Midterm 4 Flashcards

Question

•Ventro-dorsal route

Answer 1

(involving the **“temporoparietal junction”** and **“ventral prefrontal cortex”**) acts as a **‘circuit breaker’** (e.g. attentional disengagement from ongoing activity caused by exogenous stimuli) **TPJ and VFC** \* involved in interrupting the current of attention **(exogenous)**

Answer 2

Spatial * Parietal lobes represent full visual field but in a graded fashion (salience map) * BUT: brain damage in humans to right parietal lobe has more profound effects than damage to left (‘neglect’) * Possibly right LIP contributes more to salience map (right hemisphere spatial dominance makes left visual field more salient).

Answer 3

Inattentional blindness

Answer 4

a spotlight ▫But: it can be covert as well as overt

Answer 5

▫Voluntary/top-down processes/endogenous/goal-directed ▫Reflexive/bottom-up/exogenous/stimulus-driven

Answer 6

(dorso-dorsal and ventro-dorsal routes).

Answer 7

(Where/How Stream) \* Parietal \* **LIP** ("Lateral intra-parieta larea") and **FEP** ("frontal eye field") -- involved in orienting on a **salience map \*\* important for endogenous orienting \*\*** Superior longitudinal fasciculus posterior parietal cortex (-- according to Corbeta & Schulman) \*\*\*\* This hypothesis has been challenged \*\*\*\*

Answer 8

**(Ventral "What" Stream) \* Temporal \*** **TPJ ("temporal junction")** and **VFC ("Ventral prefrontal cortex")** Inferior longitudinal fasciculus Inferior Temporal Cortex Acts as a **"circuit breaker" (e.g. attentional disengagement from ongoing activity caused by exogenous stimuli)** (-- according to Corbeta & Schulman) \*\*\*\* This hypothesis has been challenged \*\*\*\*

Answer 9

* Parietal lobes represent full visual field but in a graded fashion **(salience map)** * BUT: brain damage in humans to right parietal lobe has more profound effects than damage to left (‘neglect’) * Possibly right LIP contributes more to salience map (right hemisphere spatial dominance makes left visual field more salient).

Answer 10

Endogenous Orienting our ability to intentionally attend to something | (top-down or goal-directed or voluntary attention)

Answer 11

Visual spatial attention is a form of visual attention that involves directing attention to a location in space. Spatial attention allows humans to selectively process visual information through prioritization of an area within the visual field. Spatial attention is the ability to focus on specific stimuli in a visual environment. When people look at scenes, although they may feel like they are looking at a complex mixture of stimuli, their attention is actually drawn to a handful of critical pieces of data. The brain identifies the most important information in the scene for further examination and the coordinated planning of movements. In people with neurological disorders, errors of this type of attention can develop.

Answer 12

non-spatial attentional selection(?) Diff. parts of visual ventral stream (representing different stimulus types/properties) increase in activity when attended (e.g. fusiform face area when face is attended)

Answer 13

\*Non-spatial attentional selection The 'attentional blink' (or inability to report a target stimulus if it appears soon after another target stimulus)

Answer 14

is the state or condition of being prominent. The Oxford English Dictionary defines **salient** as "most noticeable or important."

Answer 15

1. Lateral intra-parietal area 2. Dorso dorsal stream 3. FEF (frontal eye field) 4. involved in orienting in a salience map (important for endogenous orienting).

Answer 16

A failure to attend to stimuli on the oppisute side of space to a brain lesion Hemineglect, also known as unilateral neglect, hemispatial neglect or spatial neglect, is a common and disabling condition following brain damage in which **patients fail to be aware of items to one side of space. Neglect is most prominent and long-lasting after damage to the right hemisphere of the human brain, particularly following a stroke. Such individuals with right-sided brain damage often fail to be aware of objects to their left, demonstrating neglect of leftward items.** The deficit may be so profound that patients are unaware of large objects, even people, towards their neglected orcontralesional side - the side of space opposite brain damage. They may eat from only one side of a plate, write on one side of a page, shave or make-up only the non-neglected or ipsilesional side of their face (same side as brain damage). Their drawings may fail to include items towards the neglected side, for example when placing the numbers in a drawing of a clock (Fig.1). Many patients are often also unaware they have a deficit (anosognosia). Classically, the neglect syndrome has been associated with **damage to the right posterior parietal cortex.** More recent studies have begun to challenge this view, suggesting instead that a more widespread network of areas may be involved, including those that have been implicated in studies of neuroimaging of attention (discussed further in theNeuroanatomy of neglect below; see also Corbetta & Shulman, 2002 and Husain and Rorden, 2003). Differences in the location and extent of lesions (brain damage) across patients may contribute to the heterogeneity of the condition.

Answer 17

Neglect is a Disorder of Attention and Not Low-Level Perception

Answer 18

copying line bisection drawing from memory cancellation

Answer 19

still activate visual regions

Answer 20

•If cued on the left part of the visual field, patients are often able to detect objects there, especially if the object is presented alone ▫Phenomenon of “visual extinction” suggests different perceptual representations are competing for attention (and visual awareness) stimuli compete for attention in neglect condition

Answer 21

Neglect is a Disorder of Attention and Not Low-Level Perception • Visual stimuli presented to neglect patients still activate visual regions in occipital lobes, even though the patients are not aware of them. • It’s not just visual: it affects auditory and tactile judgments as well (e.g. sounds on left are mislocalized but still heard) • If cued on the left part of the visual field, patients are often able to detect objects there, especially if the object is presented alone ▫ Phenomenon of “visual extinction” suggests different perceptual representations are competing for attention (and visual awareness)

Answer 22

can **recognize single objects but CANNOT compute spatial relationships between objects** But **when is an object an object?** E.g. is a face an object, or several objects (e.g. eyes, nose etc.)? Evidence suggests that these patients can group several parts into wholes if they share color, shape, or are connected Top-down factors important too (e.g. "are ovals at top or bottom?" versus "is face the correct way up?")

Answer 23

* Some of it at least may not be completely lost: Ventral stream may continue to process neglected objects up to the stage of object recognition and possibly semantics * Evidence: ▫Recognition of a previously neglected line drawing is facilitated when it’s subsequently presented on the attended side of space (even if it’s degraded) (Vuilleumier et al., 2002) ▫Burning house experiment (Marshall & Halligan, 1988). Two houses on the left (neglected side), differed in flames, patients could not tell the difference, but when prompted, stated they’d rather live in the house without flames! •

Answer 24

A severe difficulty in spatial processing normally following bilateral lesions of parietal lobe; **symptoms include simultanagnosia, optic ataxia, and optic apraxia.** Three clinical characteristics of Balint’s syndrome **(1) Inability to perceive more than one object at a time (simultanagnosia)** (2) Inability to **reach** in the proper direction **for** an object under visual guidance **(optic ataxia)** (3) Impaired **fixation of gaze** without a primary deficit of eye movement **(optic apraxia)** (4) Basic **visual abilities normal** (e.g. visual acuity, color perception, contrast sensitivity)

Answer 25

Inability to perceive more than one object at a time. The premotor theory of attention

Answer 26

(seeing and imagining) ## Footnote A double dissociation has been found between **perceptual and representational neglect**, suggesting the brain uses different spatial reference frames for representational (mental imagery) and perceptual space. \*\* THE SPATIAL MAP YOU FORM FROM MEMORIES IS DIFFERENT FROM ACTUALLY BEING THERE

Answer 27

Patient RM has simultanagnosia: **Unable to locate objects** verbally or by reaching and pointing Impaired at locating **sounds** BUT: they can state which side of body and which body part is being touched (**body space may be different** from external space)

Answer 28

Some neglect patients attend to objects on the left side of space but omit to attend to one half of the object itself (object-based neglect) Forms a double dissociation with space-based neglect Some neglect patients attend to objects on the left side of space but omit to attend to one half of the object itself (object-based neglect) Forms a double dissociation with space-based neglect

Answer 29

**REVEAL DIFFERENT TYPES OF SPATIAL MAPS** • Perceptual vs. representational neglect • Near vs. far-spaced neglect • Personal vs. peripersonal neglect • Object-based vs. space-based neglect

Answer 30

**Feature Integration Theory** **▪ Biased Theory of Attention ▪ Premotor Theory of Attention**

Answer 31

Double dissociation between near and far space Near space = tested with line bisection using pen and paper Far space = tested with line bisection using projected image and laser pointer “Near” defined as within reach; if patient is given a stick rather than a pointer then “near” deficit extends into far space

Answer 32

Double dissociation between personal (bodily) space and peripersonal (near) space Body neglect = failure to groom left of body or notice position of limbs whereas near space neglect = visual search of array of external objects

Answer 33

It decides which information - and how much - the brain processes. Prevents an information overload by determining what we perceive.

Answer 34

The failure to detect a change, movement or disappearance of an object.

Answer 35

What if you cant pay attention? (eg because objects are presented too quickly) ▫ Report a conjunction of features that you never actually saw Illusory conjunctions provide evidence that attention is needed to combine an object’s features correctly

Answer 36

FIT and visual search: Case 1 Recall: FIT says attention is needed to bind together multiple features But only one feature is needed to find the target (So this kind of feature search doesn’t need attention) - Reaction time is independent of number of distractors Case 2: • Try to find the blue “T” in the array ((Two features needed to find the target -- Color and shape)) Now two features are needed to find the target So this kind of conjunction search DOES need attention --- More distractors, longer reaction time

Answer 37

* Feature search: a single feature is enough to identify the target, attention not needed, RT does not increase with increasing distractors * Conjunction search: **must find a combination of two features to identify the target, attention is needed, RT increases with increasing distractors**

Answer 38

The failure to notice an unexpected, but fully visible object or stimulus when attention is diverted elsewhere.

Answer 39

The failure to identify the second of two visual targets, if it is shown soon enough after the first.

Answer 40

Within ventral stream: neurons reduce their specificity of responding when multiple stimuli in their receptive field (whole is less than sum of parts) • Within parietal lobes: brain damage affects attention when multiple stimuli compete (i.e. extinction)

Answer 41

- Occlusion-contingent change : The target/changing item is covered very briefly before the change occurs. - Gap-contingent change: A blank screen is shown in-between the two different versions of the scene. - Saccade-contingent change :(saccade = rapid eye movement) A change that occurs during a saccade away from the object - Blink-contingent change:A change occurring during the blink of the participants' eye.

Answer 42

Rizzolatti et al. (1987): A centrally presented digit (e.g. 2) indicates where target a likely to appear, but it may sometimes appear elsewhere. • An unexpected shift of attention is harder when crossing midline (location 3 requires new saccade in the opposite direction) than not (location 1 only requires modifying existing saccade in the same direction). Notice locations 1 and 3 are equidistant from location 2.

Answer 43

Moore & Fallah (2001). Monkeys had to press a lever when detecting a change in luminance in a specific region of the visual field. Detection was faster when Frontal Eye Fields (a prefrontal area involved in planning saccades) were weakly stimulated electrically: - weakly enough not to produce a saccade. - importantly, it only facilitated detection if the change in luminance happened in the appropriate receptive field.

Answer 44

( major theory of the role of attention in visual search) explains how attention selects perceptual objects and binds the features of those objects (eg color shape etc) into a reportable experience Also a model of Object perception

Answer 45

• Preattentive (whatever the brain does before engaged) ▫ Features such as color, size, orientation perceived ▫ Features extracted in separate brain regions ▫ Attention not required; effortless • Focused attention (not necessarily intentional) ▫ Features integrated together into a single object ▫ Requires attention; capacity limited; effortful

Answer 46

There’s no a priori way of defining what constitutes a feature. * Pop-out isn’t necessarily pre-attentive. It might simply reflect stimulus-driven (exogenous) attention. * Visual search data could be explained in terms of how easy it is to perceptually group objects together (single features are easy, conjunctions are harder), rather than in terms of parallel feature perception followed by serial attention (Duncan and Humphreys, 1989) * FIT is an early selection model (i.e. attention allocated on the basis of perceptual features) but there’s evidence of late selection (i.e. attention allocated on the basis of semantics). E.g. Negative priming.

Answer 47

* Proposed by Desimone and Duncan (1995) * Rejects “spotlight metaphor”. * Attention is not a single mechanism, but rather an “emergent property of many neural mechanisms **working to resolve competition** for visual processing and control of behavior. * Competition occurs **at multiple stages** rather than at some fixed bottleneck—i.e. neither early nor late selection but something more dynamic. * Competition occurs **in parallel** at most stages * **Serial processing** arises at the **response level**, not perceptual processing (because you can only fixate one location at a time).

Answer 48

Rizzolatti et al. (1987) • The **orienting of attention** is nothing more than the **preparation for action** • **Covert** attention is an action plan (e.g. saccade) that is **prepared but not executed** • It is thus primarily a **theory of spatial attention**

Answer 49

Patient RM has simultanagnosia: ▫ Unable to locate objects verbally or by reaching and pointing ▫ Impaired at locating sounds ▫ BUT: they can state which side of body and which body part is being touched (body space may be different from external space)

Answer 50

▫ Information currently “in mind” ▫ NOT memory for what happened a few minutes or hours ago ▫ Different kinds of working memory • Information currently held in mind • Different kinds: ▫ Verbal (e.g. hold a phone number in mind) ▫ Visual • Limited capacity • Capacity often tested by measuring span • Try to remember the numbers: ▫ 8, 4, 2

Answer 51

Short-term memory • Limited capacity • Capacity often tested by measuring span • Try to remember the numbers: ▫ 7, 3, 8, 1, 4, 8, 7, 9 3, 8, 8,3 • Typical span is 7 plus or minus 2

Answer 52

• Chunking: capacity is 7 plus or minus 2 chunks, not items XIBMSATMTVPHDX • But the number of chunks isn’t the only influence on capacity... • Word length ▫ Span is lower for longer words (e.g. skeleton, binoculars) • Opportunity to rehearse ▫ Articulatory suppression

Answer 53

• Concept of working memory expands on that of short-term memory ▫ Working memory plays a wider, more active role in cognition (e.g. reasoning), vs. STM implies a passive role in retention • Working memory = a limited-capacity store for retaining information over the short term (**maintenance)** and for performing mental operations on this store **(manipulation)--** Example: doing mental arithmetic 25 – 7 + 2 = 20 What did you have to do? Had to keep the three numbers in mind **(maintenance)** and perform subtraction and addition on them **(manipulation)**

Answer 54

• Stored information: what happened seconds, minutes, or years ago • Need not be presently active or consciously accessible • Unlimited capacity • Different kinds...

Answer 55

• Declarative (explicit) vs. non-declarative (implicit) memory • Declarative memory: consciously accessible ▫ Includes episodic + semantic; impaired in HM ▫ This suggests MTL is critical for declarative memory • Non-declarative: not consciously accessible ▫ Skills, priming, habits ▫ Are these impaired in HM?

Answer 56

(LTM)Episodic memory: Memory for events of own life Anterograde: strongly impaired ▫ Retrograde: gradient of impairment

Answer 57

(LTM) Semantic memory ▫ Memory for facts about the world ▫ Anterograde: strongly impaired ▫ Retrograde: seemingly not impaired? ▫ But: most semantic knowledge acquired early in life, and is frequently re-encountered (rehearsed) ▫ When this is taken into account, there is also a gradient of retrograde impairment for semantic • Take-home: episodic and semantic memory are different, but both depend on the MTL

Answer 58

(LTM)Non-declarative: not consciously accessible ▫ **Skills, priming, habits** ▫ Are these impaired in HM? ▫ Inference: Non-declarative does not depend on the MTL (Skills can still play piano, knows how to use a knife and Recognizes wife. Knows who his sister is, Knows facts about the world, can still talk Not shown: would be able to keep a phone number in mind so long as he can rehearse it)

Answer 59

NONDECLARATIVE PRIMING - * Definition: Exposure to a stimulus that influences later responses to that stimulus * Word stem completion: Try it! * Ele\_\_\_\_ * Did you put elephant or element? * Earlier exposure to “elephant” made you more likely to complete the stem as “elephant” \* •Priming NOT impaired in amnesia even though recognition (episodic memory) is impaired

Answer 60

MTL CONSISTS OF : HIPPOCAMPUS PARAHIPPOCAMPAL CORTEX PERIRHINAL CORTEX ENTORHINAL CORTEX

Answer 61

**•Anterograde amnesia** ▫Difficulty with memory for events AFTER brain damage **Forming new memories** **•Retrograde amnesia:** ▫difficulty with memories from BEFORE brain damage **Retrieval of old memories**

Answer 62

•Dissociation #1: **•Short-term memory: Spared** **•Long-term memory: Impaired** * Forgot the events of daily life as quickly as they occurred * Inference: **LTM but not STM depends on the MTL** * But: Childhood memories relatively intact… HM: Dissociation #2 •**Severe anterograde amnesia** **•Gradient of retrograde amnesia** •Inference: **MTL is critical for forming new memories and retrieving recently formed old memories** ▫**Less critical for retrieving distant memories** HM: Dissociation #3**???????** •Episodic vs. semantic memory **•Episodic memory:** **▫Memory for events of own life** **▫Anterograde: strongly impaired** **▫Retrograde: gradient of impairment** * ▫* * So HM has a problem with long term memory, especially with forming new memories* * Is that true for all kinds of long term memory?* **•Semantic memory** ▫Memory for facts about the world **▫Anterograde: strongly impaired** **▫Retrograde: seemingly not impaired?** ▫***But: most semantic knowledge acquired early in life, and is frequently re-encountered (rehearsed)*** ▫When this is taken into account, there is also a gradient of retrograde impairment for semantic **•Take-home: episodic and semantic memory are different, but both depend on the MTL** ▫ **•Together, episodic and semantic memory are called declarative memory** *Third dissociation: episodic vs. semantic (notice question mark here)*

Answer 63

•HM’s oldest episodic and semantic memories were intact ▫Can the MTL be the place where memories are stored? ▫No. Otherwise those older memories would have been also eliminated. •Memories appear to be stored where the information was initially processed…

Answer 64

▫Consolidation is the process by which moment-to-moment changes in brain activity are translated into permanent structural changes in the brain •

Answer 65

\*hint - consolodation takes years ## Footnote Anterograde amnesia: events can’t be turned into permanent changes in the brain Retrograde amnesia: memories that aren’t fully consolidated will be damaged

Answer 66

▫Declarative memories may involve binding together different types of information ▫MTL may be an indexing system that links together different aspects of an event \*\* * What kinds of information might be involved in your memory for an episode from your life?* * Think about your last birthday party…* * Information from different senses, emotion, semantics (understanding of what happened – what did this event mean), what were you thinking at the time, what did you learn from the episode*

Answer 67

**•Recollection:** vivid re-experiencing of a memory and details of the **context** in which it was encoded **\*\*\*\*NOT VAGUE** ▫“I met Steve at Sarah’s party last Thursday and we talked about Breaking Bad” •Familiarity: feeling of knowing that an item was encountered, but without any contextual details ▫“I know that guy from somewhere…” •Aggleton & Brown (1999) propose that recollection and familiarity are supported by different MTL structures ▫

Answer 68

•How to study the formation of different kinds of memories: **_Subsequent memory paradigm_** ▫Scan (fmri/ pet) subjects as they study various items \*\*\* *Which brain areas were active??* ▫Later, outside the scanner, give a memory test ▫What brain areas were active when a subject successfully formed a memory? **•What areas of the brain were active for items that were later recollected vs. familiar?** **RECOLLECTION: HIPPOCAMPUS, PARAHIPPOCAMOAL CORTEX** ^was the context remembered along with the item? *E.g., where I met Steve (context) in addition to Steve’s face (item)* **FAMILIARITY: OTHER MTL STRUCTURES - ESP PERIRHINAL CORTEX**

Answer 69

**•The medial temporal lobes are critical for certain types** ▫Episodic + semantic ( = declarative) ▫Less so for older memories ▫Amnesia is a deficit in declarative memory **•Some types of memory do not depend on the medial temporal lobes** ▫STM/Working Memory ▫Non-declarative memory e.g. skill learning, priming

Answer 70

RECOLLECTION: HIPPOCAMPUS, PARAHIPPOCAMOAL CORTEX ^was the context remembered along with the item? E.g., where I met Steve (context) in addition to Steve’s face (item) FAMILIARITY: OTHER MTL STRUCTURES - ESP PERIRHINAL CORTEX

Answer 71

role of the dorso-dorsal stream in attention as one of orienting within a salience map (as described above) and involving the LIP and FEF.

Answer 72

ventro-dorsal branch as a “circuit breaker” that interrupts ongoing cognitive activity to direct attention outside of the current focus of processing. This attentional disengagement mechanism is assumed to involve the \*temporoparietal region\* (and ventral prefrontal cortex) and is considered to be more strongly right lateralized. For instance, activity in this region is found when detecting a target (but not when processing a spatial cue) whereas activity in the LIP region shows a strong response to the cue

Answer 73

Inability to reach in the proper direction for an object under visual guidance (optic ataxia) Balints syndrome

Answer 74

Impaired fixation of gaze without a primary deficit of eye movement Balints syndrome

Answer 75

(simultanagnosia)

Answer 76

CANNOT compute spatial relationships between objects Unable to locate objects verbally or by reaching and pointing ▫ Impaired at locating sounds ▫ BUT: they can state which side of body and which body part is being touched (body space may be different from external space)