Psychology and neuroscience

Dr. Andrew YoungBehavioural Neuroscience Group

amjy1@le.ac.uk

PS1009

Applied Psychology

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Psychology and brain function

• As psychologists we study the interaction between an organism and its environment

• Perceiving the environment (sensory perception)

• Behavioural responses

IntegrationDecision

Transmission

The Brain

Neurones

Chemicals(Neurotransmitters)

Neuronal connectivity

Electrical activity

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Brain function and behaviour

Paul Broca (c1860)• Studied a patient called ‘Leborgne’

• intelligent and capable of comprehending spoken and written language

• but unable to speak more than a very few meaningless syllables for 21 years

• capable of communication using motor gestures

Post-mortem study of brain showed:• single lesion towards back of left

frontal lobe• first evidence for highly localised

control of function in the cortex

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Types of measurement

• Post-mortem studies

• Provides anatomical information

• Of limited value for functional studies

• Living neurones in isolation (in vitro - e.g. cultures, slices)

• Show how living neurones can function

• But give limited information on behaviour

• Studies intact brains

• Effects of brain injury on behaviour

• Effects of drugs with known pharmacology on behaviour

• Monitoring brain activity during behaviour

• Underpinned by post-mortem and in vitro studies

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Study of normal brain function

• Perception – vision, sight, smell, taste

• Movement

• Language

• Learning and memory

• Sleep

• Pain and analgesia

• Mood

• Personality

• ….. many more

• Neuronal systems involved – e.g. hippocampus• Electrical process involved – e.g. LTP• Neurotransmitters involved – e.g. glutamate

(* see PS1003 lectures)

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Study of abnormal function

• Studying neuronal processes and/or neurotransmitters involved in

• Perceptual disorders

• Motor disorders

• Schizophrenia

• Depression

• Anxiety

• Parkinson’s disease

• Ischaemia (stroke)

• Epilepsy

• Addiction

• ….. many others

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Symptoms of psychosis

Abnormal ideas : • delusions (mood, persecution, grandiose, hypochondriacal)

Abnormal perceptions : • hallucinations (mainly auditory)

Formal thought disorder : • derailment, loss of goal, neologisms, poverty of speech content

Motor, volition and behavioural disorder : • catatonia, abnormal posture, avolition, mutism,

Emotional disorders : • affective flattening, emotional withdrawal, anhedonia.

Difficult to measure objectively

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Can psychology help us understand schizophrenia?

Understanding biological basis of psychological function- relationship with dysfunction in psychiatric disease

• effects of brain injury on behaviour

• effects of drugs on behaviour

• pharmacology of drugs with therapeutic effects

• studies with tasks which rely certain brain areas

• brain imaging studies, especially function in these tasks

• use of animal models of psychological function

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Effects of brain injury on behaviour

• Temporal lobe dysfunction (e.g. temporal lobe epilepsy)

• Can lead to some symptomssimilar to positive symptomsof schizophrenia.

• Frontal lobe damage (e.g.frontal lobectomy)

• Leads to symptoms similarto negative symptoms ofschizophrenia.

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Effects of drugs on behaviour

Several drugs known to cause symptoms similar to schizophrenia:

• Amphetamine – causes hallucinations and delusions very similar to positive symptoms of schizophrenia

• Are positive symptoms associated with increased dopamine?

• LSD – causes hallucinations which are similar the positive symptoms of schizophrenia

• Are positive symptoms associated with increased serotonin?

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Pharmacology of drugs with therapeutic effect

• Classical (‘typical’) antipsychotic drugs

• Antagonists at dopamine receptors

• Newer (‘atypical’) antipsychotic drugs

• Antagonists at both dopamine and serotonin receptors

Dopamine and serotonin over-activity both implicated in schizophrenia.

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Studies using tasks relying on certain brain areas

• Positively symptomatic schizophrenics are deficient in tasks requiring temporal lobe function

• e.g. selective attention – latent inhibition (learning to ignore irrelevant stimuli)

• Schizophrenics are deficient in tasks requiring frontal lobe function

• e.g. Wisconsin card sort, Tower of Hanoi

• First degree relatives of schizophrenics are also deficient in frontal lobe tasks.

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Brain imaging studies

• Functional magnetic resonance imaging (fMRI) studies have looked at brain areas activated during these tasks:

• e.g. Latent inhibition

• How does this differ in schizophrenic patients?

Z-coordinate of slice -2 4 9

LeftRight

Young AMJ et al., 2005

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Animal models of psychological function

Latent inhibition in animals – relationship with schizophrenia

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Schizophrenia

Latent inhibition provides a model for studying theneural basis of schizophrenia

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Information processing deficits in schizophrenia

These may be indicative of deficits in sensory gating (e.g. selective attention).

Kraepelin (1913)"Schizophrenic patients are unable to exclude irrelevant sensory information from their awareness"

McGhie & Chapman (1961)Pateint A : "I can't shut things out"Patient B : "I let all the sounds come in that are there"Patient C : "I'm attending to everything at once, so I don't

really attend to anything"

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Psychology and neuroscience

• Understanding the neural and neurochemical basis of psychological function in the normal brain

• Perception

• Intrinsic processing

• Motor output

• ‘Behaviour’

• Studying the neural and neurochemical basis of behaviour gives us insights into dysfunctions underlying psychiatric disease.