Week 2 - Structure of the brain Flashcards
Negative feedback loops in which part/s of the brain ensure that cortisol levels do not rise indefinitely?
- Hypothalamus
- Pituitary gland
What is the enteric nervous system?
An internal network of neurons within the gut which can work independently and in concert with the brain
What is the ‘gut-brain axis’?
Bidirectional communication between the brain and the GI tract involving the immune system, neurons and the endocrine system
How is the enteric nervous system different from the other parts of the peripheral nervous system?
There are some reflexes that operate entirely in the gut without any input from the CNS
At the simplest level, what are the three main parts of the brain?
- Cerebrum
- Cerebellum
- Brain stem
What regions are in the cerebrum?
- Cerebral cortex
- Subcortical regions
How big is the cerebrum?
It is the largest part of the brain
Where is the cerebellum located?
In the back of, and below, the cerebrum
What is the cerebellum associated with?
- Control of balance
- Movement
Under what is the brain stem located?
Below the cerebrum
What is the brain stem responsible for?
Control of involuntary processes such as heart rate and breathing
What is the structure that covers the cerebrum?
The cerebral cortex
What are the four lobes of the cerebrum?
- Frontal lobe
- Occipital lobe
- Parietal lobe
- Temportal lobe
What is the role of the frontal lobe?
- Controlling movement and language
- Higher cognitive skills such as reasoning and planning
What is the role of the parietal lobe?
- Processing information about touch
- Spatial awareness
What is the role of the temporal lobe?
- Processing auditory information
- Speech
- Memory
What is the role of the occipital lobe?
- Processing visual information
What is the name of the ridges found in the outer layer of the brain?
Gyri
What is the name of the grooves found in the outer layer of the brain?
Sulci
What is the prefrontal cortex?
A subdivision of the frontal lobe
What is the prefrontal cortex responsible for?
- Executive function
- Planning complex behaviour
- Decision-making
- Moderating behaviour
What is the orbitofrontal cortex?
A subregion of the prefrontal cortex
What is the purpose of the orbitofrontal cortex?
It is involved in reward and emotions
What does the pituitary gland do?
- Releases certain hormones into the blood
- Responds to signals from the brain
How (directionally) is the top of the brain described?
In the dorsal, or superior, direction
How (directionally) is the lower part of the brain described?
The ventral, or inferior, direction
Where is the cerebellum located?
Towards the posterior of the brain, at the lowest point, spanning both hemispheres
In which region of the brain would you find the brain stem?
The ventral region
Where in the brain would you find the parietal lobe?
At the top and back, spanning both hemispheres
Where in the brain would you find the occipital lobe?
At the back, roughly mid-height, spanning both hemispheres
Where in the brain would you find the ooccipital lobe?
Low on the side on each hemisphere
Where in the brain is the prefrontal cortex?
The anterior region of the frontal lobe - the very front/topmost, spanning both hemispheres
Where would you find the motor cortex?
Just behind the prefrontal cortex, on both hemispheres
Where is the primary somatosensory cortex?
It is part of the occipital lobe, spanning both hemispheres at the back of the brain
What is the type of cut which divides the two hemispheres of the brain?
A sagittal cut
What is the singulate cortex responsible for?
- Emotions
- Resolving conflicts
- Deciding a course of action
What is the corpus callosum?
A large bundle of myelinated neurons which connects the two hemispheres
How many ventricles does the brain have?
4r
What is the hippocampus responsible for?
- Organisation/retrieval of memories
- Spatial learning tasks
- Navigation
What is the amygdala involved with?
- Behaviour
- Emotions
- Retrieval of unpleasant memories
What is the hypothalamus responsible for?
- Control of emotional reactions
- Eating
- Drinking
- Connects with pituitary gland to trigger hormonal secretions to emotions
The brain stem consists of which areas?
- Midbrain
- Pons
- Medulla
What is the ventral tegmental area?
An area within the midbrain involved in addictions and rewards
What is the ventral tegmental area responsible for:
- Addiction
- Rewards
What do the pons play roles in?
- Control of arousal
- Waking
- Sleep
What subconscious processes does the medulla control?
- Breathing
- Digestion
- Control of heart rate
- Blood vessel function
What is cerebrospinal fluid (CSF)?
Fluid which surrounds the brain and spinal cord.
It provides cushioning and buoyancy, protects against trauma, removes waste products
What is the function of the nucleus accumbens?
It is an area which receives input from dopaminergic neurons in the ventral tegmental area
What is the nucleus accumbens important for?
- Motivation
- Addictions
What are the types of cells which form the blood-brain barrier?
- Astrocytes
- Pericytes
- Endothelial cells
What class of cells do astrocytes belong to?
Glial cells
What is the main function of astrocytes?
To support the environment of the brain
What is the function of pericytes within the blood-brain barrier?
- Control brain blood flow
- Maintain blood-brain barrier
What types of substances may move across the blood-brain barrier?
- Fat-soluble molecules such as oxygen and CO2
- Glucose
- Amino acids
What types of substances are not able to pass across the blood-brain barrier?
- Pathogens
- Some drugs
Which feature of the blood-brain barrier ensures that bacteria and viruses are unable to cross from blood vessels to the brain tissue?
The tight junctions between endothelial cells in the blood vessels
What is the neurovascular unit?
The cells of the brain that help regulate the brain’s blood supply
Which are the types of cells that make up the neurovascular unit?
- Neurons
- Astrocytes
- Pericytes
- Microglial cells
- Endothelial cells
What is one of the key functions of astrocytes?
To detect activity in neurons and alter dilation of local blood vessels accordingly
What are the four ventricles of the brain?
- Two lateral ventricles
- Third ventricle
- Fourth ventricle
What is the choroid plexus?
A region of the ventricles that produces CSF via filtration of the blood
How is CSF described?
As an ultra-filtrate of blood plasma
What electrolytes does CSF contain?
- Sodium ions
- Chloride ions
- Bicarbonate ions
What is the lymbic system?
A group of structures which are involved with memory, emotion and arousal
What are the structures of the lymbic system?
- Hypothalamus
- Hippocampus
- Amygdala
How does an MRI work?
A patient is exposed to a strong magnetic field and then to a radio-frequency wave, which affect the behaviour of nuclei atoms in water molecules
What is the substantia nigra involved in?
- Movement
- Reward
- Addiction
What does an fMRI do?
Registers blood flow to functioning areas of tissue. It highlights brain areas that are active in a specific cognitive task
How does a PET scan work?
Radiolabelled compounds are ingested and can be detected in brain regions where activity is high
What does the ‘PET’ in PET scan stand for?
Positron emission topography
What is spatial resolution?
A measure of the accuracy with which structures or activities can be localised within the brain and distinguished from one another
What is temporal resolution?
A measure of the accuracy of recording changes over time
What is a ‘default mode network’ (DMN)?
A collection of brain regions that are thought to be activated when an individual in in a ‘resting’ state
Which regions are thought to be involved with the DMN (default mode network)?
- Medial prefrontal cortex
- Parietal cortex
- Posterior cingulate cortex
What is the salience network thought to be involved with?
Choosing which aspects of the external environment require the most focus at any given time
What is the central executive network involved with?
Complex, cognitively demanding tasks
What is a correlation coefficient?
A parameter that indicates the strength of a relationship between two variables
How is a correlation coefficient expressed?
- As a number between 1.0 and -1.0
- Denoted by the symbol r (italicised)
What are ‘fibre tracts’?
Bundles of axons that connect one brain region to another
What is white matter?
Parts of the neuronal fibres which are coated in a myelinated sheath
What are the names of the two classifications of fibre tracts within the brain?
- Association fibres
- Commissural fibres
What function do association fibres perform within the brain?
They connect brain regions within the same hemisphere
(e.g. parts of the limbic system to the frontal lobe)
What function do commissural fibres perform within the brain?
They connect regions across the he)
What is the corpus callosum?
A large bundle of fibres which connects the two hemispheres of the brain
What is ‘brain lateralisation’?
The tendency for one side of the brain to be dominant for a particular task
For most people, which side of the brain is dominant for naming objects?
The left side
Which side of the brain is mainly responsible for speech?
The left hemisphere
What is DWI (diffusion weighted magnetic resonance imaging)?
A type of MRI which tracks the direction of movement of water molecules
What can DWI (diffusion weighted MRI) be used for?
Mapping the pathways of fibre tracts
What is a ‘connectome’?
A map of all the the various connections of fibre tracts within the brain
