Biological basis to behaviour?

1. Biological basis to behaviour? • Where are memories stored? • Where are memories formed? • What is an emotion? • Are functions in the brain localised? • How is neurochemistry related to behaviour? • What is consciousness?

2. Assessing biological basis of behaviour? • Neuronal communication – how would you measure this? • Chemical communication – how would you measure this? • Peripheral measures? • Invasive measures? • How do we assess what is happening in the body?

3. Final solution • Autopsy • Animal studies • Problems?

4. Assessing electrical signals • How would you assess electrical signals in the brain? • EEG – electroencephalography • Technique of recording the electrical activity of the brain through the skull • Where would you use EEG and for what?

5. Interpretation of EEG • EEG reading involves the interpretation of wave forms: • Frequency • Morphology • EEG can be split into different frequency bands. The most commonly used in EEG spectral analysis these: • Delta = 0.53 - 4.22 Hz • Theta = 4.4 - 7.9 Hz • Alpha = 8.1 - 13.01 Hz • Beta1 = 13.2 - 17.9 Hz • Beta2 = 18.1 - 29.9 Hz

6. Method • EEG electrodes are usually placed in a standard pattern • Can be hundreds of electrodes – 124, 248 etc • Main problem is in analysis – much research is in this area • Can have ‘maps’ of brain activity • But how do you know where to put the electrodes – different systems eg 10-20 system

8. Alpha • Alpha is seen in normal relaxed adults • It is usually best seen in the posterior regions of the head on each side, being higher in amplitude on the dominant side but can also be seen frontally. • It is brought out by closing the eyes and by relaxation • It is abolished by opening the eyes and by anything alerting for instance opening the eyes or by thinking, reasoning. • It is the major rhythm seen in normal relaxed adults - it is present during most of life especially beyond the thirteenth year when it dominates the resting tracing.

9. Beta • Beta activity is 'fast' activity. Occurs mainly when individuals are alert, thinking and with eyes open • It is usually seen on both sides in symmetrical distribution and is most evident frontally. • It is accentuated by sedative-hypnotic drugs especially the benzodiazepines and the barbiturates. • It may be absent or reduced in areas of cortical damage.

10. Theta and Delta • Theta activity is classed as "slow" activity. • It is the normal rhythm in sleep and is abnormal in awake adults • Delta activity has the slowest waves. It is quite normal and is the dominant rhythm in infants up to one year and in stages 3 and 4 of sleep.

11. Types of assessment using EEG • Resting EEG versus Event related Potential • What can resting EEG tell us, how can it be used, where can it be applied?

12. Examples of where EEG is applied • Sleep research • Epilepsy • Brain asymmetry – for instance in mood

13. Some examples of assessing EEG asymmetry in mood • Infants • when spontaneously producing happy faces show greater left frontal activation (less alpha power) • greater right frontal activation (less alpha power) when spontaneously producing sad faces (Fox & Davidson, 1988; Fox, Henderson, Rubin, Calkins, & Schmidt, 2001). • Healthy volunteers who had undergone mood induction with positive and negative emotional clips • greater left frontal activation with positive mood induction • greater right frontal activation with negative mood induction (Wheeler, Davidson, & Tomarken, 1993). • Patients with unipolar depression compared to controls had less left sided activation (more alpha power) in the mid-frontal region (Debener et al., 2000; Henriques & Davidson, 1991). • Conclusion - • Less alpha power (more activation) in the left hemisphere appears to correspond to positive mood, while more alpha power (less activation) corresponds to negative mood. • Less alpha power in the right hemisphere corresponds to negative mood. • The differences in activation could be due to either an increase in hemispheric function in a particular emotional state or could be due to inhibitory processes.

14. EEG and Arousal • Eysenck (1967) proposed that introversion/extraversion differences are based upon levels of activity of the cortico-reticular loop with introverts having higher levels of activity than extraverts. • Introverts therefore being chronically more aroused than extraverts. • EEG is one method by which to measure this proposed difference in arousal. • EEG is relatively quick and easy to measure and has a very rapid response. • When an individual is more alert the frequency of the EEG becomes faster.

15. Event Related Potential • What is an event related potential? • ERP’s are brain responses time-locked to some “event” • Event may be a sensory stimulus (such as a visual flash or an auditory sound), a mental event (such as recognition of a specified target stimulus), or the omission of a stimulus (such as an increased time gap between stimuli)

16. AEP • Auditory evoked potentials (AEPs) are a subclass of ERPs. • The "event" is a sound. • AEPs (and ERPs) are very small electrical voltage potentials originating from the brain recorded from the scalp in response to an auditory stimulus (such as different tones, speech sounds, etc.).  • The AEPs that are recorded from the top of the head originate from structures within the brain (e.g., the auditory cortex, the auditory brainstem structures, the auditory VIIIth cranial nerve). • They are very low in voltage: from 2-10 microvolts for cortical AEPs to much less than 1 microvolt from the deeper brainstem structures. Their low voltage combined with relatively high background electrical noise requires the use of highly sensitive amplifiers and computer averaging equipment

18. AEPs have important clinical applications • Screening for hearing loss in infants • Assessing hearing thresholds • Assessment of 8th nerve and auditory brainstem status in adults and children

19. P300 • What is it? • Why measure it? • Is it specific? • What does it mean?

20. What is the P300? • The P300 is a positive ERP component peaking at approximately 300 ms after stimulus onset. • It is a late-appearing component of the event-related potential. • P stands for positive voltage potential and 300 represents 300 millisecond poststimulus. • Its amplitude increases with unpredictable, unlikely, or highly significant stimuli and thereby constitutes an index of mental activity • The P300 is typically elicited by novel and low probability (rare) stimuli, but is also sensitive to other parameters such as task relevance. • The P300 is one of the most commonly used ERP components in the study of the effects of drugs of abuse on cognitive processing.

21. Radiological Investigations • Computerised Tomography (CT) • Positron Emission Computed Tomography (PET) • Single Photon Emission Computed Tomography (SPECT) • Magnetic Resonance Imaging (MRI)

22. CT • Uses X-rays • Density information gives an image of the head and brain • To detect defects in the blood-brain barrier or increased vascularity an iodine containing material can be injected. This will result in increased contrast between normal and abnormal tissue.

23. PET • Individual is injected with a radioactive tracer of a biologically active compound such as carbon, fluorine, nitrogen, oxygen • Image is based on detection of positrons • Positrons are tiny particles emitted from a radioactive substance administered to the patient. • Can also use radioactive tracers which will attach to brain neurotransmitters, receptors etc

25. Examples of where PET can be used What Can PET Detect? Coronary Artery DiseasePET imaging is useful in being able to detect whether a patient will need coronary bypass surgery. TumorsPET imaging is very accurate in differentiating malignant from benign growths, as well as showing the spread of malignant tumors. Diseases of the BrainPET imaging can provide information to pinpoint and evaluate diseases of the brain. PET imaging can show the region of the brain that is causing a patient's seizures and is useful in evaluating degenerative brain diseases such as Alzheimer's, Huntington's, and Parkinson's. Within the first few hours of a stroke, PET imaging may be useful in determining treatment therapies. Cognition Pet imaging is very useful in real time studies assessing differences in cognitive tasks e.g. intelligence, disorders

26. SPECT • Uses a radiotracer, radiation is given off as a result of gamma emission. • Used for mapping brain metabolism and function • Allows recording of regional differences in eg cerebral blood flow • Can use radioactive tracers which attach to receptors • Tracer remains in place for longer time, therefore can be a delay between injection and recording

27. Where can SPECT be used? • Differences in brain metabolism characteristic of conditions such as attention deficit/hyperactivity disorder and various organic mood disorders. • Drug-induced changes in brain metabolism, e.g. ectasy, cocaine • Changes in the brain as a result of receiving a physical or psychological stimulus or challenge (these changes can be correlated with MRI findings). • Localization of regions of decreased perfusion/function, which may represent a focus of seizure activity. Identification of such a focus can help in surgical therapy.

28. MRI • Does NOT use radioactive tracers or X-ray • Uses radiofrequency waves and a strong magnetic field • Useful across whole body and can aid detection of cancer, heart and vascular disease, stroke, and joint and musculoskeletal disorders. • MRI requires specialized equipment and expertise and allows evaluation of some body structures that may not be as visible with other imaging methods.

29. Explanation of MRI • ‘When the nuclei of certain atoms – usually hydrogen protons – are placed in a high magnetic field, they align with the axis of spin in the direction of the field. A radiofrequency applied at right angles to the field changes the angle of spin, and the return to equilibrium when the radiofrequency pulse ceases is associated with the emission of a radiofrequency characteristic of the element and its physicochemical environment. In MRI, gradient magnetic fields in the three directions allow spatial detection of signal data and a two-dimensional image to be formed’

31. MRI • Different scan sequences allow different tissue types and pathologies to be highlighted. • A contrast agent is sometimes injected in the sample to augment these differences and improve sensitivity.

32. Two Types • fMRI – functional MRI • sMRI – structural MRI

33. Functional MRI • Measures signal changes in the brain which are due to changing neural activity. • Where might this be used?? • The brain is scanned at low resolution but at a rapid rate (typically once every 2-3 seconds). • Increases in neural activity cause changes in the MR signal via a mechanism called the BOLD (blood oxygen level-dependent) effect. • Increased neural activity causes an increased demand for oxygen, increasing the amount of oxygenated haemoglobin relative to deoxygenated haemoglobin. • Deoxygenated haemoglobin reduces MR signal, the vascular response leads to a signal increase that is related to the neural activity. • However the basis for this relationship between blood oxygen and activity is under research.

34. Advantages • According to current medical knowledge, it is harmless to the patient. • It only utilizes strong magnetic fields and non-ionizing radiation in the radio frequency range. • Compare this to the other imaging techniques we have discussed. • However MRI can not be carried out with anyone who has any shell fragments, surgical protheses or pacemakers • MRI is has higher-quality images than eg CT scan because of the high contrast resolution of soft tissue. • The spatial resolution achieved per second of scanning time, however, is better in CT, giving CT the advantage in assessing, for example, bony abnormalities. • NOISY

35. Other ways of assessing biological bases of behaviour • CSF • Blood • Cortisol • Heart rate • Cognitive correlates • AND……..

36. Tomorrow Friday 27th Tutorial Groups to discuss Arousal • Group 4: 9.15-9.45 • Group 2: 9.45-10.15 • Group 3: 10.15-10.45 • Group 1: 10.45-11.15

37. Practical Week 4 THURSDAY Groups 1 and 2: Laboratory session on Thursday 2nd February 2005 in WP 3.18 Group 1 in lab 12.15pm – 1.15pm Group 2 in lab 1.15pm – 2.15pm Groups 3: Discussion Group on Thursday 2nd  February 12.30pm – 1.15pm in DB113 Group 4: Discussion Group on Thursday 2nd  February 1.30pm – 2.15pm in DB113 FRIDAY Groups 3 and 4: Laboratory session on Friday 3rd February 2005 Group 3 in lab 9.15 am – 10.15am Group 4 in lab 10.15 am – 11.15am Groups 1: Discussion Group on Friday 3rd February 9.30 am – 10.15am in WA211 Group 2: Discussion Group on Friday 3rd February 10.30 am – 11.15am in WA211

38. Week 5 • Week 5 • Thursday • 9.15-11.15 Data Analysis in Room EM252 • Note no Friday formal class but feel free to drop in and chat about your assignments with Me

39. Tasks • For the practical you will be asked to write up the data of the report • However in the exam you will be asked about AROUSAL • You can chose an area in this where you are interested - discuss with your group • This is to give you practice critically appraising an area in class and should improve your exam skills

40. Important • In the discussion groups I expect you to have met as a group 2-3 times and given each other tasks to find materials • I expect you to be able to explain to me different aspects of arousal

41. Week 6 • Free for discussion of what we have covered • How about Localisation of function?

42. Arousal

43. What is arousal? • How can we define arousal? • How can we measure it? • Is there a specific time period? • Is it physiological or psychological? • What mechanisms come into play? • What can arousal affect?

44. Arousal • Arousal is a major aspect of many learning theories and is closely related to other concepts such as anxiety, attention, agitation, stress, and motivation. • The arousal level can be thought of as how much capacity you have available to work with. • What do you think that this means?

45. Yerkes-Dodson law • One finding with respect to arousal is the Yerkes-Dodson law which predicts an inverted U-shaped function between arousal and performance.  • What does this mean in terms of performance?

46. Optimal performance Perfromance Level of arousal

47. Level of arousal and Performance • A certain amount of arousal can be a motivator • But too much or too little will certainly work against the performance • Too little arousal has an inert affect on the learner, while too much has a hyper affect.

48. The Autonomic Nervous System • The sympathetic nervous system • called into play in situations needing energy and arousal • fight or flight. • The parasympathetic nervous system • involved when the body is trying to save energy. • The two systems often operate in opposition to each other.

49. Practical • You will be performing a task during which you may show some signs of arousal • This may enhance or diminish your performance • Ethics?- what do you think of the ethics of such a study?

50. What will you be doing? • Collecting physiological and psychological data before and after test • The test is a cognitive task • Why do you think you collect data before and after? • How will you perform the analysis? • What tests could you perform?