Biopsych

How does the peripheral nervous system divide

Automatic and somatic nervous

How does the automatic nervous system divide

Sympathetic and Parasympathetic nervous systems

Component of CNS

Brain and spinal cord

Function of the brain

Centre of conscious awareness

Cerebral cortex (outer layer) highly developed, separates humans and animals

Function of spinal cord

Extension of brain, responsible for reflex actions

Passes information to peripheral NS

Function of peripheral nervous system

Sends information to CNS from world

Transmits information from CNS to muscles and glands

Function of somatic nervous system

Associated with voluntary movement

Sends info to CNS from sensory receptors, send info from CNS to muscles

Function of automatic nervous system

Sends information to and from internal organs, operates involuntarily

Function of sympathetic nervous system

Responding to dangerous/ stressful systems, FIGHT OR FLIGHT

Function for parasympathetic nervous systems

Known as rest and digest, state body returns to after being in a stressed situation

What is the endocrine system

Information system of glands and hormones that works through the bloodstream

Key hormone glands

Hypothalamus, pituitary (brain)

Thyroid (neck)

Adrenals, pancreas (trunk)

Ovaries, testes (sex organs)

The master gland

Pituitary = Controls the release of hormones from all other endocrine glands in the body

Triggering of fight or flight

Hypothalamus triggers activity of sympathetic NS

Adrenaline released from adrenal medulla and triggers physiological changes

Leaving fight or flight

Parasympathetic NS returns body to resting state, PNS actions are antagonist of SNS

PNS reduces activities in body that were triggered by SNS and adrenaline

Sensory Neuron

Carry info from PNS to CNS

Long dendrites and short axons

Relay Neuron

Connect sensory neurons to other relay or motor neurons

Short dendrites and short axons

Motor Neurons

Connect CNS to effectors (muscles and glands)

Short dendrites and long axons

Cell body of a neuron

Includes a nuclear, genetic information of the neuron

Dendrites of neuron

Carry electrical impulse towards the cell body from neighbouring neurons

Axon of a neuron

Carry the impulse away from cell body to other neurons

Covered in myelin sheath

Myelin sheath of neuron

Fatty layer than protects the axon and helps speed up the electrical impulse

Segmented by nodes of ranvier

Nodes of ranvier in neuron

Gaps within the myelin sheath, force the impulse to jump across the gaps

Without gaps, the impulse is slowed

Electrical transmission between neurons

Resting neuron = Negative charged inside compared to outside

Stimulated neuron = Positive charge on inside, for split second, causes action potential

Neuron VS Synpase : Method of transmission

Signals within neurons are electrical

Signals between neurons, aka across a synapse, are chemical

Synaptic transmission

Electrical impulse reaches end of neuron (presynaptic terminal), triggers release of neurotransmitters from synaptic vesicles

Neurotransmitter crosses gap and taken up by post synaptic receptor sites

Message converted from chemical to electrical

Function of neurotransmitters

Relay message across synapse

Each neurotransmitters has specific molecular structure to fit to the post-synaptic receptor site

Each neurotransmitter has a specific function

Excitation

Excitation = Increasing positive charge of neighbouring neuron

Adrenaline causes excitation , increases positive charge of neighbouring neuron and increase chance the neighbouring neuron will fire and continue the impulse

Inhibition

Inhibition = Decrease the positive charge of neighbouring neuron

Serotonin causes inhibition when received by neuron, makes it negatively charged and less likely to fire

Summation

Excitatory and inhibitory influences from neurotransmitters are summed up

If net effect is inhibitory, post-synaptic neuron is less likely to fire

If net effect is excitatory, post-synaptic neuron more likely to fire

Action potential is only triggered is summation of signals reaches a threshold

Define localisation of function

Theory that different areas of the brain are responsible for different behaviours, processes or activities

Who were key names in developing localisation theories

Broca and Wernicke

How do hemispheres in the brain work

Left hemisphere controls right side of the body, right hemisphere controls left side of brain

Cerebral cortex

Outer layer of both hemispheres, about 3mm thick

Much more developed in humans than in animals

Motor cortex

Back of the frontal lobe, both hemispheres

Controls voluntary movement

Somatosensory cortex

Front of both parietal lobes, separated from motor cortex by the central sulcus

Responsible for sensory information from skin, amount of area devoted = its sensitivity

Visual cortex

Occipital lobe, right visual field to left lobe, left visual field to right lobe

Auditory cortex

Both temporal lobes

Analyses speech based information

Broca’s Area

Small area in left frontal lobe, responsible for speech production

Damage = Broca’s Aphasia = laborious speech, lacks fluency

Wernicke’s area

In the left temporal lobe, responsible for language comprehension

Damage = Wernicke’s aphasia = Nonsense, but fluent, speech

EVAL : Evidence for localisation

Peterson et al : Brain scans to show how Wernicke’s was active in listening, and Broca’s active in reading

Tulving et al : Episodic memory in right prefrontal cortex, semantic memory in left prefrontal cortex

EVAL : Neurosurgical evidence

Dougherty et al: Cingulotomy on 44 OCD patients, 32 weeks after 1/3 ptp has successful response

EVAL: Phineas Gage

Tempering iron through his left frontal lobe, personality had a complete 180 turn

EVAL: Lashley’s Research on holistic

Removed 10-50% of the brains of rats running mazes

No area proven to be more important in the rats process to learning the mazes

Define brain plasticity

Tendency to change and adapt as a result of experiences and learning

Childhood brain growth

Gopnik et al : Ages 2/3, each neuron has around 15,000 synaptic connections

As we age, the connections we rarely use get deleted and the ones frequently used are strengthened = synaptic pruning

Early attitudes to development of brain

Early thoughts = Changes were restricted to the developing brain and that the adult brain was fixed in function and structure

Research in plasticity : Maguire et al

Studied brains of London taxi drivers, found much higher volume of grey matter in posterior hippocampus than matched control group

Posterior hippocampus = Area associated with spatial and navigational skills

Longer they had been in job, more pronounced the structural differences

Research into plasticity : Draganski et al

Imaged brains of med students 3 months before and after final exams

Learning induced changes in posterior hippocampus and parietal cortex

Functional recovery after trauma

Unaffected areas often adapt and compensate, even taking over functions

Neuroscientists suggest this can occur quickly first after trauma and then slowly

What happens to brain in recovery

Rewire and reorganise by forming synaptic connections close to damaged area

Secondary neural pathways not typically used are activated to enable functioning

3 key things that occur in brain recovery

Axonal sprouting : New nerve endings grow to connect with undamaged nerve cells

Reformation of blood vessels

Recruitment of homologous areas: Areas in opposite hemisphere can overcompensate for lack in one hemisphere

EVAL: Practical application of plasticity

After injury, recovery slows down after weeks, so therapy is need to maintain the improvements e.g. movement therapy or electrical stimulation

EVAL : Negative plasticity

Retiring can have negative consequences

Medina et al: Prolonged drug use can result in poor cognitive function and increased risk of dementia

Ramachandran and Hirstein: 60-80% of amputees develop phantom limb syndrome, causing pain. Thought to be as a result cortical reorganisation

EVAL : Age and plasticity

Generally as age increases, plasticity decreases

Bezzola et al : Golfers 40-60 years old took 40 hours of golf training. FMRIs showed lower activity in motor cortex in novice group vs control. Suggests they had more efficient neural representations after training

EVAL: Support from animal studies

Hubel and Wiesel : Sewed one eye shut of a kitten, the visual cortex of the shut eye was not idle but processing information from the open eye

EVAL : Cognitive reserve and disability free recovery

Schneider et al : In people with brain injuries, those that had spent more time in education has a greater chance of disability free recovery.

40% of participants that achieved DFR had more than 16 years education compared to 10% that had less than 12 years

Define Hemispheric Lateralisation

Two hemispheres of the brain are functionally different and certain mental processes and behaviours are controlled by one hemisphere

Split Brain research

Sperry : All participants had undergone a commissurotomy, corpus callosum has been cut down the middle and the hemispheres weren’t connected

Sperry: Procedure

Image or word projected in ptp right visual field

Same or different word projected in left visual field

Sperry Findings : Describe what you see

Picture in right visual field = Describe easily (left hemisphere process, speech is in left)

Picture in left visual field = Could not describe what it was, some said nothing (right hemi processes, no speech centre)

Sperry Findings: Recognition by touch

Object placed in left visual field (RH), could not verbally match, BUT could select a matching object, or an object with association, with their left hand (RH), when the objects were behind a screen

Sperry Findings: Composite words

Two words, one in each visual field e.g. key in left visual and ring in right visual

Participant would grab object from left visual field with their left hand (both controlled by right hemi) but say the word in their right visual field

E.g. participant would grab the key with their left hand and say the word ring

Sperry Findings: Matching faces

Individual asked to match a face to series of other faces.

Picture processed by left visual field (right hemisphere) consistently selected but images in right visual field (left hemisphere) consistently ignored

When composite face (two separate halves) presented, one half to a visual field, right visual (left hemisphere) would be properly described and left visual (right hemisphere) would be selected as matching image

EVAL : Sperry demonstrated lateralised function

Produced research with valid conclusion (left hemisphere geared to analytic and verbal task, right hemisphere adept at spatial tasks)

Sperry research was key in understanding brain processes

EVAL : Sperry’s methodology

Highly specialised and standardised procedure

Participants stare at fixation point, image flashes up for 0.1 second so eyes could not move across their half of image

Allowed Sperry to vary aspects methodically and ensure information limited to one hemisphere

EVAL : Theoretical basis of Sperrys work

Sperry’s work prompted theoretical debate about communication between hemispheres

E.g. Pucetti : Duality of brain, we are in effect two minds

EVAL : Problems with generalisation of Sperry

Unusual sample, small sample (11 people) took part in all variations, all had history of seizures

Can be argued participants have unique changes in the brain that influence findings

EVAL: Over simplifications of findings

Overemphasis and oversimplification of hemispheres

Modern neuroscientists argue distinction of “verbal” and “non-verbal” hemispheres is not as clear cut

In regular brain, the hemispheres communicates in everyday tasks and behaviours associated with one hemisphere can be equally performed by the other

Ways of investigating the brain

FMRI, EEG, ERPS, post mortems

fMRIs

Detect changes in levels of blood oxygenation to areas of the brain, More oxygen indicates more activity

Produces 3D images

EVAL: fMRIs positive

Does not rely on radiation, virtually risk-free, non-invasive

Very high spatial resolution

EVAL: fMRIs negative

Poor temporal resolution, 5 second time lag

Comparatively expensive

EEG - Electroencephalogram

Measures electrical activity via electrodes, brainwave patterns provide overall account of activity

Used as diagnostic tool for unusable patterns of activity

EVAL: EEG positives

Diagnostic tool e.g. epilepsy, random burst of activity

Contributes to understanding of sleep

High temporal resolution, detects activity up to a single millisecond

EVAL: EEG negatives

Generalised nature of information, cannot pinpoint exact source of activity

Does not distinguish between activities in adjacent locations

ERPs- Event related potentials

Use of statistical averaging techniques, extraneous brain activity can be filtered out

ERPs are the remaining brain activity, directly related to the event

EVAL: ERPs positive

Much more specificity than ERPs

Same good temporal resolution as EEGs

Different ERPs can describe precise cognitive functions

EVAL- ERPs negative

Lack of standardisation in methodology

In order for ERP to be pure data, they have to eliminate all other data, which is hard to achieve and isolate

Postmortems

Areas of damage in the brain are examined as causes of death or affliction in the brain

Compared to neurotypical brains

EVAL: Postmortem positives

Foundation of early understanding for key processes of brain e.g. Broca’s and Wernicke’s area

Improve medical knowledge and generate hypotheses

EVAL: Postmortem negatives

Causation: Damage to the brain may not be linked to deficits, or even have caused them

Ethical issues of consent, some individuals may not be able to provide informed consent

What is a circadian rhythm

A biological rhythm that lasts 24 hours

Siffre’s cave study : what did he do

Spent two months underground without natural light

Spent 6 months underground without natural light

Siffre’s Cave Study : What did he find

His free-running biological clock settled to just beyond 24 hours, closer to 25 hours

Other circadian rhythm studies

Aschoff and Weber

Folkard et al

Aschoff and Weber

PPTs spend 4 week deprived of natural light

Majority sleep/wake cycles extended to 24-25 hours

Folkard et al

12 people in cave for 3 weeks, using clock to mark there sleep and wake times

Researchers sped up clock so days were 22 hours

Only 1 PPT adjusted to regime

EVAL : Application to shift work

Boivin et al : Reduced concentration at 6am for those on shift work

Knutsson : Shift workers are 3X more likely to develop heart issues

RESEARCH INTO SLEEP/WAKE CYCLES CAN BE PRACTICALLY APPLIED

EVAL: Application to drug treatment

Certain peak times are when drugs are most effective

Led to guidelines for timing of drug dosing

EVAL : Case studies and small samples

Individuals and small groups = Not necessarily representative of larger population

Siffre was 60yo during one of his studies ∴ his internal clock works slower

EVAL: Siffre’s control

Had an artificial lamp turned on when he was awake

Other studies (Czeisler et al) adjusted their PPT sleep schedules with the use of dimming lights

What is an infradian rhythm

Less than one cycle occurs within 24 hours

Examples of infradian rhythms

Menstrual cycle, SAD

Menstrual cycle : Infradian

Lasts 24-35 days

Research into menstrual cycle for infradian: Stern and McClintock

Showed exogenous factors can cause synchrony within women

Collected pheromones from 9 women in different stages, coated in alcohol and frozen

Day 1 = Pads from beginning of cycle rubbed on upper lip, day 2 = day 2 of cycle etc etc

68% of women experienced changes within cycle

EVAL : Synchrony cycle

Too many confounding variables, any pattern could be expected to occur by chance

Small samples used

EVAL : Evolution and menstruation

Would have been advantage for women to menstruate at the same time, for collective care

HOWEVER, avoidance of synchrony would be preferred, as there would be too much competition, wouldn’t be evolutionarily strong

Seasonal Affective Disorder

Persistent low moods, often occurring within darker months, disrupts sleep/wake cycle

Many think it is due to prolonged release of melatonin (due to darkness), which prevents release of serotonin until later in the day