Intro to cog neuroscience

what is cognition?

neurobiological processing of info, applying knowledge, and changing preferences - to know, conceptualise and recognise - construction of memory, attention, language, perception and motivation - can be natural/artificial, conscious/unconscious

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define neuroscience and what it entails

it uses fMRI, EEG, MEG, TMS - and is known as a bottom-up process (uses electrophysiology to map brain processes)

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define psychology

looks at behaviour and how the mind/brain/external factors influence how we live - top down process

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what is cognitive neuroscience

a sub-discipline within neuroscience and psychology that intersects both psychology and neuroscience - it is the understanding of translating mental processes into physical and outward behaviour

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background on cognitive neuroscientists?

tend to come from psychological backgrounds & studied psychology as a degree - various backgrounds including neurobiology, psychiatry, neurology, physics, computer scientists, linguists etc

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when did cog neuroscience first come about?

originated by a pseudoscience/phrenologist movement in 1948 in a journal - believed could understand which areas of the brain were important in tasks based on feeling scalp/bumps on head (Franz Joseph Gall)

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who was John Jackson?

prolific psychiatrist (clinical observations) - idea of localisation due to epileptic wife who had problems with left side of the body during episodes - suggested a signal starts from a region in the brain and propagates and an area responsible

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who was Oliver Sacks?

inspired by Jackson and found that L-dopa could get people out of a coma-like state suggesting their brain had swelled - led to understanding that brain was divided into lobes which have different actions/functions

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when did the term cognitive neuroscience get created?

in 1980's the interaction between cog scientists and neuroscience was beginning to emerge - Miller and Gazzaniga coined the term cog neuroscience

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what are the main objects of cog neuroscience approach?

to understand how mental processes are generated in the brain: including enhancement of knowledge, clinical applications (disorders), methods in human cognition, and use of various techniques

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what are the various techniques of cog neuroscience?

lesion studies (animal models), EEG, single-unit recording (single electrode to measure neuron response), MEG (magnetic field), PET and SPECT (radioactive dye to look at tissues), TMS (magnetic fields disrupt neurons), fMRI (magnet - active brain)

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what do lesion studies entail?

go into brain and remove brain region to understand its function - knock out brain region A, if can perform then A has no role, lesion region B and if cant do it then it has a role, if not then neither brain region has a role - simple but powerful

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what are the main neuroimaging techniques?

PET, fMRI, EEG, MEG, TMS

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what is PET and fMRI and what main assumptions do they rely on?

used to LOCATE WHERE something happens - 1. determine blood flow to see whether that region is active or not (neurons fire and need energy from blood flow to region) - 2. difference in blood across brain related to difference in neural activations

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how does fMRI work?

£550 per hour - need willing pps - find fMRI scanner - think about what brain areas want to look at (need good control, task, subtract task from control, whatever left in brain area is important for that task)

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give an example of a fMRI task? (eye movements)

studying eye movements - give smooth pursuit movements or saccades and contrast the two - control condition is fixating - A = eye move with fixation + noise, B = fixation + noise - (A-B = eye movement only)

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what is EEG?

measuring WHEN happens, through electrical activity using electrodes - popular, easy, cheap, reliable, good at measuring different types of signals, but noisy - oldest technique alongside single-cell recording - invented by Hans Berger (1920's) -

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how many electrodes and what brain waves do EEG use?

68/128/245 electrodes (more electrodes the greater sensitivity/localisation/accuracy of signals - look at how fast and regular a signal is - delta waves (slowest) .5-4hz (waves per s), theta 4-8hz, alpha 8-13hz, beta 13-30hz, gamma (fastest) 30-42hz

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which waves are unconscious and conscious?

delta (instinct) and theta (emotion) are unconscious -alpha (consciousness), beta (thought) and gamma (will) are conscious

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what 2 things do EEG measure?

1. brain waves - how fast signal is - 2. event related potentials (ERP's) - signal in relation to an event

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how are ERP's measured?

release visual stimulus at time 0 - initially early perceptual info from visual image on occipital cortex - more widespread activity in PFC - familiarity/knowing - recollect specific details in hippocampus - clearly identity and make behav response

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how quick can ERP's happen?

within 1 second

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why is fMRI slower than EEG?

fMRI has to wait for blood to enter area to detect that there is a shift in signal

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what is the main difference between fMRI/PET and EEG's?

fMRI: WHERE (good spatial resolution but poor temporal) - EEG: WHEN (weak spatial resolution but good temporal) - it wouldnt be good to mix the two techniques

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give an example of EEG? (face recognition)

present face for 1 second, repeat - baseline of no face - create averaged response to face - lot of repetitions to make the signal robust (200) then compare faces to objects - comparison between blue line (faces) and red line (objects) - compare ERPs

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what does an MEG measure?

electrical potentials released by brain - by measuring magnetic waves generated by neurons - measured using a SQUID - to detect small magnetic field brain is releasing

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MEG compared to EEG?

it is more accurate - because magnetic waves better indicator of WHERE signal coming from rather than just looking at electrodes - not as commonly used however it costs more, is restrictive of movement, requires expertise, time/money investement

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what is TMS?

transcranial magnetic stimulation - temporally disrupting neurons in brain by sending magnetic pulse (small and localised disrupting only a few temporarily) - if task performance is disrupted can assume these neurons are involved in the task

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difference between TMS and other techniques?

TMS is casual, whereas others are correlational

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what did the Sheffield group in 1958 do?

created first stimulator which first achieved TMS - first pretend to stimulate the brain and then stimulate it - use of sham lesions to get a baseline

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identify the measure, spatial resolution, temporal resolution, and cost of fMRI.

measure: blood brain flow - spatial resolution: +/- 3mm - temporal resolution: 1-2 sec - cost: very high

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identify the measure, spatial resolution, temporal resolution, and cost of EEG.

measure: brain electrical activity - spatial resolution: +/- 10mm - temporal resolution: 1ms - cost: relatively low

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what is optical imaging?

remove scalp and skull - image the brain through sending in light and see how much is reflected back to see how oxygenated the area is - ranges from invasive animal models using probes directly over brain tissue, to non-invasive probes passing light

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what is VBM? (voxel based morphometry) - Bandettini (2009)

comparison of local grey matter concentration between subjects - high resolution MRI scans compared after segmentation and spatial normalisation

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what is DTI? (diffusion tensor imaging) - Bandettini (2009)

characterisation of white matter and directionality of white matter tracts - DTI can create voxel-wise maps of FA as well - it determines the direction by measuring the diffusing spins

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what type of subject is preferred for optical imaging?

children because they have thinner skulls

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Intro to cog neuroscience

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