w6 percept & cogn FIRST COGNITION CLASS

The mind is often associated with…

Cognition

Cognition

The collection of mental processes and activities used in perceiving,

remembering, thinking, and understanding, as well as the act of

managing those processes (mental control).

(Ashcroft, 2010)

In (slightly) other words…

• Cognitive processes are mental activities (e.g. thinking) which enable

us to acquire, store and use knowledge in everyday life

• Cognitive Psychology – the scientific study of how the mind works

when thinking about things

Cognitive Neuroscience

the scientific study of how the brain implements cognitive function.

Neural bases of cognition and behaviour in Humans (and Animal research) …measured with brain recording techniques.

Cognitive Neuropsychology

understand cognition through affected brain function, e.g. brain injury (lesions)

Relationship between brain function and behaviour.

Examination of changes in normal function after brain injury.

Experimental Cognitive Psychology

Cognitive psychology focused on using experimental designs.

ex: eye-tracking/eye movements to see what ppl pay attention to. Virtual Reality & Neuro-VR (see Seftleben & Kessler 2024).

Scientific Method

Theory, prediction, experiment, observation

Experimental design

• Independent Variable(s) (IV) under experiment’s control: e.g. Experimental group (lesions patients) vs Control group (no lesions) Or: different conditions, experimental (distractions) vs control (no distractions)

• Dependent Variable(s) (DV), e.g. data measured through a task: e.g. Performance and/or brain activity on a memory or attention task

Experimental Cognitive Psychology Pros

• Control

• Cause – effect relationships

• Large N

• Inferential Statistics

• Tasks can be used for

complex measures of

behaviour and brain activity - Cognitive Neuroscience

Experimental Cognitive Psychology Cons

• Indirect

• Artificial (not realistic)

• May lack ecological validity

• Narrow range of tasks

• Traditionally tends to

ignores individual

differences

Lesion studies

• Disruption of brain function comes about through natural damage (strokes, etc.)…

• …elicited damage (e.g. animal models)

• Infer the function of a region (or cognitive mechanism) by “removing it” and measuring the effect on the rest of the system

Reverse Inference

• Infer the function of a region (or cognitive mechanism) by “removing it” and measuring the effect on the rest of the system

Two Traditional questions of Human Neuropsychology

(1) What functions are disrupted by damage to region X?

– Addresses questions of functional specialization

– Tends to use group study methods

(2) Can a particular function be spared/impaired relative to other cognitive functions?

– Addresses questions of what the building blocks of

cognition are (irrespective of where they are)

– Tends to use single case methodology

Hemispatial Neglect

• damage in right parietal lobe

• struggle to see contralesional side of objects/visual field

Neuro-methods

CONSIDER: temporal resolution vs spatial resolution

CT, MRI, PET, fMRI, TMS, EEG, ERP, MEG

Functional Magnetic Resonance Imaging

fMRI

Neural activity requires energy. Energy acquired by breaking down glucose. (glycolysis) Glycolysis requires oxygen.

Oxygen is carried to the brain in the blood by haemoglobin.

Oxyhaemoglobin and de-oxyhaemoglobin have different

magnetic properties;

MR signal is increased for highly oxygenated blood and

is decreased for de-oxygenated blood

FMRI HAS BAD TEMPORAL RESOLUTION (blood response takes seconds to peak) but excellent spatial resolution!

Magnetism and electricity

H.C. Oersted, 1820:

Deflection of compass needle by electric current

Transcranial Magnetic Stimulation (TMS)

• Coil contains a wire carrying an electric current. Rapid change in the current creates a magnetic field

• The magnetic field induces a current in the nearby neurons through electromagnetic induction (causing them to "fire", i.e. generate action potentials)

• This disrupts the cognitive function that they may be doing at that point in time

One can elicit finger movements (motor evoked potentials, MEP) by stimulating the correct cortical hand/finger area.

TMS conditions

• TMS brain stimulation is relatively mild.

• Not used on people with epilepsy or pregnant women

• Number and rate of pulses is regulated by ethical guidelines

• Relatively high spatial and temporal specificity.

• Can help ascertain CAUSALITY (e.g. of effects obtained with a correlational method)

Magnetoencephalography

Direct measurement of neural activity with high temporal and good spatial resolution (MEG)

Electroencephalography

Direct measurement of neural activity with high temporal and low (EEG) spatial resolution

Event Related Potentials (ERP)

• Based on EEG (or MEG = ERF) (electroencephalography) recordings

• EEG signal is averaged over many events & synchronized to some aspect of the event (e.g. onset of a stimulus, e.g. picture of a face)

• Electrodes record a series of positive and negative peaks

• Timing and amplitude of the peaks is related to different aspects of the stimulus and task (e.g. an attention task)

Neural Oscillations in EEG and MEG

look at the brain worms

BTW, Berger initially wanted to “find” telepathy…

DIFFERENT OSCILLATION CATEGORIES

KEEP WORKING LAD. EXAMS OVER SOON.

pros/cons of looking at oscillations (eeg/erp/meg)

• Brain oscillations can be extracted from the same EEG or MEG data that you use for ERPs you just don’t average before extracting the different frequencies.

• Brain oscillations are directly related to neural activity and this electrical activity is conducted instantaneously to the scalp – like ERPs.

• The major frequency ranges (or bands) relevant for cognition are theta (3-7 Hz), alpha (8-12 Hz), beta (13-30 Hz, and gamma (30+ Hz).

• Oscillations can tell us about spontaneous, ongoing (continuous), or top-down brain activity that is averaged out in ERPs.

• But for extracting frequencies you lose temporal resolution or precision. ERPs can reflect the timing of brain processes more precisely.