Cognitive Neuroscience Flashcards
What is cognitive neuroscience
The scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes
It addresses the questions of how psychological/cognitive functions are produced by neural circuits in the brain
Studying how the brain controls our different cognitive abilities (memory, language etc)
Why can the brain block out environment
To get done tasks that are important in the moment
How can we see what functions patients with brain damage (Alzheimer’s etc) can still perform
By studying the brain
What must happen so the brain can understand information processed in our environment
- the brain cannot understand all the information processed in our environment e.g light waves/sound waves
- they need to be converted into electrochemical signals that the brain can understand
Photoreceptors in the eye
- the back of the eye has photoreceptors
- these are the cells that will convert the light energy into an electrochemical signal
- these electrochemical signals are sent to the brain
- all photoreceptors have axons
Fovea
- highest number of photoreceptors
- vision is the most accurate
Optic nerve
- axons from photoreceptor cells leave the eye
- no photoreceptor cells in optic nerve: essentially blind in this area
Does everyone have blind spots in their eye
Yes however you are unaware as your brain is clever enough to fill in that information
Somatosensory Cortex
- in the brain there is a right and left somatosensory cortex
- this is the brain area that receives information about sensation (pain on the body part, something touching you)
Left part of body-> send signal to right
somatosensory cortex
Right side of body-> send signal to left
somatosensory cortex
How are body parts mapped on the brain
- very differently to on the body e.g eye and nose are close together
- different body parts have a larger cortex- size of brain area associated to a body part does not necessarily relate to size of body part in real life
- more cortex allocated for body part= more sensitive e.g face, lips
Why should neuroscience matter to psychologists
- humans (and animals) are biological system
- the basic assumption of all modern neuroscience and psychology: mental functions are the product of activity in the nervous system
The nervous system
- receives sensory information from the environment
- integrates and processes information (converts into electrochemical signals)
- regulates internal functions
- produces motor actions in response to environment
How can healthy brain be affected
- e.g alcohol affected- will make the brain not work as efficiently
Living beings: Levels of observation
- Body
- Systems - forms overall body
- Organs - make up systems e.g central nervous system
- Tissues- lots of different tissue can make up an organ
- Cells- bundle of cells make up tissues
- Genes- stored within cells
Cell communication
If communication is disrupted between cells or they die, this can have affects on behaviour
The living cell
- membrane (structure): semi-permeable, can let something in & out, protects cell
- nucleus
- nucleolus: contains chromosomes- DNA
- mitochondria: converts nutrients into ATP for chemical energy, cell requires this to perform certain functions
- channels (made of proteins): exchange materials e.g nutrients
- other proteins: specialised functions of cell, other proteins in them
Cells of nervous system
1) neurons:
do much of communication within nervous system
2) glia cells:
have support roles, 10X as much glia cells as neurons
- type of glia cell is Schwann cell- insulates cell to ensure signal along the cell happens quickly and is not lost
Neurons structure
- dendrites (at top)
- axon hillock
- Schwann cells
- nucleus
- cell body (soma)
- axon
- axon terminal
- nodes of Ranvier
- look slightly different depending where they’re from
Neurogenesis
- new neurons can be formed from neural stem cells (embryonic stem cells)
- this happens in some (not all) parts of the brain e.g denate gyrus in hippocampus
- can be facilitated by environment and mental stimulation e.g learning of new information
The neuron: an excitable cell
- may differ depending which area of brain they are in
- essentially have very similar structure
Nucleus within neurons
- contains all DNA for that cell
Dendrites within neurons
- look like tree branches, important for receiving incoming signals from neighbouring cells
- important for input into cell
Axon within neurons
- takes signal away from the cell (cells tend to have one axon) signal will travel down axon to terminal buttons at end and send signal to neighbouring cell
Axon hillock within neurons
Cell body connects to axon where cell decided if it will fire it not
Schwann cells
Glia cells which form the Myelin Sheath, insulates axon so signal doesn’t get lost and is quick
Nodes of Ranvier
- little gaps in axon, Bayern the myelin sheath
- electrical impulse travelling along the cell, jump over these gaps= quickens the transmission of signal across the cell
= called SALATORY CONDUCTION
Axon terminal
Has axon buttons at the end
Santiago Roman allowed us to understand anout tiny gap between axon terminals of one cell and dendrites of another
- 2 cells are not touching, tiny gap called synapse, signal crosses synapse
When dendrites of a cell receive lots of stimulation from other cells
Cell will decide if they need to fire -> send electrical impulse down axon-> down to synapse
What happens when electrical impulse gets to synapse
- electrical impulse cannot jump across synapse
- chemical signal must be used at synapse
Order of events when receiving electrical signal to send to brain
- Spatial summation - electrical signals fired due to stimulation
- Action potential - electrical signal across axon
- Neurotransmitter release - chemical signal released as neurotransmitters and attach to receptors in postsynaptic terminal
The action potential electricity and chemistry stage
Electricity:
1) most single atoms have an electric charge (+ or -) charged atoms are called ions
2) an overall difference in charge between nearby areas creates an electric potential (aka voltage)
Chemistry:
3) diffusion: particles diffuse to equate concentrations across space
Multiple sclerosis
Autoimmune disease- ones own immune system damages the myelin sheath
Types of neuron
- cerebellum (purkinie cell)
- hippocampus (pyramidal fell)
- Retina (bipolar cell)
Motor neuron disease
A family of diseases in which motor neurons degenerate and die
Communication between neurons
is the process by which one neuron communicates with another
Presunaptic cell becomes postsynaptic cell
Neurotransmitters
- glutamate
- GABA (y-aminobutync-acid)
- acetylcholine (Ach)
- dopamine
- serotonin (5-HT)
- norephinephrine (NE, aka noradrenaline)
Neurotransmitter- glutamate (Glu)
Function:
- the most common excitatory neurotransmitter in the brain
- important for learning and memory
What can go wrong:
- too much -> over-excitation -> seizures, migraines
- role in Obsessive- compulsive disorder (OCD)
Neurotransmitter - GABA (y- aminobutync-acid)
Function:
- the most common inhibitory neurotransmitter in the brain
- counteracts the effects of glutamate
- regulates and prevents over-excitation
What can go wrong:
- GABA deficiency ->
- seizures, tremors, insomnia
- increased responsiveness t stress -> increased risk of anxiety disorder and phobias
Neurotransmitter - Acetylcholine (ACh)
Function:
- regulates motor control:
- excitatory in synapses between
neurons and skeletal muscles
- inhibitory in synapses between neurons and
the heart
- also important in attention, learning, memory, arousal
What can go wrong:
- role in depression
- Alzheimer’s disease- associated with degeneration of cholinerhic neurons
Alzheimer’s disease
- the most common form of dementia
- definitive diagnosis- only post- mortem
- symptoms - impairments to: • memory • language • reasoning • orientation • judgement
Neurotransmitter - dopamine
Function: - plays an important role in: • movement • motivation/reward, pleasure, arousal - tied to addiction
What can go wrong:
- too much -> linked to schizophrenia
- not enough -> tremors, difficulty initiating and stopping movement (typical of Parkinson’s disease)
Parkinson’s disease
- results from degeneration of dopamine producing brain cells
- primary symptoms:
• tremor in hands, arms, legs, jaw and face
• difficulty initiating AND stopping movements
• rigidity or stiffness if limbs and trunk
• slow movement
• impaired balance
Neurotransmitter - seratonin (5-HT)
Function:
- regulates mood, appetite, sleep
- involved in arousal and aggression
- involves in cognitive functions- learning & memory
Neurotransmitter - Norephinephrine (NE, aka noradrenaline)
Function:
- regulates mood, arousal e.g vigilance to danger
What can go wrong:
- not enough-> mood disorders e.g depression
Drug types and the synapse
- Agonists:
Mimic or increase the effect of a neurotransmitter - Antagonists:
Block or decrease the effect of a neurotransmitter
Different agonists
- block reuptake (blocks cell from reabsorbing substance therefore increasing amount in brain)
examples: Prozac (SSRI) and cocaine (blocks dopamine, norephinephrine & seratotin reuptake) - increase neurotransmitter release
examples: amphetamines (stimulate release of dopamine and norepinephrine) - increase production of neurotransmitter
examples: L-dopa (precursor of dopamine, used for Parkinson’s) - binds and activate post-synaptic receptors
examples: nicotine (activated Ach receptors
Cannabis (activates CB1 cannabinoid
receptor- anandamide)
Different antagonists
- bind to post-synaptic receptor and block it
example: Haloperidol (prevents dopamine from activating receptors by blocking them; used to treat Schizophrenia) - prevent release if neurotransmitter:
example: Botulinum Toxin (prevents Ach vesicles from fusing with membrane)
Nervous system
An interacting network of neurons that conveys electrochemical information throughout the body
Central nervous system
The part of the nervous system that is composed of the brain and spinal cord
Peripheral nervous system (pns)
The part of the nervous system that convey the central nervous system to the body’s organs and muscles
Somatic nervous system
A set of nerves that convey information into and out of the central nervous system
Organisation of nervous system
Nervous system
⬇️ ⬇️
Peripheral CNS
⬇️ ⬇️ Autonomic Somatic (controls voluntary (controls self movements of skeletal regulated muscle) action of internal organs and glands)
⬇️ ⬇️
Sympathetic Parasympathetic
(arousing) (calming)
Autonomic nervous system - sympathetic and parasympathetic
- a set of nerves that carry involuntary and automatic commands
- controls and regulates blood vessels, organs (including the heart) and glands
Sympathetic nervous system:
- set of nerves that prepare body for action in threatening situations
- increases arousal
- for Fs: fight, flight, feed, mate
Parasympathetic nervous system:
- set of nerves that help body return to normal resting state
- reduces arousal
How do the two systems sympathetic and parasympathetic act (subsystems of autonomic nervous system)
In a coordinated manner of eachother
They complement eachother
Polygraph machine and it’s issues
- measures arousal
- they assess the autonomic systems activity
- measures: blood pressure, heart and breathing rates, skin conductance
Issue:
- some people have high arousal threshold (psychopaths)
Spinal reflexes
Simple pathways in the nervous system that rapidly generate muscle contractions
Regions of spinal cord
- 4 main sections
- each controls different parts of the body
- damage higher up spinal cord usually portends greater impairment.
- contain dorsal horn and ventral horn
What is in grey and white matter within the spinal cord
- grey matter: cell bodies
- white matter: Myelinated axons
Major divisions of the brain
- The brain can be organised into 3 main parts
- moving from the bottom to the top, from simpler functions to more complex: the hindbrain, the midbrain and the forebrain
Hindbrain
- phylogenetically ancient
- coordinates information flow to/ from the spinal cord
- controls basic functions of life
- includes the medulla, reticular formation, the cerebellum and pons
Medulla - within hindbrain
- extension of the spinal cord into the skull
- controls:
- Heart rate
- Circulation
- Respiration
Reticular information - within hindbrain
- brain structure that regulates:
- Sleep/ wakefulness
- Level of arousal
Cerebellum - within hindbrain
- a large structure of hindbrain that controls fine motor skills/activity
- doesn’t initiate movements but refined and smooths them
Pons- within hindbrain
- brain structure that relays information from the cerebellum to the rest of the brain
Midbrain
- coordinates basic functions related to perception and action
- important for orientation and movement
- includes structures such as the tectum and tegmentum
Tectum (dorsal) - within midbrain
- part of midbrain that orients an organism in the environment
- superior colliculi- vision
- inferior colliculi - audition
Tegmentum (ventral) - within midbrain
- part of the midbrain involved in movement and arousal
- pleasure seeking
- substantia nigra
• high level of dopamine gives it dark colour
• pale colour in Parkinson’s disease
Dorsal and ventral
refer to back (dorsal)
front or belly (ventral) of an organism.
Forebrain
- highest level of the brain
- critical for complex cognitive, emotional, sensory and motor functions
- divided our into 2 parts:
- Cerebral cortex
- Underlying subcortical structures;
thalamus, hypothalamus, pituitary gland,
amygdala and hippocampus
- corpus callosum connects the two hemispheres of the brain
Basal ganglia within forebrain
- set of subcortical structures
- Plan initiation of intentional movements
Thalamus- within forebrain
- subcortical structure
- relates and filters information from the senses and transmits to cerebral cortex
Hypothalamus - within forebrain
- subcortical structure
- regulates internal body functions; temperature, hunger, thirst and sexual behaviour
Pituitary gland - within forebrain
- ‘master gland’ of body’s hormone producing system
- regulates hormones
Hippocampus - within forebrain
- creates and integrates new memories into a network of knowledge
- (not long term storage)
Sub- cortical structures - within forebrain
- areas of the forebrain housed under the cerebral cortex near the very centre of the brain
- thalamus, hypothalamus, pituitary gland, amygdala and hippocampus
Amygdala - within forebrain
- part of limbic system
- located at tip of each horn of the hippocampus
- central role in emotional processing and memory, particularly fear
Limbic system
- group of forebrain structures:
- hippocampus, amygdala and hypothalamus
Cerebral cortex and lobes
- 4 major lobes of the cerebral cortex are the occipital love, parietal lobe, temporal lobe, frontal lobe
Corpus collosum
- thick band of nerve fibres
- connects large areas of cerebral cortex in each side of brain
- supports communication of information across the hemispheres
Occipital lobe
- region of cerebral cortex whose functions include processing informations about touch
Somatosensory cortex
- outermost layer of the parietal lobe area
- containing a representation of the body map
Left and right hemisphere within cortex
- both sides work together
- left- sequences right- spatial arrangement
Neuropsychology (lesion methods)
- investigating brain- behaviour relationships by studying the effects of localised brain damage (can be acquired by head injury, stroke)
Brocas aphasia
- effortful speech
- short, ungrammatical phrases
Mirror neurons
- cells that are active when performing an action oneself or when observing the same action performed by another
Temporal lobe
- a region of the cerebral cortex responsible for hearing and language
- semantic knowledge
Frontal lobe
- region of the cerebral cortex that has specialised areas for movement, abstract thinking, planning, memory and judgement
Association areas
- areas of the cerebral cortex
- composed of neurons that help provide sense and meaning to information registered in the cortex
Primary visual cortex
- outermost layer of the occipital lobe area
- visual information is processed
Primary auditory cortex
- outermost layer of the temporal lobe
- where auditory information is processed
How can a person acquire brain damage
- traumatic head injury
- stroke (haemorrhage)
- neurodegenerative disorders (Parkinson’s, Alzheimer’s)
- viral infection (HIV)
Frontal lobotomy
- moniz develops as treatment for mental illness
- destroys frontal lobes or damages connections to limbic system
Gene and chromosomes
Gene- the unit of hereditary information transmission
Chromosomes- strands of DNA wound around each other in a double- helix configuration (every cell has 23 pairs)
Epigenetics
The mechanisms of interaction between the environment and genes
Genetic methylation
- a mechanism that silences a gene and is believed to play a major role in long-term changes that shape our development
Heritability
- a measure of the variability of behavioural traits among individuals that can be accounted for by genetic factors
Electroencephalogram (EEG)
A device used to record electrical activity in the brain
Computerised axial tomography
- a technique that combines multiple X-ray photographs into a single image
Magnetic reasonable imaging (MRI)
- a technique that uses a powerful magnet to cause charged molecules in soft tissue to realign to produce measureable field distortions
Position emission tomography (PET)
- a technique that uses radioactive markers to measure blood flow in the brain
Functional magnetic resonance imaging (fMRI)
- a technique that uses a powerful magnet to cause haemoglobin molecules to realign to measure blood flow in the brain
