Psych Biological Approach - brain

Techniques to Study the Brain

MRI (Magnetic Resonance Imaging)

• high resolution, three dimensional image of brain structure

FMRI (Functional Magnetic Resonance Imaging)

• Unlike structural imaging techniques, fMRI allows us to see brain processes (blood flow, levels of oxygen, etc)

Both apply a very strong magnetic field to the brain

Neuroplasticity

Refers to the brain's ability to adapt by forming new connections as a result of experience, learning, or following an injury. Reasons for change are both genetic and environmental - as a result of experience

Neural branching

• Nerve cells grow and form new branches

Neural pruning

• Connections between neurons become broken if they are not used.

Localization of function

Specific brain regions have specific functions related to specific behavior

(However, there are many parts of the brain that deal with memory)

Neurotransmitters

Neurons communicate with each other via electrochemical signals called neurotransmitters

The nervous system functions by transmitting electrical impulses along neurons, which then trigger chemical signals at synapses to communicate with other neurons, muscles, or glands.

Hormones - Oxytocin

Oxytocin is a hormone that is synthesized in the hypothalamus and released into the bloodstream by the pituitary gland

It has been referred to as the “love hormone”, the “bonding hormone”, and the “cuddle chemical”

It plays a role in sexual reproduction, childbirth and social bonding

In humans, it’s released during orgasm, labor contractions, breast feeding, hugging, and skin to skin contact 

Evolutionary explantation for disgust

Disgust is not only a response to potential sources of physical harm, such as diseases, but it can also extend to behaviors or objects associated with out-groups or strangers. Our immune system is designed to develop resistance to pathogens it has encountered before, so we are more vulnerable to new or "novel" pathogens carried by members of an out-group.  

In intergroup conflict, the feeling of disgust towards out-groups can contribute to a sense of aversion or avoidance. Sharing personal items, like a toothbrush, is an intimate act, and individuals may feel a heightened level of disgust or discomfort when contemplating such actions with members of an out-group.  This emotional response can serve as a psychological mechanism reinforcing social boundaries and promoting in-group cohesion.

Maguire et al (2002) - techniques to study the brain, localization, and neuroplasticity

A) Investigate the relationship between taxi driving experience and hippocampal size.

M) Took 16 right-handed taxi drivers with an average of 14.3 years of experience vs. 50 people who didn’t drive taxis (control condition).

Performaed brain scans using MRis.

R) Found that taxi drivers had a larger posterior hippocampus but a smaller anterior hippocampus. There was no difference between the groups in terms of the general volume of the hippocampus, but there was significant redistribution of grey matter from the anterior to posterior hippocampus in the brains of taxi drivers.

Greenstein et al (2006) - neuroplasticity

A) Longitudinal study of the relationship between cortical structure and intelligence

M) Took 307 children between 6-19 years old and divided them into 3 groups based on IQ tests, low intelligence, average intelligence, and superior intelligence.

Did 2-3 MRI scans over the course of the study

R) Found no relation between coritical thickness and IQ, but found that smarter kids had a rapid period of cortical thickening in frontal lobes due to neural branching and then a rapid reduction of cortical size as they matured due to neural pruning.

Ultimately found that cortical thickness changes with age, but happens at a more rapid pace for children of higher IQ.

Milner’s study of HM - Localization of function, techniques to study the brain

HM had an accident when he was young resulting in epileptic seizures. An experimental surgery to stop these seizures was a lobotomy of his temporal lobe, severely damaging his hippocampus.

This resulted in memory loss, making it so he was unable to recall the recent past or create new memories, despite his memories still being intact from before the surgery. He had partial retrograde amnesia.

Milner studied HM by having him carry out IQ tests, interviews, and cognitive tests.

Found that he could create procedural memories, learning tasks, but not episodic memories. Concluded that hippocampus was responsible for transferring short-term to long-term memories.

Fisher et al (2005) - Neurotransmitters

A) Investigate brain activity in early stage intense love

M) Took 10 men and 7 women who were currently “intensely in love” (but not with each other) were recruited for the study by word of mouth as well as through flyers.

All participants were placed in an FMRI and for 30 seconds each participant viewed a photograph of their lover, then given a 40 second filler activity, then showed a photo of a casual acquaintance for 30 seconds

R) When looking at photos of their lover, participants showed higher activation in dopamine-rich neural systems, primarily the ventral tegmental area (VTA) and caudate nucleus.

Dopaminergic activity is associated with motivation and feelings of pleasure. In this way, dopamine activity in the brain plays a role in romantic love.

Curtis et al (2004)

A) To determine if disgust was an evolutionary behavior that evolved as a survival instinct.

M) Volunteers completed a survey online. There were about 40,000 participants from 165 countries.

Data was gathered in a survey placed on the BBC Science website. First, participants were asked a series of demographic questions, such as age, sex and country of origin. Then they were asked to rate 20 photographs for disgust on a scale from 1 to 5. These photographs were similar pairs of digitally manipulated stimuli - on of the photographs in the pair was disease - salient and the other one less salient. The more of a stranger the less people wanted to share a toothbrush e.g. Least likely to share a toothbrush with postman (59%)

R) Ratings of disgust in response to disease salient stimuli were higher than ratings of disgust towards similar stimuli that were digitally manipulated to be less disease salient. Results were consistent across cultures. Results were more pronounced amongst females. Ratings of disgust in response to disease salient stimuli declined with age. Disgust related to strangers → more likely to carry novel pathogens and hence present a greater disease.

Schneiderman (2014)

A) to investigate the relationship between oxytocin levels and self reported feelings of romantic attachment and observational pair-bond behavior

M) Mixed method longitudinal study using 163 western university students

“New Lovers”: (60 heterosexual couples) Average age (22-25 years)

“Singles”: 43 participants Avg age: 24

Measure 1: Levels of plasma (blood) oxytocin

Measure 2: Self-reported interviews: alone (Romantic Couples Interview)

Measure 3: pair-bond observations: Mins. (scored 1-5)

Measure 4: relationship status 6 months later

R) New lovers had significantly greater oxytocin levels than singles

Couples with higher levels of oxytocin stayed together (6 months later) more often than couples with low oxytocin

High oxytocin= higher levels of interactive reciprocity in the observation (r= 0.29)