Schizophrenia

Question 1

What is the lifetime risk of schizophrenia? (1)

Answer 1

0.7-1%

Question 2

Fill the gaps relating to schizophrenia. (3)

Schizophrenia has a ………………. basis, but ………………… and …………………. factors also play a big part in its emergence.

Answer 2

genetic

environmental

social

Question 3

Given that there is no cure for schizophrenia, describe the long-term outcomes for patients. (3)

I.e. 30% of patients…

Answer 3

About 30% of patients can live with their delusions and hallucinations

About 30% to 40% of patients respond well to medication and/or CBT

About 30% to 40% of patients remain treatment-resistant

Question 4

What is the risk for schizophrenia if a parent has it? (1)

Answer 4

6%

Question 5

What is the risk for schizophrenia if a sibling has it? (1)

Answer 5

9%

Question 6

What is the risk for schizophrenia if an identical twin has it? (1)

Answer 6

48%

Question 7

Is schizophrenia onset typically earlier in men or women? (1)

Answer 7

Men

Question 8

Is schizophrenia more prevalent in men or women? (1)

Answer 8

Men

Question 9

Give two factors regarding place/time of birth that increase schizophrenia risk. (2)

Answer 9

Winter birth

Born in urban environment

Question 10

Give five potential infectious factors which may increase schizophrenia risk. (5)

Answer 10

Influenza

Respiratory

Rubella

Poliovirus

CNS

Question 11

Give 5 prenatal risk factors which may increase risk of Schizophrenia. (5)

Answer 11

Famine

Bereavement

Flood

Unwantedness

Maternal depression

Question 12

Give 5 obstetric factors which may increase risk of schizophrenia. (5)

Answer 12

Rh incompatibility

Hypoxia

CNS damage

Low birth weight

Pre-eclampsia

Question 13

Inflammation in the developing brain is thought to lead to both autism and schizophrenia.

Describe the differences between neuroinflammation which will likely lead to autism vs schizophrenia. (2)

Answer 13

Autism = persistent, chronic inflammation

Schizophrenia = inflammation which subsides (becomes latent)

Question 14

Describe how inflammation in the developing brain (which subsides) may lead to schizophrenia-like symptoms later in life. (1)

Answer 14

Microglia are primed to react stronger to the next insult/injury later in life.

Question 15

Very briefly describe the dopamine hypothesis of schizophrenia. (2)

Answer 15

Overstimulation of dopaminergic pathways

in cortical and limbic areas.

Question 16

Very briefly describe the glutamate hypothesis of schizophrenia. (1)

Give a piece of evidence for this hypothesis. (1)

Answer 16

NMDA receptor hypofunction

Evidence: ketamine blocks NMDA receptors and chronically can lead to psychotic symptoms

Question 17

Give four ‘components’ or ‘factors’ in the immunological theory of schizophrenia. (4)

Answer 17

Abnormal immunological findings in subgroups of schizophrenic patients

Neurodegeneration

Viral infections

Microglial activation

Question 18

Describe the 2 hit hypothesis of schizophrenia. (2)

Answer 18

2 separate life stressors cause the symptoms of schizophrenia

(Usually an early stressor during early development, then a subsequent one).

Question 19

Describe how a ‘life stressor’ in early development affects dopamine in the brain. (1)

Answer 19

There will be altered dopamine development due to genetic and/or environmental risk factors.

Question 20

Give five potential life stressors which may affect dopamine development in early/prenatal life. (5)

Answer 20

• Maternal infection
• Foetal neuroinflammation
• Hypoxia
• CNS damage
• Low birth weight

Question 21

Give three potential life stressors which may affect behaviour and dopamine function in childhood. (3)

Answer 21

Trauma

Maternal separation

War/famine

Question 22

Fill the gaps relating to the development of schizophrenia. (4)

Life stressors in prenatal life, early life, or childhood, may cause …………………. behavioural abnormalities, and this could be due to the early effects of …………………… dysfunction and extraneous effects of ………………………. or …………………….. insults.

Answer 22

subtle

dopamine

genetic

environmental

Question 23

Give six symptoms that may be experienced in the ‘prodrome’ to schizophrenia, usually in adolescence. (6)

The prodrome will usually be accompanied by clear abnormalities in which neurotransmitter system? (1)

Answer 23

Anhedonia

Social withdrawal

Hallucinations

Paranoia

Anxiety

Insomnia

• Clear dopaminergic abnormalities

Question 24

Disease onset in schizophrenia is usually accompanied by acute psychosis.

Describe how dopamine changes at this time. (1)

Answer 24

Dopaminergic flux

Question 25

Schizophrenia treatment is able to stabilise which symptoms, mediated by which neurotransmitter? (2)

Answer 25

Dopamine-based psychotic symptoms

Question 26

Schizophrenia treatment typically does not treat negative symptoms, and these symptoms tend to persist. Hypothesise why these symptoms might persist. (1)

Answer 26

They are caused by the consequences of altered dopamine development on glutamate and GABA.

Question 27

Name an animal model of schizophrenia that is not genetic. (1)

Answer 27

Maternal separation

Question 28

Describe the maternal separation animal model of schizophrenia. (3)

Answer 28

Take pups away from mothers at P9 for 24 hours Mother doesn't take care of pups as well when they're returned to the cage Schizophrenic symptoms shown in adulthood

Question 29

Give four symptoms that rodents typically show in adulthood following the maternal separation model of schizophrenia. (4)

Answer 29

Anxiety Depression Changes to prepulse inhibition Social withdrawal

Question 30

Give five negative symptoms of schizophrenia. (5)

Answer 30

Social withdrawal Depression Apathy (lack of enthusiasm) Avolition (lack of motivation) Anhedonia (reduced experience of pleasure)

Question 31

Name two positive symptoms of schizophrenia. (2)

Answer 31

Hallucinations Delusions

Question 32

What is a hallucination? (1) What is the most common type of hallucination in schizophrenia? (1)

Answer 32

A false perception Auditory (patients report hearing people talking about them)

Question 33

What is a delusion? (1) Describe two common delusions in schizophrenia. (2)

Answer 33

A persistent bizarre or irrational belief. Commonly, patients report being persecuted or believe wild conspiracy theories.

Question 34

What is a bizarre delusion? (1)

Answer 34

Imagining impossible situations

Question 35

What is a non-bizarre delusion? (1)

Answer 35

Imagining possible situations

Question 36

What is a mood-congruent delusion? (1)

Answer 36

Occurs when in a manic or depressive state.

Question 37

What is a mood-incongruent delusion? (1)

Answer 37

Happens without a particular mood's influence

Question 38

What is a Capgras delusion? (1)

Answer 38

The belief that a loved one like a mother or sibling has been replaced by an imposter.

Question 39

What is a Cotard delusion? (1)

Answer 39

A belief that you are dead or your body has disintegrated or no longer exists.

Question 40

What is a delusion of persecution? (1)

Answer 40

The belief that you are being unfairly mistreated, harmed, or watched. The conviction is so strong that the person may seek help from the authorities.

Question 41

What is the most common delusion that people experience? (1)

Answer 41

Delusion of persecution

Question 42

What is a delusion of reference? (1)

Answer 42

The belief that something like a poster, a song, or a billboard advertisement has a direct message or a hidden meaning for you. A person with this delusion may see a sign that has nothing to do with them but they believe the message is directed at them specifically.

Question 43

What is the difference between a hallucination and a delusion? (2)

Answer 43

Delusions are unshakeable beliefs (thoughts) that are not real. Hallucinations are sensory experiences — such as hearing, seeing, smelling, or feeling things that are not really there.

Question 44

What is a delusion of control? (1)

Answer 44

The belief that an external entity (a person or a force) is controlling your thoughts, behaviours, and impulses.

Question 45

What is a delusion of grandeur? (1)

Answer 45

Exaggerated or inflated self-belief regarding power, fame, knowledge, skill, talent, or strength.

Question 46

What is a delusion of thought manipulation? (1)

Answer 46

The belief that thoughts have been inserted into your mind or are being broadcasted to others.

Question 47

What is an erotomanic delusion? (1)

Answer 47

The belief that someone, usually someone famous or otherwise out of reach, is in love with you.

Question 48

Describe the auditory verbal hallucinations that are highly characteristic of schizophrenia. (1)

Answer 48

Typically take the form of voices speaking either to or about an individual.

Question 49

Fill the gaps relating to schizophrenia. (4) ......................... medications markedly reduce auditory verbal hallucinations, suggesting ......................... involvement in these phenomena. Nevertheless, the majority of patients with AVHs show some persistence of their hallucinations even while receiving this medication, indicating that other systems (e.g. ........................ and ........................) may also contribute.

Answer 49

Antipsychotic dopaminergic glutamate GABA

Question 50

Suggest a piece of evidence supporting dopaminergic involvement in auditory verbal hallucinations in schizophrenia. (1)

Answer 50

Antipsychotic medications markedly reduce AVHs.

Question 51

Suggest a piece of evidence supporting non-dopaminergic involvement in auditory verbal hallucinations in schizophrenia. (1)

Answer 51

The majority of patients with AVHs show some persistence of their hallucinations even while receiving antipsychotic medication.

Question 52

Give two general changes to the auditory cortex that are associated with auditory verbal hallucinations in schizophrenia. (2)

Answer 52

Volume loss Functional hyperactivity

Question 53

Local pathology within which brain region may contribute to auditory verbal hallucinations in schizophrenia? (1)

Answer 53

Auditory cortex

Question 54

Fill the gaps relating to auditory verbal hallucinations in schizophrenia. (2) Impaired ......................... input to the auditory cortex may have an important role, as AVHs are observed during ...............................

Answer 54

thalamocortical sensory deprivation

Question 55

Deficits in which sensory system strongly contribute to the overall psychosocial dysfunction in schizophrenia. (1)

Answer 55

Auditory system

Question 56

Fill the gaps relating to schizophrenia. (15) One key process that is affected by impaired sensory capabilities in schizophrenia is the ability to interpret the ......................... of verbal communications. In Western languages, tonal transitions do not contribute strongly to the perception of .......................................... but do convey non-verbal information such as ................... or ...................... For example, happiness is typically accompanied by an increase in both the ........................... and ............................... in speech, whereas sadness is conveyed by reductions in .......................... and ................................ Consistent with other auditory findings, Mandarin-speaking individuals with schizophrenia show notable deficits in the ability both to identify and to discriminate words that are ................................. but ................................. Other types of non-verbal information, such as attitudinal prosody (...........................) are also conveyed by subtle shifts in the ...................... In schizophrenia, deficits in tone matching strongly correlate with deficits in prosodic processing, including both ....................... and .......................... prosody. These deficits can lead to impairments in ..............................

Answer 56

prosody individual speech sounds (phonemes) emotion attitude base pitch degree of pitch variation base pitch pitch variability phonetically identical tonally distinct sarcasm pitch emotional attitudinal social functioning

Question 57

People with schizophrenia struggle to interpret the prosody of verbal communications. Give three examples of 'prosodic features' of speech. (1)

Answer 57

Intonation Syllabic stress Rhythm

Question 58

Describe how the tone-matching experiment works when investigating schizophrenia. (3)

Answer 58

Tones are presented sequentially, and subjects must report whether the second tone is the same or different from the first, or whether it is higher or lower in pitch. The interval between the tones was either silent (easy condition) or auditory stimuli were played in between the two tones (difficult condition). In addition, subjects were either asked to stay silent between tones (no distraction) or asked to count aloud (distraction).

Question 59

The ability to match tones following a brief delay depends on what, in both individuals with schizophrenia and control subjects? (1)

Answer 59

Formation of an echoic memory trace

Question 60

How long does an echoic memory trace typically last in both schizophrenic and control subjects? (1)

Answer 60

10-30 seconds

Question 61

Are people with schizophrenia typically better or worse than controls at a tone-matching experiment? (1)

Answer 61

Worse

Question 62

Fill the gaps relating to the tone matching experiment in schizophrenia. (4) When the performance of schizophrenic patients in the easy discrimination task was compared with that of controls in the difficult condition, performance decay curves .......................... over the 20‑second interval. This indicates that patients with schizophrenia have deficits primarily in the ........................., rather than .................................., of sensory information. This is consistent with a pathology of the ...................................

Answer 62

overlapped encoding retention primary auditory cortex

Question 63

Briefly describe the auditory pathway. (5) *This kind of relates to schizophrenia

Answer 63

Auditory information ascends via the cochlear nucleus, superior olivary complex, and inferior colliculus to the medial geniculate nucleus of the thalamus and then to the auditory cortex.

Question 64

True or false? Explain your answer if necessary. (1) Individuals with schizophrenia have intact performance on routine hearing tests or auditory brainstem responses.

Answer 64

True

Question 65

True or false? Explain your answer if necessary. (1) Routine hearing tests and auditory brainstem responses are very informative about the existence of potential cortical-level dysfunction in schizophrenia.

Answer 65

False - individuals with schizophrenia have intact performance on routine hearing tests or auditory brainstem responses

Question 66

Describe one of the most common MRI alterations in schizophrenia. (1)

Answer 66

Reduced volume of the superior temporal gyrus.

Question 67

When are volume reductions in the superior temporal gyrus usually present in the time course of schizophrenia? (1) What is the significance of this? (1)

Answer 67

Present before initial diagnosis and therefore do not seem to be an artefact of medication or prolonged illness duration.

Question 68

Describe a piece of evidence supporting the fact that superior temporal gyrus grey matter volume reductions are specific to schizophrenia and not psychosis. (1)

Answer 68

Not found in bipolar disorder with psychosis

Question 69

True or false? Explain your answer if necessary. (1) Superior temporal gyrus volume reductions in schizophrenia have been found to arise from extensive alcohol use in these patients.

Answer 69

False - STG volume reductions not induced by alcohol dependence

Question 70

Fill the gaps relating to schizophrenia. (3) Grey matter alterations within the ......................... are associated with the first ............................ in adolescence in patients that later develop ...........................

Answer 70

auditory cortex psychotic episode schizophrenia

Question 71

Fill the gaps relating to schizophrenia. (2) Immunocytochemical studies of the auditory cortex of patients with schizophrenia show a 27% reduction in ........................................... in deep layer 3 ...................................... cells.

Answer 71

dendritic spine density supragranular pyramidal

Question 72

True or false? Explain your answer if necessary. (1) In schizophrenia, reductions in spine density in the auditory cortex are caused by an overall loss of pyramidal neurones.

Answer 72

False - it is caused by a reduction in the number of spines per neuron

Question 73

Give two potential functional consequences of the loss of dendritic spine density in layer 3 of the auditory cortex in schizophrenia. (2)

Answer 73

Reduction in neuronal connectivity Impaired pattern separation of inputs that represent different sound frequencies (disruption of sensory neural coding mechanisms)

Question 74

Give a possible explanation for the deficits in sound frequency discrimination seen in people with schizophrenia. (2)

Answer 74

Reduction in dendritic spine density in layer 3 of the auditory cortex which could impair the pattern separation of inputs that represent different sound frequencies.

Question 75

Fill the gaps relating to schizophrenia. (4) Although the medial geniculate nucleus has not been directly studied in post-mortem tissue of individuals with schizophrenia, one study showed that the density of ........................................ boutons in the thalamocortical recipient layer of the primary auditory cortex (i.e. deep layer 3) was unchanged. This shows that thalamocortical input to the auditory cortex is .............................. However, a reduction in dendritic spine density in the supragranular cortical layers, are thus consistent with findings that indicate individuals with schizophrenia have intact ....................................... but impaired ......................................

Answer 75

VGluT2-immunoreactive intact simple auditory detection thresholds tone matching abilities

Question 76

True or false? Explain your answer if necessary. (1) Input from the thalamus to the auditory cortex remains intact in patients with schizophrenia.

Answer 76

True

Question 77

Fill the gaps relating to schizophrenia. (7) Proteomic analysis of 155 synaptic proteins in the primary auditory cortex tissue found that schizophrenia is associated with the altered expression of various ................................ signalling proteins. The two most significantly reduced proteins were .................... and .................., which are calcium-permeable subunits of ........................ receptors. .......................... protein levels were found to be unchanged. However, this does not rule out altered ............................... status of the protein and thus altered ion channel functioning. There was also a marked reduction in immunoreactivity for the ............................, which is a regulator of dendritic plasticity in the auditory cortex of individuals with schizophrenia.

Answer 77

glutamatergic GluR3 GluR4 AMPA NMDAR phosphorylation microtubule-associated protein 2 (MAP2)

Question 78

Fill the gaps relating to schizophrenia. (6) Reductions in ................................. density and spine density are correlated in the ................................ of individuals with schizophrenia. These reductions within ...................... boutons in layer ............ of the primary auditory cortex might contribute to .................................... and dysregulations in the .............................. of postsynaptic pyramidal neurons.

Answer 78

synaptophysin punctum auditory cortex glutamate 3 functional glutamatergic deafferentation (synapse loss) structural integrity

Question 79

Fill the gaps relating to schizophrenia. (7) There is evidence for ...................... but not ....................... changes in inhibitory neurons in the primary auditory cortex in schizophrenia. Levels of ..................... protein are reduced by ~40% within inhibitory boutons in deep layer 3 of the auditory cortex in individuals with schizophrenia. This is one of two enzymes that catalyze the conversion of ..................... to ...................... Therefore, decreased levels leads to reduced ........................ and .......................... in the auditory cortex.

Answer 79

functional structural GAD65 glutamate GABA inhibitory tone overexcitation

Question 80

Describe the molecular/cellular changes which occur in layer 3 of the auditory cortex in people with schizophrenia. (5)

Answer 80

- Reduced GluR3 and GluR4 (AMPA subunits) - Reduced MAP2 - Reduced synaptophysin - Reduced GAD65 - Reduced spine density

Question 81

Describe how dopamine agonists and NMDA antagonists affect auditory verbal hallucinations during acute challenges. (1)

Answer 81

Produce only mild AVHs

Question 82

Describe how dopamine agonists and NMDA antagonists affect hallucinatory-like activity during chronic administration in monkeys. (1)

Answer 82

Both cause hallucinatory-like activity (eg. the animals may make threatening gestures at non-existent objects in space)

Question 83

True or false? Explain your answer if necessary. (1) Adaptive changes induced during persistent hyper-NMDAR-hypo-dopaminergic states may be crucial for manifestations of hallucinations in schizophrenia.

Answer 83

False - it is the hypo-NMDAR-hyper-dopaminergic state which may induce hallucinations

Question 84

Describe how the activity of the superior temporal sulcus is altered in schizophrenia, when measured using fMRI. (1)

Answer 84

Hyperactivity

Question 85

Fill the gaps relating to schizophrenia. (3) ........................ brain stimulation methods such as low-frequency transcranial magnetic stimulation (TMS) or cathodal transcranial direct current stimulation applied over the auditory cortex are reported to reduce the frequency and the severity of ............................ in schizophrenia. A recent meta-analysis reported a 2.9‑fold ............................ response rate to active than to sham transcranial magnetic stimulation (TMS).

Answer 85

Inhibitory auditory verbal hallucinations higher

Question 86

Fill the gaps relating to schizophrenia. (7) There are Theories of Abnormal ........................ that attempt to explain the positive symptoms of Schizophrenia. According to these models, the primary cause of positive symptoms is an abnormal .........................., otherwise known as a ............................ .................................. may follow as a secondary consequence of attempts to understand the anomalous ..................................... For example, if patients can hear their own thoughts being spoken aloud, which is a ..................................., it would seem logical to conclude that other people can also hear them, which is a .................................

Answer 86

perception sensory experience hallucination delusions sensory experience hallucination delusion

Question 87

According to theories of abnormal perception, what causes the positive symptoms of schizophrenia and how are they related? (2)

Answer 87

The primary cause is an abnormal sensory experience (a hallucination) and delusions may follow as a secondary consequence of attempts to understand the anomalous sensory experience.

Question 88

Fill the gaps relating to schizophrenia. (9) At the physiological level, neural networks involved in ............................., .............................. and the processing of ................................. (i.e. the generation of our prior beliefs about the world) and the neural networks required for ...................................... of the external world are highly interconnected. Moreover, both prior beliefs and perception are dependent on the accuracy of our ........................... This suggests that a single pathophysiological deficit could explain both ............................. and ................................. For example, a dysregulation in communication between the ............................... and ..................................... may explain complex phantom percepts, such as auditory hallucinations.

Answer 88

learning memory formation sensory information higher cognitive perception predictions abnormal perceptions abnormal beliefs parahippocampal area association cortices

Question 89

Fill the gaps relating to schizophrenia. (7) Positive symptoms of schizophrenia may be caused by an abnormality in the brains’ .......................... mechanisms, such that new evidence (including sensory information) is not properly ......................, leading to false ............................. This failure may occur due to abnormal neuromodulation of the .......................... of superficial pyramidal cells in cortical hierarchies (e.g. by ...................... and ......................... interneurons). A wide range of psychotic symptoms can be explained by a failure to accurately ....................... sensory stimuli based on our generative models of the world.

Answer 89

inferencing integrated prediction errors post-synaptic gain GABAergic dopaminergic predict

Question 90

Describe a theory behind why schizophrenia emerges in late adolescence or early adulthood, based on Bayesian information processing. (1)

Answer 90

Bayesian inferential processes become more prominent as inhibitory neurotransmission (particularly in the prefrontal cortex) matures.

Question 91

Fill the gaps relating to schizophrenia. (10) In Schizophrenia, subtle changes in .......................... and ............................. may cause sensorimotor disturbances leading to stimuli feeling unusual. Similarly, background sights and sounds that should be ......................... in the present context may be ........................ This leads to difficulties in allocating one’s ......................... to the ........................... aspects of the environment. Persistent and noisy ............................. up the hierarchy could lead to the patient’s strange experiences. The world will feel strange, and there may be a sense that there is an underlying cause that must be discovered. This is referred to as a ............................... Inferences are then required to account for these strange experiences, giving way to a compelling sense that a particular perception has a significant meaning for the patient (...............................). When this inference is specific and related directly to the self it is referred to as a ..................................., a common positive symptom.

Answer 91

motor function sensory perception irrelevant enhanced attention most salient prediction-error signals delusional mood a delusional perception delusion of reference

Question 92

Describe a possible reason why people with schizophrenia may develop delusions. (1)

Answer 92

They need to develop a set of beliefs that must account for a great deal of strange and sometimes contradictory data (eg. hallucinations).

Question 93

Describe why people with schizophrenia often experience delusions of persecution. (1)

Answer 93

If one imagines trying to make some sense of a world that has become strange and inconsistent, and laced with sinister meaning and messages, the sensible conclusion might well be that one is being deliberately deceived.

Question 94

Give a possible consequence of persistent false prediction errors (uncanny coincidences) for people with psychosis/schizophrenia. (1)

Answer 94

They may abandon their well-established high-level models of the world.

Question 95

Fill the gaps relating to schizophrenia. (7) In terms of the predictive coding framework, the problem that leads to the positive symptoms of Schizophrenia starts with .................................. being propagated upwards through the hierarchy. This strongly signals that there has been a change, leading to a compelling demand for a new ..................... and a discounting of ............................... However, as the errors are ..................., these adjustments in the ..................... can never fully resolve the problem. As a result, ............................... will be propagated even further up the system to ever-higher levels of .............................

Answer 95

false prediction errors inference the existing model false model prediction errors abstraction

Question 96

It has been suggested that disruption to which neurotransmitter system accounts for changes in the salience of a stimulus in schizophrenia? (1)

Answer 96

Dopamine

Question 97

Fill the gaps relating to schizophrenia. (4) A stimulus that evokes ...................... firing will grab attention and will demand an ......................... or an ................................, and it is this that forms the germ of a ...............................

Answer 97

dopamine explanation updating of belief delusional belief

Question 98

It is hypothesised that neuronal firing mediated by which neurotransmitter encodes the precision (or uncertainty) of prediction errors? (1)

Answer 98

Dopamine

Question 99

What role might dopamine have on inference according to the predictive coding framework? (2)

Answer 99

Dopaminergic neurone firing may encode the precision (or uncertainty) of prediction errors and this precision weights the influence of prediction errors on inference.

Question 100

True or false? Explain your answer if necessary. (1) Serotonergic neurone firing is crucial for optimizing the balance between top-down prior beliefs and bottom-up sensory evidence.

Answer 100

False - it is dopamine

Question 101

Fill the gaps relating to inference in schizophrenia. (5) The size of the prediction error is meaningless without an estimation of its ........................ The salience of a sensory stimulus is not only coded by the ........................ of the prediction error, but also its ....................... Therefore, altered ......................... signalling could modulate the top-down predictions of the magnitude of sensory inputs, thus altering the precision of ....................................

Answer 101

precision magnitude uncertainty dopamine bottom-up prediction errors

Question 102

Fill the gaps relating to schizophrenia (or really just normal Bayesian information processing). (13) Normally, predictions are encoded at ........................ of a hierarchical system and are sent as ........................ signals to ...................... Whenever the incoming sensory data violate these predictions, a ............................ signal is sent to update the ................................... at higher levels. Formalized as Bayesian inference, predictions (also known as the ......................) and sensory data (also known as the .........................) are represented in the form of probability distributions. The posterior results from the combination of .................. and ..................... according to Bayes’ rule, weighted by their respective .........................., and updates the .......................... The new posterior mean is simply the old ....................... added to a .......................... prediction error.

Answer 102

higher levels predictive lower levels prediction error predictive model prior likelihood prior likelihood precisions predictive model prior mean precision-weighted

Question 103

Fill the gaps relating to schizophrenia. (7) In psychosis, the balance between predictions and sensory data has been proposed to be disrupted, with a decreased precision in the ............................... and increased precision of the ........................... This imbalance biases Bayesian inference toward the ....................... and away from the ...................., resulting in the abnormally strong weighting of ........................ Candidate mechanisms for decreased and increased precisions in the different factors are ............................... receptors and ............................... activity, respectively. Some psychotic phenomena may be explained by a compensatory increase in feedback signalling at higher levels of the hierarchy.

Answer 103

representation of priors likelihood likelihood prior the prediction error hypofunction of glutamatergic NMDA increased dopamine

Question 104

Fill the gaps relating to schizophrenia. (6) One of the most striking features of Schizophrenia is ......................... (false or distorted ........................), such as people hearing other people talking about them or hearing their thoughts spoken aloud without an external sound source, i.e. without the person speaking to them really being present. Theories of abnormal perception assume that the fundamental problem underlying positive symptoms is that the patient loses the ability to distinguish between ................................., i.e. that the patient persistently attends to stimuli that should be .............................. and generates complex accounts of why these stimuli are ......................... Failure to ignore irrelevant stimuli that result from one’s own thoughts and actions might be due to a failure to .....................................

Answer 104

hallucinations perceptions relevant and irrelevant stimuli ignored important tag these stimuli as self-generated

Question 105

Fill the gaps relating to schizophrenia. (10) Many of the positive symptoms associated with Schizophrenia involve misattribution of ...................... actions to ...................... Therefore, certain positive symptoms may be caused by a defect in ............................ A significant difference between self-generated actions and something that occurs outside one’s control is that one can ................................ with self-generated actions. If something is predictable it is easy to .................... and its sensory consequences can be ......................., because they are ....................... By contrast, a sensory experience that derives from an external stimulus is not ......................... and hence not ......................... or adapted to the outside world. Unpredictable things are difficult to ................., because it is crucial to experience them to update our understanding of the environment.

Answer 105

self-generated others self-monitoring predict what will happen ignore dampened unsurprising predicted suppressed ignore

Question 106

Fill the gaps relating to schizophrenia. (9) Normally, one can easily distinguish one’s own actions from those of others, even though every act performed has ......................... that could just as easily have arisen from an .......................... At the physiological level this ability to discount one’s own actions requires a form of ........................, i.e., the brain uses ............................. that generated the action to ...................... and ..................... the salience of the sensory consequences of the action. Several experiments have found that patients with positive symptoms .......................... responses to the sensory consequences of their own actions or their own speech. If one’s experience of the sensory consequences of one’s action was not attenuated, then an active movement would feel like a ............................., i.e. it would feel as if the action was being driven by an ..........................

Answer 106

sensory consequences external cause self-monitoring motor commands predict reduce fail to attenuate passive movement external force

Question 107

Describe how the brain 'self-monitors' to identify self-generated stimuli, and what are the results of this? (2)

Answer 107

The brain uses motor commands that generated the action to predict and reduce the salience of the sensory consequences of the action.

Question 108

Fill the gaps relating to schizophrenia. (9) Although a failure of self-monitoring can explain the features of passive experiences that characterize many positive symptoms, it does not seem very relevant to ....................... For example, the sudden onset of a belief that ‘my neighbour is trying to poison me’ does not have an obvious link to ................................ For these positive symptoms, it seems more plausible that the underlying problem lies with the ..................................., rather than with the perceptions from which the beliefs are derived. Although logical reasoning does not seem to be markedly impaired in patients with Schizophrenia, there is evidence of problems with ...................................... This concept is associated with a ..................... approach to the study of belief formation. Within this framework, a belief is the .......................... that some proposition about the world is ......................... This probability is continually updated by ............................. Abnormal belief formation occurs when beliefs are ............................... on the basis of new evidence.

Answer 108

delusions abnormal sensation formation of beliefs probabilistic reasoning Bayesian subjective probability true new evidence not updated appropriately

Question 109

Fill the gaps relating to schizophrenia. (7) Abnormalities in the integration of ............................ into beliefs have been observed in ........................ patients. Once a belief has become sufficiently strong, deluded patients show an abnormal ...................... against contradictory evidence. In addition, patients with delusions .............................. potential outcomes when making decisions. These anomalies of ........................... and ............................... correspond to clinical observations of delusions. Patients all too easily develop ..........................., which they then hold with great confidence and immunity to any counter evidence.

Answer 109

new evidence deluded bias abnormally weight probabilistic learning decision making false beliefs

Question 110

Describe how the updating of prior beliefs may be altered in schizophrenia and lead to delusions. (2)

Answer 110

People with schizophrenia may develop a ‘prior belief’, but then fail to update that belief based on the evidence that is presented to them. They disregard evidence and do not update their beliefs.