Week 1: Misperception
Lecture slides + notes
Cognition
= mental action/process of acquiring and understanding through thought, experience, and the senses
- A perception, sensation, idea or intuition resulting from the process of cognition:
Schizophrenia hallucinations misperception
Psychiatry
= study in medicine which focuses on the diagnosis, treatment and prevention of mental, emotional
and behavioral disorders.
- Psych = mind, soul spirit and iatry =medical treatment
DSM-5
= Diagnostic and Statistical Manual of Mental Disorders
- Categorical, dimensional and multiaxial
- Many disorders overlap and fall into different ‘boxes’
- Nowadays more focus on dimensional aspect (e.g. daily life)
Mental disorder
= a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion,
regulation, or behavior that reflects a dysfunction on the psychological, biological, or developmental
processes underlying mental functioning.
- Are usually associated with significant distress or disability in social, occupational, or important
activities.
Schizophrenia spectrum disorders
Overall, problems with social and professional functioning and a reduced insight:
- Schizophrenia
- Schizoaffective or schizophreniform disorder
- Psychotic disorder NOS (Not Otherwise Specified)
o Often used to describe patient's psychotic states early on in the diagnostic process,
when it is not clear how best to classify symptoms
Schizophrenia
= syndrome in which you lose contact with reality (psychosis) and disconnect with your surroundings
- Schizo = split and phrenia = mind
- Often confused with multi-personality disorder
Symptoms
- Cognitive symptoms, positive symptoms = extra, negative symptoms = missing
o Positive hallucinations, delusions
o Negative difficulty expressing emotions, lack of motivation, isolating, disinterest in
day-to-day life
o Cognitive difficulty with attention and applying information to make decisions
- Negative and cognitive symptoms influence the day-to-day life the most
- Negative and positive symptoms are measured with questionnaires and by looking at behavior
Hallucination
= a sensory perception without an external source/stimuli, while being awake; perception going wrong
(misperception)
- Different from dreaming (because awake), from memory (because no external stimuli) and not
limited to a time frame
, - Hallucinations can occur in all sensory organs
o Visual (sight): lights, shapes, colors and indiscrete objects
o Auditory (hearing): voices, music, whistling
o Gustatory (taste; digestive system): unpleasant flavors
o Tactile (touch): insects crawling
o Proprioceptive (sensation of position of body parts in relation to the body; body's ability
to sense movement, action, and location): floating above the ground
o Thermoceptive (sense of heat or temperature): extreme cold or heat without being ill
o Olfactory (smell): smoke, flowers, etc.
o Nociceptive (pain): unexplained pain without external stimulus
o Equilibrioceptive (balance)
- Hallucinations are present across multiple diagnoses, like schizophrenia, hearing impairment,
PTSD, Parkinson’s, dementia etc.
Delusion
= fixed beliefs that are false or imaginary; conviction that you act upon
- Different than a hallucination
How an hallucination may arise:
Bottom-up processing
= what am I seeing?; taking sensory info and then assembling and integrating it
Top-down processing
= did I see it before?; using models, ideas, and expectations to interpret sensory information
Sensory deprivation
= sensory information is excluded from an individual (almost all senses)
- Individual starts to hallucinate as bottom-up is excluded, but top-down is still present
- Shows that essentially everyone can hallucinate
Auditory verbal hallucinations (AVH)
= hearing speech without source
- Not your own voice, so not self-derived
- Perceptual phenomenon, not your own thought or idea
- Voices can be heard inside and outside the brain
Mostly prevalent in children and adolescents according to Sommer et al.
Psychosis
= loss of contact with reality
- Psychotic experiences (8%) psychotic symptoms (4%) psychotic disorder (3%)
- Healthy individuals can also have frequent (once every two weeks) non-clinical hallucinations
- >50% of voices have negative emotional content is a >82% for psychotic disorder
- 100% of voices have negative content is a >90% for psychotic disorder
Visibility of hallucination in the brain
- Can be measured in the brain using fMRI (Functional Magnetic Resonance Imaging)
- Hallucinations brain activity is different than the brain activity during thinking
Brain activity during hallucination is the same for healthy voice hearers (non-psychotic) as
clinical cases
- Brain activity related to voice hearing seems to overlap
,Sommer, Koops, & Blom (2012). Comparison of auditory hallucinations across different
disorders and syndromes
Key points:
- Auditory hallucinations (AHs) are a common symptom across various psychiatric,
neurological, and healthy populations.
- AHs can be distinguished based on their phenomenology, content, and associated features.
- AHs can occur in a variety of disorders and syndromes, including schizophrenia, bipolar
disorder, depression, anxiety, post-traumatic stress disorder (PTSD), Parkinson's disease,
epilepsy, and migraine.
- The upcoming publication of the DSM-V may help improve the differential diagnosis of AHs
across different disorders and syndromes.
- Further research is needed to better understand the underlying mechanisms and neural
correlates of AHs, as well as to develop effective treatments for this symptom.
The main differences of AHs in the different disorders mentioned are:
1. Psychiatric disorders: AHs in psychiatric disorders, such as schizophrenia, schizoaffective
disorder, and brief psychotic disorder, are often negative in content and associated with
distress. They may involve derogatory voices, commands, or prohibitions, and comment on
the patient's actions and thoughts.
2. Neurological disorders: AHs in neurological disorders, such as epilepsy and Parkinson's
disease, are often positive in content and not associated with distress. They may involve
music, singing, or other pleasant sounds.
3. Healthy individuals: AHs in healthy individuals are often related to sleep, fatigue, or stress,
and are not associated with any underlying disorder or syndrome. They may involve hearing
one's name being called, or other non-specific sounds.
Sommer, Daalman, Rietkerk, et al. (2010). Healthy Individuals With Auditory Verbal
Hallucinations; Who Are They? Psychiatric Assessments of a Selected Sample of 103 Subjects
Key points:
- The study conducted psychiatric assessments on a selected sample of 103 subjects with
frequent (once every two weeks) AVH and compared them to 60 controls.
- The results showed that while these individuals did not have clinically defined delusions or
other symptoms, they did exhibit a general increased susceptibility (or sensitivity) to
schizophrenia.
- The Schizotypal Personality Questionnaire (SPQ) and Peters Delusion Inventory (PDI) were
used to assess the participants.
- The SPQ scores were significantly higher in the AVH group compared to the control group.
- Logistic regression analysis showed that SPQ scores were a significant predictor of AVH.
- The Nagelkerke approximation of R2 was high: 0.80, suggesting that the model is a good fit
for predicting the presence or absence of AVH.
- The PDI scores were removed from the logistic regression model due to high correlation with
SPQ scores.
- The study suggests that AVH may be a marker of vulnerability to schizophrenia, and that
further research is needed to better understand the relationship between AVH and
schizophrenia.
, Week 2: The human brain
Lecture slides + notes + Ward Chapter 2: introducing the brain
Neuron
= type of cell that makes up the nervous system
- Dendrite; receiving end on the cell body (soma)
- Axon; sending end
- Nodes of Ranvier in between myelin (fatty substance
around axons that speed conduction) sheets
Synapse
= the small gap between neurons in which neurotransmitters are released, permitting signaling
between neurons
- Information flow from axon to dendrite
- Action potential; a sudden change (depolarization and repolarization) in the electrical
properties of the neuron membrane in an axon
o When the action potential is reached, neurotransmitters (chemicals) are released
Gray matter, white matter and cerebrospinal fluid
- Gray matter; cell bodies (with dendrites)
- White matter; (myelinated) axons (+ other support cells such as glia)
o Three white matter tracts:
a. Association tract= within hemisphere
b. Commissure tract = between hemispheres, via the corpus callosum
c. Projection tract= connection brain with rest of the body
- Ventricles; hollow chambers containing cerebrospinal fluid (CSF)
Corpus callosum
= a large white matter tract that connects the two hemispheres
- Also mainly white due to myelinated axons
- Commisure white matter tract
Forebrain, midbrain and hindbrain
