brain & behaviour

Anterior /rostral

Front

Posterior/caudal

Back

Dorsal

Top

Ventral

Bottom

Lateral

Towards side

Medial

Towards middle

Ipsilateral

Same side

Contralateral

Opposite side

What is the transverse section of the brain

Cut down the middle → front and back

What is the saggital section of the brain?

Cut in half left and right

What is the horizontal section of the brain?

Cut in half top and bottom

How heavy is the brain?

1400 G (around 2% bodyweight)

Name the 3 meninges (and what that is )?

Membranes around the brain → dura mater, arachnoid, pia mater

Dura mater

Durable → outer most layer, tough & flexible

Arachnoid

Middle layer of meninges - like sheet of cellophane

Pie mater

Soft, last layer of meninges → adheres to the surface of the brain

What are ventricles & what are the 4 in the brain?

A set of hollow chambers within the brain filled with CSF -protects brain with a watry cushion → this includes: lateral ventricles, third ventricles, cerebral aqueduct, fourth ventricle

Outline brain development in foetuses

Development of nervous system begins 18 days after conception → by 21st day, these ridges touch eachother and form the neural tube which becomes the brain and spine

What is in the forebrain?

Contains telencephalon and dichephaion → telencephalon contains cerebral cortex, basal ganglia and limbic system

Cerebral cortex

Thin wrinkled layer of tissue covering the brain consisting of two hemispheres

Cerebrum

Composed of grey matter ( composed of cell bodies of neurons ) & white matter (axons and dendrites)

Telechephalon

The limbic system → set of structures involved in learning memory and emotion eg. Hippocampus amygdala

Diencephalon

Part of the forebrain consisting of largely the thalamus and hypothalamus → thalamus - main sensory relay for all senses

Tectum

Part of the midbrain, comprised of superiorcolliculi (sensory pathway involved in fast eye movement ) and inferior colliculi ( part of auditory pathway )

Tegmentum

Part of midbrain → role in motor movement

Role of spinal cord

Communicates with sense organs and muscles below the head → includes dorsal and ventral routes

What does the hindbrain contain?

Mesencephalon and mylencephalon

Met encephalon

Includes cerebellum (mini brain involved in motor coordination and smooth execution of movements ) and pons (involved in sleep and arousal )

Myencephalon

Contains medulla oblongata → involved in basic life functions such as breathing. Swallowing, heart rate, sleep wake cycle

Autonomic nervous system

Controls the body's vegetative functions, cardiac muscles and glands → all nerves are efferent

Bell- magendie law

Dorsal roots carry sensory information to the CNS → afferent, ventral roots carry motor information to the muscles and glands away from the CNS → efferent

Somatic nervous system

Part of peripheral nervous system that controls muscles and transmits somato sensory info.

Autonomic nervous system

Controls negative functions

What is a neuron

Makes up the nervous system and supports cognitive function

Sensory neurons

Detect changes in internal and external environment (cns&pns, light sound touch etc.)

Motor neurons

Controls muscle contraction and gland secretion ( CNS & PNS)

Interneurons (relay neurons)

Lie entirely in the CNS and are involved in cognition → e.g. Perceiving learning, remember

Multipolar neuron

Neuron with one axon and many dendrites attached to its soma

Bipolar neuron

One axon and one dendrite attached to its soma

Unipolar neuron

Neuron with one axon attached to its soma → axon divides (into dendrites) with one branch receiving sensory information and the other sending information to the CNS

Glial cells

' glue ‘ nervous system together as supporting cells

Astrocytes

'Star cells. → provide physical support to neurons, nourishment

Oligodendrocytes

Supports axons and produces myelin sheath

Nodes of ranvier

Bare portion of axon

Blood-brain barrier

Semi-permeable barrier between CNS and circulatory system, helps regulate the flow of nutrient rich fluid into the brain

Area postrema

Region of the medulla where the blood brain barrier is weak → allows toxins in the blood to stimulate the area which initiates vomiting

Membrane potential

Electrical charge across a cell membrane → difference inside and outside

Resting potential

Membrane potential of a neuron when its not being altered by excitatory or inhibitory postsynaptic potentials usually about. -70mv

Depolarization

Reduction of negative charge (toward zero) of the membrane potential

Action potential

Brief electrical impulse that provides the basis for conduction of information along an axon

Threshold of excitation

The value of the membrane potential that must be reached to produce an action potential

Hyperpolarisation

Increase in the membrane potential of a cell

What 2 forces is membrane potential a balance of

Diffusion ( movement of molecules from an area of high to low conc.) and electrostatic pressure (when substances dissolve in water they split into 2 parts w opposing decnical charge Na + and CI- ions

Now wide is the synaptic cleft

20NM → action potentials cannot cross the synaptic cleft so nerve impulses are instead carried by neurotransmitters

Where are neurotransmitters made and stored

Made by presynaptic neuron and stored in synaptic vesicles

How do neurotransmitters get to the post-synaptic neuron

Membrane of the post-synaptic neuron has chemical-gated ion channels called near receptors, these have specific binding sites for neurotransmitter

Excitatory postsynaptic potential (EPSP)

Excitatory depolarization of the postsynaptic membrane

Inhibitory postsynaptic potential (IPSP)

Inhibitory hyper polarisation of the postsynaptic membrane

Psychopharmacology

The study of the effects of drugs

Antagonist drugs

A drug that opposes or inhibits the effects of a particular neurotransmitter on the postsynaptic cell

What are agonist drugs?

A drug that facilitates the effects of a particular neurotransmitter on the postsynaptic cell

What / where are the sites of action

Locations at which molecules of drug interact with processes of these cells → sites include: production of NTs, storage and release of NTs, effects on receptors ,effects on reuptake

Direct agonist/antagonist

A drug that binds with and activates a receptor → mimics the effect of a neurotransmitter

Indirect agonist/antagonist

A drug that attaches to a binding siteon a receptor and facilitates the action of the receptor does not interfere with the binding site of the principal neurotransmitter

Now do reuptake inhibitors work?

Usually molecules are taken back up to terminal button through reuptake or destroyed by an enzyme - inhibiting drugs attach to either transporter molecules that allow reuptane & deactivate them OR to the enzyme that would usually destroy the nt

Placebo and placebo effects

An inert substance given to an organism in lieu of a physiologically active drug used to control for effects of merely administering a drug → observing placebo effects allows experimenters to tell what effects actually. come from the drugs

Nocebo effect

People can feel worse after n intervention that should have no ill effects

What are the two main NTs in the brain (excitatory and inhibitory )

Excitatory = glutamate, inhibitory= GABA or glycerine in the spinal cord

Achtycholine

Ach → primary nt secreted by axons of the central nervous system, all muscular movement is accomplished by Ach - parasympathetic branch of ans also involved in perceptual learning

What are the two Ach receptors

Nicotinic and muscarinic → these are called cholinergic synapses

Nicotinic receptor

An ionotropic acetylcholine receptor stimulated by nicotine & blocked by curare (paralysis)

Muscarinic receptor

A metabotrophic acetylcholine receptor _stimulatedby muscarine and blocked by atropine

What are 2 drugs that affect acetylcholine

Botulinum toxin and black widow spider venom

Botulinum toxin

(Botox) an acetylcholine antagonist, prevents release by terminal buttons and causes muscles to relax

Black widow spider venom

A poison produced by the black widow that triggers release of acetylecholine causing convulsions ( agonist)

Monoamines

Dopamine, norepinephrine, epinephrine and serotonin → all belong in the same family of nt, because their molecular structure is similar, some drugs affect the activity of all of them

Dopamine

The reward neurotransmitter - hits decision-making part of the brain natural rewards include: food, water, sex

Addiction

A state in which an organism engages in compulsive behaviour, behaviour is reinforcing (rewarding/ pleasurable) loss of control for limiting intake

Tolerance

A state in which an organism no longer responds to a drug, a higher dos e is required to achieve the same effect

Dependence

A state in which an organism functions normally only in the presence of a drug- can be seen through withdrawals

Are addiction and dependence the same circuit?

No, possible to be dependent on morphine without being addicted.

Ni grostriatal system

Starts in the substantia nigra and terminates in the basal ganglia: plays a role in the control of movement → neurological disease characterised by tremors, rigidity of limbs and difficulty initiating movement

Serotonin (5-ht )

Influences regulation of mood, control of eating, sleep, dreaming and arousals

MDMA

Drug that serves as a noradrenic and serotonergic agonist (ecstasy) has excitatory and hallucinogenic effects → prevents reuptake and brings more serotonin to the synapse - heightened senses; hyperthermia, clouded thinking reduced appetite

Depression

Stems sometimes from serotonin deficiency → antidepressants work by blocking reuptake of serotonin in the presynaptic cell

Norepinephrine / noradrenaline

Hormone and neurotransmitter → involved in fight/fight respond - medications that inhibit NE can treat depression, also related to mania

Amino acids

Most common in the CNS include : glutamate, gamma aminoblityric, glycine

Glutamate

Most important excitatory nt in the brain

GABA

Most important inhibitory nt in spinal cord → allows us to fine tune our thoughts and actions

Tranquilizers

Benzodiazepine (anxiolytic); an indirect agonist for GABA receptor, used for tranquilis, effects e.g. Valium. Xanax

Stress

The way we respond to a stressor (adverse event)

Chronic stress

Muscles in the body in a constant state of guardedness, tension - type headache, long term blood/heart problems

What term did Walter cannon coin ?

Fight or flight → short term response, but becomes problematic when it’s longtime (eg. Stomach ulcers, depression)

How have causes of morality changed since the early 1900s?

Used to be infections diseases and childbirth, now more cumulative such as heart disease, cancer

HPA axis

Hypothalamus → pituitary gland → adrenal cortex

Role of hypothalamus (stress)

Generally involved in homeostasis → bard stimulated this in cats which led to undirected rage so involved in right / fight response → also releases stress hormone corticotropin releasing hormone (CRH)

The pituitary gland

Located beneath the hypothalamus, 'master gland ‘,weighs 0.5 G → releases somatotropin's (e.g.hgh - growth), Thyrotrophin's (TSH, metabolism). Gonadotrophin's ( lh, FSH - fertility), corticotrophins ( adrenocorticotrophic hormone /ACTH stress response )

Adrenal glands

Sits on top of kidneys, releases hormones related to stress e.g. Cortisol, epinephrine

What happens when you have too much cortisol?

Cushing's syndrome → rapid weight gain in trunk and face, acne, reduced libido and fertility - thin skin and chronic tiredness