Lecture 3: Biological Basics Flashcards
What is the Phineas Gage case-study?
Man lost part of his brain. His personality changed and it changed his ability to plan.
What are neurones?
- building blocks of the brain
- 100 billion when born
- lose 10,000 a day
- connects to 50,000 other neurons
What are sensory neurones?
- help recode information.
- transmit to spinal cord/brain.
- outside world —–> signal
What are interneurons?
- simply ‘pass it along’.
- neurons that communicate with other neurons.
What are motor neurones?
-responsible for transmitting messages from CNS to muscles.
What are Glial cells?
- 10 to 1 neuron.
- waste disposal + axon protection
- learning + memory.
What are the different parts of a neurone?
- Dendrites
- Soma
- Axon
- Axon terminal/terminal button
- Synapse
What is the role of the dendrites?
-Absorb chemical information/stimulation from other neurones.
What is the role of the soma?
-If dendric activity large enough, an electric action potential fired.
What is the role of the axon?
-Conducts electrical signal to terminal buttons at the end of the axon.
What is the role of the axon terminal/terminal button?
-Electrical signal ——–> chemical squirt
What is the role of the synapse?
-Jump chemical has to make to be taken up by the next dendrite.
How can we observe individual action potentials?
Attach micro-electrodes to axons.
What is the charge of a resting neurone?
Around -70mV.
What is the stage of + charge (+40 action potential)?
Depolarization.
What is the stage of - charge?
Repolarization.
What charge does a neurone have in the refractory period?
Overcompensates resulting in - charge.
How long does it take for a neurone to return to resting state?
5 minutes (200Hz).
Are neurones all the same?
No. Different neurones have different responsibilities. Yet all the neurones work together.
How are differences in sensory environment coded?
By changes in the rate of axon firing or by the magnitude of neurone firing.
What are the three type of feature detectors?
1) Simple cells.
2) Complex cells.
3) End-stopped cells.
What do simple cells do?
Respond to size, orientation and colour.
What do complex cells do?
Respond to orientation and direction.
What do end-stopped cells do?
Respond to orientation, direction and size.
What does it mean if a neurotransmitter is inhibitory?
Firing rate hyperpolarization.
What does it mean if a neurotransmitter is excitatory?
Firing rate depolarization.
What is the resting potential of a neurone?
- -70mV.
- electrical charge inside (relative to outside) when neurone at rest/receiving no stimulation.
When is action potential more likely and what happens?
When negative resting potential changes to positive charge.
- achieved by depolarization.
- sodium enters the cell from the outside.
What happens to achieve hyperpolarization?
- Chloride enters from outside the cell.
- Becomes more negative.
What is a lesion study and what might it show?
- Brain intact + study behaviour.
- Remove part and notice change.
- Perhaps removed brain area is critical for completion of behaviour.
- Possible to lesion communication links.
What is a single dissociation deficit?
Perhaps 2 functions performed by different brain areas.
e.g. one can process non-words but not process words.
What is a double dissociation deficit?
Can begin to build case that different parts of the brain do different things.
e.g. one can process words but not non-words and another subject can process non-words but not process words.
What are 4 techniques that are considered later insights into brain processes?
1) Transcranial Magnetic Stimulation (TMS).
2) Event-related potentials (ERP).
3) Positron Emission Topography (PET).
4) Magnetic Resonance Imaging (MRI).
What is TMS?
Transcranial Magnetic Stimulation
- sends weak electrical fields across cortical surface.
- leads to temporary disruption of electrical activity.
What is ERP?
Event-related potentials
-records weak electrical fields generated by large scale neural ensembles that permeates through the skull.
What is PET?
Positron Emission Topography
- after ingestion of radioactive tag.
- attaches itself to glucose.
- glucose uptake related to increased brain activity.
What is MRI?
Magnetic Resonance Imaging
-Records BOLD signal on the principle that oxygenated blood has different magnetic properties than deoxygenated blood.
What are the pros and cons of TMS?
Transcranial Magnetic Stimulation
PROS:
1) relatively safe way of stimulation lesions.
CONS:
1) Effects not long-lasting.
2) Cannot be used for sufferers of epilepsy.
What are the pros and cons of ERP?
Event-related potentials
PROS:
1) precise temporal recording (millisecond).
CONS:
1) spatially diffuse (what does no ERP modulation mean?)
What are the pros and cons of PET?
Positron Emission Topography
PROS:
1) allows insights into functionality of brain regions.
CONS:
1) poor spatial resolution.
2) involves radioactive substances.
What are the pros and cons of MRI?
Magnetic Resonance Imaging
PROS:
1) popular in revealing brain networks.
CONS:
1) BOLD signal very slow.
2) not sure what really means.
What is the role of the Brain Stem?
Regulates breathing and heart rate.
What is the role of the Cerebellum?
Regulates balance and body control.
What is the role of the Hippocampus?
Hub related to learning, memory and space.
What is the role of the Hypothalamus?
Controls endocrine (hormone) system.
What is the role of the Thalamus?
Relays sensory signals to cortex (smell).
What is the role of the Corpus Callosum?
Connection between the hemi-spheres.
What is the role of the Cerebral Cortex?
- Part of the forebrain.
- Conscious function.
What are the 7 key parts of the brain?
1) Brain Stem
2) Cerebellum
3) Hippocampus
4) Hypothalamus
5) Thalamus
6) Corpus Callosum
7) Cerebral Cortex
What are the parts of the Cerebral Cortex?
1) Frontal Lobe
2) Parietal Lobe
3) Temporal Lobes
4) Occipital Lobe
What is the role of the Frontal Lobe?
- related to personality and executive functioning
- lobotomy helped with psychological problems yet resulted in a loss of planning and social inhibition.
What is the role of the Parietal Lobe?
- host to the somatosensory homunculus
- it has the body mapped out spatially
- stimulation of brain regions lead to specific sensory experience.
What are the roles of Temporal Lobes?
-intimately connected with first stages of processing auditory information.
What is the role of the Occipital Lobe?
- processing of visual information starts its journey.
- specific area dedicated to the processing of basic visual building blocks (e.g. colour, motion, orientation).
What is the Endocrine System?
-Interacts with autonomic nervous system for body regulation and secretion of hormones into bloodstream.
What other system do the Endocrine and Nervous Systems interact with?
The Immune System.
What is the role of the Immune System?
-generates antibodies to destroy biological enemies.
What is an autoimmune reaction?
The immune system incorrectly identifies a part of the body as an enemy and starts to attack.
(e.g. Arthritis is the attack of connective tissues).
Why does there need to be variation within a species?
Traits that are of evolutionarily adaptive value are naturally selected.
What is a mutation?
A copy error in gene replication producing ‘chance’ characteristics.
What also plays a role in characteristics other than genetics?
Environmental factors.
How many pairs of chromosomes does each cell in your body have?
23 (except for sperm and unfertilised egg).
What are the two types of characteristics?
1) Phenotype
2) Genotype
What is a Phenotype?
Characteristics inherited from your parents that you express.
What is a Genotype?
Characteristics that are not expressed but just carried by you.
What does it mean if a characteristic is recessive?
Both parents need to pass the gene for it to be a phenotype (expressed) for you.
When can a recessive phenotype reappear when both parents do not express the characteristic?
Through randomisation.
