Brain and Behaviour Flashcards
What is the cortex made of?
Grey matter
What is the goal of Cognitive Neuroscience?
To determine the relationship between the physiology of the brain and the functions of the mind
Want to figure out how the brain learns language, acquires knowledge, forms memories and other cognitive activities
What does grey matter contain?
Cell bodies of the neurons / nerve cells
What is white matter?
Axons of the nerve cells
Why is the brain folded?
To increase the cortical surface area in a smaller volume
What does the corpus callosum do?
Connects the two hemispheres of the brain together
What are the major lobes of brain named after?
The skull bones that they lie beneath
What is the cortex (the outer layer of the brain) made of?
Cell bodies and dendrites of individual neurons
What does the central sulcus do?
Separates the anterior part of the brain from the posterior part of the brain
What is a lesion?
Refers to any damage to the brain
What happens if the brain does not receive any blood / oxygen?
The brain tissue dies
What is Hemifield neglect?
When a person suffers damage to one side of the brain, a deficit in attention and awareness of one side in space is seen
Aphasia - Broca’s area
can understand language BUT cannot produce language, have difficulties speaking
Aphasia - Wernicke’s area
can speak fluently BUT do not make any sense
What is the Cortical Homunculus?
A pictorial representation of the anatomical divisions of the primary motor cortex and primary somatosensory cortex
ie - the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body
What the two groups of brain imaging techniques?
Structural and Functional
What do structural brain imaging techniques tell us about?
The brain’s composition
What do functional brain imaging techniques tell us about?
How the brain processes events
What are the further categories of functional brain imaging?
Electrical activity and blood flow
What does structure mean with regards to the brain?
The form of the brain - it’s composition and interrelated parts
What does function mean in relation to the brain?
The actions of the brain - what a particular part does and how it works
What does CT stand for?
Computerised Tomography
What does a CT scan do?
- transmits x-rays through the brain
- different brain tissues have different densities therefore they show up differently on the x-ray
What does MRI stand for?
Magnetic Resonance Imaging
What type of brain imaging technique is a CT scan?
Structural
What type of brain imaging technique is a MRI?
Structural
What does a MRI do?
- uses a magnet to align the protons in brain tissue
- the alignment is interrupted frequently by brief radio wave pulses
- different brain tissues are made up of different elements with different numbers of protons which all have different densities meaning they take different times to realign due to the differing densities
- this differential timing of realignment is transformed into an image
What are the advantages of an MRI?
- produce very detailed and accurate images of the brain
- can see damaged brain tissue very clearly
What are issues with both PET and MRI?
- not good for recording everyday activities
- this means we need to recorded the electrical potentials or blood flow in the brain
What does EEG and ERP stand for?
Electroencephalogram
Event Related Potentials
What type of brain imaging technique are EEG’s & ERP’s?
Functional - Electrical
What does an EEG do?
- measures the electrical potentials generated by the brain
- does this by attaching electrodes to the surface of the scalp
- large number of electrodes used to cover the surface area of the scalp
- can locate the source of the electrical activity
What is an ERP?
An average of electrical activity over a numerous amount of trials
What are the advantages of an EEG?
Measures events in real time (100 milliseconds)
What are the disadvantages of an EEG?
- cannot map the electrical activity in the actual brain
- the activity picked up may be located deep within the brain
- do not know in terms of spatial location where that activity is coming from within the brain due to its high levels of folding
What does MEG stand for?
Magnetoencephalogram
What type of brain imaging technique is MEG?
Functional - Electrical
What is an MEG and what does it do?
- whole helmet of magnetic sensors essentially
- still measures electrical activity but measures the magnetic fields created by the electrical activity of the brain
- powerful detectors record the magnetic fields produced
What are the advantages of a MEG?
- magnetic fields are not deflected by the skull or brain which means you can detect which part of the brain it is coming from
- this is unlike electrical activity which is deflected by various parts of the brain
What are the disadvantages of a MEG?
- problems with detecting deep sources of magnetic fields
- more accurate for recording cortical activity
What does TMS stand for?
Transcranial Magnetic Stimulation
Describe TMS
- a coil where a magnetic field is simulated producing a pulse
- if you give a strong sustained stimulation - wearing out a bit of cortex so you are basically simulating a brain lesion
- milder simulations - excitation or facilitation effects which are used by psychologists for experiments
What does FUNCTIONAL blood flow allow us to do?
- if you can track where the blood or oxygen is going, you can track the more active sites of the brain
- blood and oxygen flow more to the areas of the brain which are more active
What does PET stand for?
Positron Emission Tomography
What type of brain imaging technique is a PET scan?
Functional - blood flow
What is a PET scan?
- when radioactive water is injected into a subject which contains positrons
- the radioactive positrons follow the blood flowing to active areas of the brain
- the positrons set off detectors that measure their position which shows up on the image
- look at different slices of the brain so you can look at differences in blood flow whilst completing different tasks
What are the advantages of a PET scan?
They have a fairly good spatial resolution of 1 cm of brain space
What are the disadvantages of PET scans?
- no time resolution
- health issues with introducing radioactivity into a person
What does fMRI stand for?
function Magnetic Resonance Imaging
What does an fMRI do?
- measures the position of the blood with high or low levels oxygen
- blood carries oxygen which has magnetic properties therefore the magnet measures the position of blood with high/low levels of oxygen
What are the advantages of fMRI?
Very good spatial resolution of 2mm
What are the disadvantages of fMRI’s?
- issues with measuring blood flow as it is a metabolic consequence
- does have a better time resolution than a PET scan of about 1 to 2 seconds, but still 1 second counts for a lot in psychology
What is the nervous system?
The body’s control centre
What is the Peripheral Nervous System?
- contains all the neural structures that lie outside the brain and spinal cord
- branches out from the spinal cord & brain to reach the extremities of the body
What are the two major divisions of the Peripheral Nervous System?
The Somatic Nervous System and the Autonomic Nervous System
What is the Somatic Nervous System?
A system of sensory and motor neurons which allow us to sense and respond to our environment
What do sensory neurons do?
Carry messages from our sense to the central nervous system
What do motor neurons do?
Carry messages from the brain & spinal cord to the muscles that control our voluntary movements
What is the Autonomic Nervous System?
A system that senses the body’s internal functions and controls many glands and muscles
What are the 2 divisions of the Autonomic Nervous System?
Sympathetic and Parasympathetic
What does the sympathetic part of the autonomic nervous system do?
Activation or arousal (fight or flight)
What does the parasympathetic part of the autonomic nervous system do?
- Slows down body processes
- Maintains a state of tranquility
What do both parts (sympathetic and parasympathetic) of the autonomic nervous system achieve?
Homeostasis - a delicately balanced or steady internal state
What does the Central Nervous system contain?
The brain and the spinal cord
What does the spinal cord do?
Connects most parts of the peripheral nervous system with the brain
What is the spinal cord made of and what does it do?
Densely packed bundle of nerve fibres
Transmits messages from sensory and motor neurons between the brain and the rest of the body
What side of the spinal cord do sensory neurons connect to?
The back of the spinal cord
What side of the spinal cord do motor neurons connect to?
The front of the spinal cord
Describe a basic spinal reflex
- touch something hot - sensory receptors in skin trigger nerve impulses in sensory nerves
- these impulses enter the back of the spinal cords and synapse with Interneurons
- these Interneurons excite motor neurons that send impulses to your hand so that it pulls away
What are the 3 major subdivisions of the brain?
1) the Hindbrain
2) the Midbrain
3) the Forebrain
What does the Hindbrain do?
Co-ordinaries movement into action
Which features are in the hindbrain?
Brainstem, Cerebellum, Medulla & Pons
What does the Brainstem do?
Regulates functions such as heart rate, breathing & swallowing
Consists of the Pons and Medulla
What do the Pons do & what are they involved in?
- carry nerve impulses between higher & lower levels of the nervous system
- involved in sleep & arousal
What does the Medulla do and what is is involved in?
- plays an important role in body functions such as heart rate & respiration
- involved in breathing & circulation
What does the Cerebellum do & what is it involved in?
- concerned primarily with muscular movement, co-ordination and aids motor memory
- involved in fine muscle movement & balance
- regulates movements requiring precise timing
- also plays a role in learning & memory
- easily disrupted by alcohol
What does the Midbrain consist of?
Clusters of sensory & motor neurons
What structure does the Midbrain contain?
Reticular Formation
What does the Reticular Formation do & what is it involved in?
- alerts higher centres of the brain that messages are coming
- then it either blocks or allows these messages
- plays a central role in consciousness, sleep and attention
What does the Forebrain contain?
Cerebrum, Thalamus, Hypothalmus & the Limbic System
What is the Cerebrum & what is it involved in?
- major structure of the forebrain
- consists of 2 large hemispheres that wrap around the brain stem
- involved in sensing, learning, emotion, consciousness and voluntary movement
What is the Thalamus and what is it involved with?
- like a switchboard - organises inputs from sensory organs and routes them to the appropriate areas of the brain
- basically a relay centre for incoming sensory information
Give an example of disrupted functioning in the Thalamus
Schizophrenia
- garbled sensory information gets passed around
What is the Hypothalamus and what is it involved with?
- plays a major role in motivation & emotion
- control hormonal secretions that regulate sexual behaviour, metabolism, reactions to stress and to pleasure/pain
- also regulates basic biological needs such as hunger, thirst, sleep, temperature
- contains the Suprachiasmat Nucleus (SCN) which regulates circadian sleep & wake cycles
What does the Limbic System do?
- helps co-ordinate behaviours needed to satisfy motivational and emotional urges that arise in the hypothalamus
AKA controls emotion and motivation
What structures are within the Limbic System?
Hippocampus and Amygdala
What does the Hippocampus do?
Involved in learning and memory
Specifically with the forming and retrieving of memories
What does the Amygdala do?
Involved in emotion & aggression
Organises motivational and emotional response patterns such as aggression and fear
What is the Cerebral Cortex?
- sheet of grey, in myelinated cells that form the outermost layer of the brain
- has fissures (folds) - this increases the surface area of the brain in the small volume of the skull
What do the fissures in the Cerebral Cortex do?
Split the brain into four lobes
Name the four lobes of the brain
Frontal, Parietal, Occipital and Temporal
What does the Motor Cortex do?
Controls the 600 or more muscles involved in voluntary body movements
Why is it that if a person’s right motor cortex is damaged, they are paralysed on the left side of the body?
Because the nerve tracts from the motor cortex cross over at the level of Medulla
This means each hemisphere governs movement for the opposite side of the body
What is the Somatic Sensory Cortex?
- receives sensory input that gives rise to our sensations of heat, touch, cold and to our senses of balance and body movement
- each side of the body sends sensory input to the opposite hemisphere of the brain
- the amount of cortex devoted to each body area is directly proportional to that region’s sensory sensitivity
Eg nose, ears, tongue etc have a larger amount of cortex compared to the back or feet
What is Wernicke’s area involved with?
Speech comprehension
What is Broca’s area involved with?
Mainly the production of speech
Also connected with the motor cortex region that controls the muscles used in speech
Define Aphasia
A disorder of language produced by lesions in certain areas of the cortex
Describe Broca’s aphasia
Organisation of speech suffers
Ideas are all there
Fluency suffers - can’t form a complete, flowing and coherent sentence
Describe Wernicke’s aphasia
Fluency of speech is in tact - flowing sentences
Ability to speak meaningful words is gone - made up words
What does studying patients with brain damage allow us to do?
Investigate what areas of the cortex are involved with
What is an Apraxia?
Disorder in action
What are Agnosia’s?
Disorders of perception
What functions does is left hemisphere of the brain associated with?
Language, logic, critical thinking, numbers, reasoning
What functions is the right hemisphere of the brain associated with?
Creativity, intuition, recognition of faces, expression of emotions, music, colour, images
What connects the two hemisphere of the brain?
The corpus callosum
What is the corpus callosum made up of?
A broad white band of myelinated nerve fibres
What is the Association Cortex involved with?
Many important mental functions such as perception, language and thought
Involved in higher mental processes - defines us as humans essentially
What happens if the Association Cortex is damaged?
In specific parts, disruption or loss of functions such as speech, understanding, thinking and problem solving can occur
Define Agnosia
The inability to identify familiar objects
What does the Parietal Lobe do?
Organises visual and auditory space
Tells us where things are in space
Detects moving objects in space
Organises which part of space we pay attention to
Damage here = neglect symptoms
Define neglect syndromes
The result of certain lesions of the right parietal lobe that leaves a patient in attentive to stimuli on the left causing them to ignore the left side of their body
Describe the Temporal Lobe
- lobe of the cortex lying below the temples in each cerebral hemisphere
- includes the primary auditory projection area, Wernicke’s area and (subcoritcally) the amygdala & hippocampus
What can damage to the Temporal Lobe result in
Disturbances of visual and auditory perception
Impaired organisation & categorisation of verbal material
Disturbance of language comprehension
Impaired long-term memory
Right side lesions can also effect recognition of visual content for example, recall of faces
Describe the Frontal Lobe
29% of the human brain, least understood part
Involved in emotional experience
Damage can result in the loss of intellectual abilities such as planning and carrying out action sequences
Describe the Prefrontal Cortex
The seat of executive functions
Define executive functions
Mental abilities that allow people to direct their behaviour in an adaptive fashion
Eg goal setting, judgement, strategic planning, impulse control
Damage = inability to understand & anticipate future consequences
What is a lobotomy?
Neurosurgical treatment which surgically cuts the connections between the prefrontal areas of the frontal lobes and the rest of the brain
What are Neurons & date their three main parts
Basic blocks of the nervous system
Soma = cell body
Dendrites = specialised receiving units that collect messages from neighbouring neurons & send them onto the cell body
Axon = conducts electrical impulses away from the cell body to other neurons, muscles or glands
What are Glial cells?
Cells in the brain acting as guard wires for growing neurons
Provide a supportive scaffolding for mature neurons
Form the myelin sheath and blood-brain barrier
What does the blood brain barrier do?
Protects the brain from noxious substances & some drugs
What are Nodes of Ranvier?
Gaps between the glial-cell wrappers that form the myelin sheath round axons
Crucial to the speed of the neural impulses going along the myelinated axons
What is a synapse?
The juncture of 2 neurons
Consists of the presynaptic and post synaptic membrans as well as the synaptic cleft between them
How can drugs affect synapses?
1) mimic the effect of the neurotransmitter (agonist)
2) influence the release of the neurotransmitter from vesicles
3) block re-uptake of the neurotransmitter from the synapse
4) block receptors in the post synaptic membrane (antagonist)
5) produce more or less of the neurotransmitter
6) prevent vesicles from releasing the neurotransmitter
