Transcript Neuroscience in Physical Therapy Sensation II

PTP 512
Neuroscience 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 Study
http://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-A2-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
Classification of Language Disorders
Figure 19.4,
Blumefeld,
2010
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=dy8Wvy
kiLto
 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=XMnrgVVHGU
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
Output via:
Autonomic connections
Somatic connections
Reticular connections
Hormonal pathways
BLUE = Emotions
GREEN = Processing
Memory
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)
Serve as antiinflammatory
agent
Suppress immune
responses
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
Increased stress
Increased cortisol
Decreased neuronal
growth rate
May lead to decreased
cognitive ability
• 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
Gould 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