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HAVE NOTES BY SIDE THROUGHOUT AS LOTS OF DIAGRAMS

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the nature of behavioural neuroscience

Behavioral neuroscience is a combination of psychology and physiology – combination of neuroscience and behaviour

The methods and the theories of these two fields are combined to try and explain how biology gives rise to psychology.

These combined methods and theories have been applied to the topics we cover in this series: Consciousness, sleep, reproduction, emotion, feeding, learning and memory, neurological disorders, mental illness, and addiction.

Reductionism and generalisation

The utility of laboratory models

Extract once process and study it – discover principle (reductionist) and generalised to a broader context
- E.g. Pavlovian conditioning

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history of behavioural neuroscience

Descartes produced the first reductionist (mechanistic) account of movement

Spiritualism

Hydraulic pressure moves statue – underlying principle of Descartes theory

Balloonist theory – heat withdrawal reflex – heat causes fluid in pipes to expand – causes pressure to change up the pipe into the brain – brain channels pressure to correct location which causes muscles to move

Bit like heart/pump

How does it explain other processes? – e.g. withdrawal of hand from something cold

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neural conductance

Galvani (1737-1798)

Gross anatomy in frogs

Electricity makes contact wit sciatic anatomy in legs – leg twitches

Static electricity could produce heat

Emerging theories of electricity at the time

Volta (1745-1827)

“Electrochemistry”

Produced same leg twitch with electricity from battery – no heat involved

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neuron theory

Golgi (1843-1926)

Printing on clothes etc. very common at the time

Applied to brain tissue

Dye sticks to cells and enable to see more clearly what was there

Microscope also invented

Repeated pattern of highly organised structure

Diff functional roles played by different cells

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doctrine of specific nerve energies

How can the same electrical impulse (in different cells) give rise to different sensory experience?

Diff parts of brain use same mechanisms but separated in functions to give rise to diff sensory experiences

Kinaesthesia – crossing of sensory experiences

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lesions and neural basis of behaviour

Flourens (1794-1865)

Cut part of brain to test functionality – what behaviour is affected – correlation

Very unethical experiments

e.g. cut frontal brain – reduced movements

Cut cerebellum – lose balance and smoothness of movement

Cut brainstem = death as controls phys

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cog neuroscience

Broca (1824-1880)

Diagnostic and clinical diagnoses

Know what part of behav missing

Post mortem to see where damage in brain was

Correlation

Lots of noise in the data

Impairment in ability to produce speech but comprehension still in tact

Just left of motor strip that controls tongue, face and lips – why speech production disrupted

Specialised part of the motor strip that extends beyond part of the face

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somatotopic organisation

Circa (1870)

Dogs have skull removed but alive and pinned with pegs to washing line

Prod parts of the brain see which parts of the body moved

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alien hand syndrome

Characterized by a limb that seems to perform meaningful acts without being guided by the intention of the patient

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alien hand

foreign/unco-op behav of hand - name for syndrome and all of components

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posterior alien hand

AHS that may follow posterior lesions, char by levitation and abnormal postures

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magnetic apraxia/repellent apraxia

instinctive grasping/avoiding w/ abnormal posture

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compulsive manip of tools

manip objects by abnormal hand against patients own will - used mainly in Japanese lit

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anarchic hand

autonomous behav of limb w/o denial of ownership

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strangers hand sign

detail of ownership of limb

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strange hand sign

original meaning of alien hand sign - failure to recognise abnormal hand as own

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autocriticism, interhem autocricism

expression of astonishment w/ behav of hand

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diagnostic dyspraxia

conflict between desired act and perf act

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intermanual conflict

hands act cross-purposes to each other

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agonistic dyspraxia

compulsive automatic execution of orders by one of hands when patient asked to perf movement w/ other hand

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Goldstein

described the case of a 57-year-old woman who suffered a stroke and thereafter perceived her left hand as having a will of its own.

On one occasion, the hand grabbed her by the throat and choked her, requiring great effort to pull it off…

Upon the woman’s death, Goldstein (1908) examined her brain and found lesions in the right hemisphere and in the corpus callosum, the large fibre bundle connecting the right and left hemispheres.

Corpus callosum – communication channel

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AHS and corpus callosum

Often due to damage to the anterior (front) corpus callosum

Disruption in communication between the two sides of the brain

Pressure in area where blood leaked out but also lack of blood to rest of brain leads to death of cells

Unpredictable how the damage pattern will occur

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AHS and anterior CC

Lesions of the anterior corpus callosum disconnect the two frontal cortical regions.

Primary motor cortex = sensory part – receive info from all parts of the body

Sensation and movement are interconnected but on diff sides of the channel

Premotor – origin of consciousness – activation ramps up before movement occurs

More complex decision making regions further forwards

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AHS and premotor and primary motor areas

Due to disconnection of the premotor and primary motor areas between the two hemispheres?

Damage around motor cortex during stroke

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AHS and descending pathways

Descending pathways from the motor cortices remain intact enabling control of muscles – goes into the striatum – then thalamus (junction box of the spine)

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AHS and basal ganglia

Basal ganglia motor circuit is complex and we will cover it in a later lecture.
- Between striatum and thalamus
- Decision making and movement control

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AHS and descending motor pathway

Descending motor pathway continues through the brainstem: Midbrain, pons, circuits the cerebellum (for fine motor refinement) then back out to medulla and into the spine.
- Lots of fibres
- Pons – ‘mini separate brain’
- Contralateral
- Fibres cross at the thalamus

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AHS and cerebellum

Cerebellum turns jerky movement into smooth movement

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AHS and somatotopic organisation

The somatotopic organisation in the motor cortex is preserved in the descending motor pathway, so that specific motor cortical regions control specific body parts.

Neurons for different areas exist at different spinal vertebrae.