It Doesn t Take A Lot of Brains to Understand the Brain: Functional Neuroanatomy Made Ridiculously Simple

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Allen Wright
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1 It Doesn t Take A Lot of Brains to Understand the Brain: Functional Neuroanatomy Made Ridiculously Simple 6 th Annual Northern Kentucky TBI Conference March 23, James F. Phifer, Ph.D. Clinical Neuropsychologist drphifer@radicalrehab.com 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 1

Left Brain Dysfunction Decreased attention to detail Impaired sequencing ability Impulsive, globalistic reasoning Dyscalculia Gerstmann s syndrome Dyscalculia R-L confusion Dysgraphia Impaired

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

2 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 Agnosia Right Brain Dysfunction 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 2

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

Failure cannot be attributed to either sensory or motor deficits What do these patients look like?

3 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 Sitting posture of patient with unilateral neglect Patients pose a considerable challenge for rehabilitation professionals PATIENT DRAWINGS 5 3

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

t 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

4 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 4

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

5 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 ) 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 5

6 Two separate systems exist in brain for modulating affect a. Positive affect - sense of enthusiasm, happiness, joy b. Negative affect - sadness, distress, anxiety Positive affect is related to mesolimbic pleasure pathways, with control centers in left frontal lobe 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 Negative affect is related to pain pathways of periaqueductal gray area, with control centers in right frontal lobe * 3/10/2012 * 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 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 * 3/10/2012 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 understimulated and under-concerned (heard woman scream, assumed not in trouble 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. 6

7 Right frontal activation associated with vigilance to threat-related cues, anxiety Decreased right frontal activity associated with inability to experience emotional consequences of punishment 7

Higher Cortical Function

Emilie O Neill, class of 2016 Higher Cortical Function Objectives Describe the association cortical areas processing sensory, motor, executive, language, and emotion/memory information (know general location