Describe the two divisions of the nervous system

• central nervous system

• peripheral nervous system

2 main functions of the nervous system

• collect, process and respond to information in the environment

• co-ordinate the working of organs and cells

What does the central nervous system contain? (NS)

• the brain (processes info)

• the spinal cord (receives & transmits info)

the brain

• centre of all conscious awareness

• cerebral cortex - 3mm

• highly developed, differentiates us from other animals

spinal cord

• extension of brain

• passes messages to and from brain

• connects nerves to PNS

• responsible for reflex actions

peripheral nervous system

• transmits messages via neurons

• divided into 2 subsystems/nervous sytems

What are the two divisions of the peripheral nervous system ? (PNS)

• The autonomic and somatic nervous systems

Describe the function of the autonomic nervous system (part of PNS)

governs vital functions like breathing, digestion and stress responses

Describe the function of the somatic nervous system (part of PNS)

governs muscle movement and recieves info from sensory receptors

What are the two divisions of the autonomic nervous system? (ANS)

• The sympathetic and parasympathetic nervous systems

endocrine system

• works along the NS to control vital functions

• acts slower than nervous system but is powerful

what do glands do

produce hormones which are secreted in the bloodstream, affecting cells w receptors for it

why do hormones lead to several responses?

they affect more than 1 organ

thyroxine affects heart rate and metabolic rate

what’s the key endocrine gland

pituitary gland

• master gland

• controls release of hormones

endocrine and ANS working together - what happens when a stressor is perceived

• when a stressor is perceived, the hypothalamus activated the pituitary gland which triggers activity in the sympathetic branch of the ANS

• the ANS changes from its normal resting state to the sympathetic state

sympathetic nervous system

The sympathetic nervous system is responsible for the body's fight-or-flight response, activating in times of stress or danger. It increases heart rate, dilates airways, and redirects blood flow to muscles.

parasympathetic nervous sytem

Parasympathetic Nervous System

The parasympathetic nervous system is responsible for rest and digest functions in the body, conserving energy and promoting digestion. It works in opposition to the sympathetic nervous system.

adrenaline

• released from adrenal medulla

• triggers physiological changes which creates physiological arousal necessary fro fight or flight repsonse

immediate and automatic response

• starts as soon as threat is detected

• (sympathetic) changes in teh body explain why stress, panic or excitement can feel sickly

parasympathetic action

• after threat, body returns to PS nervous system returns body to resting state

• it acts as a brake and reduces activities of the body that were increased by actions of the sympathetic branch

Describe the role of the parasympathetic nervous system (part of ANS)

• decreases fight / flight stress response

• reduces:

1. heart + breathing rate

2. sweat

3. narrows pupils

4. stimulates digestive system

whats rest and digest

Rest and Digest is when the body conserves energy for digestion and recovery, controlled by the parasympathetic nervous system.

What is homeostasis?

• when there is a balance between sympathetic & parasympathetic nervous systems, the body is normal and regulated

what is the endocrine system?

• a collection of 8 major glands within the body that regulate bodily functions, growth and psychological factors (emotions + behaviour)

what is the role of the pituitary gland within the endocrine system?

• located in the brain, the pituitary gland controls the release of hormones from other glands

• releases ACTH hormone for fight / flight response

what is the role of the hypothalamus gland within the endocrine system?

• located within the brain, the hypothalamus links the nervous system to the endocrine system and maintains homeostasis

• releases hormone CRH for fight/ flight response

what is the role of the adrenal glands within the endocrine system?

• works to regulate the effect of the fight/ flight response

• releases hormones adrenaline and cortisol

what are neurons?

• nerve cells which process & transmit information through electrical / chemical signals x

what is the sensory neurons job?

to carry information from the environment to the CNS

relay neuron’s job

connect sensory neurons to the motor or other relay neurons

motor neurons job

connect the CNS to effectors like muscles and glands

What neurons make up the reflex arc?

• sensory neuron , relay neuron & motor neuron

features of a neuron

• myelin sheath

• nodes of Ranvier

• axons

• dendrites

• terminal buttons

• cell body

myelin sheath

nodes of ranvier

Insulating layer around nerve fibers, speeds up signal transmission.

Nodes of Ranvier are gaps in the insulating layer around nerve fibers, known as myelin sheath, which help speed up the transmission of nerve impulses.

axons

dendrites

Axons are long, slender projections of a nerve cell that transmit electrical impulses away from the cell body to other neurons, muscles, or glands.

Dendrites are branch-like extensions of a neuron that receive signals from other neurons and transmit them to the cell body for processing.

terminal buttons

cell body

Terminal buttons are small knobs at the end of axons that release neurotransmitters to communicate with other neurons.

Cell body is the part of a neuron t3hat contains the nucleus and other organelles, responsible for maintaining the cell's functions.

what cell structures does the sensory neuron contain?

• sensory receptors

• cell body

• dendrites

• myelin sheath

• axon terminals

• axon

what cell structures does the relay neuron contain? (located in spine)

• dendrites

• cell body

• axon

• axon terminals

what cell structures does the motor neuron contain?

• cell body

• dendrites

• axon terminals

• axon

• effector (muscle)

• myelin sheath

what are the symptoms of the fight or flight stress response? (ANS)

• increased heart + breathing rate

• sweating

• pupil dilation

• digestive system stops

In which order do the reflex arc neurons act?

sensory →relay → motor & brain → reflex movement

explain the reflex arc

• sensory neuron detects a sensation, causing an electrical signal to travel through the axon terminal to the relay neuron

• relay neuron passes this to the CNS to process it and the motor neuron, causing the affected limb to move

• info is sent to the motor neuron before the brain, which is why reflexes are automatic

structure of a the three neurons

long dendrites

short axons

short dendrites

short axons

short dendrites

long axons

location of neurons

• sensory neurons are located in the PNS in clusters (ganglia)

• motor neurons have long axons, forming part of the PNS

• relay neurons are mostly in the brain and visual system

what is a synapse?

• a gap between neurons/ the point where one neuron can send a message / communicate to an adjacent neuron

how do neurons communicate

through neural networks

what is synaptic transmission?

the process by which one neuron communicates with another by sending messages across the synapse

what is a neuron?

a nerve cell

what are neurotransmitters?

the body’s chemical messengers that carry info between nerve cells

what are the features of the presynaptic neuron?

• direction of action potential

• vesicle

• axon terminal

• transport protein

example of a neurotransmitter

acetylcholine

• found at point where a motor neuron meets a muscle, causing them to contract

what are the features of the postsynaptic neuron?

• synaptic cleft (in between pre & post)

• receptor site

what does the action potential do?

• transmits info from one place to another

excitation

when a neurotransmitter increases the positive charge of a postsynaptic and make the post-synaptic cell more likely to fire

inhibition

when a neurotransmitter increases the negative charge of a postsynaptic neuron and make them less likely to fire

how does synaptic transmission actually work?

• action potential arrives at axon terminal of presynaptic neuron, causing the vesicles to merge with the membrane of the presynaptic neuron

• this releases the neurotransmitters into the synaptic cleft, where the neurotransmitters diffuse across, reaching the postsynaptic cell

what is summation?

the positive/negative effects of the excitatory + inhibitory influences on the post-synaptic cell

what is the process of summation?

• excitatory + inhibitory influence are summed

• action potential of postsynaptic neuron is only triggered if the sum of the excitatory & inhibitory signals reach a particular threshold - the neuron may or may not fire

define localisation of function within the brain

different regions of the brain are specifically responsible for different behaviours, processes or activities

According to localisation, what happens if an area of the brain gets damaged

The function associated with the aerial will also be damaged

what is the holistic theory

all parts of the brain are involved in the processing of thought and action

which areas of the brain are on both hemispheres (sides) of the brain?

• motor, somatosensory, visual & auditory

which areas of the brain only appear on the left hemisphere (side) of the brain?

• Broca & Wernicke’s area

outline the 4 lobes of the brain

• frontal lobe (movement)

• temporal lobe (audio)

• parietal lobe (sense)

• occipital lobe (visual)

outline the 6 localised areas within the brain

• motor area

• somatosensory

• visual area

• Wernicke’s area

• auditory area

• Broca’s area

where is the motor cortex located and what is its function?

• frontal lobe

• voluntary movement - opp side

• damage = loss of control over fine movements

where is the somatosensory cortex located and what is its function?

• parietal lobe

• processing & receiving sensory info

• damage = loss of sensation

• amount of som.sen. area devoted to a body part denotes its sensitivity

where is the visual cortex located and what is its function?

• occipital lobe

• receives & processes visual info

• damage to LR hemisphere can cause blindness in the RL field

• each eye sends info from visual field to visual cortex

where is the Wernicke’s area located and what is its function?

• left temporal lobe

• described p with no issue producing language but trouble understanding

• damage = speech is fluent but meaningless (Wernike’s aphasia)

where is the auditory area located and what is its function?

• temporal lobe

• auditory receiving and processing - analyses speech based info

• damage = deafness

where is Broca’s area located and what is its function?

• left frontal lobe

• speech production

• damage = difficulty producing fluent speech + slow speech (Broca’s aphasia)

outline Broca’s research into LOF (eval point)

• Broca identified an area in the left frontal lobe as responsible for speech production because his patient ‘tan’ ‘s Broca’s area was damaged & could only say the word ‘Tan’

• This supports LOF as Broca’s area is specifically on the left hemisphere of the frontal lobe

evaluation on localistaion of function

brain scan support

support for holistic theory

case study

mental disorders

localistion of function - brain scan support

• petersen et al. Used brain scones to show wernicke’s area active w listening task and brocas during reading

• tulving semantic and episodic mem resides in different parts of the prefrontal cortex

• Objective methods for measuring brain activity have provided sound scientific evidence

Localization of function - Phineas Gage

• Metal rod punctured his head and removed most of his front allobe

• He survived but his personality changed from calm to quick tempered

• It can be hard to make meaningful generalizations from one study and conclusions are subjective

Localisation of function - damage to areas of the brain have been linked to mental disorders

• Neurosurgery is a lost resort which targets specific areas which may be involved

• Cingulotomy isolates the cigulate gyrus (OCD)

• Dougherty et al reported on OCD patients who had undergone a cingulotomy. After 32 weeks almost 30% had met the criteria for successful response to surgery and 14% for partial response

define hemispheric lateralisation

• each hemisphere of the brain is specialised to perform different functions

• certain mental processes are mainly performed by one hemisphere rather than the other

• The visual area in the left and right occipital lobe in the left and right hemisphere - respectively

left and right hemispheres - langauge

• Language is lateralised

• RH only produces rudimentary was phrases for contributes emotional context to what's said

• LH = analyser

• RH = synthesiser

ipsilateral

Wiring appears on the same side of the body

vision nad how its wired

• Simultaneously contralateral and ipsilateral

• Each eye receives light from the left and right visual field

• The LVF on both eyes is connected to the RH and the RVF of both eyes is connected to the LH

• Visual areas can then compare the slightly different perspective and a depth perception

• Similar to auditory input - disparity from the two inputs helps us allocate the social sounds

Split brain research

• Connection between the RH and LH is severed - mainly corpus callosum

• Used to reduce epilepsy

• During a seizure the brain experiences a major electrical Storm which travels between hemispheres and to reduce these fits the connection is cut

• Research studies how the hemispheres function when they can't communicate with each other

Sperry procedure

• 11 split brain individuals were studied with a special setup where an image or word could be predict projected to their RVF and the same or different image would be projected to the LVF

• For normal brain the corpus calossum would immediately share the iformation between hemispheres providing a complete picture of the visual world

• Presenting the image to one hemisphere meant the info can't be conveyed between hemispheres

sperry consclusions

Shows how some functions are lateralised and supports the view that LH is verbal and RH is silent but emotional

Connectivity between different regions of the brain is important

what participants did Sperry (1968) use

• 11 participants who had their corpus callosum cut down the middle (which separates the two hemispheres) in order to treat epilepsy

what was Sperry’s procedure? (1968)

• participants were asked to cover one eye & vice versa while shown words / images to describe , assuring that the R and L visual fields were tested

  • because the ppts hemispheres were severed, the information could not be conveyed to both hemispheres, so the ppts were unable to provide a full understanding

In Sperry’s study, how did the ppts draw the words/images ?

• right visual field (left hemis) drew poorly while the left visual field (right hemis) drew clearly

In Sperry’s study, how did the ppts recognise the words/images by touch?

• ppts were able to understand and match an object without seeing it to an image with their left hand but could not verbally identify it

• (this may be because of language areas being in the left hemisphere)

why are Sperry’s findings difficult to generalise? (eval)

• cannot be generalised to wider population because of dispositional ppt factors

• small sample, epileptic, undergone drug therapy, varying amnts of corpus callosum cut (therefore ppts brain state varies)

• the comparison ‘control group’ were not epileptic which makes them an invalid comparison as epilepsy was not the independent variable being studied

why do Sperry’s findings lack mundane realism? (eval)

• Sperry’s experimental procedure was highly artificial because the task did not reflect how ppts would likely process info in day to day life

• Also, in real life, both hemispheres would be able to access info simply though the person moving their head

hemispheric lat and split brain research eval

Evidence for lateralization

Evidence against analyzer and sympathiser idea

Recent split brain research

Generalizability problems

hemispheric lat and split brain research - lat. evidence

• Fink et al - PET scans to show which areas were active during a visual processing task

• When normal participants were asked to attend to larger elements of an image regions of the RH were more active, when required to focus on the finer detail areas of the LH would here as as far as dominate

• Hemispheric collection is a feature of the normal brain and the split brain, objective evidence, more validity

hemispheric lat and split brain research - Evidence against analyzer and sympathiser idea

• Might be different functions but research shows people don't have a dominant side of the brain which creates a different personality

• Nielsen al analysed brain scans (7-29) and from certain hemispheres used for certain tasks but no evidence of a dominant side no artist brain

• decreases the validity of the findings of research in hemispheric naturalization

hemispheric lat and split brain research -Recent split brain research

• gazzaniga split green participants do better than normal controls and certain tasks. For example they could identify the odd one out and similar objects more than normal controls

• Perhaps in the normal brain the LH’s cognitive strategies are watered down by the inferior RH

  Supports Sperry that both sides of the brain are distinct and helps it to be more trustworthy by supporting research conducted long ago

hemispheric lat and split brain research - generalisbility

• The behaviour of the flip brain group was compared to a neurotypical control group

• No participants in control had epilepsy- CV

• Differences observe could be due to epilepsy not split brain

• Some unique features of the split brains abilities may have been due to the next sea and not split range. Due to this CV you can't generalize the findings for the rest of society

define why the brain is contralateral

• each hemisphere of the brain controls the opposite side of the body

• left/right right/left