PSY10060 2024 Lecture 2 - Methods PDF

MEASURING BRAIN AND BEHAVIOUR Dr Sarah Cooney [email protected] G214 Newman PSY10060: Brain and Behaviour Outline Lecture 2 Levels of Analysis Nervous system & Neuron primer Brain & Behaviour Research Methods 1. Connectional Methods 2. Correlational Methods 3. Lesion Methods 4. Stimulation Method...

MEASURING BRAIN AND BEHAVIOUR Dr Sarah Cooney [email protected] G214 Newman PSY10060: Brain and Behaviour Outline Lecture 2 Levels of Analysis Nervous system & Neuron primer Brain & Behaviour Research Methods 1. Connectional Methods 2. Correlational Methods 3. Lesion Methods 4. Stimulation Methods Scientific Perspective on Brain and Behaviour All psychological phenomena - including emotion, perception, attention, memory, reasoning, conscious experience - are the product of brain activity. THE HUMAN NERVOUS SYSTEM Human Nervous System – Major Divisions Central nervous system (CNS) Brain and spinal cord Peripheral nervous system (PNS) Sensory and motor connections The brain – major structures Cerebrum (forebrain) Hemispheres Brainstem Cerebellum Neuron structure Communicates with other cells Receives and transmits ‘messages’ Produces electrical impulses – action potentials Video resources 2-minute neuroscience The neuron https://www.youtube.com/watch?v=6qS83wD29PY Action potential https://www.youtube.com/watch?v=W2hHt_PXe5o Synaptic transmission https://www.youtube.com/watch?v=WhowH0kb7n0 Scale in studying the nervous system Time How can we link Brain to Behaviour? Connectional Methods Tracing Connections Diffusion Tensor Imaging DTI Role of a neuron depends on its INPUTS & OUTPUTS Wide variety of methods used to trace connections: 1. to and from a neuron Uses MRI scanner 2. to and from a region of the brain Non - invasive Detailed maps of the diffusion of water within neural tissue Connectional Methods In order for connectional methods to work we need to know the approx. functions of the INPUT & OUTPUT regions. Correlational Methods  Involves making observations of brain activity while an individual is performing some type of behaviour. Correlational Methods Invasive: Record electrical activity of neurons via microelectrodes implanted in brain Less – invasive: 1. Electroencephalography (EEG) 2. Magnetoencephalography (MEG) 3. Positron emission tomography (PET) 4. Functional Magnetic Resonance Imaging fMRI Magnetic Resonance Imaging (MRI) Differences in the properties of tissue create major differences in how protons in the tissue behave when they are placed in a strong magnetic field. Images > must partially magnetize the body. Every MRI contains a superconducting magnet Structural Analysis: Magnetic Resonance Imaging (MRI) Strong magnetic field passed through the brain, followed by a radio wave Very clear 3D images of various type of tissue within body Excellent spatial resolution < mm Functional Magnetic Resonance Imaging (fMRI) When neurons become more active, they need more oxygen fMRI can detect changes in the magnetic properties of blood Measures ratio of oxygenated to deoxygenated blood Blood oxygen level-dependent (BOLD) response MRI vs. fMRI MRI studies brain fMRI studies brain structure function Video resource – fMRI and DTI https://www.youtube.com/watch?v=EpnAwIJSJ38 https://www.youtube.com/watch?v=Jtvsbiq3Xl0 Studying the damaged brain Neuropsychological testing Effects of brain damage on specific cognitive functions e.g., temporal lobe lesions associated with memory disturbance Memory is not a single function – semantic, procedural, episodic… Rare to be impaired in all forms of memory - each must be tested separately Lesion Studies We need to back up our findings from correlational studies with causational studies Study the effects of brain damage – lesions. Neuropsychological testing Effects of brain damage on specific cognitive functions Wide variety of events cause lesions: 1. TBI – traumatic brain injury 2. Stroke – bleeding or blockage of blood supply into tbrain region 3. Tumours 4. Degenerative diseases 5. infections Studying the damaged brain Single and double dissociations Patient versus control Patient X versus Patient Y Resources - MRI Virtual MRI https://www.youtube.com/watch?v=Jtvsbiq3Xl0 MRI images example https://www.youtube.com/watch?v=e4v78RDd17s Researcher scans his own brain for a year and a half https://www.kurzweilai.net/stanford-researcher-scans-his-own-brain -for-a-year-and-a-half-the-most-studied-in-the-world Functional and Structural Brain Stimulation: DBS Deep-brain stimulation (DBS) Electrodes implanted in the brain to stimulate a targeted area with a low-voltage electrical current to facilitate behaviour Therapeutic applications: Parkinson’s disease Depression OCD Image: Parkinson’s UK  Functional and Structural Brain Stimulation: TMS Transcranial magnetic stimulation (TMS) Magnetic coil placed over the skull to stimulate underlying brain area Wire in coil carrying an electric current - rapid change in the current creates a magnetic field This induces a current in the nearby neurons, causing them to ‘fire’ (generate action potentials) Can be used to disrupt ongoing cognitive or motor function (‘virtual lesion’) Transcranial Magnetic Stimulation (TMS) TMS is relatively mild Many natural situations stimulate the brain Not used on people with epilepsy Number/rate of pulses regulated by ethical guidelines Can be used to treat depression Resources - Brain Stimulation DBS https://www.youtube.com/watch?v=3pSMFYhh5E8 TMS https://researchcentres.city.ac.uk/cognitive-neuroscience/t ms Measuring the Brain’s Electrical Activity The brain is always electrically active Electrical activity can be used to study brain function Four major techniques 1. Single-cell recording 2. Electroencephalography (EEG) 3. Event-related potentials (ERP) 4. Magnetoencephalography (MEG)  Single Cell Recordings Measuring single-neuron action potentials with fine electrodes Electrodes placed next to cells (extracellular) or inside (intracellular) Extracellular recording - distinguish activity of up to 40 neurons Intracellular recording - study of a single neuron’s electrical activity Can be used in humans when electrodes implanted for clinical reasons E.g., DBS surgery Recording Action Potentials from Single Cells Electroencephalography (EEG) Recording from thousands of cells Reveals features of the brain’s electrical activity EEG signal changes with behaviour Recordings from the cortex show an array of patterns – some are rhythmical Electrical activity continues even during sleep or coma Electroencephalography (EEG) Can be used to measure ongoing brain activity or changes in response to a particular event/stimulus Characteristic EEG Recordings What activity state does each of these waveforms show? Characteristic EEG Recordings Electroencephalography (EEG) and event-related potentials (ERPs) EEG Spatial resolution ~ centimetres Temporal resolution ~ milliseconds Mapping Brain Function with ERPs Complex electroencephalographic waveforms are related in time to a specific sensory event To counter noise effects, the stimulus is presented repeatedly, and the recorded responses are averaged Stimuli can be visual (VEP), auditory (AEP), motor (MEP), somatosensory (SEP) Detecting ERPs E.g., auditory stimulus Tone presented at time 0 EEG response recorded After many successive presentations the EEG wave sequence develops a distinctive shape Resources – EEG and ERPs https://www.cardiff.ac.uk/cardiff-university-brain-research-i maging-centre/facilities/electroencephalography-labs https://www.youtube.com/watch?v=tZcKT4l_JZk Comparing Neuroscience Research Methods Considerations Temporal resolution Spatial resolution (accuracy of localization) Invasiveness Cost E.g., Behavioural methods generally less expensive than imaging