Unit 2: Biopsych Flashcards
The structure of a neuron :
- less than a mm to up to a m long
- cell body includes nucleus ( genetic material )
-dendrites protude from cell body and carry nerve impulses - the axon carries impulses away from cell body down length of neuron - covered in a fatty layer of myelin sheath which protects axon and speeds up the electrical transmission.
- myelin sheaths gaps allows it to do this if it was continuous it would have the opposite effect. speeds up by forcing transmissions to jump across the nodes of Ranvier.
- terminal buttons communicate with the next neuron.
What do the 3 types of neurons do ?
motor - connect CNS to effectors such as muscles and glands. short dendrites and long axons.
sensory - carry messages from the PNS to the CNS. long dendrites and short axons
relay - connects the sensory to motor neurons or other relay ones. short dendrites and short axons.
How many neurons are located in the brain ? and what are the 3 types?
80 billion
3 types:
- motor
- sensory
- relay
What is summation in postsynaptic neuron fire ?
- the excitatory and inhibitory influence on a particular neuron are summed if the net effect is inhibitory snd post synaptic neuron is less likely to fire and if it is excitatory it is more likely to fire
What is inhibition in neurotransmitters ?
when a neurotransmitter ( like serotonin ) increase the negative charge of the postsynaptic neuron. This decreases the likelihood that the neuron will pass on the electrical impulse.
What is excitation in neurotransmitters ?
when neurotransmitters ( such as adrenaline ) increases the positive charge of the post synaptic neuron. increasing the likelihood that the neuron will pass on the electrical impulse to the post synaptic receptor sites.
What is synaptic transmission ?
the process by which neighbouring neurons ( neural networks ) communicate with each other by sending chemical messages across the synapse that separates them.
when the chemical impulse reaches the end of the neuron ( the presynaptic terminal ) it triggers the release of neurotransmitters from tiny sacs called synaptic vesicles.
What are neurotransmitters ?
brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another. They can both perform an excitatory and inhibitory functions.
once the neurotransmitters crosses the synapse it is taken up by the postsynaptic receptor site ( dendrites of next neurons )
each neurotransmitters has its own specific molecular structure that fits perfectly into a post synaptic receptor site ( lock and key ). They also have specialist functions.
Changes associated with the parasympathetic state :
- decreased heart rate
- decreased breathing rate
- constricted pupils
- stimulates digestion
- stimulates saliva production
- relaxes rectum
What does the PNS do? and what are it’s 2 subsystems ?
transmits messages via neurons to and from the CNS
subdivided into :
- autonomic nervous system ( ANS ) - which governs vital functions such as breathing, heart rate, digestion, sexual arousal and the stress response.
- somantic nervous system ( SNS ) - controls muscle movement and receives info from sensory receptors.
What did Paul Broca identify in the 1860s about cognitive neuroscience?
identified how damage to an area of the frontal lobe ( Broca area ) could permanently impair speech production.
The endocrine system :
one of the body’s major info systems that instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs in the body.
the hormones:
- control vital functions
- acts slowly but has widespread affects.
- thyroid gland - thyroxine ( increases metabolic rates )
- pituitary gland - in brain - it controls the release of hormones from all other endocrine glands in the body.
How does the fight or flight response work ?
- endocrine + ANS work together
- first thing that happens is the hypothalamus triggers activity in the sympathetic branch of the ANS. The ANS changes from parasympathetic resting states to the aroused sympathetic state
- then adrenaline is released from the adrenal medulla ( a part of the adrenal gland ) into the blood. Thos triggers physiological changes like increased heart rate necessary for the fight or flight response - automatic response.
- once the threat was passed the parasympathetic nervous system returns to its resting state
- rest and digest response
What are 2 brain imaging techniques?
- fMRI
- PET scan
- ‘brain fingerprinting’
What is a genotype ?
the particular set of genes that a person has
What is a phenotype ?
the characteristics of an individual determined by both genes and the environment.
What are the 2 main functions of the nervous system ?
- to collect, process and respond to info in the environment
- to co-ordinate the working of different organs and cells in the body
What are the 2 sub-systems are the nervous system divided into ?
- central nervous system ( CNS )
- peripheral nervous system ( PNS )
What 2 parts are the CNS made up off ?
- the brain - centre of all conscious awareness ( cerebral cortex ) allows higher mental functions
- the spinal cord - extension of the brain. responsible for reflexes.
Changes associated with the sympathetic state ?
- increased heart rate
- increased breathing rate
- dilated pupils
- inhibits digestion
- inhibits saliva production
- contracts rectum
What does the Autonomic nervous system ( ANS ) do ?
transmits info to + from organs. operates automatically. divided into the parasympathetic and sympathetic sub-systems
What does the Somatic nervous system do ?
transmits info from receptor cells in sensory organs to the CNS. It also receives info from the CNS that directs muscles to act.
What does the CNS consist of ?
brain and the spinal cord
What does the PNS do ?
sends info to CNS from outside world and transmits these messages from the CNS to muscles and glands in the body.
What is the endocrine system ?
main info systems. it instructs glands to release hormones directly to the bloodstream and directed towards target organs
The main endocrine glands and where they are in the body ?
- hypothalamus ( CRH ) - links NS to ES
- pituitary ( ACTH ) - controls the release of hormones from other glands - master gland -
- thyroid ( thyroxine ) - modulates metabolism
- adrenals ( adrenaline ) - regulates the effects of the fight or flight response
- pancreas ( insulin ) - regulates blood sugar levels
- pineal ( melatonin ) - modulates sleep patterns maintaining day/night rhythms.
- thymus ( thymosin ) - stimulates the development of T cells in the immune system
- ovaries ( oestrogen ) - develops a secondary sexual characteristics in females
- testes ( testosterone ) - leads to development of secondary sexual characteristics in males.
Localisation of function :
the theory that different areas of the brain are responsible for different functions.
The motor area of the brain :
a region of the frontal lobe involved in regulating movement
The somatosensory area :
an area of the parietal lobe ( top section ) that processes sensory info such as touch
The visual area :
a part of the occipital lobe ( located at the back of the brain ) that receives and processes visual information.
The auditory area :
located in the temporal lobe ( bottom of brain ) and concerned with the analysis of speech-based info
Localisation vs holistic theory in the brain :
localisation states that different parts of the brain perform different tasks and are involved with different parts of the body.
Paul Broca and Karl Wernicke discovered this in the 19th century
before such investigations scientists generally supported the holistic theory of the brain - that all parts were involved in processing thought and action.
Hemispheres in the brain :
the brain is divided into two symmetrical halves. left side of your body is dominated by the right hemisphere vice versa. certain functions are dominated by a particular area this is called laterisation
The cerebral cortex :
outer layer of both hemispheres. its about 3mm thick. it separates us from other animals as it gives us higher function. it is grey hence grey matter
What does it mean for the homeostasis to be maintained ?
our internal environment is regulated by a balance between the sympathetic and parasympathetic systems
What is depolarisation ?
when excitatory neurotransmitters are detected by receptor in the post synaptic cell. when detected by these receptors the electrical charge becomes more positive and likely to fire. this is depolarisation.
What is hyper polarisation ?
when a inhibitory neurotransmitter is detected by receptors in the post synaptic neuron the charge becomes more negative meaning it is less likely to go through the process of reuptake. this is hyper polarisation
What does the structure of a neuron ensure ?
that signals are uni-directional meaning info can only be passed between the pre and post synaptic neurons in one direction.
Psychological and physical effects of adrenaline :
psychological:
- increased anxiety
- increased attention
- alertness
physical:
- increased blood flow to brain and skeletal muscles
- decreased blood flow to skin and the digestive and immune systems.
- dilated pupils
- faster breathing rate
What is the suprachiasmatic nucleus (SCN) ?
a bundle of nerve cells in the hypothalamus in each hemisphere of the brain. It is a primary endogenous pacemaker in mammals and is influential in maintaining circadian rhythms. It lies above the optic chiasm and receives info about light directly from it. A process which continues when your eyes are closed enabling the biological clock to adjust while we are asleep.
Animal studies about the suprachiasmatic nucleus :
- Patricia DeCoursey et al (2000) destroyed the SCN connection in the brain of 30 chipmunks who were then returned to their natural habitat and observed for 80 days. She found that their sleep/wake cycle dissapeared and many were killed by predators.
- Martin Ralph et al (1990) bred ‘mutant’ hamsters with 20 hour sleep wake cycles. When SCN cells from the foetal tissue of a mutant hamster were placed into the brain of a normal hamster their cycle defaulted to 20 hours.
both of these emphasise the role of the SCN in establishing and maintaining a circadian sleep wake cycle.
What does the pineal gland do ?
the SCN passes light info to the pineal gland, which is a pea like structure in the brain behind the hypothalamus. During the night the pineal gland increases its production of melatonin as it detects less light.
What does melatonin do ?
it is a chemical that induces sleep as is inhibited during times of wakefulness. It is also suggested to be connected to seasonal affective disorder.
Experiment on light being an exogenous zietgeber ?
Scott Campbell + Patricia Murphy (1998) demonstrate light may be detected by receptor sites on the body even when not received by the eye. 15 participants were waken at various times and a light pad was shone on the backs of their knees. This caused a deviation of 3 hours in the sleep/wake cycle in some cases.
Research on social cues being an exogenous zietgeber ?
Research suggests that schedules imposed by a parent on a child is a factor. As by about 6 weeks your circadian rhythm begins and at about 16 weeks most babies are entrained.
Evaluations of endogenous pacemaker and exogenous zietgebers ?
- ethics in animal studies
generalising findings to humans
animals were subjected to harm and risk when returned to natural habitat (DeCoursey et al (2000) )
whether what we learnt justifies this is up for debate - methodological issues in studies
findings from both Campbell and Murphy’s study have yet to be replicated. Other psychologists suggests that there may have been slight light exposure to p/pants eyes ( confounding variable ).
and isolating the exogenous zietgeber as a singular thing doesn’t give an insight into other influences and the extent to which these may interact. - interactionist synchrony
in real life pacemakers and zietgebers interact and it therefore makes little sense to separate the two for the purpose of research
What are ultradian rhythms ?
rhythms that occur more than once in 24 hours. Such as the stages of sleep.
What are infradian rhythms ?
rhythms that have a frequency of less than one cycle in 24 hours. Such as menstruation or seasonal affective disorder ( SAD )
How did psychologists recognise the stages of sleep ?
using an EEG scan
What are the 5 stages of sleep ?
1+2 = light sleep : brain wave patterns start to become slower ( alpha waves ) becoming even slower as sleep gets deeper ( theta waves )
3+4 = deep/slow wave sleep : difficult to wake. Involves delta waves which are even slower and have a greater amplitude than previous waves.
5 = REM sleep : body is paralysed and brain activity speeds up as if awake. REM stands for rapid eye movements, which we can see during this stage. Correlated with the experience of dreaming.
How long does each stage of sleep last ?
90 minutes
Example of research that demonstrates endogenous systems can be affected by exogenous zietgebers :
Kathleen Stern + Martha McClintock ( 1998 ) demonstrated that menstrual cycles may synchronised as a result of the influence of female pheromones. Showing despite it being a endogenous system it can be affected by exogenous factors.
Evaluations of the infradian and ultradian biological rhythms :
- Methodological limitations in synchronised studies
other factors could affect a womens cycle like : stress, diet changes, or exercise that could affect as confounding variables. meaning any correlation in McClintocks and Stern’s study could of occurred by chance.
it also relies on self report methods and has a small sample size.
Trevathan et al (1993) failed to find evidence for menstrual synchrony.
+ practical application - SAD
light box - resets melotonin. relieves symptoms in up to 60% of sufferers ( Eastman et al 1998 ) placebo ?
+ evidence supports the idea of distinct stages of sleep
dement and kleitman ( 1957 ) monitored sleep patterns of 9 adult p/pants in a sleep lab - brain waves recorded on a EEG scan.
REM activity highly correlated with dreaming - p/pants woken during REM sleep recalled dreams accurately.
despite the small sample this study suggests REM sleep is an important component of the ultradian sleep cycle
What is a circadian rhythm ?
a rhythm that lasts about 24 hours. For example the sleep/wake cycle.
Siffre’s cave study :
he had spent several periods underground to study the effects on his biological rhythms . derived from sound and light but with access to food and water . Siffre spent 2 months in caves of the southern alps and later 6 months in Texan caves. In each case his biological rhythms settled to just beyond 24 hours - around 25. He also continued to fall asleep and wake on a regular schedule.
Evaluations of circadian rhythms :
- poor control in studies
they still had access to artificial light. Charles Czeisler et al ( 1999 ) was able to adjust p/pants circadian rhythms from 22 to 28 hours using dim lights. - individual difference
Jeanne Duffy et al ( 2001 ) revealed natural preferences for rising early/ going to bed early and the opposite. There are also age differences in preferred sleep wake patterns.
+ practical application to shift work
given researchers knowledge of what happens when you disrupt your circadian rhythms. Like people do In shift work causing a rise in accidents ( Bolvin et al (1996) ) and being 3x more likely to develop heart disease (Knuttson (2003) ). This research into the sleep/wake cycle may have economic implications in terms of how to best manage workers productivity.
What are all the different methods of investigating the brain :
- electroencephalogram ( EEG )
- functional magnetic resonance imaging (fMRI)
- post mortem examinations
- event related potentials (ERP)
What is an electroencephalogram (EEG) ?
a brain scan that records the tiny electrical impulses produced by the brains activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain
What is functional magnetic resonance imaging ( fMRI ) ?
used to measure a brains activity while performing a task that uses MRI technology. Enabling researchers to detect which regions of the brain are rich in oxygen and thus are active.
What are event-related potentials
( ERP’s ) ?
The brains electrophysiological response to a specific sensory, cognitive, or motor event can be isolated through statistical analysis of EEG data.
What are post-mortem examinations ?
the brain is analysed after death to determine whether certain observed behaviours during the patients lifetime can be linked to abnormalities in the brain.
Evaluations of ways of investigating the brain :
fMRI’s
+ doesn’t use radiation, virtually risk free, non invasive, straightforward to use, images have high spatial resolution.
- expensive, only captures clear images if the patient is completely still, poor temporal resolution ( 5 sec lag ), only measures blood flow.
EEG’s
+ high temporal resolution, contributed greatly to our understanding of the stages of sleep.
- information is generalisable, doesn’t pin point the source of activity in the brain.
ERP’s
+ excellent temporal resolution as derived from EEG measurements, more specific than EEG’s
- in order to get pure date background noise must be eliminated ( not always possible )
Post Mortem’s
+ provided foundation for early understanding of key neural processes, Broca and Wernikes both relied on this.
- issues of causation, ethical issues of consent from patient before death or if they weren’t able to provided informed consent.
Sperry’s split brain research ( 1968 ) procedure :
a general procedure where an image or word was projected into a patients right visual field ( processed by left ) + the same or different projected into the left visual field ( processed by right ). In a ‘normal’ brain the corpus callosum would immediately share info between the hemispheres however with split brain patients the info could not be conveyed between hemispheres as they had undergone surgery to cut their corpus callosum as a treatment for severe epilepsy.
Sperry’s ( 1968 ) findings :
- describing what you see :
If shown in a patients right visual field it could be described but if shown in the left visual field it could not. This is due to the lack of language centres in the right hemisphere. - recognition by touch :
patients could not verbally label things in the left visual field but they could collect select a matching object from a bag using their left hand or one most closely related. Therefore they could understand what something was using the right visual field they just couldn’t verbalise it. - composite words :
if two words were presented simultaneously one either side of the visual field , key on left and ring of right. Patients would say the word ring but select a key with their left hand. - matching faces :
right hemisphere seems dominant in recognising faces.
What is hemispheric lateralisation ?
the concept that the 2 halves/hemispheres of the brain are functionally different and certain processes are controlled by one hemisphere and not the other, like language.
Evaluations of split brain research into hemispheric lateralisation :
- issues with generalisability
unusual and small sample - only 11
did epileptic seizures cause unique changes in the brain which may have influenced findings.
some participants experienced a more severe corpus collosum surgery than others - some participants brain hems were more disconnected
+ strengths of methodology
highly specialised and standardised procedure
image was only flashed onto the screen for 1/10 of a second so patients wouldn’t be able to glance over to other side of their visual field.
- differences in function may be overstated
modern neuroscientists would suggest the distinction is much more messy than this as behaviours typically associated with one hemisphere can be effectively performed by the other hemisphere if the situation requires it.
What happens to the brain during recovery ?
it starts to form new synaptic connections near to the area of damage. This process is supported by a number of structural changes in the brain including:
- axonal sprouting
- reformation of blood vessels
- recruitment of homologous ( similar ) areas of the brain on the opposite side to perform a specific task
Study on medical students brains developing :
Dragonski et al ( 2006 ) imaged the brains of medical students before and after their final exam learning induced changes occurred in the posterior hypo campus and parietal cortex.
Who studied London taxi drivers grey matter volume ?
Maguire et al ( 2000 ) they had a larger volume of grey matter in their hypocampus than the control group due to the ‘knowledge’ test they have to take.
Study seeing how being bilingual effects the brain :
Mechelli et al ( 2004 ) found a larger parietal cortex in the brains of those who were bilingual compared to matched monolingual controls.
Evaluations of plasticity and functional recovery of the brain after trauma :
+ support from animal studies
Hubel and Wiesel ( 1963 ) sew one eye of a kitten shut and analysed the brains cortical response. Found that the visual cortex area associated with the shut eye wasn’t idle as predicted by continued to process info from the open eye.
+ the concept of cognitive reserve
Schneider et al ( 2014 ) the more time brain injury patients spent in education the greater the chance for a disability free recovery. 2/5 patients who achieved this had more than 16 years of education compared to 10% who had less than 12 years in education.
- negative plasticity
it can have maladaptive behaviour consequences . 60-80% of amputees develop phantom limb syndrome due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss (Romachamdreun and Hirstein 1998)
What is the auditory area ?
located in the temporal lobe and is concerned with the analysis of speech based info
What is the motor area ?
a region of the frontal lobe involved in regulating movement
What is the somatosensory area ?
an area in the parietal lobe that processes sensory info like touch
What is the visual area ?
a part of the occipital lobe that receives and processes visual info
What is the Broca area ?
an area in the frontal lobe of the left hemisphere responsible for speech production
What is the Wernikes area ?
an area in the temporal lobe go the left hemisphere responsible for speech comprehension.
Evaluations of the localisation of function in the brain :
- plasticity
the brain appears to be able to reorganise itself to recover lost functions - recovered stroke victims
+ neurosurgical evidence
the practise of surgically removing areas of the brain to control behaviour was developed in the 1950s in the form of lobotomys a process we still use today. Dougherty et al ( 2002 ) 44 OCD patients undergone a cingulatomy after 32 weeks 1/3 had a successful response and 14% had partial success. Suggesting localisation of behaviours associated with serious mental disorders.
+ Phinease Gage
a meter length pole went through his left cheek passing behind his left eye and exiting his skull taking a portion of his frontal lobe with it . He survived but this accident changed his personality. Suggesting that the frontal lobe may be responsible for regulating mood.
What is the suprachiasmatic nucleus ( SCN ) ?
a tiny bundle of nerve cells in the hypothalamus . it is a primary endogenous pacemaker and is influential in maintaining circadian rhythms such as the sleep wake cycle. It lies just above the optic chiasm and receives info about light from it enabling our biological clock to adjust even when our eyes are closed
