ptp 512 neuroscience in physical therapy cognition and affect
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PTP 512Neuroscience in Physical Therapy
Cognition and Affect
Min H. Huang, PT, PhD, NCS
Updated Reading Assignments
Lundy: 391, 442-454, 460-465
PRE-FRONTAL LOBE FUNCTION
Frontal Cortex
Prefrontal cortex is anterior to the motor, premotor, and limbic areas.
Functions of Prefrontal Cortex
• Working Memory– The ability to hold a limited amount of
information that is immediately available for a variety of cognitive functions.
• Self awareness and self recognition – A cognitive ability to differentiate between
self and environmental cues; understand the behaviors or emotion of others; insight
– Preferentially involves right prefrontal cortex
Functions of Prefrontal Cortex
• Executive functions (goal-oriented behavior)– Decide on a goal– Plan how to accomplish the goal– Execute a plan– Monitor the execution of the plan – e.g. what to buy, what to wear, how to get
to the hospital
Marshmallow Studyhttp://www.youtube.com/watch?v=x3S0xS2hdi4&feature=related
"How do you juggle what you desperately want to do right now vs. what you know to be best for yourself long term? Its not easy for anyone,” said Jeremy Gray, assistant professor of psychology and co-author of the study. “We found that a part of prefrontal cortex that helps integrate goals and values appears to contribute to both self-control and to performance on tests of abstract reasoning and problem solving, helping to explain why self-control and intelligence are related.”http://opac.yale.edu/news/article.aspx?id=5989
Tasks to Test Executive Functions in Children
Test of Executive Function: Trail Making Test B
• Requires working memory, processing speed, visuospatial skills, selective and divided attention, psychomotor coordination
• TMT B: connect 1-A-2-B-3-…..L-13
Reitan, 1993; Carr, 2010
Prefrontal Cortex Disorders
• Dorsolateral prefrontal lesions tend to produce an apathetic, lifeless, abulic (unable to make decisions) state
• Orbitofrontal lesions cause impulsive, disinhibition, poor judgment, emotional lability
• Left prefrontal lesions are more associated with depression
• Right prefrontal lesions are more associated with behavioral disturbances resembling mania, indifference or euphoria
Communication/Language
• In 94% of people, left (dominant) hemisphere houses spoken language functions, and is also involved in reading and writing functions
• In non-dominant hemisphere, analogous areas deal with nonverbal communication, including comprehension of gestures, facial expressions, tone of voice, and posture and providing the instruction for producing gestures or facial feature
• Wernicke’s area (Left parietotemporal cortex)– Comprehension of spoken word
• Broca’s area (Left frontal lobe)– Provides instruction for language output,
including motor plans to produce speech and grammatical functions
• Reading/Interpret written symbols involves Wernicke’s area and also requires intact vision, visual association cortex to recognize written symbols
• Writing involves Wernicke’s and Broca’s areas
Information Flow from Hearing to Speech
Figure 19.4, Blumefeld, 2010
Classification of Language Disorders
Receptive (Wernicke’s) Aphasia: Cannot understand spoken language
This patient’s speech is fluent and some of her sentences even make sense but she also has nonsense sentences, made up of words and parts of words. She can’t name objects (anomia). She doesn’t have a pure or complete receptive aphasia but pure receptive aphasias are rare.
Larsen & Stensaas. http://library.med.utah.edu/neurologicexam /html/mentalstatus_abnormal.html#05
Expressive (Broca’s) Aphasia: Cannot find the words to say
This patient has normal comprehension but her expression of language is impaired. Her speech is nonfluent and often limited to just a few words or phases. Her ability to write is also effected. Patients with expressive aphasia are aware of their language deficit and are often frustrated by it.
Larsen & Stensaas. http://library.med.utah.edu/neurologicexam/html/mentalstatus_abnormal.html#06
Broca’s aphasia
Patient has impaired fluency, normal comprehension, impaired repetition.
Often caused by a left MCA superior division infarct.
Wernicke’s aphasia
Patient has normal fluency, impaired comprehension, impaired repetition.
Often caused by a left MCA inferior division infarct.
Global aphasia
Patient has impaired fluency, impaired comprehension, impaired repetition
Can be seen in large left MCA infarcts that include both superior and inferior divisions
Conduction aphasia
Normal fluency, normal comprehension, impaired repetition, paraphasia
Cause by damage to neurons that connect Wernicke’s and Broca’s areas; often misdiagnosed as Werknicke’s aphasia
Flaccid Dysarthria
• Caused by damage to lower motor neurons (CN IX, X, and/or XII)
• Breathy, soft, and imprecise speech
• http://www.youtube.com/watch?v=dy8WvykiLto
In pure dysarthria, language generation and comprehension are not affected. Only the production of speech is impaired
Spastic Dysarthria• Damage to upper motor neurons • Harsh, awkward speech
http://library.med.utah.edu/neurologicexam/html/mentalstatus_abnormal.html
Spasmodic Dysphonia
• Interruptions in speech cadence and volume affecting voice quality
• http://thedianerehmshow.org/shows
• http://www.youtube.com/watch?v=XM-nrgVVHGU
LIMBIC SYSTEM
Limbic System
• Functions– Mood (subjective feelings, sustained,
ongoing emotional experience)
– Affect (observable demeanor)
– Processing of some memory
– Regulation of feeding, drinking, defensive, and reproductive behaviors
Limbic System Connections
• Amygdala interprets
– Facial expressions
– Body language
– Social signals
BLUE = EmotionsGREEN = Processing Memory
Output via:Autonomic connectionsSomatic connectionsReticular connectionsHormonal pathways
Emotions Link with Motor Behaviors:regulation of behaviors and motivation
Emotion:Somatic Marker Hypothesi
• Emotion signals do not make decision but are crucial for sound judgment and decision making process
• Falling in love or taking cocaine lowers threshold at which pleasure centers fire– Can have a romanticized view of the world
and surroundings which can affect judgment– When pleasure centers fire, it is more difficult
for pain and aversion centers to fire
Emotion Link with Immune System
Short-term Stress Response
Hypothalamus (after 5 min)
Pituitary stimulates adrenal glands to secrete cortisol
Mobilize energy (glucose)
Suppress immune responses
Serve as anti-inflammatory
agent
Emotion Link with Immune System
Chronic Stress Response
• If stress response is not attenuated, cortisol increases stress related diseases:– Colitis
– Cardiovascular disorders
– Adult onset diabetes
• Stress response can be perpetuated either by physical or psychological factors
Stress Linked to Common Disorders
Emotion Link with Immune System
• Immune suppression helps– Decrease inflammation
– Regulates allergic reactions and autoimmune responses
• Chronic immune suppression– Reduces skin resistance to viruses,
bacteria, and fungi
Seeman TE, 2001
Steen RG: The Evolving Brain, 2007
Emotion Link with Immune System
• Study of 1,189 people over age 80 showed 23% higher risk of mortality for those with higher stress levels
• Resistance to effects of chronic stress is generally better in people with:– Higher intelligence
– Positive self-concept
– Optimistic attitude
Stress Link with Neuronal Growth Rate• Study done on rats looking
at the effect of stress on the rate of hippocampal neurogenesis (hippocampus involved in memory processing)
• Once stress was removed, rats performed better again in a maze test
Increased stress
Increased cortisol
Decreased neuronal growth
rate
May lead to decreased cognitive
abilityGould E, Tanapat P: 1999
MEMORY
Declarative (Explicit) Memory
Declarative (Explicit) Memory
• Easily verbalized knowledge• Requires attention for recall• Three stages
– Immediate (1-2 seconds)– Short-term
• For recognizable stimuli• Loss within 1 min unless info rehearsed
– Long-term• Relatively permanent storage• Consolidation
Short-Term Memory (STM)
• HM, a patient with severe epilepsy, received surgery that removed his bilateral hippocampus– He was unable to remember any new
information from 1 year prior to surgery to present, i.e. unable to have new STM
– His long-term memory (LTM) was intact
Mechanisms for Memory Formation• STM
– Temporary changes in cell membrane excitability
• LTM
– Structural changes in neurons
– Cellular process = long term potentiation (LTP)
• Persistent enhancement of synaptic transmission following repeated stimulation of synaptic connections
Blumenfeld. 2010. Neuroanatomy through Clinical Cases.
Procedural (Implicit) Memory
• Recall of movement skills and habits
• Also called implicit memory
• Changes in performance without conscious awareness
• Requires practice to establish memories
• Once skill is learned, requires less attention
• HM able to increase procedural memory
Stages for Forming Procedure Memory• Cognitive
– Try to understand the task– Verbal guidance of task
• Associative– Refinement of movement patterns that are
most effective• Autonomous
– Movements are automatic– Require less attention– Can dual task during movement
CONSCIOUSNESS
Brainstem, Thalamic, and Cortical Circuits Important for Maintaining Consciousness
Figure 2.23, Blumefeld, 2010
Consciousness
• Level of consciousness is severely impaired in damage to the brainstem reticular formation, bilateral thalami or cerebral hemispheres
• Level of consciousness may also be mildly impaired in damage to unilateral cerebral hemisphere or thalamus.
• Toxic or metabolic factors can affect functions of these structures and are common causes of impaired consciousness
Consciousness Neurotransmitters
• Serotonin
– Modulates general arousal
• Norepinephrine
– Contributes to attention and vigilance
– Projects to sensory areas
• Acetylcholine– Voluntary direction
of attention toward an object
• Dopamine– Initiation of motor
or cognitive actions– Motivation
Coma
• Unarousable, no response to pain
• No evidence of eye opening either spontaneous or in response to stimulation
• Do not follow commands, without volitional behavior, nor verbalize/mouth words, mute
• Lack of sleep‐wake cycles
Vegetative State (VS)
• State of arousal without behavioral evidence of awareness of self or capacity to interact with the environment
• Features that are major distinction from coma: regular sleep‐wake cycles, spontaneous eye opening, purposeless eye movements (tracking), blinking, normal respiratory patterns, trunk/limb movements when awake
Minimally Conscious State (MCS)
• Minimal but definite >1 behavioral evidence of self or environmental awareness
• Follow simple commands, gestural or verbal yes/no response (regardless of accuracy)
• Intelligible verbalization
• Movement or affective behaviors that occur to environmental stimuli and are not reflexes
Other Disorders of Consciousness
• Stupor: Arousable by pain
• Obtunded: Sleeping more than awake; drowsy and confused when awake
• Delirium: Reduced attention, orientation, perception, confusion, and agitation
• Syncope (fainting): Brief loss of consciousness due to a drop in blood pressure, e.g. orthostatic hypotension
Lock-In Syndrome (NOT a disorder of consciousness)
• Mimic the signs of impaired consciousness but consciousness if intact
• Quadriplegia, preserved awareness and arousal, abnormal breathing patterns
• Caused by damage to upper motor neurons (damage to corticospinal and other descending pathways at pons) that completely prevents the patient from moving
• The patient may be able to voluntarily use eye movements to communicate
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