Transcript Biological rhythms, sleep and dreaming

COGNITIVE
SCIENCE
17
Final review
COGNITIVE
SCIENCE
17
Final review
Biological rhythms
(periodic physiological fluctuations)
Types of rhythms
1.
2.
3.
4.
Ultradian (Basic Rest-Activity Cycle) p294
Circadian (sleep-wake cycle) p319-326
Infradian (menstrual cycle)
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 freerunning rhythms
3. Isolated suprachiasmatic nucleus continues to cycle
4. 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
Minutes
of
Stage 4
and
REM
Decreasing
Stage 4
25
20
15
Increasing
REM
10
5
0
1
2
3
4
5
Hours of sleep
6
7
8
Troubled Sleep…
1) Night terrors (pavor nocturnus)
2) Nightmares
3) Sleep deprivation p301
4) Narcolepsy p297-299
Night Terrors and Nightmares
Sleep
stages
Awake
1
2
3
REM
• Night Terrors (p299)
– occur within 2 or 3
hours of falling asleep,
usually during Stage 4
– high arousalappearance of being
terrified
4
0
1
2
3
4
5
6
Hours of sleep
7
• Nightmares (p295)
– occur towards morning
– during REM sleep
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.]
What is a BCI?
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)
How do EEGs work?
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
Field recording systems from Quasar, Advanced Brain Monitoring, and Pineda et al (2003).
Components
How do BCIs work?
o
o
o
o
General Schematic
P300 BCI
Mu BCI
Other BCIs
Components
All BCIs have at least four components:
1) Signal Acquisition
2) Feature Extraction
3) Translation Algorithm
4) Operating Environment
The Four BCI Components
(Wolpaw et al., 2002; Allison et al., 2007)
Selective attention: SSVEP
Steady state visual evoked potential (SSVEP)
Herrmann et al, Exp. Brain Research 2001
SSVEP
6 Hz
15 Hz
Steady state visual evoked potential (SSVEP) BCI (Kelly et al., 2005)
Emerging User Goals

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.
BCI Stroke Rehabilitation
BCI Autism Rehabilitation
UCSDnews.ucsd.edu
Emotions (Chapter 11)
Responses of the whole organism,
involving...

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
physiological arousal (autonomic/hormonal)
expressive behaviors (behavioral)
conscious experience (cognitive)
Are Emotions Universal?
Basic Emotions--presumed to be hard wired and
physiologically distinctive
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Joy
Surprise
Sadness
Anger
Disgust
Fear
Pg 380
Expressing Emotion

Culturally universal expressions
James-Lange Theory of Emotion

Pg 390
Experience of emotion is awareness of
physiological responses to emotion-arousing
stimuli
Sight of
oncoming
car
(perception of
stimulus)
Pounding
heart
(arousal)
Fear
(emotion)
Cannon-Bard Theory of Emotion
Sight of
oncoming
car
(perception of
stimulus)
Pounding
heart
(arousal)

Emotion-arousing
stimuli
simultaneously
trigger:


Fear
(emotion)
physiological
responses
subjective experience
of emotion
Schacter’s Two-Factor Theory of
Emotion

Pounding
heart
(arousal)
Sight of
oncoming
car
(perception of
stimulus)
Fear
(emotion)
To experience
emotion one
must:


Cognitive
label
“I’m afraid”
be physically
aroused
cognitively
label the
arousal
Physical Arousal
Autonomic nervous system controls
physiological arousal
Sympathetic
division (arousing)
Parasympathetic
division (calming)
Pupils dilate
EYES
Pupils contract
Decreases
SALIVATION
Increases
Perspires
SKIN
Dries
Increases
RESPIRATION
Decreases
Accelerates
HEART
Slows
Inhibits
DIGESTION
Activates
Secrete stress
hormones
ADRENAL
GLANDS
Decreases
secretion of
stress
hormones
Arousal and Performance

Performance
level
Difficult tasks
Low
Easy tasks
Arousal
High
Performance
peaks at lower
levels of arousal
for difficult tasks,
and at higher
levels for easy or
well-learned tasks
Amygdala is
deep within the most elemental parts
of the brain.
Cognition and Emotion
The brain’s shortcut for emotions
Brain Structures That Mediate Emotion
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Hypothalamus
Limbic System
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limbic cortex
amygdala
Brainstem
Hypothalamus

What does it do?
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Integration of emotional responses
Forebrain, brain stem, spinal cord
Sexual response
Endocrine responses
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neurosecretory
oxytocin, vasopressin
Hypothalamus

How do we know that it integrates emotions
and behaviors?

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Ablation studies
Stimulation studies
Primary Emotions: Fear and Anger
Ablation Studies
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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)
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Output to Reticular Formation
Brainstem: Reticular Formation
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Brainstem web
100+ cell groups
Controls
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sleep-wake rhythm
Arousal
Attention
Limbic System
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Link between higher cortical
activity and the “lower”
systems that control
emotional behavior
Limbic Lobe
Deep lying structures
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amygdala
hippocampus
mamillary bodies
Limbic Lobe

What is it?

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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
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Removal of temporal
lobe in animals
Pre-op

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aggressive, raging
Post-op
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docile, orally fixated,
increased sexual and
compulsive behaviors
Kluver- Bucy Syndrome in Humans
 Severe temporal lobe damage
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tumors, surgery, trauma
Visual Agnosia
Apathy/ placidity
Hyperorality
Disturbance in sexual function (hypersexuality)
Dementia, aphasia, amnesia
Amygdala

What is it?

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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:
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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
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Conditioned emotional response
Abolish fear response


cut central nucleus from amygdala OR
infuse NMDA antagonist into amygdala during
learning
Memory
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
Organization of experience….what would you do without it?
Common Model of Memory
Processes
Rehearsal
Sight
Elaboration
and
Organization
Smell
Sound
Sensory
Memory
Attention
Short-Term
Memory
Long-Term
Memory
Retrieval
Taste
Touch
Lost
Lost
Time Course of Memory Processes
Memory Processes
Sensory
Short Term
Long Term
Holds information
for a fraction of a
second
Information remains Information remains
for about 15-20
for days, months,
seconds
and years
Perception and
attention
Chunking
Retrieval:
Rehearsal: Rote and More frequent
Elaborative
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’s Taxonomy of Memory
Squire & Zola, PNAS, 1996
Memory Disorders
Two main types of Amnesia:
• Anterograde (“forward”) Amnesia
• Retrograde (“backwards”) Amnesia
Memory Disorders
Anterograde Amnesia
• Problem: forming new memories postinjury/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
•
•
•
•
•
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Consolidation of STM to LTM
Spatial and contextual memory
Episodic memory
Declarative memory
Detection of novel stimuli
Neurogenesis
Hippocampus Malfunctions
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Severe anterograde amnesia
Mild retrograde amnesia
Problems navigating space
Seizures
Early Alzheimer’s Disease
H.M.:
• “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.”
Spatial Navigation (cont.)
Volume of hippocampus
Time as London taxi driver
Place cells in
hippocampus
map 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 Aphasia
Brodmann 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 Aphasia
Brodmann 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 Model
1. 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 Model
2. 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 hearingimpaired 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 midgestation, 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.
Progression of Schizophrenia
Louis Wain
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 shortterm 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