Neuropsychology
Study of the relationship between brain and behavior
Often analyzing the deficits in human function following brain injury or pathology; ablation or lesion approach
Single-case studies
Provides powerful diagnostic tool to determine sites of brain lesions
May provide insights into normal brain function
Major advances are developing in areas of imaging technology
Unit Objectives
• To review function of some major brain regions
• To understand differences in findings using brain damaged and intact individuals
• To gain an overview of the types of tasks that allow predictions of brain-behavior relationships
• To familiarize self with diagnostic tests used to assess function
Tests and Assessment
Some examples:
Intelligence tests
• Binet: IQ = MA / CA * 100 (ave = 100, sd = 15)
• Wechsler IQ (WAIS): verbal and performance subtests
Personality tests
• inventories: MMPI, many different dimensions
• projective tests: Rorschach, Thematic apperception test (TAT)
Basic idea is to allow individual to project her/his personality through descriptions, generating stories, etc.
To assess function, tests, or batteries of tests are administered
Cognitive tests• Mini mental state exam (MMSE): One of the most widely used tests for assessing cognitive mental status.
WHY? Quick and comprehensive test of multiple functions
• Memory tests:
•Wechsler Memory Scale: Prose passage (declarative), paired associates (verbal assoc), priming task (“implicit”)
• Working memory: backward digit, listening (verbal), arithmetic (calculation)
• Famous face
• Procedural tasks: Tower of Hanoi, serial response task
• Executive function: Wisconsin Card Sort Test
• Attention: visual-spatial (line bisecting, embedded figures drawing), cognitive (stroop)
Tests and Assessment
• Visual – spatial Mental rotation / rod and frame: V-S manipulationRey-Osterrieth Figure: drawing Block designEmbedded figure
• Language: fluency, comprehension, naming, repetition, grammar,
• Calculation: arithmetic
• Sensory-motor: tracking, finger tapping
• Recognition tests:Objects, faces, places
• Laterality and function of corpus callosum: L-R: Block design, R-O figure, emotion detection, Chimeric stimuli, dichotic listening, dichaptic presentation
Tests and Assessment
Different approaches to define
Overview of Brain Areas
Gross Anatomy: 4 lobes
FrontalExecutive MotorSequences, starting and stoppingAppropriate emotional
responses
ParietalMultimodal assocSpatial processingObject recognitionS-M coordination
OccipitalVision
TemporalObject recognitionMemoryAuditionemotions
Overview of Brain Areas
Gyri and sulci
Cytoarchitectonic
Maps of the Cerebral Cortex
Some subcortical structures
Some subcortical structures
Structure – Function relationships
Cortex has Topographic Organization
somatosensory
motor
This map is very PLASTIC and DYNAMIC!
Hemispheric Specializations
Function:• Verbal L, Visuospatial R• component (L) vs global identification (R) • spatial processing (R)• face, object recognition (R)• emotion detection (R)• temporal processing (L) • language (L)
Structure:
While damage to each hemisphere can result in specific deficits, actions = unified processing of single brain
Left vs Right
Split-Brain Procedure
Evidence from Split-Brain Patients
LH regulates language output
RH superior at face and object recognition, spatial processing
Accuracy low Accuracy high
Evidence from Lateralized Lesioned and Intact Individuals
Tasks:
•Wada technique
•divided visual field (tachistoscopic), dichaptic presentation, dichotic listening
Findings:
•RH processes nonverbal info, nonverbal sounds, global aspects, emotion detection
•LH processes verbal info (95% right handers), local aspects, details,
Emotion detection: which looks happier?
Neuropsychological bases of specific mental functions
Object recognition
Spatial processing
Attention
Language
Memory
Executive function
DementiaVisual processing pathways:
• dorsal stream --“where”
• ventral stream -- “what”
Object Recognition
Inability to perceive or to identify stimulus through specific sensory modality = AGNOSIA
Visual agnosias:
Apperceptive visual agnosia: can’t form “percept” of parts; can’t recognize objects
Associative visual agnosia: can’t draw from knowledge; don’t know what looking for
Prosopagnosia: inability to recognize or differentiate faces
Rule out memory disorders or primary sensory problems
Examples of visual agnosias
Apperceptive agnosias: inability to form perceptual categorization
Associative agnosia: able to group, but unable to do so from memory
Apperceptive agnosia
Associative agnosia
A Special Agnosia: Problems with Face Recognition
Configural information important for recognizing faces
Evidence: Intact participants exhibit more difficulty remembering inverted stimuli than up-right stimuli
This inversion effect is greater for faces than for other objects, such as houses
Damage to ventro-medial areas of RH impair face recognition
What’s wrong with this picture?
Spatial Processing
Perception involves a multitude of basic skills
localization of points in space
depth perception
orientation of lines
geometric relations
motion
rotation
Construction
Route Finding
Processing can involve extrapersonal or intrapersonal space.
Damage to parietal, occipital, and temporal cortex disrupts spatial processing; worse with RH damage
Dorsal visual stream
Construction deficits
Block design test shows evidence of
B. RH damage
C. LH damage
Rey-Osterrieth figure: Shows evidence of damage to posterior regions of RH (temporo-parietal)
HemineglectInattention to space contralateral to lesion
Language disorders: Aphasias
Memory and Amnesia
Anterograde (e.g. Leonard Shelby in Memento):
• impairment in LTM, not WM
• global in modality
• impairment in memory for new info, but not skills
• inflexibility of learned material
Retrograde: • varies in length of time
• has a temporal gradient
• never ALL memory
• skilled performance tends to be spared
Differences between Anterograde and Retrograde
Multiple memory systemsCase study: H.M.
Many taxonomies have been derived: explicit v implicit, declarative (relational) v procedural, episodic v semantic, working v reference
Not all forms of learning and memory are affected in amnesics
Brain Correlates
Medial temporal lobes / Hippocampus
Midline Diencephalon
Neocortex
Frontal lobes
Basal Ganglia / Caudate nucleus
Memory for information and events is processed in a distributed fashion, with different attributes handled by different cortical and subcortical systems
Memory Disorders
Retrograde vs anterograde amnesia
Frontal Lobe and Executive Function
Mini Mental State Exam
QUICK AND EASY: Simple 30 point scaleOrientation (10 pts): what (yr, season, date, day month?) and where (state, county, town/city, bldg, floor?)
Registration / Memory (3 pts): 3 objects, “pen, ball, ring”
Attention / calculation (5 pts): serial 7’s backward from 100
Recall (3 pts): Ask for all 3 objects
Language (8 pts): Naming (2 pts): point to pencil, watchReading (1 pt): “No ifs, ands, or buts.”Listen and do (3 pts) : “Take paper in your right hand. Fold paper in
half. Put paper on floor.”Read and do (1 pt): “CLOSE YOUR EYES.”Writing (1 pt): Ask to write a sentence of choice.
Visual-spatial construction (1 pt): copy design:
27-30 = Normal23-26 = Borderline < 22 = Abnormal
MMSE Ratings
Alzheimer’s ratings20-26 Mild AD10-19 Moderate AD < 10 Severe AD
Performance on MMSE varies with age and educationRemember the MMSE is not a true dementia diagnostic
It is a useful tool for a quick memory screening and to chart change with time
Dementia
Neuropathology of Alzheimer’s Disease
Progression of AD
Deficits Associated with Chronic Alcohol Use
Visuospatial problems
Learning and memory deficits
Mid-line diencephalic pathology
Thiamin (B1) deficiency
Deficits in oxidative metabolism?
Assessment Issues
Validity: does a test measure what it sets out to measure?
predictive: test can predict future performance (e.g. MCATs predict performance in med school)
construct: performance fits well with scheme about what test attempts to measure
(e.g. MCATs measure ability to retain loads of material and to endure long, exams)
Reliability: consistency of a test
Test-retest: repeated tests yield same results
Split-half: performance on similar portions yield same results
Summary
Brain damage can produce specific and reliable deficits in behaviors, providing a powerful diagnostic tool.
Findings suggest that the brain is lateralized and specialized in function across different neural systems.
Functional consequences of brain damage may lend insights into normal brain function in intact individuals.
Improvements in functional imaging technology will allow researchers and clinicians to explore the workings of the intact brain and to provide treatment with minimal invasion.