COGNITIVE SCIENCE 17

Final review

COGNITIVE SCIENCE 17

Final review

Biological rhythms (periodic physiological fluctuations)

Types of rhythms

1. Ultradian (Basic Rest-Activity Cycle) p294

2. Circadian (sleep-wake cycle) p319-326

3. Infradian (menstrual cycle)4. Circannual (annual breeding cycles)

All rhythms allow us to time events and anticipate change!

With Zeitgeber

See p319.

Suprachiasmatic nucleus (SCN) is master

pacemaker

1. Activity in suprachiasmatic nucleus correlates with circadian rhythms

2. Lesions of suprachiasmatic nucleus abolish free-running rhythms

3. Isolated suprachiasmatic nucleus continues to cycle4. Transplanted suprachiasmatic nucleus imparts

rhythm of the donor on the host

p 320-324

Timing Photoreceptors

• The existence of photoreceptors not specialized for visual functioning– Regulate photoperiodism (sensitivity to length of night)– Entrainment of circadian rhythms

• Melanopsin-containing cells found in monkey retinal ganglion cell layer (Provencio et al., 2000) – Most likely comprise the retinohypothalamic tract– Sensitive to wavelengths in the 484-500 nm (blue light)

Single Cycle of Sleep

Typical Nightly Sleep Stages

Hours of sleep

Minutesof Stage 4 and REM

1 2 3 4 5 6 7 80

10

15

20

25

5

Decreasing Stage 4

Increasing REM

Troubled Sleep…

1) Night terrors (pavor nocturnus)

2) Nightmares

3) Sleep deprivation p301

4) Narcolepsy p297-299

Night Terrors and Nightmares

• Night Terrors (p299)– occur within 2 or 3

hours of falling asleep, usually during Stage 4

– high arousal- appearance of being terrified

• Nightmares (p295)– occur towards morning– during REM sleep

0 1 2 3 4 5 6 7

4

3

2

1

Sleepstages

Awake

Hours of sleep

REM

What is a BCI?

• Brain-Computer Interface

• Enables communication without movement or motor control.

• Some target patients cannot use any interface requiring voluntary movement.

What is a BCI?

One of the first uses was designed for Locked-in Syndrome, a condition marked by total immobilization yet complete consciousness.

This can follow stroke, injury or disease (MS) which damages the ventral pons.

[One notable patient, journalist Jean-Dominique Bauby, dictated his memoir using a system of blinking his left eye to chose a letter. The Diving Bell and the Butterfly.]

Most BCIs translate your brain’s electrical activity (EEGs) into messages or commands.

Performing mental tasks produces electrical activity detectable with electrode caps.

What is a BCI?

BCIs may be:

• Non-invasive (usually EEG)• Invasive

•ECoG (surface of cortex)•depth recording (in brain)

What is a BCI?

Newer EEG recording systems:

• Require less or no prep time and skill• Require less or no gel• Require fewer electrodes• Are more portable• Handle artifacts better• Are wireless• Are cheaper

How do EEGs work?

Field recording systems from Quasar, Advanced Brain Monitoring, and Pineda et al (2003).

How do BCIs work?

o General Schematico P300 BCIo Mu BCIo Other BCIs

Components

All BCIs have at least four components:

1) Signal Acquisition

2) Feature Extraction

3) Translation Algorithm

4) Operating Environment

Components

The Four BCI Components(Wolpaw et al., 2002; Allison et al., 2007)

Selective attention: SSVEP

Herrmann et al, Exp. Brain Research 2001

Steady state visual evoked potential (SSVEP)

Steady state visual evoked potential (SSVEP) BCI (Kelly et al., 2005)

SSVEP

6 Hz 15 Hz

Replacing conventional interfaces for disabled users in conventional settings. (BOTH for communication and rehab).

Replacing conventional interfaces for conventional users in specific settings.

Supplementing conventional interfaces.

Emerging User Goals

BCI Stroke Rehabilitation

BCI Autism Rehabilitation

UCSDnews.ucsd.edu

Emotions (Chapter 11)

Responses of the whole organism, involving...

physiological arousal (autonomic/hormonal)expressive behaviors (behavioral)conscious experience (cognitive)

Basic Emotions--presumed to be hard wired and physiologically distinctive

Joy Surprise Sadness Anger Disgust Fear

Are Emotions Universal?

Pg 380

Expressing Emotion

Culturally universal expressions

James-Lange Theory of Emotion

Experience of emotion is awareness of physiological responses to emotion-arousing stimuli

Fear(emotion)

Poundingheart

(arousal)

Sight of oncoming

car(perception of

stimulus)

Pg 390

Cannon-Bard Theory of Emotion

Emotion-arousing stimuli simultaneously trigger:

physiological responses

subjective experience of emotion

Sight of oncoming

car(perception of

stimulus)

Poundingheart

(arousal)

Fear(emotion)

Schacter’s Two-Factor Theory of Emotion

To experience emotion one must:

be physically aroused

cognitively label the arousal

Cognitivelabel

“I’m afraid”

Fear(emotion)

Sight of oncoming

car(perception of

stimulus)

Poundingheart

(arousal)

Physical Arousal

Autonomic nervous system controlsphysiological arousal

Sympatheticdivision (arousing)

Pupils dilate

Decreases

Perspires

Increases

Accelerates

Inhibits

Secrete stresshormones

Parasympatheticdivision (calming)

Pupils contract

Increases

Dries

Decreases

Slows

Activates

Decreasessecretion of

stress hormones

EYES

SALIVATION

SKIN

RESPIRATION

HEART

DIGESTION

ADRENALGLANDS

Arousal and Performance

Performance peaks at lower levels of arousal for difficult tasks, and at higher levels for easy or well-learned tasks

Performancelevel

Low

Arousal

High

Difficult tasks Easy tasks

Amygdala isdeep within the most elemental partsof the brain.

Cognition and Emotion

The brain’s shortcut for emotions

Brain Structures That Mediate Emotion

Hypothalamus Limbic System

limbic cortex amygdala

Brainstem

Hypothalamus

What does it do? Integration of emotional responses Forebrain, brain stem, spinal cord Sexual response Endocrine responses

neurosecretory oxytocin, vasopressin

Hypothalamus

How do we know that it integrates emotions and behaviors? Ablation studies Stimulation studies Primary Emotions: Fear and Anger

Ablation Studies

Cats Remove cerebral

hemispheres: rage Remove hemispheres

and hypothalamus: no rage

Stimulation Studies on Cats

Lateral hypothalamic stimulation:

rage, attack

Other areas: defensive, fear

Hypothalamus:Routes of information

Input from: cortex (relatively unprocessed)

Output to Reticular Formation

Brainstem: Reticular Formation

Brainstem web 100+ cell groups Controls

sleep-wake rhythm Arousal Attention

Limbic System

Link between higher cortical activity and the “lower” systems that control emotional behavior

Limbic Lobe Deep lying structures

amygdala hippocampus mamillary bodies

Limbic Lobe

What is it? Cingulate gyrus Parahippocampal

gyrus Where is it?

Encircles the upper brain stem

around corpus callosum

Limbic System

What does it do? Integrates information from cortical

association areas How do we know this?

Kluver - Bucy Syndrome

Kluver - Bucy Syndrome

Removal of temporal lobe in animals

Pre-op aggressive, raging

Post-op docile, orally fixated,

increased sexual and compulsive behaviors

Kluver- Bucy Syndrome in Humans Severe temporal lobe damage

tumors, surgery, trauma Visual Agnosia Apathy/ placidity Hyperorality Disturbance in sexual function (hypersexuality) Dementia, aphasia, amnesia

Amygdala

What is it? Nuclear mass

Where is it? Buried in the

white matter of the temporal lobe, in front of the hippocampus

Amygdala: What Does It Do?

Connects to: olfactory bulb and cortex brainstem and hypothalamus cortical sensory association areas “Emotional Association Area”

Amygdala

Conditioned emotional response:

Neutral stimulus can be associated with aversive stimulus, resulting in same autonomic, behavioral and hormonal responses.

Pg. 366

Amygdala and Learned Emotions Learned fear: rats and classical conditioning

Conditioned emotional response Abolish fear response

cut central nucleus from amygdala OR infuse NMDA antagonist into amygdala during

learning

Memory

Organization of experience….what would you do without it?

The ability to retain learned information and knowledge of past events and experiences and to be able to retrieve that information.

Learn ---- Retain ---- Retrieve

Encoding ---- Maintenance ---- Retrieval

Short-Term Memory

Sensory Memory

Long-Term Memory

Sight

Sound

Taste

Touch

Smell

Attention

Elaboration and

Organization

Retrieval

Rehearsal

Lost Lost

Common Model of Memory

Processes

Time Course of Memory Processes

Memory Processes Sensory

Holds information for a fraction of a second

Perception and attention

Short Term

Information remains for about 15-20 seconds

Chunking

Rehearsal: Rote and

Elaborative

Long Term

Information remains

for days, months,

and years

Retrieval:

More frequent activation of neuron patterns leads to more efficiency

Memory Processes

• How do memories get from working memory to long term memory storage?– consolidation

• How do we get them back?– Retrieval– Indexing

Long Term Memory

Squire & Zola, PNAS, 1996

Squire’s Taxonomy of Memory

Memory Disorders

Two main types of Amnesia:

• Anterograde (“forward”) Amnesia

• Retrograde (“backwards”) Amnesia

Memory Disorders

Anterograde Amnesia• Problem: forming new memories

post-injury/operation• Korsikoff’s Syndrome (chronic alcoholics),

Alzheimer’s, patients like H.M. with hippocampal/thalamus damage

• Can read, write, converse, remember life until damage was done

Memory Disorders

Retrograde Amnesia:• Problem: loss of memory for some period before

brain injury• ECT and head traumas• “Trace consolidation theory” -- memory hasn’t had

time to become firmly established, but... several years?

• Sometimes memories do come back gradually

Memory Disorders

What amnesiacs can do:

• procedural memory tasks (mirror tracing)

• implicit memory tasks ( _L_P_A_T)• behavioral conditioning

Memory in the Brain

Other important brain areas and functions:• Pre-frontal cortex—retrieval, working memory• Hippocampus & other parts of Thalamus--

consolidation• Amygdala--emotional events, fear

conditioning• Occipital & Temporal Lobes—

visual/auditory memories

Hippocampus Functions

• Consolidation of STM to LTM

• Spatial and contextual memory

• Episodic memory

• Declarative memory

• Detection of novel stimuli

• Neurogenesis

Hippocampus Malfunctions

• Severe anterograde amnesia

• Mild retrograde amnesia

• Problems navigating space

• Seizures

• Early Alzheimer’s Disease

• “Right now, I’m wondering, Have I done or said anything amiss? You see, at this moment everything looks clear to me, but what happened just before? That’s what worries me. It’s like waking from a dream; I just don’t remember.”

• “…Every day is alone in itself, whatever enjoyment I’ve had, and whatever sorrow I’ve had.”

H.M.:

Time as London taxi driverV

olu

me

of h

ipp

ocam

pu

s Spatial Navigation (cont.)

Place cells inhippocampusmap out the environment

Place cells respond as a function of external cues

Activity-Dependent Synaptic Plasticity (cont.)

• Long-term plasticities– Short-term potentiation/depression– Long-term potentiation/depression

LTP is a persistent increase in synaptic efficacy that can be rapidly induced

Bliss and Lomo, 1973

Glutamate (NT) opens NMDA receptors, IF it has been recently depolarized…

Rapid firing makes this possible.

Slow firing make it more difficult (LTD).

Importance of Communication

• Different forms – Verbal (speech)– Sign (gestures)– Writing (symbols)

• Important social behaviors• Have made cultural evolution possible• Enabled discoveries to be cumulative

– Knowledge passed from generation to generation

Language Acquisition

• Modularity (Chomsky, 1959)– Is there a language “mental organ”? Or does it

arise from more primitive functions?• Is it unique to humans?

– What causes the difference?– Evolution of Language:

• Gestures were important • Language and thought

– Are they interrelated? Yes, but don’t need language to be able to think.

• Universal grammar?– Enables infants to acquire language in any culture,

provided it’s during the language critical period

Birdsong• Similar to human languages in

sensitive (critical) period• Stages of development

(learning):– Initial exposure to the song

of tutor (father)– Successive approximation of

produced song to the stored model

– Crystalization of the song in permanent form

• Deafening and distorting studies by Konishi – changes the nature of the song learned

• Brain damage studies confirm vocal control centers view

• Neurogenesis in birds responding to birdsong

Human language as unique

• Syntax and productive properties – rules governing word order and usage.

• Language comprehension is rapid and automatic

• Language production is rapid

Language Disorders

• In language disorders– 90-95% of cases, damage is to the left

hemisphere– 5-10% of cases, to the right hemisphere

• Wada test is used to determine the hemispheric dominance– Sodium amytal is injected to the carotid artery– First to the left and then to the right

Brain Lateralization

• LH more specialized for the analysis of sequences of stimuli that occur quickly but sequentially (comprehension and production).

• RH more specialized for the analysis of space and geometrical shapes and forms that occur simultaneously.– Involved in organizing a narrative (selecting and

assembling the elements of what we want to say) – understanding prosody ( vs. monotone)– recognizing emotion in the tone of voice – Understanding jokes

Language Disorders

• Paraphasia:– Substitution of a word by a sound, an incorrect

word (“treen” instead of “train”)

• Neologism:– Paraphasia with a completely novel word

(colloquialism or slang)

• Nonfluent speech:– Talking with considerable effort

• Agraphia:– Impairment in writing

• Alexia:– Disturbances in reading (sparing writing)

Three major types of Aphasia

• Broca’s aphasia– Nonfluent speech

• Wernicke’s aphasia– Fluent speech but unintelligible

• Global aphasia– Total loss of language

Others: Conduction, Subcortical, Transcortical Motor/Sensory

Brain areas involved in Language

Broca’s AphasiaBrodmann 44, 45

• Lesions in the left inferior frontal region (Broca’s area), caudate nucleus, thalamus, etc.

• Nonfluent, labored, and hesitant speech (articulation)• Most also lose the ability to name persons or subjects

(anomia)• Can utter automatic or overlearned speech (“hello”;

songs)• Have difficulty with function (the, in, about) vs content

words (verbs, nouns, adjectives) (agrammatism)• Comprehension relatively intact• Most also have partial paralysis of one side of the body

(hemiplegia) – next to motor cortex• If extensive, not much recovery over time

Wernicke’s AphasiaBrodmann 22, 30

• Lesions in posterior part of the left superior temporal gyrus, extending to adjacent parietal cortex

• Unable to understand what they read or hear (poor comprehension)

• Unaware of their deficit• Fluent but meaningless speech• Can use function but not content words• Contains many paraphasias

– “girl”-“curl”, “bread”-“cake”• Syntactical but empty sentences• Cannot repeat words or sentences• Usually no partial paralysis

Wernicke-Geschwind Model1. Repeating a spoken word

• Arcuate fasciculus is the bridge from the Wernicke’s area to the Broca’s area – damage here hinders repitition

Wernicke-Geschwind Model2. Repeating a written word

• Angular gyrus is the gateway from visual cortex to Wernicke’s area

• This is an oversimplification of the issue:– not all patients show such predicted behavior (Howard, 1997)

Sign Languages

• Full-fledged languages, created by hearing- impaired people (not by Linguists):– Dialects, jokes, poems, etc.– Do not resemble the spoken language of the same

area (ASL resembles Bantu and Navaho)– Pinker: Nicaraguan Sign Language– Another evidence of the origins of language

(gestures)

• Most gestures in ASL are with right-hand, or else both hands (left hemisphere dominance)

• Signers with brain damage to similar regions show aphasia as well

Signer Aphasia

• Young man, both spoken and sign language:– Accident and damage to brain– Both spoken and sign languages are affected

• Deaf-mute person, sign language:– Stroke and damage to left-side of the brain– Impairment in sign language

• 3 deaf signers:– Different damages to the brain with different

impairments to grammar and word production

Dyslexia

• Problem in learning to read• Common in boys and left-handed• High IQ, so related with language

only• Postmortem observation revealed

anomalies in the arrangement of cortical cells– Micropolygyria: excessive

cortical folding– Ectopias: nests of extra cells

in unusual location• Might have occurred in mid-

gestation, during cell migration period

Dyslexia

Cna yuo raed tihs? Olny 55 plepoe out of 100 can.    i

cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig

to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in waht oerdr the ltteres in a wrod are, the olny iproamtnt tihng is taht

the frsit and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it whotuit a pboerlm. Tihs

is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Azanmig huh?

yaeh and I awlyas tghuhot slpeling was ipmorantt!

 

Acquired Dyslexia = Alexia• Disorder in adulthood as a result of disease or injury• Deep dyslexia (pays attn. to wholes):

– “cow” becomes “horse”; cannot read abstract words– Fails to see small differences (do not read each letter)– Problems with nonsense words (e.g. glab, trisk)

• Surface dyslexia (pays attn. to details/phonemes):– Nonsense words are fine– Problems with irregularly spelled words (e.g. yacht, pint)

• Suggests 2 different systems:– One focused on the meanings of whole words– The other on the sounds of words

PET by Posner and Raichle

• Passive hearing of words activates:– Temporal lobes

• Repeating words activates:– Both motor cortices, the

supplemental motor cortex, portion of cerebellum, insular cortex

• While reading and repeating:– No activation in Broca’s area

• But if semantic association:– All language areas including

Broca’s area

• Native speaker of Italian and English:– Slightly different regions

PET by Damasios

• Different areas of left hemisphere (other than Broca’s and Wernicke’s regions) are used to name (1) tools, (2) animals, and (3) persons

• Stroke studies support this claim• Three different regions in temporal lobe are used• ERP studies support that word meaning are on

temporal lobe (may originate from Wernicke’s area):– “the man started the car engine and stepped on

the pancake”– Takes longer to process if grammar is involved

Other studies

• Right ear advantage in dicothic listening:– Due to interhemispheric crossing

• Words in left-hemisphere, Music in right– Supported by damage and imaging studies– But perfect-pitch is still on the left

• Asymmetry in planum temporale:– Musicians with perfect-pitch has 2x larger PT– Evident in newborns, thus suggesting innate basis for

cerebral specialization for language and speech

Planum temporale

Used in language and music

Schizophrenia is a PSYCHOTIC DISORDER

A severe mental disorder in which thinking and emotion are so impaired that the individual is seriously out of contact with reality.

Louis Wain

Progression of Schizophrenia

Early onset schizophrenia: Wave of gray matter loss - begins in parietal cortex and spreads forward

Schizophrenia

Refers to a group of disorders

There is not one essential symptom that must be present for a diagnosis.

Instead, patients experience different combinations of the main symptoms of schizophrenia.

It is NOT split or multiple personality disorder.

Two Categories of Symptoms in Schizophrenia

• Positive symptoms

• Negative symptoms

Positive Symptoms

• Distortions or excesses of normal functioning – delusions, – hallucinations, – disorganized speech,– thought disturbances, – motor disturbances

• Positive symptoms are generally more responsive to treatment than negative symptoms

Delusions

• False beliefs that are firmly and consistently held despite disconfirming evidence or logic

• Individuals with mania or delusional depression may also experience delusions.

• However, the delusions of patients with schizophrenia are often more bizarre (highly implausible).

Types of Delusions

• Delusions of Grandeur– Belief that one is a famous or powerful

person from the past or present

• Delusions of Control– Belief that some external force is trying to

take control of one’s thoughts (thought insertion), body, or behavior

Examples of Delusions of Control

Believing that thoughts that are not your own have been placed in your mind by an external

source

A 29-year-old housewife said, “I look out of the window and I think the garden looks nice and

the grass looks cool, but the thoughts of Eamonn Andrews come into my mind. There

are no other thoughts there, only his… He treats my mind like a screen and flashes his

thoughts on it like you flash a picture.”

Examples of Delusions of Control

Believing that your behavior is controlled by an external force

A 29-year-old shorthand typist described her (simplest) actions as follows: “When I reach my hand for the comb it is my hand and arm which

move, and my fingers pick up the pen, but I don’t control them… I sit there watching them move, and they are quite independent, what they do is nothing to do with me… I am just a puppet who is manipulated by cosmic strings. When the strings are pulled my body moves

and I cannot prevent it.”

Types of Delusions

• Thought Broadcasting– Belief that one’s thoughts are being broadcast

or transmitted to others

• Thought Withdrawal– Belief that one’s thoughts are being removed

from one’s mind

Types of Delusions

• Delusions of Reference– Belief that all happenings revolve around

oneself, and/or one is always the center of attention

• Delusions of Persecution– Belief that one is the target of others’

mistreatment, evil plots, and/or murderous intent

Hallucinations

• Sensory experiences in the absence of any stimulation from the environment

• Any sensory modality may be involved– auditory (hearing); – visual (seeing); – olfactory (smelling); – tactile (feeling); – gustatory (tasting)

• Auditory hallucinations are most common

Common Auditory Hallucinations in Schizophrenia

• Hearing own thoughts spoken by another voice

• Hearing voices that are arguing

• Hearing voices commenting on one’s own behavior

Disorganized Speech / Thought Disturbances

• Problems in organizing ideas and speaking so that a listener can understand

• Loose Associations (cognitive slippage)– continual shifting from topic to topic without

any apparent or logical connection between thoughts

• Neologisms– new, seemingly meaningless words that are

formed by combining words

Disorganized Motor Disturbances

• Extreme activity levels (unusually high or low), peculiar body movements or postures (e.g., catatonic schizophrenia), strange gestures and grimaces

Negative Symptoms

• Behavioral deficits that endure beyond an acute episode of schizophrenia

• More negative symptoms are associated with a poorer prognosis

• Some negative symptoms might be secondary to medications and/or institutionalization

Types of Negative Symptoms

• Anhedonia– inability to feel pleasure; lack of interest or

enjoyment in activities or relationships

• Avolition – inability or lack of energy to engage in routine

(e.g., personal hygiene) and/or goal-directed (e.g., work, school) activities

Types of Negative Symptoms

• Alogia– lack of meaningful speech, which may take

several forms, including poverty of speech (reduced amount of speech) or poverty of content of speech (little information is conveyed; vague, repetitive)

• Asociality– impairments in social relationships; few friends,

poor social skills, little interest in being with other people

Types of Negative Symptoms

• Flat Affect– No stimulus can elicit an emotional response– Patient may stare vacantly, with lifeless eyes

and expressionless face. – Voice may be toneless. – Flat affect refers only to outward expression,

not necessarily internal experience.

Genetic Studies

• Twin• Blood relatives• Adoption• High-risk populations

(e.g., children of schizophrenic parents)– Calcineurin and short-

term memory (Tonegawa, 2003)

Biological Finding

• The Dopamine Hypothesis– Disturbed functioning in dopamine system

(i.e., excess dopamine activity at certain synaptic sites)

• Supportive evidence: – Phenothiazines reduce dopamine activity and

psychotic symptoms are reduced; – L-Dopa and amphetamines increase dopamine

activity and can produce psychotic symptoms

Problems

• A large minority of people with schizophrenia are not responsive to antipsychotic medications affecting dopamine.

• Other effective medications (Clozapine) work primarily on serotonin, rather than dopamine, system.

• Antipsychotic drugs block dopamine receptors quickly, but relief from symptoms is not seen for weeks.

• Enlarged ventricles • Indicates deterioration or atrophy of brain tissue

Problems

• Differences are relatively small compared with control groups, and many schizophrenic patients fall within normal range.

• Reported in only 6 to 40 percent of schizophrenic patients in a variety of studies.

• Also reported in some patients with mood disorders.

Biological Finding

• Low relative glucose metabolism in frontal areas

Problems

• Participants are generally chronic patients on heavy neuroleptic medications.

• Some evidence indicates that antipsychotic medications influence cerebral blood flow even in patients who are currently medication free.

Biological Finding

• Cognitive dysfunctions (visual processing, attention problems, recall memory problems)

Environmental Factors

• Family Characteristics

• Social Class

Social Class and Schizophrenia

• Schizophrenia is most common at lower socioeconomic status (SES) levels

• Breeder Hypothesis– stressors associated with low SES increase

the likelihood that schizophrenia will develop

• Downward Drift Theory– individuals with schizophrenia drift into low

SES areas because they cannot function in other environments