[Cognitive Neuropsychology Methods]

DR. ASHOK JANSARI: My name is Dr. Ashok Jansari.[Dr. Ashok Jansari, Cognitive Neuropsychologist, GoldsmithsCollege, University of London] I work at GoldsmithsCollege, University of London.And I'm a cognitive neuropsychologist.In this tutorial, we're going to gothrough the main methods used in cognitive neuropsychology.And by the end of it, you're goingto have a small toolkit that's goingto help you understand the methodology

DR. ASHOK JANSARI [continued]: of cognitive neuropsychology.[Main Methods]One of the main issues in studying neuropsychologyis who you study.[Who you study] Now, this is aboutwhether you study a single person intensely,and that's known as single cases,or whether you study large groups of people.

DR. ASHOK JANSARI [continued]: Now, ultimately, this comes down to availability of participantsand rarity of a disorder.[Availability of participants and rarity of disorder]Now, for example, in the study of memory and amnesia,there's a patient known as HM, [Patient HM]who's the most famous patient with amnesia ever studied.As a result, he was studied intensely-- just

DR. ASHOK JANSARI [continued]: him and no other patients.But over time, as people understood amnesia more,we started getting group studies wherepeople who were doing research in this areastarted putting five, six, seven, eight patients togetherinto one group.So we have single cases [Single cases vs groups] versus groups.

DR. ASHOK JANSARI [continued]: Now, sometimes, it depends on availability of participantsand different patients.And sometimes, it depends on how much detailyou want on a particular issue.Also, there are some cases which are very rare.And with those cases, you want to study that person completelyon their own.

DR. ASHOK JANSARI [continued]: [Hybrid approach: case theories]Nowadays, there's a hybrid approach know as case theories.And in the case theories, you havea group of patients who all have a similar disordersuch as amnesia, but you try to maintain the individual natureand detail within each patient.So thereby, you're studying a number of people,

DR. ASHOK JANSARI [continued]: but you're still keeping some of the detail from case studiesalive.[Healthy Controls]As with cognitive psychology, one of the main techniques thatis used is studying the behavior of patientsunder different experimental conditions.[Different experimental conditions]

DR. ASHOK JANSARI [continued]: Now, the important thing here is the use of healthy controls.[Use of healthy controls] And the useof appropriate healthy controls is a vital componentof cognitive neuropsychology because, effectively,what we're doing is looking at someone like HM,who doesn't have intact memory, and wewant to know what the brain damage has done to his memory

DR. ASHOK JANSARI [continued]: system.And we want to compare him to other people.Now, who these healthy controls arebecomes a very important part of our equation.When we study HM, for example, and his memory is reduced,we want to make sure that the problem isn'tbecause of his gender, his age, or his intellectual abilities.

DR. ASHOK JANSARI [continued]: Therefore, in our healthy control group,[Same gender, age, intellectual abilities as Patient HM]we try to get people the same genderis him, the same age as him, and the same intellectual abilityas him.When we find any difference between himand the healthy controls, we can bemore sure that it's the amnesia that'scaused the memory problem rather than all

DR. ASHOK JANSARI [continued]: of these other variables.Therefore, the use of appropriate healthy controlsis one of the most vital ingredients usedin cognitive neuropsychology.[Neuroimaging]An important part of the toolkit for some neuropsychologistsis using neuroimaging.

DR. ASHOK JANSARI [continued]: Neuroimaging involves looking at the brain, either physicallyor functionally. [Looking at the brainphysically or functionally] Now, the neurologists of the 1800s,they had to wait till their patients died until they couldautopsy their brains to see which parts of the brainwere damaged to try to infer what was happeningin different parts of brain.

DR. ASHOK JANSARI [continued]: Now, we can look at people while their alive to see whichparts of their brains are damagedand which parts of our brains are functioningwhen we're remembering, seeing, making decisions, et cetera.A number of different techniques can be used.[Types of brain scan.MRI, CAT, fMRI, tDCS, MEG, EEG]MRI scan, CAT scan, fMRI, tDCS, MEG, EEG.

DR. ASHOK JANSARI [continued]: It's almost an alphabet soup of different letters.But there are different techniquesfor different types of jobs.But overall, they can tell us about function [Function]or physical location. [Physical Location]Now an important thing to do is to notethat these techniques are still being developed,so they're not perfect.

DR. ASHOK JANSARI [continued]: And one of the important things is that we alwaysgo back to behavioral testing. [Behavioral testing]So neuroimaging is a very useful part of the toolkit,but it's not the only thing that neuropsychologists use.[Double Dissociations]One of the most important tools that a neuropsychologist can

DR. ASHOK JANSARI [continued]: use is a double dissociation.A double dissociation is a conceptual tool.[Conceptual tool] What we're lookingfor is two patients, one of whom can do A but not B,and another patient who can do B but not A.Now, let's take the example of HM, [Patient HM]the famous amnesic.We saw that with HM, his short-term memory was intact,

DR. ASHOK JANSARI [continued]: [Short-term memory intact, long-term memory affected]but his long-term memory was affected.Now, at that point, you could saythat maybe short-term and long-term memory are separate.But when we find a patient who is the exact opposite of HM,who's got an intact short-term memorybut a bad long-term memory, we have

DR. ASHOK JANSARI [continued]: a classic double dissociation.HM has got good short-term memorybut bad long-term memory.And a patient called KF [Patient KF]has got bad short-term memory but a good long-term memory.And this double dissociation or reverse pattern between the twopatients [Reverse pattern] shows usthat, at least at some level, these two systems

DR. ASHOK JANSARI [continued]: are parallel and work side by siderather than one after another.Now, the reason that double dissociationsare so important across neuropsychologyis that it allows neuropsychologists to separateout functions into smaller parts that we can work on separately.And they occur across all of neuropsychology.

DR. ASHOK JANSARI [continued]: For example, when we look at someone's face,we can work out who they are, [Who they are,and what emotion they are showing]and we can work out what sort of emotionthey're showing, whether they're happy or sad.Now what we find is that there are some people whocan't recognize a face, so they can't tell you who someone is.A condition known as Prosopagnosia.[Prosopagnosia]But those patients may still be able to tell you

DR. ASHOK JANSARI [continued]: whether the person is happy or sad.But we also have patients who are the exact opposite.They can tell you who someone is,but they can't tell you what sort of emotionthey're showing.So here we have another double dissociationbetween working out identity from a faceand emotion from a face.

DR. ASHOK JANSARI [continued]: The fact that we get these two separate, opposite patternsshows us that, at least at some level,these two processes are separate and parallel.And that allows us to create more complex modelsof what is happening in the brain when we look at a face.So overall, double dissociations are an extremely powerful tool

DR. ASHOK JANSARI [continued]: that helps us refine our models of brain functions.[Conclusion]In summary, there are many different methodsthat we can use in neuropsychology.Sometimes, [Who you study] it's about who you study,whether you study one person or whether youstudy a whole group.

DR. ASHOK JANSARI [continued]: We've also got to be careful about who our healthy controlsare [Healthy controls] so that wecan infer that the processes that we're studyingare actually caused by the brain damage.So the use of appropriate healthy controlsis very important.If neuroimaging is available, [Neuroimaging] thenwe can also use that to try to inferlocation of function or processes

DR. ASHOK JANSARI [continued]: that are happening in the brain.But these have got to be used with caution.Finally, double dissociations area very powerful conceptual tool thatcan be used to separate out processes.Which tools you use and when you usethem will depend on the research questionyou're looking at and the availabilityof different participants.

DR. ASHOK JANSARI [continued]: So it's really a [INAUDIBLE] that cause this thing.There's a toolkit, and you use those as appropriate.