What are the divisions of the nervous system
CNS
PNS- Somatic Nervous System
- Autonomic nervous system- sympathetic, parasympathetic
What makes up the cns?
the brain and the spinal cord
The brain has two hemispheres and cerebral cortex
The spinal cord is responsible for reflex actions
What does the peripheral ns do?
transmits messages to and from the CNS
What is the role of the somatic NS
controls muscle movement
received info from sensory receptors
what is the role of the autonomous NS?
governs vital functions in the body, such as breathing, heart rate, digestion
Name 7 glands in the endocrine system
Hypothalamus Pituitary Thyroid Adrenals Pancreas Ovaries Testes
What is the role of the pituitary gland?
It is located in the brain
Controls the release of hormones from all other endocrine glands in the body
What hormone does the thyroid gland produce?
Thyroxine
This affects the cells in the heart, and increase metabolic rates, affecting growth rates
Name a hormone the adrenal gland produces
Adrenaline
Part of the bodies immediate stress response system
strong effect on the cells of the cardiovascular system
part of the fight or flight response
Describe the fight or flight response
stressor - hypothalamus triggers activity in the sympathetic branch - adrenaline realised from adrenal medulla- physiological changes - parasympathetic returns body to resting state
describe a sensory neuron
carries messages from pns to cns
long dendrites
short axons
describe a relay neuron
connects sensory neurons to motor neurons
short dendrites
short axons
describe a motor neuron
connects cns to muscles and glands
short dendrites
long axons
how big can neurons be?
a mm to a metre long
what makes up a neuron?
soma (cell body)- has a nucleus
dendrites carry impulses towards cell body
axons carry impulses away
myelin sheath protects axon and speeds up impulse
nodes of ranvier - gaps in the myelin sheath, , speeds up impulse
terminal buttons- communicate with next neuron in the chain across a synapse
what is action potential
when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential
What is a synapse
the gap between two neurones
how are signals between neuroma transmitter compared with inside neurons
chemically by synaptic transmission, electrically within the neuron
what happens when an electrical impulse reaches the end of the neuron (presymaptic terminal)
triggers the release of neurotransmitter from synaptic vesicles which leave the presynaptic nerve terminal and is taken up by the post synaptic receptor sites
give an example of a neurotransmitter
serotonin
acetylcholine- found where a motor neuron meets a muscle, on its realise , muscles contract
what is meant by excitatory and inhibitory
excitation- when a neurotransmitter increases the positive charge of the post synaptic neuron
inhibition- when a neurotransmitter makes the charge more negative
What is localisation of function in the brain?
the theory that different areas of the brain are responsible for different behaviours
what is the outer layer is the hemispheres called?
cerebral cortex
what is the motor area
voluntary movement in opposite sides of the body
back of frontal lobe
what is the somatosensory area
sensory info from skin is represented
separated from motor area by the central sulcus
front of parietal lobe
what is the visual area?
each eye sends info from eight visual field to left visual cortex and vice versa,
damage to left hemisphere can produce blindness in parts of the right visual field in both eyes
occipital lobe
where are the language areas of the brain restricted to?
the left side
what is broca’s area
left frontal lobe responsible for speech production
damage caused Broca’s aphasia, such as patient Tan
What is Wernicke’s area?
Left temporal lobe
Responsible for language comprehension
Evaluation of localisation if function in the brain
Brain scan evidence
What did Petersen et al (1988) find?
Used brain scans
showed how Wernickes area was active during listening tasks
Broca’s area active during a reading task
Evaluation of localisation if function in the brain
Brain scan evidence
What is Tulving et al (1994) find?
Revealed that semantic and episodic emperors are in different areas of the pre-frontal cortex
Evaluation of localisation if function in the brain
Neurosurgical evidence
What did Freeman do?
developed lobotomy (1950s)
severing connections in frontal lobe to control aggressive behaviours
Evaluation of localisation if function in the brain
Neurosurgical evidence
What is Dougherty et al (2004) find?
44 OCD patients
underwent a cingulotomy
after 32 weeks- 1/3 met criteria for a successful response, 14% for a partial response
Evaluation of localisation if function in the brain
Case study evidence
Who was Phineas Gage?
in 1848, a metre length pole went through his head , taking a portion of his brain (left frontal lobe)
turned quick tempered and rude
Evaluation of localisation if function in the brain
Evidence against
what did Lashley find?
removed different areas (10-50%) if the cortex in rats that were learning a maze
no area was proven to be any kore important
learning apeared to require every part of the cortex
what is plasticity?
the brains tendency to change and adapt as a result of learning and experience
what is functional recovery?
following damage, the brains ability to redistribute or transfer functions
what is synaptic pruning?
synaptic connections peak at 15,000 at age 2-3
rarely used connections are deleted and frequently used ones are strengthened
Plasticity
What did Maguire et al (2000) research and find?
London taxi drivers brains have significantly more grey matter on the posterior hippocampus (the development of spatial and navigational skills)
Plasticity
What did Draganski et al (2006) find?
images brains of medical students 3 months before and after final exams
learning-induced changes occyred in posterior hippocampus and parietal cortex
Plasticity
What did Mechelli et al (2004) find?
Larger parietal cortex in bilingual people
What is spontaneous recovery?
functional recovery occurring quickly after trauma
slows down after a few weeks
how does functional recovery work?
new synaptic connections are made , secondary neural pathways are activated to enable functioning
Functional recovery
What changes in the brain?
axonal sprouting - growth of new nerve endings
reformation of blood vessels
recruitment of homologous areas
Evaluation of plasticity and functional recovery
practical application
what did research contribute to?
Neurorehabilitation - use of movement therapy and electrical stimulation of the brain
Evaluation of plasticity and functional recovery
Negative plasticity
What is negative about plasticity ?
60-80% of amputees develop phantom limb syndrome - due to cortical reorganisation in somatosensory cortex
Evaluation of plasticity and functional recovery
Age and Plasticity
What did Bezzola et al (2012) find?
40 hours of gold training caused nerve changes in the neural representation of movement in the participants ages 40-60
using fMRI researchers observed reduced motor cortex activity in novice golfers
Evaluation of plasticity and functional recovery
Cognitive research
What did Schneider at al (2014) research?
the more time brian injury patients spend in education, the greater chance of a disability free recovery
2/5 of patients who achieved DFR has more than 16 years of education, compared to 10% of less than 12 years
what is split brain research?
a series of studies involving epileptic patients who had experienced a surgical separation of the hemispheres
what is hemispheric lateralisation?
the idea that 2 halves of the brains are fundamentally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other
What did Sperry (1968) research?
Split- brain studies
Corpus callousness cut to control frequent and severe seizures
What was the procedure of Sperrys studies?
image projected into a patients right visual field and another of the left
What was the findings of Sperrys studies?
Lack of language centres in the right hemisphere meant that only a picture shown in the right visual field they could describe
able to select a matching object with left hand but now able to say it
Evaluation of split brain research
Demonstrated lateralised brian functions - left the analyser, right the synthesiser
strengths of methodology -
standardised and well controlled
theoretical basis -
promoted debate about 2 hemispheres in everyday functioning , Pucetti- two minds
Generalised
WAYS OF INVESTIGATING THE BRAIN
What is fMRI?
3D images and detects changes in blood oxygenation and flow that occur due to neural activity
shows which part of the brain are involved in mental processes
WAYS OF INVESTIGATING THE BRAIN
what is an EEG?
measures electrical activity in the brain via electrodes
unusual arrhythmic patterns of activity may indicate neurological abnormalities , eg epilepsy
WAYS OF INVESTIGATING THE BRAIN
What is an ERP?
ERPs use statistical averaging techniques , and all extraneous brain actitovy from an EEG is filtered out
What are event related potentials?
types of brain waves that are triggered by particular events
WAYS OF INVESTIGATING THE BRAIN
What are post-mortem examinations?
looking at the brain after death of people with rare disorders and compares with a neurotypical brain
What are the strengths of an fMRI?
doesn’t rely on radiation
non invasive
high spatial resolution
What are the weaknesses of an fMRI?
expensive
person has to stay still
poor temporal resolution
only measures blood flow
What are the strengths of EEG?
invaluable diagnosis of epilepsy
contributed to a better understanding of sleep
high temporal resolution
What are the weaknesses of EEG?
generalised info
low spatial resolution
What are the strengths of ERPs?
temporal resolution
Been able to identity many ERPs and describe precise role in cognitive functioning
what are the weaknesses of ERPs ?
lack of standardisation
difficult to completely eliminate extraneous variables
What are the strengths of post mortems?
vital in providing a foundation for early understanding of key processes, (broca and wernicke)
improve medical knowledge
what are the weaknesses of post-mortems?
correlation ≠ causation
ethical issues of informed consent
What is a biological rhythm?
distinct patterns of changes in body activity that conform to cyclical time periods
What are circadian rhythms?
24 hours cycles
regulates a number of body processes, such as the sleep/wake cycle
What are biological rhythms governed by?
endogenous pacemakers
exogenous zeitgebers
What was Siffre’s cave study?
2 months in a cave deprived of natural light and sound
resurfaced in mid-september but believed it to be mid- august
his free running biological rhythm settled down to just beyond 24 hours
What was Aschoff and Wever’s study?
participants spent 4 weeks in a WW2 bunker
all but one participant displayed a circadian rhythm of between 24 and 25 hours
What was Folkard et als study?
12 people in a dark cave for 3 weeks
researchers sped up the clocks for a 24 hour day was now 22 hours
only one participant was able to keep up
Evaluation of circadian rhythms
Practical application shift work
Night workers concentration reduced around 6am
shiftwork and poor health- 3x more likely to develop heart disease
May have economic implications on managing workers productivity
Evaluation of circadian rhythms
Practical application - drug treatments
effect on pharmacokinetics (the action of drugs on the body and how well they are absorbed)
research revealed how they are peak times when drugs will be more effective
led to development of guidelines to do with timing and drug dosing
Evaluation of circadian rhythms
Use of case studies/ small samples
not representative
Siffre re-did his cave study aged 60, found his internal clock ticked much more slowly
evaluation of circadian rhythms
individual differences
Duffey et al- revealed some people have a preference to go to bed early and wake up early (larks) and the opposite (owls)
Czeisler et al- individual cycles can vary from 13-65 hours
What is an infradian rhythm?
a type of biological rhythm
frequency of less than one cycle every 24 hours
eg menstrual cycle
What is an ultradian rhythm?
frequency of more than one cycle in 24 hours
eg stages of sleep
What is the menstrual cycle?
28 days
oestrogen releases an egg
progesterone makes womb lining thicker
What did Stern and McClintock find and study?
synchronisation due to pheromones
29 women, 9 samples taken from different stages of the cycle
68% experienced changes which bought them closer to the odour donor
What is SAD
seasonal affective disorder
depression
circannual
What causes SAD?
the pineal gland secretes melatonin until an increase in light, in winter, less light in mornings so secretion of melatonin for longer, inhibits serotonin production
What are the stages of sleep?
stage 1+2 : light sleep, easily woken, alpha and theta waves
stage 3+4: delta waves, deep sleep
stage 5 + REM: body is paralysed, rapid eye movement, brian activity speeds up, dreaming
Infradian and ultradian rhythms evaluation
Evolutionary basis of menstural cycle
pregnant same time, newborns cared for collectively, greater chance of survival
however
Schank argued if too many cycles together, produce competition for highest quality male so evolutionary disadvantage
infradian and ultradian rhythms evaluation
methodological limitations in synchronising studies
too many factors affect cycles - stress, diet
small samples
any patterned is no more than what would have been expected by chance
infradian and ultradian rhythms evaluation
evidence supports idea of distinct stages of sleep
Dement and Kleitman- sleep patterns of 9 p.s , REM correlates with dreaming and brain activity varied to how vivid dreams were
replications found similar findings
infradian and dan ultradian rhythms evaluation
Practical application: SAD
phototherapy
stimulates very strong light in morning
reseats melatonin levels
60% of sufferers symptoms relieved
What is the suprachiasmatic nucleus?
an endogenous pacemaker
bundle of nerve cells in hypothalamus
sits about optic chiasm
receives info about light
Shat did DeCoursey study and find?
destroyed SCN connections in 30 chipmunks
sleep/ wake cycle disappeared
significant proportioned killed by predators
What did Ralph et al find and study?
hamsters with 20 hour cycle
when SCN cells from them were transplanted into normal hamsters, these hamsters defaulted to 20 hours
What is the pineal gland?
during night, pineal gland increases production of melatonin , which is the hormone that induced sleep
What did Campbell and Murphy study and find?
light may be detected by skin receptor sites on body
15 participants woken up during sleep with light pads shone on the back of knees
What are social cues?
an exogenous zeitgeber
by 16 weeks old, babies are entrained
adult determined mealtimes and bedtimes
How can someone beat jet lag?
adapting to local times for eating and sleeping, entrains circadian rhythms
EVALUATION OF ENDOGENOUS PACEMAKERS AND EXOGENOUS ZEITGEBERS
Beyond the master clock
Peripheral oscillators found in adrenal glands, lungs, skin
highly influenced by SCN but can act independently
EVALUATION OF ENDOGENOUS PACEMAKERS AND EXOGENOUS ZEITGEBERS
Damiola et al
changing feeding patterns in mice can alter circadian rhythms of liver cells by up to 12 hours
EVALUATION OF ENDOGENOUS PACEMAKERS AND EXOGENOUS ZEITGEBERS
Ethics in animal studies
animals exposed to harm
EVALUATION OF ENDOGENOUS PACEMAKERS AND EXOGENOUS ZEITGEBERS
Influence of exogenous zeitgebers may be over stated
Miles et al: blind man with a circadian rhythm of 24.9 hours
despite expire to social cues , his sleep/wake cycle could not be adjusted
