selecting a goal for an intended action (promotor theory)
Non-response based - facilitating memory & consciousness
Attentional resource limitation & selection - eliminated by practice

Question 7

Attention

Answer 7

Selecting ideas in ones mind or aspects of the physical environment for further active processing

Question 8

Attention: characteristics

Answer 8

Attentional beam/ spotlight/ focus -> fovea / peripheral
Detection of attended than unattended stimuli - faster
Consequences of attention -> priority, not acuity
Spatial and temporal limitations

Question 9

Paradigms: attentional blink

Answer 9

Evaluates temporal limitations of attention

Question 10

Attention: characteristics

Answer 10

Feature-based versus spatial attention (goal or no)
Local/ global processing ( big letter made of little letters- faster at recognising if they are the same)
Endogenous / exogenous cueing ( endogenous = you choose / exogenous = e.g. a cup falling - grabs your attention without you choosing)
Overt / covert attention (can look at one thing and be actually attending to another )
Top-down / bottom-up attention (previous knowledge influencing or no)

Question 11

Top-down/ bottom-up: orienting brain

Dorsal system:

Ventral system:

Answer 11

Dorsal system: 
Voluntary orienting (covert/overt)
Top-down attention

Ventral system:
Involuntary orienting (unexpected)
Bottom up attention

Question 12

Attention: brain basis

Not single brain region
System of networks
Not the whole brain

Answer 12

Neuroimaging
Electrophysiology 
Neuropsychology
Pharmacology 
Studies on humans (all age groups) and animals
Behavioural paradigms (several)

Question 13

Neural electro physiological markers: MMN

Answer 13

Mismatch negativity (MMN):
Perception of unexpected or deviant stimuli

Question 14

Attention & the posterior parietal cortext

Answer 14

The human posterior parietal cortex is divided by the intraparietal sulcus (IPS) into the superior parietal lobe (SPL) and the inferior parietal lobe (IPL)
The IPL consists of the Angular Gyrus (Ang) and the supramarginal gyrus (Smg)and boarders on the superior temporal gyrus at a region often referred to as the temporoparietal junction (TPJ)

Question 15

Attention: three brain networks

Select

Answer 15

Also referred to as ‘executive attention’

Involves mechanisms for monitoring & resolving conflict among thoughts, feelings, and responses.

Question 16

Attention: three brain networks

Orient

Answer 16

Defined as the selection of information from sensory input

Aligning attention (overt or covert) to source of sensory signals

Question 17

Attention: three brain networks

Alert

Answer 17

Defined as achieving and maintaining a state of high sensitivity to incoming stimuli

Levels of alertness vary with influence of warning signals

Question 18

Agnosia: disorder of perception

Answer 18

Impairment in higher visual processes necessary for object recognition

Relative preservation of elementary visual functions. Absence of dementia. Preserved general knowledge about objects

Able to recognise objects through other modalities (touch, audition, verbal description)

Question 19

Integrative agnosia

Answer 19

A form of visual agnosia in which one retains the ability to recognise elements of objects but is unable to integrate these elements together into comprehensible perception.

Question 20

Optic aphasia

Answer 20

A condition in which a person cannot name a visually presented object, despite being able to indicate the identity of the object through gesture and sort the visual stimuli into categories

Question 21

Balint’s syndrome

Answer 21

Agnostic syndrome that results from large bilateral parietal lesions and is composed of three deficits: (1) paralysis of eye fixation with inability to look voluntarily into the peripheral visual field, (2) optic ataxia, and (3) disturbance of visual attention such that there is neglect of the peripheral field

Question 22

Prosopagnosia

Answer 22

Inability to recognise familiar faces despite adequate elementary visual function (visual field, visual acuity, colour)

Faces no more important than objects (face blindness)

Use of secondary information for recognition (voice, hair, smell, clothing)

Question 23

Apperceptive agnosia

Answer 23

Difficulty forming a complete visual perception

Visual form agnosia: inability in simple shape discrimination. Inability to group local visual elements into contours, surfaces, and objects

Diffuse bilateral damage to the lateral occipital lobes, critical structures involved in visual perception

Preserved visual acuity, visual fields, brightness discrimination, colour vision, and fixated maintenance (elementary visual functions)

Question 24

Associative Agnosia

Answer 24

Adequately perform figure-copying, but often unable to identify the copied image.

Uses shape cues to try to identify the presented object (as opposed to colour and texture). Often mistakes objects for one that is similar in shape.

Failure of the structured perception to appropriately activate the network of knowledge about the functional, contextual, and categorical properties.

Category-specific visual agnosia (CSVA) usually distinguishes between biological (fruits) and nonbiological objects (tools).

Question 25

Simultanagnosia

Answer 25

Inability to appreciate the overall meaning of a complex picture or stimulus, with preserved perception of isolated elements or details within the stimulus. Dorsal stimultagnosia cannot detect more than one object at a time and have difficulty shifting attention from object to object. Impairments result from an inability to disengage attention from a specific object or a region of space. Ventral stimultagnosia characterised by the reduced ability to recognise multiple visual stimuli rapidly.

Question 26

Loss of vision

Answer 26

Damage to different parts of the visual pathways from the eye to the visual centres of the brain leads to different patterns of visual field loss

Question 27

Loss of vision: Hemianopsia

Answer 27

Loss of vision over half of the visual field, typically from damage to the optic radiations that project to V1 or damage to V1 itself.

Question 28

Loss of vision: cortically blind

Answer 28

Cortically blind - lesions in primary visual cortex

Question 29

The phenomenon of Blindsight

Answer 29

Some cortically blind patients retain the ability to detect visual information within this blind region. Forced choice trials (detection of a light flash - occurred on 50% of trials) Only close to chance when flashed in blind spot (43% - labelled DISC) Otherwise way above chance detection Reports not seeing “light” but noticing change.

Question 30

Neglect: Disorder of attention

Answer 30

Unilateral spatial neglect: failure to respond, orient or report stimuli presented on the opposite side of the brain lesion [high heterogeneity in USN Presentation] Inability is not attributable to primary sensory or motor deficits Right hemisphere brain lesions to the lateral posterior parietal lobe Precise location and size of parietal lobe lesion varies (inferior / superior) Mechanism: spatial attention theory Attentional bias- excessive orienting to ipsilesional side of space and away from contralesional side Mechanism: spatial representation theory Disrupted conscious representation of left side of space

Question 31

Neglect: disorder of attention Egocentric USN Allocentric USN Other USNs

Answer 31

Neglect: disorder of attention ``` Egocentric USN Neglect of the contralesional side of space as defined by the midline of the body, head, or retina Body-centred Heat-centred Retinocentric ``` Allocentric USN Neglects the right side of individual items regardless of where the items appear with respect to the viewer. Stimulus-centred Object-centred Other USNs Distinguished by not only reference frame but also sensory modality, regions of space affected, or mode of output. (E.g. neglect dyslexia, neglect dysgraphia)

Question 32

Which attentional network is affected in neglect?

Answer 32

Conflicting evidence (neuropsychological & neuroimaging) Disorder associated with diverse presentations Both DAN & VAN are involved via complex dynamics (Involving alerting, orienting and conflict-monitoring)

Question 33

Consciousness

Answer 33

Consciousness is a subjective experience Sentience (Phenomenal awareness, subjective experience) Access to information (ability to report content of one’s experiences of the world) Self-knowledge (conscious awareness of ourselves)

Question 34

Measuring conscious experience Libet experiment Brain imaging

Answer 34

Libet experiment - showed that the brain conducts the action before we are conscious of it Failures to report a conscious experience may be due to failures of attention, memory, inner speech rather than the absence of relevant conscious experience. Can ask people in a vegetative state to imagine certain activities for different answers to questions. Communicated with them- they were actually conscious

Question 35

Theories of consciousness Baar’s Global Workspace Theory Dehaene & Nacchache’s Theory

Answer 35

Baar’s Global Workspace Theory: - Unconscious processes take place in local modules distributed across the brain - Conscious processing involves global access to these widespread modular representations - Competition among processors and outputs for a limited capacity resource (GW) that “broadcasts” information for widespread access. - Dynamic, flexibility in processing - GW capacity limits correspond to the limits typically placed on focal attention or working memory in many cognitive models. Dehaene & Nacchache’s Theory - Baar’s model further developed with proposed connections to particular brain systems - Consciousness (both in the access & phenomenal sense) occurs when & only when the relevant content enters the larger global network involving both primary sensory areas as well as many other areas including frontal and parietal areas associated with attention - Conscious perception begins only with the “ignition” of larger global network; activity in the primary sensory areas will not suffice.

Question 36

Anil was sitting in bed at 11pm and reading a book. He is suddenly distracted by a loud scream coming from outside his house. Which specific attentional system will be activated as a response in this situation? A. Executive B. Orient C. Alert D. Spatial

Answer 36

C.Alert