Biological Psychology

What were Aristotle’s key arguments for the Heart against the Brain as the Centre of Mind?

• The heart is essential for life but the brain isn’t

• The heart is sensitive to touch but the brain isn’t

• The heart is affected by emotion but the brain is neutral

What developments did Descartes make in the understanding of the brain?

• He tried to explain the brain in terms of machines

• He believed in dualism

• He identified the pineal gland as where the non-physical mind and the physical body could interact

What is Dualism

The philosophical position that behavior is controlled by two entities

What developments did Gall make in the understanding of the brain?

• He tested the consequences of damage to the brain

• He believed the brain is the organ of the mind

• The mind is composed of multiple, distinct faculties

• Each faculties must have a separate seat in the brain

• The size of an organ is a measure of its power

• The shape of the brain is determined by the development of the various seats

• BUT he believed the surface of the skull could be read as an accurate index of psychological aptitudes and tendencies

What was Lavery’s Electric Phrenometer?

• 1907- told you where your lumps were and what your skills were

What developments did Golgi make in the understanding of the brain?

The brain is composed of a large network of interconnected tubes

What developments did Cajal make in the understanding of the brain?

Looked at cellular structures to show that nerve cells are discrete entities

What developments did Brodmann make in the understanding of the brain?

• Depending where you look in the brain, it is structured differently

• Realised similar cellular structures were grouped together and therefore must have similar behaviours

What developments did Kleist make in the understanding of the brain?

Compiled a comprehensive functional mapping of the cerebral cortex from 1600 WWI head wound casualties

What developments did Bailey and von Bonin make in the understanding of the brain?

Looked at where the neurons travelled and realised they are all interconnected

What is Cytoarchitecture?

The study of what cells look like, where they are, and what they connect to- anatomically and functionally

What is neuropsychology?

The study of the relationship between the brain and human behavior (used to have to wait for a patient to die to work out what area was damaged)

What is an MRI?

Studies brain anatomy

What is an fMRI?

Studies blood flow around the brain as it diverts to areas in the brain being used to understand brain function.

What is the subtraction method in an MRI?

Taking a control brain scan away from the stimulation brain scan to be left with the difference so that you can see which areas in the brain were active for the activity

What is the listening technique?

If you pout a listening electrode in, you can hear what is happening with a neuron

What is near infra-red spectroscopy (nIRS)?

Applying intense near infra-red illumination to the skull, where sensitive detectors will pick up heightened activity

What is direct brain stimulation?

• Used electrical currents

• Mapped what happened when parts were stimulated

What is transcranial magnetic stimulation?

• Uses magnetic currents

• Stimulates specific parts of the brain

What was wrong with Thompson’s attempt at brain stimulation?

He was only able to stimulate the retina

What is the difference between a sensory and motor neuron?

Sensory neurons carry information towards the central nervous system (CNS) away from receptors (skin, eyes etc) for sensation

Motor neurons carry information away from CNS to muscles/glands for action

What is the Neuronal Membrane?

Every cell in the body is surrounded by a membrane that separates fluid inside the cell (intracellular) from fluid outside the cell (extracellular). The neurons contain ion pumps and channels.

What is the function of the Neuronal Membrane?

The ion pumps and channels control the movement of ions into and out of the cell, this movement causes electrical signals

What ions are contained in intracellular and extrcellular fluid?

• Sodium (Na+)

• Potassium (K+)

• Chloride (Cl-)

• Large negative ions (A-)

Why are cells negatively charged by default?

A- ions are stuck in the cell

What is the charge of a neuron at rest?

-65mV

Resting membrane potential

What are the ion channels doing at rest?

• Na+ are closed, so can’t move

• K+ is open so can move

  • Attracted into the cell as it is negative

  • Attracted out of the cell as there is less potassium out

  • Two forces are in equilibrium

• Sodium-Potasium pump

What are the ion channels doing at rest?

• Na+ are closed, so can’t move

• K+ is open so can move

  • Attracted into the cell as it is negative

  • Attracted out of the cell as there is less potassium out

  • Two forces are in equilibrium

• Sodium-Potasium pump

What is the sodium-potassium pump?

• At rest, more postive ions outside than inside, so cell is negative

• Na/K pimp continually pushes out 3 Na+ ions and pumps in 2 K+ ions

• Causes increased K+ concentration inside cell vs increased Na+ outside

What is an action potential?

Neuron stimulated = equilibrium upset

An action potential is generated if the net change is above -50mV

Where does an action potential occur?

Generated at the axon hillock and then propogated down the axon

When do the sodium ion channels open?

When the cell is stimulated above threshold- Na+ causes cell to become more positive

How does an action potential fall?

• Once cell is positively charged, K+ are attracted the the negative outside of the cell

• Concentration also forces K+ out cell

• Loss of K+ causes the cell to become more negative

What is Myelin?

A fatty substance that allow axons to conduct action potentials faster

What is the refractory period?

Voyage drops below resting, and there is a brief break before another action potential can occur

What determines the strength of a stimulus?

Increased firing rate NOT a ‘big’ action potential

What happens when an action potential reaches the presynaptic terminal?

A chemical neurotransmitter is released into the junction between the neurons (synapse) which will either have an excitory or inhibitory effect

How do the sodium ion channels work?

• Sodium is attracted into the cell because there is more Na+ outside than inside

• Na+ is attracted to negative cell

What is a synapse?

Formed by the termination of an axon from one neuron onto the dentrite of another

When were we able to see synapes?

With the electron microscope

What synapses cause movement?

Synapses found between neurons and muscles- the axons that activate muscles are located in the spinal cord

How do neurotransmitters work?

• Made in the cell body, stored in vesicles and transported along the axon to the presynaptic terminal

• Remain dormant until an actional potential arrives

• When an action potential arrives, synapse opens Calcium (Ca++) channels

• Ca++ binds to the synaptic vesicles and they release un the synapse

What are neurotransmitter receptors?

• Found on dendrites

• Neurotransmitter binds and opens the ion channel

How are metabotropic neurotramsitter receptors different?

• Neurotransmitter binds to the binding site

• Subunit detaches and causes the ion channel to open

• Slower, but have lasting effects

What happens if neurotransmitters removed aren’t?

• Glutamate not removed = excitotoxicity = stroke

• Mustard gas prevented the deactivation of acetylcholine

What is glutamate?

• Brain’s major excitatory neurotransmitter

What is GABA?

• Brain’s main inhibitory neurotransmitter

What is dopamine?

• Involved in movement control and in reward circuits

What is serotonin?

• Feel-good chemical

• Profound effect on mood and anxiety

What is acetylcholine?

• Neurotransmitter used at the neuro-muscular junction

What causes Parkinson’s disease?

• Loss of dopaminergic neurons in the brain stem

• Causes rigidity and trembling

• Levi-dopa mimics actions of dopamine and can help

What animals use toxins to poison ion channels?

• Puffer fish inactivate Na+, paralysing animals

• Scorpions activate Na+, scrambling information flow

• Wasps/Bees inactivate K+

Which animals release toxins that affect transmitter release?

• Black widows cause massive release of neurotransmitter at nerve-muscular junction = in paralysis

• Tetanus toxin prevents inhibitory neurotransmitters to be released in the spinal cord = hyperactivity of muscles

How do toxins block neurotransmitter receptors?

• Toxins bind to neurotransmitter receptors

• Prevents the victim from making an escape

How do LSD and mushrooms work?

Mimic the effect of serotonin

How does cocaine work?

Prevents the reuptake of dopamine —> prolongs the effect of dopamine when it is released

Why do people become addicted to drugs?

• Association between drug taking and the reward circuits

• Many highly addictive drugs activate dopamine (important in the reward circuits)

What are the two main parts of the nervous system?

Central nervous system (CNS) and Peripheral nervous system (PNS)

What is the bumpy surface of the brain made up of?

Gyri (hill tops)

Sulci (valleys)

What acts as a cushion between the skull and the brain?

Cerebrospinal fluid (CSF)

What is the outer surface of the brain?

Nerve cells that cover the outer surface

What are the six layers of the cerebral cortex?

I, II, III integrative functions

IV input of sensory information

VI output to other parts of the brain

What happens in the occipital lobe?

Visual processing

What happens in the parietal lobe?

Touch, balance, movement

What happens in the temporal lobe?

Hearing, speech comprehension, memory and visual recognition

What happens in the frontal lobe?

Movement, thinking and planning

What are the Basal Ganglai important for?

Control of voluntary movement and learning new skills

What is the lambic system important for?

Navigation in space and memory function

What is the brainstem?

Hindbrain, Midbrain, Diencephalon

• Composed of nerves that run up from the body into the brain.

• Controls the brains general level of alertness

What are the cranial nerves?

Allow the brain to communicate with the muscles and sense organs of the head and neck

How does the brain communicate with the rest of the body?

Via the spina cord and the cranial nerves

How do nerve fibres leave the spinal cord?

Through gaps between the vertebrae

What is homeostasis?

The maintenance of constant, steady conditions internally

What is the sympathetic system?

Fight or flight

• Increases heart rate, dilates pupils, inhibits digestion

• Pre-ganglionic: ACh

• Post-ganglionic: Noradrenaline

What is the parasymoathetic system?

Rest and digest

• Slows heart rate, constricts pupils, stimulates digestion

• Pre-ganglionic: AcH

• Post-ganglionic: AcH

What does Anterior mean?

Near/towards the front

What does posterior mean?

Located near or towards the tail

What is sensation?

The registration of physical stimuli from the environment

What is perception?

The interpretation of sensations by the brain

How are physical stimulus converted into an electrical signal?

Sensory receptors have specialised dendrites that will open ion channels if stimulated by the appropriate external stimulus

What does unilateral damage cause?

• Loss touch and pressure sensation on same side of body

• Loss of pain and temperature on opposite side of body

What is a receptive field?

Each sensory receptor is sensitive to physical stimuli that impinge on a circumscribed area of the body

How do sensory receptors indicate how string a stimulus is?

Number of action potentials fired

\waht can excessive use of a single sense cause?

The relevant cortical area can expand

What regions of the brain are involved in processing the 5 senses?

Vision- occipital/temportal/parietal

Hearing- Temportal

Touch- Parietal

Taste- Frontal

Smell- Frontal

How do odorant molecules trigger a neural signal?

• Odorants dissolve in the olfactory mucosa

• Interact with the cilia

• Triggers matbotropic ion channels to open

How many smells can we discriminate between?

10,000

Other than scent what else are olfactory receptors for?

Can detect pheromones

What are the four basic tastes?

Salty, sour, sweet and bitter

What are tastings?

Chemicals that are detected by taste resceptros

What new tastes have been discovered?

Unami (meaty and savoury)

Receptors specific to fat

What is Gourmand Syndrome?

Damage to frontal lobe of right hemisphere can turn normal people into seekers of fine food

What is flavour?

Combination of taste and olfaction