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It Doesn’t Take A Lot of

Brains to Understand the

Brain: Functional

Neuroanatomy Made

Ridiculously Simple

James F. Phifer, Ph.D.

Clinical Neuropsychologist

drphifer@radicalrehab.com

6th Annual Northern Kentucky TBI Conference March 23, 2012 www.bridgesnky.org

Objectives

1) A simple model for understanding the

relationship between the location of a

brain injury and the resulting changes in

thinking, emotions, language, and

behavior is presented

2) Essential distinctions between the

functions of the right vs. left hemispheres

and the anterior vs. posterior aspects of

the brain are presented.

Objectives

3) Common symptoms of left brain

dysfunction are presented.

4) Common symptoms of right brain

dysfunction are presented.

5) Changes in emotional functioning with

right vs. left brain dysfunction are

discussed.

Functional Anatomy of Brain

Anterior – Output/Efferent/Motor

Posterior – Input/Afferent/Sensory

Left

detail-oriented, sequential, step-by-step,

temporal

Right

Contour, big-picture, simultaneous

relationships, spatial

Left Brain Dysfunction

Language is composed of sequences of details (e.g., united vs. untied)

Language Disorders

Broca’s aphasia – slow, effortful, decreased fluency

Wernicke’s aphasia – fluent paraphasic jargon, impaired comprehension

Apraxia – inability to perform learned motor sequences

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Left Brain Dysfunction Decreased attention to detail

Impaired sequencing ability

Impulsive, globalistic reasoning

Dyscalculia

Gerstmann’s syndrome Dyscalculia

R-L confusion

Dysgraphia

Impaired graphesthesia

Finger agnosia

Predisposed to Depression/Anxiety/

Pessimism/Negativity

Right Parietal Lobe

Center for integrating somatic sensory

information with visual and auditory

information, for the purpose of

constructing an awareness of the body

(schema) and its relation to extra-personal

space

Right Brain Dysfunction

Topographical Disorientation

Impairment of cognitive “maps”

Difficulty understanding and recalling

relationships among places

Agnosia

Lack of recognition of familiar objects

perceived by the senses – color, angle of

orientation, edge, motion cues are utilized in

form discrimination

Right Brain Dysfunction

Agnosia

Prosopagnosia – impaired facial recognition

Environmental agnosia – inability to recognize familiar

places

Visual Object agnosia – inability to recognize

common objects

Flat Affect, Dimunition of emotional responsivity

Aprosodia

inability to comprehend or produce emotional

component of speech

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Right Brain Dysfunction

Constructional Apraxia

Hyperattention to Detail

Neglect of “big picture,” larger perspective

Task Impersistence

Failure to carry tasks through to completion

Predisposed to Apathy/Indifference to

Threat/Failure

Unilateral Neglect Defined

Failure to report, respond, or orient to

novel or meaningful stimuli presented to

the side opposite a brain lesion (Heilman,

1979)

Failure cannot be attributed to either

sensory or motor deficits

What do these patients look

like? May:

Bump wheelchairs into left side of doorway / forget to lock and/or unlock brakes of wheelchair

Fail to locate or eat food on left side of plate

In dressing, may not put left arms (for right side brain lesion) through left sleeves or put left socks and shoes on

May shave or make-up only the right side of the face

Not read words on left side of page

Patients pose a considerable challenge for rehabilitation professionals

Sitting posture of patient with

unilateral neglect

PATIENT DRAWINGS

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Drawing a Clock Writing Text

Characteristics of Unilateral

Neglect Most common with

right hemisphere

lesions

Usually associated

with lesions of the

parietal lobe

Features of USN Hemi-inattention (1/2 of universe ceases to exist)

Extinction on bilateral simultaneous stimulation

Right gaze preference

Denial of disability (anosognosia); e.g., driving

Hemialexia/Hemiagraphia

Asomatognosia: failure to recognize own limb (“Get this baby off my knee”; “There’s a wild animal in my bed”)

Motor neglect – failure to use left extremity

Allesthesia – mislocation of stimuli to right side; e.g., “circling” effect

Attentional Theories of Neglect

Relationship between a photograph and

total visual space is analogous to the

complex relationship between the contents

of awareness and the vast quantities of

available information

“Attention” refers to the neural

mechanisms that select the part of

stimulus space that is to capture the

center of awareness

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Attentional Theories of Neglect

Attention is a composite of two major operations (Mesulam, 1985):

1) Matrix or “tone” function: concerns sensitivity or regulation of overall information processing capacity, detection efficiency

2) Vector or channel function – concerns direction and target of attention in any one of behaviorally-relevant spaces (e.g., body space, extrapersonal space, mnemonic, visceral)

USN as a Disorder of Directed

Attention An important vector aspect of attention is the ability to direct the focus of awareness toward behaviorally-relevant sensory events in extrapersonal space;

“It can be concluded that unilateral neglect is not a deficit of seeing, hearing, feeling, or moving, but one of looking, listening, touching, and searching. It appears that this phenomenon represents a fundamental disturbance in a vector aspect of attention - namely, in the spatial distribution of directed sensory attention” (Mesulam,

1985, pp. 141-142)

Why is left neglect more

common than right? Right hemisphere is dominant for directed sensory attention and contains the neural apparatus for attending to both sides of space;

Left hemisphere is exclusively concerned with contralateral right hemispace;

Left hemisphere lesions are unlikely to yield neglect since the intact right hemisphere can attend to right hemi-space. Right hemisphere lesions, on the other hand, will result in left neglect, since the intact left hemisphere lacks the neural mechanisms for ipsalateral attention.

Attentional Differences in the

Hemispheres of the Brain Perceptual Aspects of Neglect

Sensory events in right hemi-space have excessive impact on awareness (“right pull”)

Posner (1984) showed patients with left USN have excessive difficulty disengaging attention from targets in right hemi-space

One mechanism of neglect is abnormal magnetism exerted by right-sided stimuli

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Psychobiology of Affect Two separate systems exist in brain for modulating affect

a. Positive affect - sense of enthusiasm,

happiness, joy

b. Negative affect - sadness, distress, anxiety

You don’t need to be sad to be depressed;

Per DSM-IV, depression may be related to either:

a. persistent low mood or

b. diminished interest or pleasure in usual activities

3/10/2012 *

Psychobiology of Affect

Positive affect is related to mesolimbic

“pleasure” pathways, with control centers

in left frontal lobe

Negative affect is related to “pain”

pathways of periaqueductal gray area,

with control centers in right frontal lobe

3/10/2012 *

Post-TBI/CVA Depression

Normally there is a balance between

Positive and Negative Affect - to avoid

being too happy (mania) or too sad

(depressed)

Left frontal lesion disrupts balance,

resulting in a lack of inhibition of Negative

Affect

Right hemisphere lesion associated with

flattening of emotionality which insulates

from depression

3/10/2012 *

Psychobiology of Affect On fMRI studies (Davidson, 1995),

individuals with extreme left-side activation

rated themselves as strong, enthusiastic,

proud, excited, while those with extreme

right-side activation viewed themselves as

distressed, scared, nervous

Psychobiology of Affect

Kenworthy (1992) played tapes of positive

and negative emotional sounds to pts with

right or left hemispheric epilepsy

Left hemisphere patients described

positive sounds (e.g., baby cooing) in

negative manner (“maybe it’s in danger”)

Right hemisphere patients were under-

stimulated and under-concerned (heard

woman scream, assumed not in trouble

Psychobiology of Affect

Explains why left brain patients are at risk

for suicide and depression, while right

brain patients check out of rehab early –

underestimate their deficits and are overly

optimistic. They think “Yes, I can’t walk or

use my left arm, but I’ll get better.”

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Psychobiology of Affect

Right frontal activation associated with

vigilance to threat-related cues, anxiety

Decreased right frontal activity associated

with inability to experience emotional

consequences of punishment