PSY290 : Behavioural Neuroscience

L01 : History, Animal Research, Lobotomy and the Nervous System (Basics)

Important researchers, research techniques

1. Fluorens - Controlled lesions on animals
2. Fritsch & Hitzig - Brain stimulation on movement in dogs, suggested brain involvement in motor activity
3. Jackson - Hierarchy of processing in the nervous system
4. Darwin & Wallace - Evolutionary theory
5. Galton - Heritability of genes
6. Ramon Y Cajal (Father of modern neuroscience) - Golgi to visualise nervous system, neuron doctrine over reticular theory
7. Sherrington, Palay - Proposal and confirmation of existence of synapse
8. Otto Loewi - Conclusively identified neurotransmitter acetylcholine
9. Eccles, Hodgkin, Huxley - Characteristics of action potential

Brodmann Map

• cytoarchitecture
• 52 Brodmann areas
• dropped in favour of Talaraich + MNI Systems for delicate procedures

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Animal Research

Why are animals preferred as research subjects over humans?

• Ethics : Experiments needed to infer causal relation - unethical to do so on humans
• Logistics : Animals have a simpler, thereby easier to study, nervous system
• Evolution : Nervous system similarities among species explain behavioural similarities

Problems with animal research :

• High cost
• Difficult to extrapolate about human behaviour (specially language)
• Findings are not generalisable

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Lobotomy

Extensive lesion to the PFC of Becky the Chimpanzee -> reduced upsetting at errors -> Moniz speculated PFC damage could treat mental illness -> frontal leukotomy -> transorbital frontal lobotomy

Mistakes from Lobotomy

• Experimental method not used
• Case study : generalised one animal’s result to tens of thousands of humans
• Limited follow-up
• Consent mostly neglected

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Nervous System

Brain

• Meninges - cushions brain

  • Dura mater

  • Arachnoid membrane

  • Pia mater

• Forebrain

  • Telencephalon

    • Cortex - outermost, mostly grey matter

      • Neocortex - 6 layers, 90% of cortex

      • Allocortex - 3-4 layers, 10% of cortex

        • Hippocampus

        • Olfactory system

    • Basal ganglia

      • Caudate + Putamen

      • Globus pallidus - for movement

      • Nucleus accumbens - reinforcement learning, habit formation

    • Limbic system

      • Cingulate cortex

      • Amygdala

      • Hippocampus

      • Mamillary body

      • Septum

  • Diencephalon

    • Thalamus - relay center for all incoming sensory information except olfactory

    • Hypothalamus - drive center (fighting, fleeing, feeding, sex)

• Midbrain

  • Mesencephalon

    • Superior colliculus - vision

    • Inferior colliculus - auditory

    • Substantia nigra - motor coordination

    • Reticular formation - arousal

    • Periaqueductal grey - nociception (pain)

• Hindbrain

  • Metencephalon

    • Pons

    • Cerebellum

  • Myelencephalon

    • Medulla

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Modelling Depression

• Industry standard for testing for depression in animals -> Chronic Intermittent Stress (CIS) Test
• Features of a disorder model :
  • Behavioural impairments similar to real disorder (eg. impaired social behaviour in autism model)
  • Biological changes similar to real disorder (eg. high glucocorticoid level in animal model of stress)
  • At least partial reversibiltiy of behavioural/biological impairments by drugs thought to treat real disorder (eg. antipsychotic drugs in animal model of schizophrenia)

Anhedonia

• Def : Absence of pleasure-seeking behaviour
• Test : Sucrose preference test

Behavioural Despair

• Def : Hopelessness

• Test(s) :

  1. Forced Swim Test
  • Flaw : Thought to model stress coping rather than depression
  2. Tail Suspension Test

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