Week 4-6 Flashcards
What is the relationship between brain mass and intelligence?
Larger brain mass means a wider range of intelligent behaviour.
However absolute size does not indicate intelligence - rather the proportion of brain to body mass is more important.
What is the Encephalisation quotient?
Why is this useful?
The size of the brain relevant to body mass.
Indicates high species IQ.
Where is the cerebral cortex?
How is this different between humans and other animals?
The outer most layer of the brain.
Made up mostly of grey matter.
Has folds - small mammals have smooth cerebral cortices.
What brain functions is the cerebral cortex involved in?
Attention Perception Awareness Thought Memory Language Consciousness
What are some ways we can understand the relationship between the brain and behaviour?
Investigate what happens when the brain is damaged or impaired - can be caused by trauma, disease, accidents, or experiments
Why are accidents and disease a limited approach to understanding the function of brain areas?
The show what damage to certain parts of the brain will do to function, but can’t be controlled or replicated.
What are examples of invasive techniques?
Ablation
Surgical modification
Psychosurgery
Deep brain stimulation (DBS) - electrodes inserted into the brain to stimulate different areas
What are examples of non-invasive techniques?
EEG - electroencephallography
TMS - Transcranial Magnetic Stimulation
Transcranial Direct Current Stimulation
When would it be appropriate to use electroencephalography (EEG)?
EEG records brain activity using electrodes placed in various locations on the scalp.
Useful for: Seizure disorders Sleep disorders Changes in behaviour After severe head injuries
Pro: Can see brain responses very quickly
Con: Offers poor spatial resolution
What is MRI?
What is it useful for?
What are the pros / cons?
Magnetic resonance imaging
Powerful magnetic fields to measure different kinds of tissue in the body - white matter, grey matter, cerebral / spinal fluid
Useful for: Tumour Soft tissue injuries like ligaments Joint injuries Spinal injuries Internal organs
Pro: Bold contrast - get definition!
Con: Poor temporal resolution - blood takes time to reach brain regions
What is PET?
Positron emission tomography
Radioactive materials injected intravenously that bind with molecules in the body such as water.
Can scan before and after treatments to see which brain regions show changes.
Con: Poor temporal resolution
What is TMS?
Transcranial magnetic stimulation
Attach electrodes to the scalp to induce electric currents inside the brain
Pro: Relatively painless
What is DBS?
What is it used for?
What are the pros / cons?
Direct brain stimulation
Electrodes inserted into the brain.
Relatively new technique.
Used for: Parkinson's Essential trmor Depression OCD
Cons: Invasive brain surgery! Used only in new cases
What are the parts of the Hindbrain?
Medulla oblongata
Pons
Cerebellum
What is the medulla oblongata?
Passes messages from spinal cord and brain.
Located at the base of brain where it connects to spinal cord.
Responsible for:
Cardiovascular system
Respiratory system (coughing, sneezing)
What is the pons?
Relays signals from the forebrain to the cerebellum.
Sends information from the face, eyes, and ears to the brain.
Largest part of the brainstem.
Located above the medulla and below the midbrain.
Responsible for: Sleep Respiration Swallowing Bladder control Hearing Equilibrium Taste Eye movement Facial expressions Facial sensations Posture
What is the cerebellum?
Means ‘little brain’
Works unconsciously on aspects of motor control, gait and posture
Located below the cortex and behind the brainstem
Responsible for:
Motor control
Balance
Movement
What are the three parts of the midbrain?
Colliculi
Tegmentum
Cerebral peduncles
Responsible for visual and auditory input and processing
What is the superior colliculus?
Transforms sensory input into movement output.
Responsible for:
Receiving input from the eyes
Orientation of eyes and head
What is the inferior colliculus?
Main auditory centre of the body
What is the cerebral peduncles?
Connect the midbrain to the brainstem
Which part of the brain is associated with “higher order” or more “human” features?
Forebrain
Evolutionarily newer part of the brain which has evolved to help humans solve problems within our environment
What are the parts of the forebrain?
Cerebrum Thalamus Hypothalamus Pineal gland Limbic system
What is the cerebrum?
Largest part of the brain
Responsible for: Initiation of movement Coordination of movement Touch Temperature Vision Hearing Judgment Reasoning Problem solving Emotions Learning Reading Writing
What is the thalamus?
Relays motor and sensory signals to the cerebral cortex.
Responsible for:
Sensory inputs (vision, hearing, touch, taste)
Regulation of consciousness and alertness
Memory
Emotion
Arousal
What is the hypothalamus?
Links the nervous system to the endocrine system via the pituitary gland
Responsible for: Eating Drinking Stress regulation Temperature regulation Memorizing The Four Fs (fighting, fleeing, feeding, "mating")
What is the substantia nigra?
Damage is implicated in movement disorders such as Parkinson’s
Responsible for: Motor control Motor learning Executive functions Emotions
What is the hippocampus?
Responsible for:
Consolidating short term memories into long term memory store
Spatial recognition and memory (map reading, navigation)
Damage affects memory acquisition - still able to form physical or motor skill acquisition
What are the amygdalae?
How do we know what they are responsible for?
Responsible for:
Fight or flight response
Memory
Fear and aggression responses in animals
Case study with damage to amygdalae claimed that she was afraid of certain things but showed no fear responses to them
What are the sulci and gyri?
Sulci - valleys of the wrinkles in the brain
Gyri - Bulgy parts of wrinkles in the brain
The brain is split into hemispheres connected by what structure?
Why might you sever this?
What happens when you do?
Corpus collosum
Allows info from one hemisphere to be shared with the other
Split brain surgery may be used for severe epilepsy that travels from one side of the brain to the other
People recover well but may suffer side effects such as spatial neglect syndrome. Patients may still respond subconsciously to the object on the bad side.
What are the four lobes of the cortex?
Frontal
Parietal
Temporal
Occipital
Where is the primary motor cortex?
Centre top of the brain
What order is your motor cortex organised in?
Upper part controls feet, legs, groin and torso
Lower part controls hands, arm, face, and tongue muscles
Which body parts have larger representation in the motor cortex?
Why?
Hands and face
Humans tend to use these a lot more for fine motor movements than legs or torso
What techniques might you use to understand the motor cortex?
Brain injury
Neuroimagery
Non-invasive stimulation such as TMS - targeting the upper reaches will get twitches in the feet, etc.
The dorsal lateral pre-frontal cortex (DLPFC) is involved in what types of cognitive functions?
Executive functions: Cognitive processes Problem solving Holding items in working memory Deep thoughts Engaging in rules Future planning Inhibiting inappropriate responses E.g. Planning a dinner party, sitting an exam
Where is the somatosensory cortex?
Top middle/back
What does the somatosensory cortex do?
How do we know?
Perception of touch (pressure, pain, temperature)
Spatial navigation through environment - brain makes a map of our bodies in relation to our environment - avoids interactions with objects like walls and furniture
Penfield and Boldrey (1937)
Operations on patients with serious issues - electrical stimulation of parts of the cortex - patients would report different sensations in different parts of their bodies
How is the somatosensory cortex comparable to the motor cortex?
Also organised in a hierarchical manner:
Legs, torso, and feet represented higher
Hands, face, and neck represented lower down
Larger area associated with hands and face
What does the parietal lobe do?
Processing of sensory info - touch and limb position
Spatial navigation and awareness
Where does visual information get processed in the brain?
Through the thalamus to the occipital lobe / primary visual cortex
What is cortical blindness?
What makes it different to other forms of blindness?
Patient will be unable to see anything at all
Damage to the occipital lobe rather than anything to do with the eyes
Where does auditory information get processed in the brain?
Auditory cortex / temporal lobes
What’s the name of the brain region involved in face detection?
Fusiform gyrus
Damage to the temporal lobes can cause a few different conditions. Name and describe some of them.
Prosopagnosia
Patients can no longer identify people that they previously knew, sometimes even extending to themselves
Visual agnosia
Inability to name or describe visible objects that were once known
What are the two areas associated with language that are described?
What are they each involved in?
Broca’s area - speech production
Wernicke’s area - speech comprehension
Describe and compare the two types of aphasias discussed.
Broca’s aphasia
Unable to produce articulate speech
E.g. Tan, who could only say the word Tan but could otherwise communicate well with gestures
Wernicke’s aphasia
Can produce speech that is fluent but nonsensical.
May use filler words when they can’t find the right word.
What are some of the problems associated with taking a purely neurobiological approach to understanding the brain?
Description is not explanation
Correlation is not causation
We have a variety of evidence that implicates different areas in certain behaviours, but we don’t know why.
May be a modern expression of phrenology - we may know a particular area of the brain is active during certain activities, but we don’t know how it performs it.
The brain doesn’t perform in isolation - behaviours may be a function of complex, brain-wide networks.
What different types of brain cells are there?
What are they called and what do they do?
Neurons
10-100 billion of them in the nervous system
High level of interconnectivity that allows cognitions and behaviours to arise
Communication and processing of information in the nervous system
Glial cells
Different types with different functions
Provide nutrients to neurons and structural support to the nervous system.
What different functions do neurons have?
Sensory neurons
Transmit info from sensory receptors to the brain for processing
Motor neurons
Transmit instructions from the brain to muscles and organs in the body
Can be very long
Interneurons
Transmit info between neurons in the brain
What does the Axon do?
What covers the Axon?
What is it there for?
Carries nerve impulses away from the cell
Transmits electrical signals to the terminal buttons which then transmit across the synapse to the dendrites of the next cell.
Myelin sheath
Allows electrical impules to transmit quickly and efficiently along the cell - protects the impulse from degrading
Where do neurons interact with each other? I.e. What are the relevant parts of the neurons? What is the junction called?
Synapses
Site of transmission of electric nerve impulses between two cells
What are the four types of neuron? Where might you find each other them?
Unipolar neuron
One projectoin from the cell body which can be either a dendrite or an axon, depending on its function
Bipolar neuron
Important role in visual system
Multi-polar neurons
Most common type of neuron in the brain
Pseudo-unipolar neuron
Has only one projection from the cell body, but comprises both dendrites and an axon
Commonly observed as long sensory and motor neurons traversing the length of the body
What is grey matter made up of?
Cell bodies and dendrites of neurons
Where information processing occurs
Located on the outside of the brain
Some large areas deep in the brain