Defining functions I: from phrenology to early neuropsychology

Question 1

What is phrenology?

Answer 1

an early attempt at relating structure to function in the brain

Question 2

What are the three main premises of phrenology?

Answer 2

1. different parts of the brain are responsible for different processes
2. aptitude is related to differences in brain region size
3. brain region size influence skull shape

Question 3

What did phrenology believe careful measurements of people’s skulls will reveal?

Answer 3

relationships between skull shape and various brain functions

Question 4

Which premise of phrenology has no complete and obvious holding?

Answer 4

brain region size influences skull shape

Question 5

What is an issue that comes up in terms of population diversity and phreology?

Answer 5

you cannot determine if a particular region in the brain is the same region you are looking at from individual to individual to there being differences in brain region size between individuals; and there also being exiisting diffrences between gender groups; racial/ethnic groups; and age roups

Question 6

What are some important problems with phrenology?

Answer 6

1. inappropriate anatomical measurement - skull shape is not a sensitive measurement of brain shape and anyway the overall shape of the brain is the wrong level of analysis
2. unconstrained definition of functions - studies of prisoners aimed identifying regions associated with criminality or women with different numbers of children to find the locus of philopropogenitiveness

Question 7

When defining certain “functions” why is it important to consider them in a social milieu?

Answer 7

-some of the problems of phrenology and physiognomy the study of facial features are endemic to doing any kind of scientific research on humans
-concepts like criminality and philopropogenitiveness are complex constructs that are unlikely to have a simple biological basis

Question 8

Are there currently studies being conducted which fail to take into consideration “functions” in a social milieu?

Answer 8

-there are AI systems out there right now that are trying to classify people in various ways based on pictures of their face - like criminality
people will still apply very sophisticated technology like machine learning to ill formed questions

Question 9

What does fancy statistics and high tech data collection not make up for?

Answer 9

-cant make up for poorly defined questions

Question 10

Are decisions about what to measure and how to measure it affected by external factors?

Answer 10

yes they are never made in vaccum; i.e. definitions of cognitive processes were shaped by the goals of agencies that funded foundational work in this area (alot of cognitive science research was funded by the military)
-this means that basic facts about perception, attention, memory, decision making are also shaped by a larger social context

Question 11

Where does the construct that the brain functions as a computer or modulator come from?

Answer 11

comes from the fact that the people that funded the studies for cognitive neuroscience were also interested in computers which has funding due to military advancements so this means the way we talk about perception, attention, memory, decision making are also shaped by a larger social context; which is due to the fact that the root of cognitive neuroscience is rooted in computational framework

Question 12

How did phrenology fall out of favor?

Answer 12

-it was popular among intellectuals and a general framework - for instance in early days of the public school system phrenologists were taken seriously (i.e. phrenology was used for standardized tests)
-early scientists began to disfavor phrenology when starting to conduct experiments with lesioned animals

Question 13

What did flourens do in regards to phenrology?

Answer 13

-did crude animal experiments and he found that chickens are unperturbed until you blow out a lot of tissue; found the motor strip of monkeys; found that the more complex functions was the mass action of the brain as an organ so will not find a criminality area or language area and they usually arise as a result of mass action of the brain - just more damage to the cortex cam impact these overall functions

Question 14

What did flourens experiments consist of?

Answer 14

-they were mainly with pigeons and rabbits and they established distinct functions of the cerebral cortex, cerebellum, and mid brain structures
-but he failed to find any correspondence between specific regions in the cerebral cortex and specific senses
-instead he insisted that the size of the lesion was critical and that understanding or intelligence were the result of the cerebral cortex functioning together as a whole
-the position was held widely by most mid 19th century physiologists and anatomists
-coined the idea of holism

Question 15

Why did localism and holism go back and forth in the 19th century?

Answer 15

-nobody thinks the brain functions by mass action at this point but they are still trying to figure out if you can localize brain function

Question 16

Why did flourens and his contemporaries not have great methods for measuring cognitive capacities in animals?

Answer 16

-for sensory and motor abilities they could demonstrate associations between subcortical lesions and loss of function so even the holists admitted some degree of specialization
-but leaning as flourens did on descartes for ones definitions of mentasl functions and trying to apply this to studies of rabbits and pigeons has some obvious problems
-the tension between localism and holism will animate a lot of the debates in modern cognitive neuroscience

Question 17

In 1861, neurologist pierre paul broca presented what?

Answer 17

-the case of Tan who had lost the ability to speak after a brain injury decades earlier
-Tan has a brain injury in his twenties and lost capacity for expressive speech

Question 18

What are the three main things Tan could do?

Answer 18

-could only produce on jargon syllable (“tan”)
-seemed to otherwise be in possession of his sense
-in fact seemed to understand what was being said

Question 19

Was Tan the first observation of a specific loss of function after brain injury?

Answer 19

no but brocas stature and reputation as the founder of the society of anthropology did a lot to make localization of function a respectable pursuit

Question 20

How did the case of Tan and his aphasia support localization?

Answer 20

-since Tan could not produce sounds or speak but could understand speech and these two are heavily related functions - it somewhat supported the idea that these two were localized to different areas of the brain

Question 21

In the 1870s a number of german neurologists, lictheim, wernicke began making more systematic observations of aphasia, what did they describe?

Answer 21

specific loss of function to disconnections between centers

Question 22

What is the lichtheim house model?

Answer 22

(Look at image of model on slide 9 of week1B_functions kecture)
-model for understanding language and can relate those sounds to word forms and relate those words to meanings
a—->A—–>B——>M——->m
-peripheral, auditory, and motor control
-A is the auditory memory for words forms - literal things happen in little a so that you can abstract information in big A (big A is abstract and little a is the literal form); B is the German word for concepts; M is the abstract motor sounds; m is the literal motor sound

Question 23

In lichtheim’s house model, where would Tan’s injury lie?

Answer 23

it would be on 5 between M and m he might know the actract motion to make a sound but cannot literally make the motor sound needed in little m; the little m could also be the site of injury, the big M can also be the site of injury

Question 24

In lichtheim’s house model, someone who does not understand spoken words but can speak has a disconnect between what?

Answer 24

between A and B or A is destroyed (B cannot be destroyed or else they will have issues in reading and writing and other speaking tasks)

Question 25

What did Freud propose language came from instead?

Answer 25

from fields connecting perceptual and motor abilities to drives
-i.e. if we thing about the brain as a network of cells that communicate isnt it more likley that abstract things like how a word sounds might be an emergent property that comes from the cells communicating

Question 25

Why did Freud critique the lichtheim house model?

Answer 25

-he did not like the drawing and he wrote a monograph about aphasias and he said that you cannot localize ares in the brain to function because you cannot put psychological concepts into tissue

Question 26

What is a durable tension in regards to localism vs holism in neuroscience?

Answer 26

-can we directly relate brain area functions and cognitive functions or not?
-is the brain really organized according to our descriptions of congitive phenomena?

Question 27

What are some tools for modern neuropsychology?

Answer 27

-standardized tests permit justifiable statements about degrees of impairment relative to a sample comparison
-structural neuroimaging permits in vivo idenitfication of lesions

Question 28

What is the idea behind standardized tests?

Answer 28

if we can compare you to an appropriate comparison sample and can make some statistical inference about your performance relative to that sample is more precise than just going off of a researchers perception like if he looks like he understands

Question 29

What is the benefit of the emergence of structural neuroimaging?

Answer 29

it lets your see structural issues in the brain - if you see a glioma in the brain you do not have to wait for the person to die to see the brain you can relate patterns of injury to patterns of function while the patient is still alive

Question 30

In the 1950s to the 70s in cognitive neuropsychology with the emergence of case studies in memory like HM, face processing, attention deficits, and people with selective face blindness why were standardized testing and structural neuroimaging helpful?

Answer 30

• if someone has a brain injury we can now perform tests to figure out what has gone wrong and compare them to a norm
  -can use structural neuroimaging to look at the injury state and relate injury in the brain to functions

Question 31

What are the elements of the western aphasia battery?

Answer 31

-spontaneous speech - fluency and information content of a subjects speech as they answer questions and describe pictures
-auditory comprehension - yes no questions identifications of objects and pictures and execution of commands of controlled complexity
-repetition - repetition of words phrases and sentences
-naming - object naming, word fluency, sentence completion, and responsive speech
-reading - comprehension, oral reading, and stimulus association
-writing - to dictation, copying, writing of overlearned series, and spontaneous written formulation
-praxis - assessing both limb and oral apraxia using simple and complex gestures; fine motor control issues for the mouth and larynx and everything involved in speech gestures
-construction - nonverbal tests such as drawing problems make sure they do not have praxis and other things which sets stuff you did not learn in school

Question 32

In lichtheim’s house model where is the deficit for someone who has repetition apahsia?

Answer 32

they do not have a connection between big A and big M

Question 33

What is the purpose of the western aphasia battery?

Answer 33

-can do this battery on someone and can get a pattern in their loss of function and the measures are all standardized so you can say where they are compared to normal of the population

Question 34

How does the western aphasia battery differ from lichtheim’s house model?

Answer 34

-many of the abilities the battery tests for fit neatly into the lichtehim house model
-the difference is that deficits are defined quantitatively relative to a comparison sample

Question 35

How does the western aphasia battery relates to broca’s description of Tan?

Answer 35

-Tan would do poorly on spontaneous speech and repetition, he would have good comprehension, good reading
-he was probably praxic since his speech issues were further down motor control than they were relating to understanding

Question 36

Why is the western aphasia battery better than previous ways to identify deficits in language?

Answer 36

-rather than an impressionistic description, impairments can be described quantitatively
-this has clear advantages over informal, subjective assessment but raises its own issues

Question 37

In standardized tests what is defined as the normal range and why can this be problematic?

Answer 37

-the normal range of performance is an artifact
-sorting and ranking populations is problematic
-it is more common for researchers to compare patients to sample of individuals matched to them on a range of relevant factors (region, ethnicity, education, work history) - can use modern computation to tailor the measures of language rather than comparing people to a standard pool

Question 38

What are some concerns with case studies in cognitive neuropsychology?

Answer 38

1. pre existing conditions - we rarely have high quality data about cognitive abilties before a brain injury
2. test validity - cognitive tests can be excellent at the population level, but idiosyncratic data are common
3. confirmatory bias - with a single patient there are limits to how many things one can test this limits the precision with which the specificity of deficits that can be determined
4. holist critique - for complex cognitive functions there are many ways they could be impaired so just demonstrating a relationship between injury to a particular brain region and performance is not enough to ascribe that function to that region

Question 39

What are double dissociations in cognitive neuropsychology?

Answer 39

-if two processes can be impaired independently they cant be the same thing
-one patient shows unimpaired performance on Task 1 but impaired performance on task ii while a second patient shows impaired performance task i but not task ii then the two tasks can be deemed independent

Question 40

How did broca use the concept of double dissociation?

Answer 40

-being able to dissociate patterns of impairment or disparate functions they cant be the same thing
-double dissociation - patients that have complementary patterns of deficit someone who can make articulate speech but can understand what is being said means that since they can be imparied independently they cannot be the same thing

Question 41

What are some problems with double dissociation?

Answer 41

-task decomposition - we want to isolate processes but what we have data on are tasks that entail many processes beyond the ones were interested in
-impaired and unimpaired are often relative; patients with brain injures are rarely perfect on any non trivial task (brain injuries are complicated and when a blood vessel bursts it it not going to just one region of the brain it will affect other things so how good or bad you have to be on a certain task for us to determine if you are impaired on unimpaired

Question 42

What have computer models proven in regards to double dissociations?

Answer 42

that they can be produced in highly interactive systems without separable processes

Question 43

What is the double dissociation between broca and wernickes aphasia?

Answer 43

broca - good at comprehension, word finding, has telegraphic speech so only uses a few needed words; can pronounce words but cannot really find the words, not really like Tan who couldn’t get any words out; seemed frustrated that cannot get words out
wernicke - able to say full sentences and they do not make sense; problems with individual words than the structure of speech; has some frozen phrases (can say certain phrases fine); has made up words; can say joining words but not proper nouns or functions words are there but not joining words

Question 44

How come some people with language aphasias can swear and say certain phrases that are said all the time for expressing emotions?

Answer 44

-may have different pathways separate from the language system and may instead run parallel to it

Question 45

Overall key summary

Answer 45

-the modern study of how the brain gives rise to cognitive functions begins with neurological observations from the 19th century but arguments about localization go back much further
-from the beginning difficulties are clear:
-patients show is what you can do with damage to a brain area not what a brain area does
-lesion site and behavioral profile can be very idiosyncratic
-cognitive neuropsychology emerged as a disicpline in the mid 20th c and incorporate strategies to improve its inferential power
-double dissociation logic
-standardized tests or comparison to a reference group (gives us precision in the impairment)
-definitions of function are important in themselves (don’t mention specific brain areas at all this lecture)