Antagonists – what do they do?

dementia-3761172_640Antagonists are any chemicals that fit into receptor sites on the post-synaptic neuron, inhibiting the neuron from firing. Well-known antagonists for serotonin, which we looked at in the previous blog post, are anti-psychotic drugs like Clozapine, which acts on the HT2A serotonin receptors to decrease the effects of serotonin in the brain. Many ant-psychotic drugs also act as antagonists for dopamine, as an excess of both dopamine and serotonin has been associated with schizophrenia.

However, easy-to-understand studies referencing this effect of Clozapine are difficult to come by, so while this is useful knowledge for students on how anti-psychotic medication works, when teaching about antagonists there is more available research on the effects of scopolamine on acetylcholine, and hence on memory.  (And incidentally on motion sickness, as scopolamine is excellent at preventing nausea and vomiting!)

Scopolamine acts by blocking the acetylcholine receptors, specifically the muscarinic receptors (see the link below). Atri et al (2004)  reported how blocking the muscarinic acetylcholine receptors (mAChRs), by injecting scopolamine impairs learning of paired words.

As an age-related deterioration in cognitive function is thought to be predominantly related to a decline in cholinergic neurotransmission (relating to nerve cells in which acetylcholine acts as a neurotransmitter), scopolamine administration has often been used to model dementia. Scopolamine has therefore been extensively used for preclinical and clinical testing of treatments for cognitive impairment.  For example, Tröster et al (2013) found that scopolamine negatively affected anterograde short-term memory and verbal and nonverbal learning in middle-aged men.

Agonists – what are they?

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Biological psychology has come to the fore over the past years.  The mapping of the human genome combined with improved brain-scanning techniques has meant that the biological correlation to psychological conditions is more easily identifiable, and it is clear that many mental disorders like major depressive disorder, anxiety disorders and schizophrenia are explainable through a gene x environment interaction.  This usually means that an inherited genetic pre-disposition to a disorder, or a certain behaviour or addiction is triggered environmentally.

Talking of genes takes us to neurotransmitters.  How? Genes make proteins which make neurotransmitters and genes also transport neurotransmitters across the synapse. (See Caspi et al._2003 and the 5HTTR serotonin transporter gene).  Neurotransmitters are agonists –they bind with receptor sites on the post-synaptic neuron and cause an action potential.  Drugs are also agonists that act in the same way, but they are not natural in our nervous system.  Neurotransmitters are known as endogenous agonists (internal agonists); drugs, or any chemicals taken into the body, to deliberately stimulate a certain neurotransmitter or group of neurotransmitters, are exogenous agonists (external agonists).

An exogenous agonist for serotonin is MDMA (Ecstasy).  It works by binding with the serotonin transporter genes and also with the receptor sites, temporarily increasing the serotonin in the synapse in the neocortex (part of the cerebral cortex), the amygdala, hippocampus and hypothalamus, affecting cognitions such as memory and perceptions, as well as mood. We party!

However, studies have suggested that there is a rebound effect, whereby damage to the serotonin transporters after several doses of MDMA over a period of a few days has resulted in an ultimate decrease of serotonin in the brain, and memory and mood impairment, leading to theories that this might be linked to a motivation to take more and eventually to possible addiction. (See McCann et al MDMA and memory).

Of course, the opposite to an agonist is…an antagonist, which will be the subject of the next blog post.

Research from Psychology Sorted: Poverty and childhood cognitive development – a biological approach.

This is the first in a series of posts using research directly from our new bookpoverty3349068_640 Psychology Sorted.  The study we’re looking at today is Luby et al. (2013) on how children’s brain development and therefore their cognitive development are affected by poverty. The researchers found that exposure to poverty in early childhood impacts cognitive development by school age. However, the effect is mediated positively by good caregiving and negatively by stressful life events.

This is highly relevant in light of reports from the UK, USA and  South-East Asia of the large, and in some cases growing, number of children living in poverty.  This research can be used as an example of both localization and neuroplasticity within the Biological Approach,  and to illustrate the influence of poverty/socio-economic status on cognitive development, for those studying the Developmental Psychology option.

This was a longitudinal study of 145 children from a sample of children already enrolled in a 10-year study of preschool depression who, prior to being scanned by MRI,  had undergone regular testing.  Once a year (for a duration of 3-6 years) the children had taken part in a series of tests aimed at measuring their cognitive, emotional and social aptitudes. The involvement of significant adults in their lives was also recorded (e.g. how close they were to their caregivers) as well as the occurrence of any negative and stressful events in their lives. Once this collection of information had been amassed, each child underwent two MRI scans – one of the whole brain and one of the hippocampus and amygdala only. This study can therefore also act as an example of the use of brain-imaging technology as a technique used to study the brain in relation to behaviour.

Both the hippocampus and the amygdala showed less white and grey matter in the MRI scans of the poorer children in this study, with a positive correlation between income/needs being met and brain volume. While both the hippocampus and amygdala showed less development in poverty-affected children the researchers found that in cases where the child experienced positive care there was less negative effect on the hippocampus. Difficult and stressful life events only affected the left hippocampus.

Of course, students and teachers need to evaluate the use of this research as well: how valid is the study as an illustration of both localization and neuroplasticity? This was a relatively small sample of pre-schoolchildren from the USA who exhibited symptoms of depression.  Moreover, attempting to measure complex variables (e.g. the nature of caregiving and behavioural responses) is beset with difficulties as these variables are not exact and may lack construct validity.  Nonetheless, there was triangulation of methods, with the background data from cognitive testing providing a rich backdrop for the results of the scans, and this research is supported by other studies, such as that by Duval et al. (2017). 

Encourage your student to find and read media and academic examples of evidence and counter-evidence, and to engage in critical thinking and evaluation. For example, some poor families often cannot afford pre-school kindergartens for their children, who may be raised to some extent in isolation as well as in poverty.  This could be a confounding variable. Are there others? The student who is thinking like this is well on the way to writing a good argumentative essay on the effects of poverty on childhood cognitive development.

Coming soon – ‘Psychology Sorted’, the book!

Hi Psychology teachers from all over the world! Yes, I know that summer is beckoning but wouldn’t you like a sneaky peak at a BRAND NEW RESOURCE that is due to be out around October 1st? Written by Laura Swash and Claire Neeson, this resource will solve all those pesky teaching dilemmas such as: ‘Which studies should I use for each topic and how can I re-use them to create less bulk for the students to learn?  How can I find a streamlined, easy, cross-referenced resource that’s user-friendly (for me and my students)?  What can I use for both teaching AND revision?’ Here is a sample for you to taste, to get the ‘flavour’ of what we’re doing. Add us to your school shopping list: #1 Order ‘Psychology Sorted’ next term.  Sorted!

Sample_Section 1_Bio. updated

Bio KS1 Fisher et al_2005

Holiday Reading for all

kindle-381242_640Psychology teachers and students alike must by now either be on holiday, or be desperately looking forward to being on holiday.  Some lighter reading recommendations (with links to summaries or reviews) for those who just can’t get enough psychology are:

Alexandra Horowitz – On Looking  – 12 stories of walking through a city with different experts (one being a dog!).This is really good for TOK as well as a good discussion on schema creation.

Robert M. Sapolsky – Behave  and Why Zebras Don’t get Ulcers – why we do what we do, and why zebras don’t.  Great insight and humorous asides in both.

Ethan Watters – Crazy like US – the McDonaldization of psychiatry.  Very easy, historical view of how typically Western conceptions of mental illness have been exported to the rest of the world, and the effects of this.

Lisa Genova – Still Alice – fiction, but could so easily be fact, about a 50 year old female professor who develops early-onset Alzheimer’s disease.  Told from her perspective.  Lisa Genova has written two other fictional accounts relevant to psychology, but this is (in my opinion) far and away the best.  Heartbreaking.

Mark Haddon – The Curious Incident of the Dog in the Night-Time – Christopher is on the autistic spectrum in his behaviour, and perceives the world entirely logically, like his favourite detective Sherlock Homes.  When a neighbour’s dog is killed, he sets out to solve the murder.

Gillian Flynn – Gone Girl – This tells the story of Nick, a man who becomes the main suspect when his wife mysteriously goes missing. Though he initially seems an unlikely killer, looks can be deceiving.  Tense thriller.

Emma Donaghue – Room – This novel of a boy and his kidnapped mother in extreme isolation is a great study for child development. A sensitive telling of a horrific story.

Meg Haston – Paperweight – a newish novel (2017) that follows 17-year-old Stevie’s journey as she struggles not only with her eating disorder and her guilt over her brother’s death. Mesmerising and sensitive.

Leslie McGill – Running Scared – another novel about an eating disorder, but quite different from Paperweight.

Finally, the best-ever fiction book written about addiction, written by Beatrice Sparks many years ago, Go Ask Alice ticks all the boxes for me.

Enjoy your reading, and maybe you have some recommendations?

 

 

 

 

 

What Options do we Have?

The first year of a new IB Diploma Psychology curriculum is almost ended, and next year, if you haven’t started already, you will be teaching/studying one (SL) or two (HL) options.  But which ones?  Most teachers will probably have chosen these already, and (hopefully) used some of the studies from the options while teaching the approaches.  But for those who are not yet certain, here are the pluses and minuses – as I see them – of each.

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