PSYC1004 Biological Psychology ANU

What is biological psychology

Scientific study of behaviour and mental processes

Five perspectives to studying biological psychology

Describing the behaviour
Evolution of behaviour
Development of behaviour over the life span
Mechanisms of behaviour
Application of biological psychology

Three approaches to studying biological psychology

Somatic intervention
Behavioural intervention
Correlation

Somatic intervention

Manipulating body structure or function and looking for changes in behaviour
E.g., Administering a hormone, and measuring strength of mating behaviour

Behavioural intervention

Manipulating behaviour and looking for changed in body structure or function
E.g., Putting male in presence of female, measuring changes in hormone levels

Levels of analysis

Molecules
Synapses
Cells
Circuits
Brain regions
Systems
Organ
Social

Reductionism

The scientific strategy of breaking a system down into smaller parts to understand it

Biological explanations for behaviour

Physiological
Ontogenetic
Evolutionary
Functional

Peripheral nervous system

Lies outside the brain and spinal cord, and its responsibilities are the transmit information and carry out commands.
Divided into two systems;
1. Somatic nervous system
2. Autonomic nervous system

Somatic nervous system

Axons conveying information from sense systems to CNS, and back to muscles

What the autonomic nervous system controls

Controls heart, intestines, and other organs, aiming for homeostasis

What do neurons do

Send messages all over the body to allow everything we do.
Approximately 86 billion neurons in the human nervous system

Afferent axon/efferent axon/interneuron function

Afferent axons brings information into a structure
Efferent axons carries information away from a structure
Interneuron has its axon and dendrites within the same structure

Neuron structure

Dendrites, soma, axon, terminal buttons

Dendrites

Receives information from other neurons
Sends information to the soma

Soma

Contains nucleus, ribosomes, and mitochondria
Maintains cell health and metabolism
Receives information from the dendrites
Facilitates neurotransmission
Sends information to the axon

Axon

Receives information from the soma
Sends information to other neurons
Myelin sheath for efficient / rapid conduction
Protein / fatty substance that protects axons and helps with efficient / rapid conduction

Glion

Support cells

Types of glia

Astrocyte
Microglia
Oligendrocytes
Schwann cells
Radial

Resting potential of neuron

Neurons are covered by a membrane
H2O, O2, and CO2 can pass across the membrane
Membrane maintains an electrical polarisation between the inside and outside of the cell Inside is slightly more negative
Resting potential is the voltage difference between the inside and outside approximately 70 mV (millivolts)

Ionic concentration in neuron

The number of K+ is greater inside the neuron and Na+ is greater outside of the neuron

Action potential of neuron

Messages sent by axons are called action potentials.
Sub-threshold stimulation keeps the neurons at rest.
After 55mv threshold;
Rising: Rapid depolarisation, Na+ channels open
Peak: Na+ channels close
Felling: depolarisation, K+ channels open
Undershoot: hyper-polarisation, refractory period (1-4ms), and return to resting potential

Synapse

Synapse is a small gap between two neurons

Presynaptic neuron

Neuron that delivers synaptic transmission

Postsynaptic neuron

Neuron that is stimulated by events at the synapse

Neurotransmitters

Chemicals created in the axon or soma and diffused across the synapse

Synaptic transition process (~7 steps in detail)

1. Neurotransmitters are synthesised in the terminal buttons or soma, then stored there
2. Action potential arrives at the terminal buttons and opens the Ca+ channels and releases the neurotransmitters - called exocytosis
3. Neurotransmitters bind to receptors on the dendrites (or soma) of the post-synaptic neuron
- Neurons release many different types of neurotransmitters
- Neurotransmitters can bind to different receptor types, allowing for complex signalling
4. Neurotransmitters separate from the post-synaptic neuron
5. Neurotransmitters are reabsorbed by the presynaptic neuron
6. Postsynaptic neurons release retrograde neurotransmitters
7. Negative feedback sites respond to retrograde neurotransmitters

Types of neurotransmitter receptors

ionotropic receptors and metabotropic receptors

Ionotropic receptors

Receptor binding immediately opens ion channel
Directly affects the membrane
Very rapid signalling (1-20ms)
Short duration (100-500ms)

Metabotropic receptors

Receptor binding activates an intracellular messenger, without immediately opening
Intracellular messenger opens ion channel
Slower sequence of metabolic reactions (> 30ms)
Longer lasting (seconds, minutes, or longer)

Most common types of neurotransmitters

Glutamate and GABA

Glutamate

An excitatory neurotransmitter
Binds to NMDA and AMPA receptors
Causes an. Excitatory post-synaptic potential

GABA

An inhibitory neurotransmitter
Binds to GABA receptors
Causes an inhibitory post-synaptic potential

Excitatory postsynaptic potential

Makes the postsynaptic neuron more likely to produce an action potential

Inhibitory postsynaptic potential

Makes the postsynaptic neuron less likely to produce an action potential

Types of summation

spatial summation and temporal summation

Spatial summation

summing potentials that arrive at different synapse

Temporal summation

summing potentials that arrive at different times at the same synapse

Neuromodulators (drugs)

Do not excite or inhibit the neuron directly
Can increase or decrease the release of neurotransmitters
Effects can be widespread because they are released into extracellular fluid, ventricles, or bloodstream

Agonist drug

drugs that mimic or increase the effect of neurotransmitters

Antagonist drug

drugs that block the effect of neurotransmitters

Inverse agonist drug

drugs that decrease the effect of neurotransmitters

Inverse antagonist

drugs that activate the effect of neurotransmitters

Direct drugs

drugs that bind to neurotransmitter receptor

Indirect drugs

drugs that do not bind to neurotransmitter receptor

Drugs affecting the glutamate system and its effects

Phencyclidine and ketamine
Indirect NMDA receptor antagonist
Causes general anaesthesia in high doses
Causes hallucinogenic symptoms at low doses

Drugs affecting the GABA system and its effects

Alcohol, barbiturates, and benzodiazepines
Indirect GABA receptor agonist
Causes reduced coordination, depressed feelings, reduced anxiety/stress

Central nervous system

Spinal cord
Connects brain to rest of body Sensory nerved carry information from the body to the brain via spinal cord Motor nerves carry information from the brain to the body via spinal cord
The grey matter is densely packed with cell bodies and dendrites
- Neurons send axons to the brain

Autonomic nervous system is comprised of

sympathetic nervous system and parasympathetic nervous system

Sympathetic nervous system

Network of nerves that prepare the organs for rigorous activity Chains of ganglia

Parasympathetic nervous system

Facilitates vegetative, non-emergency response
Conserves energy

Anterior

In front

Posterior

Toward the back

Superior

Above another part

Inferior

Below another part

Lateral

Toward the side

Medial

Toward the middle

Coronal plane

Seen from front or back

Sagittal plane

Seen from side

Horizontal plane

Seen from above or below

Proximal

Close

Distal

Far

Ipsilateral

On same side

Contralateral

On opposite side

Forebrain comprised of

Cerebrum
Interbrain
Limbic system

Limbic system consists of

thalamus, hypothalamus, amygdala, hippocampus, basal ganglia, cingulate gyrus

Thalamus

Located above midbrain
Sensory information through the thalamus (except olfactory)

Hypothalamus

Located in front of the thalamus
Communicated with the pituitary gland after the release of hormones
Damage leads to abnormal eating, drinking, temperature regulation etc.

Basal ganglia

Located in front of the thalamus
Integrates motivation and emotional behaviour
Critical for learning and remembering skills
Damage leads to difficulty in starting, stopping, or sustaining movement

Hippocampus

Located below the thalamus and behind the amygdala
Associated with memory

Cingulate gyrus

Located above the corpus callosum
Involved in emotional behaviour

Amygdala

Located below the basal ganglia
Major processing centre for regulating emotions, especially fear and aggression
Involved in tying emotional meaning to memories, and decision making

Midbrain is comprised of

Tectum
Superior colliculus
Inferior colliculus
Tegmentum
Substantia nigra

Hindbrain is comprised of

Medulla, pons, cerebellum

Medulla

Located at the base of the brain, above the spinal cord Connects brain to spinal cord
Controls vital reflexes through the cranial nerves

Pons

Located above the medulla
Axons from the brain cross over to the other side of the body

Cerebellum

Located above the medulla, behind the pons
Contains approximately 70 billion neurons
Responsible for a wide range of functions

Brain ventricles

Fluid filled cavities
Four in the brain
Fluid also goes into the narrow space between the brain and the meninges
Swollen blood vessels in the meninges are responsible for the pain of a migraine headache

Cerebral cortex

Basic organisation of the brain is similar across species
Differences between species occur in the size of the cerebral cortex and the degree of folding
Contains up to six laminae (layers of cell bodies that are parallel to the surface of the cortex)
Neutrons are also organised into columns of cells

Frontal lobe

Motor control
Speech production
Attention
Working memory
Making decisions
Problem solving

Parietal lobe

Touch perception
Body orientation
Sensory discrimination

Temporal lobe

Process auditory information

Occipital lobe

Vision
Visual experience

Maturation of the brain

Human central nervous system begins to form wen the embryo is approximately 2 weeks
Muscle movements at about 7 weeks
Brain weights;
- 350g at birth
- 1000g by the end of the first year
- 1200-1400 in adulthood

Six stages of development

Neurogenesis, migration, differentiation, myelination, synaptogenesis, pruning

Vulnerability of the brain during development

Vulnerable to malnutrition, toxic chemicals, and infection
E.g., alcohol interferes with proliferation, migration, differentiation, and synaptic transmission

Neuroplasticity

The ability of the nervous system to change its activity in response to stimuli by reorganising its structure, functions, or connection
- E.g., blind people training their brains to improve their other senses
Can occur after brain damage
- E.g., after stroke

Weber-Fechner law

Perception doesn't change as much as the stimulus changes

Transduction

conversion of a stimulus into an action potential by a sensory receptor

Transmission

transfer of information between neurons

Modulation

process in which neural activity is regulated by the central nervous system

Field of view

The centre of visual field is seen by both eyes, known as the binocular field
The periphery of vision field is seen by only one eye, known as the monocular field

Optical nerve

Transmits information from the retina to the brain
Composed of axons from the retinal ganglion cells, forming a thick, cable-like bundle

Optic chaism

Allows for the partial crossing of visual information from each eye, contributing to binocular vision

Optic tract

Transmits information from the optic chaism to the lateral geniculate nucleus of the thalamus

Lateral geniculate nucleus

Sorts visual information based on various attributes

Optic radiations

Transmits information from the lateral geniculate nucleus o the primary visual cortex
Composed of nerve fibres that fan out from the lateral geniculate nucleus

Primary visual cortex

Initial cortical area responsible for processing basic visual information
Located in occipital lobe

Cornea

Focuses light entering eye

Pupil

adjustable opening in iris controlling light entering