What is Neuropsychology Study of brain–behavior relations (sometimes referred to as functional localization) Functional Lateralization – refers to notion that a function may depend on one side (hemisphere) of the brain

Definition of Clinical Neuropsychologist A clinical neuropsychologist is a professional psychologist who applies principles of assessment and intervention based upon the scientific study of human behavior as it relates to normal and abnormal functioning of the central nervous system. The clinical neuropsychologist is a doctoral-level psychology provider of diagnostic and intervention services who has demonstrated competence in the application of such principles for human welfare following:

A doctoral degree in psychology from an accredited university training program. An internship, or its equivalent, in a clinically relevant area of professional psychology. The equivalent of two (fulltime) years of experience and specialized training, at least one of which is at the post- doctoral level, in the study and practice of clinical neuropsychology and related neurosciences. These two years include supervision by a clinical neuropsychologist. A license in his or her state or province to practice psychology and/or clinical neuropsychology independently, or is employed as a neuropsychologist by an exempt agency.

Different types of Neuropsychologists/ Subareas Experimental neuropsychologists – work to understand the neural bases of cognition by doing studies – Experimental neuropsychology = cognitive neuropsychology or cognitive neuroscience Clinical neuropsychologists – work in health-related settings (e.g., hospitals, clinics) with patients – Involved in diagnosis – Involved in rehabilitation (e.g., designing programs) – May be involved in research – Clinical neuropsychology

How do we study brain-behavior relations? (Techniques) Invasive – Lesion – Inject radioactive tracer Non-invasive – Brain-imaging to see what regions are active during specific mental task – Record activity of cells to determine what activity makes them respond – Present information to different hemispheres and see which side does task better or faster

Why study brain-behavior relations? Diagnostic purposes Rehabilitation purposes Intellectual curiosity

Methods in Neuropsychology

Method of converging operations: Use a number of different methods and populations Evidence obtained from a set of experiments converge on the same conclusion – e.g., fMRI and lesion studies

Research considerations: What type of participants? How will we gather information about their brains? How will be measure behavior?

Research Participants: (1) Patients with lesions (2) Healthy Individuals (3) Animals

(1) Patients with lesions Question: What functions supported by this neural site? Studies need to include patients with lesions to a specific site and patients with lesions to a different site ‘Double dissociation’ - lesions have converse effects on two distinct cognitive functions Allow one to conclude that structures/ functions are independent

Question: What neural sites are associated with a particular deficit? – e.g., Memory impairment associated with damage to: – Brenda Milner’s work with temporal lobe epilepsy and memory where hippocampus was found to be important for learning

Problems with lesion method Brain damage messy in humans (1) People vary in their genetic and environmental characteristics e.g., differ in education, onset of dementia – Lesions vary in their extent and origin Stroke vs tumor vs bullet (2) Lesion does not allow us to observe directly the function served by the lesioned site

Only know how brain performs without that particular area We can infer the site may be critical but we can not identify all the areas that may be involved Site may not be critical in performing a particular function: rather, may contain axons that connect regions that must interact for correct performance – Disconnection syndrome Split brain Conduction aphasia

Associated problem: single cases or groups Groups of patients may be so hetergeneous in their behavior that ‘group average’ is meaningless – Argues for single case approach Problem with single case approach – Is pattern observed representative of people in general? – Does not allow one to rule out random error

Use multiple case approach, validating research findings on a series of patients, or Follow-up findings from single-case with group studies

(2) Neurologically intact Individuals These persons provide the control group that allows us to determine thedegree to which performance of brain damaged people is compromised Well-designed studies must include appropriate control group

(3) Animal Populations Allows for control over – Environmental conditions/experience – Size and nature of lesions – Genetic differences, etc.

Gathering Information about the Brain:Techniques CT Scans – Uses series of X-ray beams through head. Images developed on sensitive film. Shows anatomical image of brain density. – CSF < brain tissue < blood < bone – Darker Lighter

Advantage: – Can be used with most people Disadvantage: – Uses radiation – Dye may cause allergic reaction – Results do not have a high spatial resolution – Structure of brain only

MRI Anatomical image of substances such as water or fat - give picture of tissue density Relies on passing an external radio frequency pulse to disrupt the magnetic fields of nuclei and distort the behaviors of atoms When atoms fall back in line, they re-emit the radio-frequency signal which is detected by a receiver coil The frequency of this signal reflects the number of elements in the nucleus and the effect of the surrounding material

Advantages Does not require X-rays or radioactive material Safe, painless, non-invasive Result is high resolution

Disadvantages Expensive Cannot be used in patients with metallic devices, like clips, pacemakers, or possibly orthopedic pins Cannot be used with claustraphobic patients Assesses structure only

Functional MRI In fMRI, MR signal measures functional characteristics of brain Detects changes in blood flow to particular areas of the brain Provides both an anatomical and functional view of the brain

Advantages Noninvasive - radiation needed Multiple scans can be done on an individual so can examine changes over time (e.g., learning) – Provides a good measure of brain activity over seconds Provides a good spatial resolution

Disadvantages Cannot localize processes in time better than 1 second – fMRI does not image neural activity but rather response of vascular system to oxygen demand and this can lag functional activation as well as extend beyond period when activation occurred

PET Also provides a functional image of brain activity Radioactive substance (e.g., glucose) introduced into blood Radioactive molecule becomes stable by releasing positron, collides with electron, annihilate each other -producing energy - PET detects this energy

PET detects how much of the brain fuel (oxygen, glucose) is being used by different regions Areas that are metabolically active emit lots of energy; those that are less active emit less energy

Advantages Good at examining functioning of a variety of neurotransmitters Disadvantages Involves radiation Provides image of brain activity averaged over very long time periods (e.g., minutes whereas cognitive decisions occur in msec) Typically, data on task is averaged across many people Not very good at determining location of function in a given person (does not provide high spatial resolution)

EEG Electrical activity of the brain Provides information about general state of person (e.g., awake) Good at detecting various clinical disorders – e.g., sleep, seizures

Provides accurate measures of activity on a millisecond basis But poor at localizing activity Does not provide information about subcortical structures

Event Related Potentials (ERP) Recording of brain’s activity that are linked to the occurrence of an event (stimulus) Provides information linked to processes such as memory and attention Examine components of the waveform recorded on the scalp such as – P300 - S must respond to target stimulus (‘b’ not ‘d’, blank sound) - appears to measure attention, updating of memory

Neuropsychological Assessment Allows one to separate cognitive functions (e.g., STM vs LTM) Profile patient strengths and weaknesses – diagnosis Provide a baseline to evaluate change – e.g., remediation, improvement, decline Make statements about prognosis

Fixed batteries (e.g., Haltead-Reitan, Luria-Nebraska) Flexible battery Generally measure IQ (Wechsler tests) Also measure executive function, attention, memory, language, spatial ability, motor, sensory function, emotional function

Need good normative data Pre-morbid Estimation e.g., NART, WTAR