In the first example of split brain patients given, which brain structure is cut?

What condition was being treated?

What was the guy's name and when?

In the first example of split brain patients given, which brain structure is cut?

What condition was being treated?

What was the guy's name and when?

- corpus callosum

- epilepsy

- Roger Sperry, 1960s

What does the corpus callosum connect?

What function does it serve with regard to data?

What other corpus callosum task is really important?

What does the corpus callosum connect?

What function does it serve with regard to data?

What other corpus callosum task is really important?

- Comparable structures on each side of the brain

- Permits transfer between hemispheres

- Motor coordination of left and right side of body

What 2 types of projections are there in data transfer via the corpus callosum?

- homotropic & heterotropic

Where are homotropic CC projections most common?

- in association areas

What is a heterotropic CC projection?

How common are they?

What is a heterotropic CC projection?

How common are they?

- it mirrors ipsilateral projections

- less common than homotropic projections

Name the 3 projections in the diagram:

[image]

Name the 3 projections in the diagram:

[image]

What 2 things are still crossed when the corpus callosum is cut?

If both of these are still crossed, exactly what impairment occurs then when the CC is cut?

What 2 things are still crossed when the corpus callosum is cut?

If both of these are still crossed, exactly what impairment occurs then when the CC is cut?

- sensory inputs (ie visual field) and motor outputs (ie LH for right hand) are still crossed

- BUT the 2 hemispheres can't communicate

Which patient was the one in the split brain studies?

- patient JW

In the split brain studies, which object does the patient claim to see? Why?

In the split brain studies, which object does the patient claim to see? Why?

whatever is in the right eye's field of vision, because that goes to the left hemisphere & only the LH can produce speech (although RH has some basic comprehension abilities)

In the split brain studies, what does the patient report about the object in the left eye's field of vision?

- Nothing;  the right hemisphere processes this visual input and although it does understand what it sees, it does not have the ability to verbalize this info...

(and with the corpus callosum cut, the info can't be sent to the LH for verbalization)

What is and what is not impaired after a Posterior partial cut of the corpus callosum?

- transfer of sensory info (visual, tactile, & auditory) is disrupted

- higher-level Semantic info can still be transferred

In a posterior partial CC cut, how is higher-level/semantic info transferred despite the cut?

- via the anterior CC

Describe inter-hemispheric communication through the corpus callosum after a partial CC cut with the Splenium spared.

 - Only visual info can still be transferred

After a partial CC cut, can a patient verbally report info about objects that are only visible to the left field of vision?

- Yes; even though the left visual field goes to the right hemisphere (which can't verbalize anything), because it's a partial cut, some info can still get to the LH.  However, it will be much more difficult / take longer / they will be shittier at it.

What is the 'frequency matching' strategy with regard to the decision-making task?

- the strategy is to match the frequency a response is given to the frequency that event actually happens.  In other words, if the square can appear at the top or at the bottom of the screen, but 80% of the time it appears at the top, then you should guess 'top' on 80% of your guesses.

What is the 'maximizing' strategy with regard to the decision-making task?

- whatever event occurs most often, just guess that every time.  In other words, if the square could appear at the top or the bottom, but appears at the op 70% of the time (so only at bottom 30%...), then just guess 'top' every time so that overall, you're basically guaranteed 70% correct.

In the decision-making task, which strategy is optimal: frequency matching, or maximizing?

Which hemisphere employs which strategy?

In the decision-making task, which strategy is optimal: frequency matching, or maximizing?

Which hemisphere employs which strategy?

- maximizing is a more effective strategy

- RH uses maximizing, LH uses frequency matching

What happened in the Spatial Task study of split-brain patient JW?

What does this suggest?

What happened in the Spatial Task study of split-brain patient JW?

What does this suggest?

- spatial figure construction task = perfect using left hand / right hemi

- fails task with right hand / left hemi

- suggests RH is better at some types of spatial tasks

If shown a horse in the left visual field of a split-brain patient, can they verbally tell the experimenter what the object is or what normally goes on top of the object?  Are they able to do any mental processing on the sensory input?

- cannot verbally answer; they just say "I dunno"

- They can draw a perfect saddle (using their left hand... so right hemisphere) --> they DO understand what they see, just no verbal ability

What type of comprehension is possible for the RH's language abilities?

What type of words are understood best? What type is not?

What type of comprehension is possible for the RH's language abilities?

What type of words are understood best? What type is not?

- 'lexical comprehension'

- concrete words are best; abstract words not as good

Which normal effect that happens in language comprehension in patients without brain damage is present in the RH's language abilities?

 - the word superiority effect

Which part of speech can the RH not understand?

Which types of syntactic forms cannot be differentiated?

Which part of speech can the RH not understand?

Which types of syntactic forms cannot be differentiated?

- verbs

- singular vs. plural

and

active vs. passive

are indistinguishable

What can the RH learn in rare cases?

- rudinmentary speech

Describe the video on split-brain patients from youtube that we watched in class.

(  http://www.youtube.com/watch?v=lfGwsAdS9Dc  )

Describe the video on split-brain patients from youtube that we watched in class.

(  http://www.youtube.com/watch?v=lfGwsAdS9Dc  )

- ???

What is the main contribution we have learned from split brain studies in humans?

- each hemisphere can function independently

What 2 limitations are there regarding split brain studies in humans?

- patients are not 'normal' before surgery

- findings based on only a handful of patients

How are the conclusions researchers have drawn from split brain studies in humans best summarized?

- brain imaging studies show that both hemispheres contribute to ALL functions but to a different degree.

Briefly describe what Wada testing involves.

1) use sodium amytal to put the LH 'to sleep'

2) put object in subject's left hand and ask "what did I just give you?".....   they say "nothing."

3) show them a piece of paper with pictures of several objects on it... they can point to the object that was placed in their hand

What part of the brain is larger in the LH in humans and great apes?

To what degree do the 2 hemispheres differ?

What significant piece of evidence hints that the size asymmetry corresponds to the LH's language ability?

What part of the brain is larger in the LH in humans and great apes?

To what degree do the 2 hemispheres differ?

What significant piece of evidence hints that the size asymmetry corresponds to the LH's language ability?

- the planum temporale

- the difference is actually just very slight

- the degree to which the PT is larger in the LH is less in dyslexics

What does the difference in size of the planum temporale between the 2 hemispheres indicate about the anatomical differences between the 2 hemispheres?

- nothing, on the whole / overall / in general:

There are no gross  anatomical diff.s btwn hemispheres

What are the 3 caveats to attributing LH language to the anatomical asymmetry of the planum temporale?

1)  the differences are in Shape rather than Volume

2) 95% of adults have language asymmetry while only about 65% have structural asymmetry

3) the differences might be better explained by Microanatomy

What gets inhibited when distinct sounds are presented to the 2 ears at the same time?  What is the term for presenting sounds this way?

- ipsilateral auditory pathways

- dichotically

In auditory processing for dichotic listening tasks, for which type of processing is the RH dominant for?

The LH?

In auditory processing for dichotic listening tasks, for which type of processing is the RH dominant for?

The LH?

RH = melody

LH = verbal content

For the image shown, what would a correct 'global processing' response be for identifying what's in the image?  Response using local processing?

[image]

For the image shown, what would a correct 'global processing' response be for identifying what's in the image?  Response using local processing?

[image]

- global:  there is an 'H' and then an 'F'

- local: there are a bunch of 'F's and then a bunch of 'H's

In general, which form (global or local) is processed more quickly?

- global

What part of the brain should be unilaterally lesioned to interfere with either local or global processing?

What pathway is this part of the brain a part of?

What part of the brain should be unilaterally lesioned to interfere with either local or global processing?

What pathway is this part of the brain a part of?

- the temporo-parietal junction

- it's a part of the 'what' pathway

State which type of processing (local/global) is impaired for lesions to each hemisphere at the temporo-parietal junction.

- LH lesion = impaired local processing

- RH lesion = impaired global processing

In studies of normal (non-lesioned) people, is either hemisphere better at each task (local or global) ?

-  the RH is better at global and the LH is better at local....

BUT either hemisphere is capable of doing either task:  the differences in RT are obviously there but they are not that different

What is the first explanation we studied for why local/global hemispheric asymmetries exist?

- analytic vs. holistic dichotomy

In the analytic vs. holistic dichotomy (one explanation for hemispheric asymmetries), what specific task is the RH better at?

What aspect of this task makes the RH better suited for it?

In the analytic vs. holistic dichotomy (one explanation for hemispheric asymmetries), what specific task is the RH better at?

What aspect of this task makes the RH better suited for it?

- face processing

- faces are processed holistically

What split-brain evidence is there to support the analytic vs. holistic dichotomy?

- split-brain patients recognize unfamiliar faces better when they are presented in the LVF (RH)

What is the 2nd hypothesis we studied for explaining local/global hemispheric asymmetry?

- the spatial frequency hypothesis

In the spatial frequency hypothesis, perception requires attending to different ____  _____ .

 The local level is based on: ...... ?

The global level is based on: ........ ?

In the spatial frequency hypothesis, perception requires attending to different spatial frequencies.

 The local level is based on: ...... ?

The global level is based on: ........ ?

-Local:  attending to high spatial frequencies

-Global:  attending to low spatial frequencies

[image]For the image shown, what is the

Frequency?

Type of processing?

Better hemisphere?

[image]For the image shown, what is the

Frequency?               Low

Type of processing?      Global

Better hemisphere?      Right

Frequency?

Type of processing?

Better hemisphere?

Frequency?                High

Type of processing?     Local

Better hemisphere?    Left

Explain how the frequency hypothesis explains hemispheric asymmetries for auditory speech perception.

- High sound freq. info is important for lexical analysis (aka what words are these), which is what the LH is better at.

- Low sound freq. info impt. for prosody (global rhythm of language), which is what RH is better at.

For spatial / 'where' pathway hemispheric asymmetry, what are the 2 kinds of representations of spatial information that are possible?  (Briefly define each)

For spatial / 'where' pathway hemispheric asymmetry, what are the 2 kinds of representations of spatial information that are possible?  (Briefly define each)

- Categorical = the relative position between 2 objects or between an object & the viewer

- Coordinate = the exact positions and distances between objects (or btwn obj. & viewer)

Which hemisphere is geared toward categorical spatial representations?  Which is geared toward coordinate rep.s?

Categorical  =  LH

Coordinate  =  RH

Explain the difference between the purposes of categorical vs. coordinate spatial representations.

- Categorical is for classifying objects:  b d p q  all have the same parts but the relations btwn parts determine letter identity.

- Coordinate is for action:  e.g, to pick up coffee mug you must know exactly where it is on the table.

Task 1 = is dot above or below the line?

Task 2 = is dot near or far from the line?

*****

Which task is categorical and which is coordinate?

Based on RT, which hemi is better for which?

Task 1 = is dot above or below the line?

Task 2 = is dot near or far from the line?

*****

Which task is categorical and which is coordinate?

Based on RT, which hemi is better for which?

-task 1 = categorical, LH is better

-task 2 = coordinate, RH is better

What was Kosslyn's explanation for why each hemi was better at one of the 2 tasks?

-LH specialized for categorial relations bcz they can be represented in verbal terms (ie, 'to the left of' or 'above the line')

-RH specialized for coordinate relations bcz it is superior for visual-spatial processing

Do LH/RH lesion studies support the categorical vs. coordinate paradigm?

yes

What important caveat is there regarding the categorical-coordinate distinction?

 The observed results may simply be an extension of the spatial frequency hypothesis:  on the above/below task, the RH is worse bcz it processes low freq. info & in a fuzzy image if the dot just blends in with the line, can't tell if above/below bcz can't even tell that there are 2 seperate objects.  LH does high freq so it can.

Define the terms 'exemplars' and 'prototype' by using animals as an example.

- Dog, cat, cow, mule, camel, lion, tiger, rabbit would all be exemplars of a category

- The prototype would be the generic representation of 'animal; a 'composite' that combines the features of many exemplars

Briefly summarize the experiment that studied categorical/coordinate rep.s and learning; the one that measured RT for prototypes vs. exemplars & comparing hemispheres.

 - Ss trained to categorize some exemplars, w/o seeing prototype (learning phase). Then presented stimuli incl. previously seen exemplars, unseen exemplars, and prototypes (test phase).  RT for prototypes much faster for LH --> uses categorical reps. Trained exemplars much faster for RH -> coordinate info.  *Neither hemisphere had advantage for new exemplars, & RT for them was relatively high compared to known exemplars & prototypes RT.

What is the RH's specialty with regard to emotion?

What are the 2 main factors of this specialization?

What is the RH's specialty with regard to emotion?

What are the 2 main factors of this specialization?

- RH specializes in comprehension of emotion

- specifically, comprehending

1) facial expressions

&

2) prosody (tone of voice / inflection)

What 3 sub-categories of the task of 'expressing emotion' were discussed & how do they each correspond to brain hemispheres?

- Voluntary facial expression:  LH

- Spontaneous facial expression:  both LH & RH

- Producing emotional prosody:  RH

How is frontal/anterior hemispheric asymmetry related to affective style?

By what measurement of asymmetry was this relationship established?

How is frontal/anterior hemi. asymmetry related to affective style?

By what measurement of asymmetry was this established?

- the hemi. favored by the asymmetry affects/determines/correlated w/ personality traits

- Right-dominant = approach; left-dominant = withdraw

- Careful: bcz R-dom. = approach, intuitive to think R-dom. is positive affect. However, bcz of the tendency to approach (vs. withdraw) they are 'too attached' & cry a lot more when their mothers leave the room = negative affect.

- this exp. refers to 'asymmetry' in regard to baseline EEG activity (not size, etc.)