Week 4 - biological psychology

Question 1

When did modern biology begin?

Answer 1

Modern biology began in 1859 with the publication of Charles Darwin’s On the Origin of Species

Question 2

What key evidence did Charles Darwin use to support his theory that species evolve?

Answer 2

1. He noted the evolution of fossil records through progressively more recent geological layers (hominid skull change)
2. Referred to structural similarities among living species, suggesting they had evolved from common ancestors (eg. Human arm and a bats wing)
3. Described changes brought about in domestic plants and animals by programs of selective breeding (dogs)
4. Observed evolution in situ, unfolding quickly
5. Observed in progress (drought in Galápagos Islands increased beak size in one species of finch)

Question 3

Describe what Darwin argues - that evolution occurs through natural selection:

Answer 3

The heritable traits associated with high rates of survival and reproduction are the most likely ones to be passed on to future generations.

Question 4

Describe Darwin’s argument of survival of the fittest

Answer 4

Nature creates fitter animals by selectively breeding the fittest

Fitness, in the Darwinian sense, is the ability of an organism to survive and contribute its genes to the next generation.

Question 5

Across nearly seven million years, how much has the human brain enlarged?

Answer 5

Almost tripled in size, with most growth occurring in the past two million years.

Question 6

Describe the emergence of human kind according to Darwin

Answer 6

The first home species are thought to have evolved from one species of Australopithecus about 2 to 2.8 million years ago.

A skull found of a 3 year old Australopithecus girl (fossil is 3.3 million years old)

Having derived from the early Australopithecus, early Homo species used fire and tools and cohabitated with Australopithecus until they became extinct.

Fossilised footprints of Australopithecus hominins across African volcanic ash about 3.6 million years ago.

Question 7

Describe some key points about evolution of humans

Answer 7

About 300,000 years ago, early homo species were gradually replaced in the African fossil record by modern humans (homo sapiens)

About 130,000 years ago, modern humans began to migrate out of Africa

There is also evidence that Homo sapiens mated with other homo species (eg homo Neanderthalensis) they encountered both in Africa and Europe.

Thus we are not the product of a single ancestral population originating in Africa; rather, we are the offspring of many Homo populations that once coexisted.

Question 8

On average, how much bigger is the size of primates brain compared to what is expected for mammals of the same size?

Answer 8

About double

Question 9

How much bigger is our brain relative to chimps and mice?

Answer 9

About 4 time bigger then chimps
About 15 times larger than the mouses.

Even allowing for body size, humans have unusually large brains.

Question 10

Larger brains (eg whales) are bigger than ours. Does this mean they are more complex?

Answer 10

No - the human brain is of higher complexity

Neocortex is specially developed and complex - higher number of convolutions and high degree of folding.

Neanderthals brain was just as big as ours, probably bigger, but the pattern of development during childhood is different to modern humans - the shape of the modern brain changed significantly during the first year of life in response to environmental factors (plasticity).

Neanderthal brain is more like the chimpanzees brain in this regard, both grow steadily in the first few years. Unlike the human brain.

Question 11

The concept of evolution gave rise to the discipline of evolutionary psychology. Describe it

Answer 11

Evolutionary psychology is focused on how evolution has shaped the mind and behaviour

Attempts to explain mental and psychological traits such as memory, perception, or language - as adaptations, ie, as the functional products of natural selection

These psychological adaptations gave advantages to our ancestors, who passed on these traits to future generations through their genes

Thus according to evolutionary psychologists, many of these traits are genetically programmed

Question 12

What’re dichotomous traits that Gretel Mendel (1822-1884) studied?

Answer 12

Darwin argues that adaptive anatomical, physiological, and behavioural characteristics are passed form parent to offspring, but did not understand how.

Augustinian monk, Gregor Mendel, studied inheritance in plants, in common edible peas.

(2 distinct traits) Traits or characteristics that occur in one form or the other, never in combination. For example, seed colour is a dichotomous pea plant trait: every pea plant has either brown seeds or white seeds.

There were also other dichotomous traits he studied (eg flower colour is purple or white, stem long or short etc)

He used true breeding lines I.e. in which all interbred members produce offspring with the same trait (either white or brown seeds) and then he began cross breading the offspring.

Question 13

What did Mendel conclude from his pea experiment?

Answer 13

One trait, which Mendel called the dominant trait, appeared in all of the first generation offspring; the other trait, which he called the recessive trait, appeared in about one quarter of the second generation offspring.

He concluded:

1. The inheritance of each trait is determined by ‘units’ or ‘factors’ that are passed in to descendants unchanged (we now call these units genes)
2. An individual inherits one such unit from each parent for each trait.
3. A trait may not show up in an individual but can still be passed on to the next generation.

Question 14

Describe some key concepts in genetics

Answer 14

DNA is the molecule that holds the genetic information

DNA molecules contain a code that can be used by a cell to express certain genes

Genes expose the information required to build specific proteins. A mutation is a change in a DNA sequence, which can affect the making of a protein.

Genes are contained in the chromosomes. Chromosomes come in pairs and humans have 46 chromosomes, in 23 pairs. Children randomly get one of each pair of chromosomes from their mother and one of each pair from their father.

Question 15

What do behavioural geneticists study?

Answer 15

Individuals of known genetic similarity (eg,twin studies)

Question 16

Describe what monozygotic is?

Answer 16

Where the zygote splits - genetically identical - shared placenta - twins. Share essentially 100% of genes

Question 17

What was the Minnesota Twin Study (Bouchard et al. 1990)

Answer 17

Identical twins raised together vs. identical twins raised apart

Concordance rates of intelligence tested

Determined 70% of intelligence can be attributed to genetic inheritance

Other 30% may be attributed to other factors

The research team found that identical twins who are reared apart had the same chance of being similar as twins who were raised together. Bouchard and his colleagues concluded that genetic factors have a large influence on behavioural and psychological traits, demonstrating the strong influence of the genetics on development.

Question 18

What did the Minnesota twin study find about the effect of environment on identical twins?

Answer 18

Environment also had a decisive influence on the development of the phenotype (the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment).

Question 19

Describe the technique in biological psychology- stereotactic

Answer 19

Stereotaxic surgery in humans was made possible owing to the intervention of the apparatus by Victor Horsley, at the beginning of the 20th century (XXth century).

It is known as the Horsley- Clarke apparatus and allows the positioning of the head of the patient within a precise system of stereotaxic coordinates (x, y and z).

Stereotaxic techniques allow a wide range of manipulations of the CNS.

• lesions
• implants of dialysis probes
• implants of electrodes
• injections of tracers

Question 20

Organisms that possess two identical genes for a trait are said to be what for that trait?

Answer 20

Homozygous for that trait.

Question 21

Organisms that possess two different genes for a trait are said to be what for that trait?

Answer 21

Heterozygous for the trait.

Question 22

Describe what dizygotic is?

Answer 22

Twins, non identical.

Ovum splits, genetically distinct (1/2) separate placenta. Only share 50% of genes.

Question 23

List all the techniques in biological psychology.

Answer 23

In biological psychology we are at the interface between psychology (emphasis on explaining behaviour) and biological/medical research - our techniques are diverse.

1. stereotaxic surgery
2. cerebral lesions
3. histology and microscopy
4. neuroanatomy (Tract tracing)
5. Brain stimulation
6. Neurochemistry (in vivo micro dialysis)
7. Optogenetics
8. Genetic techniques
9. Electrophysiological recording
10. Neuroimaging
11. Animal behaviour

Question 24

Describe the technique in biological psychology- microscopy and histology

Answer 24

Fixation is the interruption of the degradation processes that begins after the cells die. The main objective is to provide maximal preservation of the tissue, both structural and chemical.

There are many types of fixation, but chemical fixation is the most widely used. Typically, paraformaldehyde is used for optical microscopy, and glutaraldehyde is utilised for electron microscopy.

(The state-of-the-art microscope contains accessories for DIC, fluorescence polarised light, phase contrast, and photomicrography using several film formats and digital image capture.)

Question 25

Describe the biological psychology technique - immunocytochemistry

Answer 25

Changes in animal behaviour that occurs during learning if following drug administration are correlated by changes in protein expression. These molecular changes are of great interest in Biological Psychology.

Immunohistochemistry and immunocytochemistry are techniques that allow immunolocalisation by means of specific antibodies. Antibodies are raised against specific proteins (also referred to as antigens). Methods of detection are typically indirect and require amplification.

Question 26

Detection of RNA and DNA

Answer 26

We use specific probes (sequence of amino acids) to detect portions of mRNA (RNA hybridisation) or DNA (DNA hybridisation). The probes are complementary to the RNA or DNA sequences.

The microscopic detection and visualisation of the probe can be achieved by means of the technique referred to as in situ hybridisation. Typically the probe is radioactive.

Question 27

Neurochemical techniques in biological psychology.

Answer 27

Radioactive glucose is taken up by the most active neurons in the CNS. We assume that these neurons show more neurophysiological activity. This technique is useful for yielding a topographical image of active areas of the brain. We can then correlate these measures with changes in behavioural output, although the spatial resolution of autoradiography is low.

Autoradiography can also be used for detecting membrane receptors (e.g. agonist binding) or determine which brain areas are targeted by a drug.

Question 28

In vivo microdialysis as a neurochemical technique for biological psychology

Answer 28

Micro dialysis. A dilute salt solution is slowly infused into the micro dialysis tube, where it picks up molecules that diffuse in from the extra cellular fluid. The contents of the fluid are then analysed.

In vivo microdialysis is an exciting technique with which to explore the relationship between brain and behaviour. This technique permits the researcher to monitor continuously the extra cellular fluid concentrations of various neurochemicals in an awake animal.

A semi-permeable membrane is attached to the tip of the cannula. The membrane permits only small molecules to be extracted from the tissue. In vivo microdialysis is useful not only for extracting chemicals from brain tissue but also for the slow and continuous infusion of drugs into the brain tissue.

Modern VOLTAMMETRY.

Question 29

Technique in biological psychology - experimental lesions

Answer 29

One of the most important techniques in Physiological psychology. Critical to delineate the functions of specific brain regions.

Underlying principle: of after the lesion the animal is unable to perform a given behaviour or shows a specific motivational or cognitive impairment, then it is assumes that the region investigated participants in that behaviour/function.

Caution: we have to take into account that individual brain structures are part of integrated circuits that perform complex functions. It is unlikely that discrete brain centres mediate behavioural responses without engaging other structures.

Question 30

Reversible and irreversible lesions

Answer 30

Typically lesions are irreversible, but reversible lesions are increasingly used.

Irreversible lesions:

Historically m, researches have used aspiration lesions (eg cortex or hippocampus).

Sectioning of tracts of bundles (“knife-cut”) are also used to disconnect certain regions of the brain.

Electrolytic lesions have been used extensively. A wire is introduced in the brain. It is insulated except at the tip, and a current is passed through it.

Question 31

Some examples of neurotoxic lesions (irreversible)

Answer 31

6-hydroxydopamine (destroys dopamine in the brain)

5,7-dihydroxytriptamine

Colchicine

Ibotenic acid

Question 32

Describe some reversible lesions

Answer 32

Reversible lesions involve temporal inactivation (eg Mins or hours) of specific brain regions by means of micro injections of local anaesthetics (lidocaine) or ion channel blockers (tetrodotoxin).

Increasingly, researchers use GABA receptor agonists, such as muscimol and baclofen, and also frozen substances which induce temporal cryogenic blockade of neuronal activity.

Other approaches: antisense treatment (nucleotide against mRNA) or protein synthesis inhibitor (eg. Anysomicin)

Advantages include repeated measures design. The animal is it’s own control.

Question 33

Describe chemical stimulation as a biological psychology technique

Answer 33

These techniques result from combining pharmacological and neuroanatomical methods. Typically, indwelling cannulae are implanted and injections of agonists/antagonists are made with fine microinjectors.

Usually injections are made acutely, but it is also possible to administer drugs chronically via osmotic mini pumps.

Question 34

Electro stimulation as a technique of biological psychology.

Answer 34

Classical techniques involve a permanently attached bipolar electrode through which a weak current is passed on. The current depolarises neurons in the vicinity of the tip of the electrode, incrementing the discharge rate of these neurons.

Rationale: increasing the activity of specific brain regions will have an impact on specific behaviours, such as feeling, sleep, aggression, etc.

Similarly electrical stimulation techniques has been used to identify the so-called reward pathways (“intracranial self-stimulation”, ICSS).

Question 35

Describe optogenetics

Answer 35

Mapping brain circuits with light.

Molecular machines: optogenetics and gated ion channels

Algae -> DNA -> brain circuit (blue light pulse initiates an action potential).

Question 36

Electrical stimulation in humans (transcranial magnetic stimulation)

Answer 36

Transcranial magnetic stimulation (TMS) is a noninvasive method to cause depolarisation in neurons. TMS uses electromagnetic induction to induce weak electric currents using a rapidly changing magnetic field; this can cause activity in specific or general parts of the brain with minimal discomfort. A variant of TMS, repetitive transcranial magnetic stimulation (rTMS), has been used for treating neurological and psychiatric disorders including migraines, strokes, Parkinson’s disease, addiction and depression.

Question 37

Electrophysiological recording as a technique used in biological psychology.

Answer 37

Electroencephalogram (EEG) is obtained by placing large electrodes in the skull (cortical EEG) of deep into the brain (subcortical EEG).
Picks up general changes in brain activity.

One of the advantages of EEG is the fact that the shape of the EEG wave is correlated with specific stages of arousal (eg relaxation, sleep, activity) and with certain brain pathologies.

For example, the presence of alpha waves with a frequency in the range of 8-12/sec is associated with a relaxed state during wakefulness.

The technique of “evoked potentials” (or “event-related potentials”) is of great interest in Psychophysiology. There are general changes in brain activity elicited by stimuli presented by the experimenter.

Question 38

Neuroimaging as a technique in biological psychology.

Answer 38

In the 70s researches began to use computerised tomography. This technique involves acquiring multiple x-ray photographies. These are combines with software to yield a 3 dimensional reconstruction of the brain.

Question 39

Describe MRI as a biological psychology technique

Answer 39

“Magnetic resonance imaging” (MRI) is a procedure that generated high resolution images of the brain. The techniques measures waves of hydrogen atoms that are emitted when they become activated by radio frequency. In clinical practice, MRI is used to distinguish pathologic tissue (such as a brain tumour) from normal tissue.

As does tomography, the MRI technique provides information about the structure of the brain. Not it’s functions.

Structural MRI can yield 3 dimensions, but still no functionality.

Question 40

Describe portion emission tomography (PET scan)

Answer 40

Position emission tomography (PET) is a nuclear medicine imaging technique which produces a 3-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a radioactive tracer, which is introduced into the body on a biologically active molecule, such as glucose (2-desoxyglucose through the carotid artery)

Shows ADHD patients have lower levels of dopamine transporters in the nucleus accumbens.

Question 41

Describe functional magnetic resonance imaging (fMRI)

Answer 41

It is a type of specialised MRI scan. It measured the hydrodynamic response (change in blood flow) related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most recently developed form of neuroimaging. Since the early 1990s, fMRI has come to dominate the brain mapping field due to its relatively low invasive ness, absence of radiation exposure and relatively wide availability.