PTP 512 Neuroscience in Physical Therapy Cognition and Affect

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