Psychological Knowledge and Understanding - Psychology

Two Components of the NS

Two Components of the NS

Central Nervous System & Peripheral Nervous System

CNS - Control Nervous System

The control unit made of; brain, spinal cord, and brain stem

Carries sensory information up the spinal cord to the brain via sensory neurons.

PNS - Peripheral Nervous System

Is linked to the outside world; 2 divisions - automatic and somatic

Carries motor messages from the brain to organs and muscles in the body.

Autonomic NS

Involuntary bodily process, operates automatically

• Carries messages from the brain to internal glands and organs via motor neurons.

• Carries sensory messages to the brain about the activity level of glands and organs via sensory neurons.

• Controls involuntary muscle movement therefore regulates internal organ function.

• Regulates the function of glands.

• Sympathetic and Parasympathetic

Somatic NS

Carriers sensory information from sensory neurons to CNS

• Carries sensory information received by sensory receptor cells to the CNS via sensory neurons.

• Carries motor messages from the CNS to skeletal muscles via motor neurons.

• Controls voluntary skeletal muscle movement.

• Controls involuntary skeletal muscle movement (reflex responses)

The 2 Divisions of the Sympathetic NS

Sympathetic and Parasympathetic

Sympathetic

Prepares the body for stress

• fight, flight or freeze

  • increase heart rate

  • increase breathing rate

  • decrease digestion

• regulates the glands and internal organ function to physically prepare the body for increased activity during heightened physical or emotional arousal

Parasympathetic

Calms the body and helps with energy conservation

• reverses bodily functioning produced by the sympathetic NS by calming the body and maintaining an energy level suitable for normal bodily functioning

Neurons

Carry nerve impulses around the body

Neurons are the basic unit of the nervous system

They use electro-chemical means to conduct electrical impulses

Sensory Neurons

Detects a stimulus and sends an impulse to The CNS.

Motor Neurons

Carries an impulse from the CNS to a muscle or gland.

Interneurons

Connects sensory neurons to motor neurons in the spinal cord.

Cell Body

contains a nucleus that controls the activities of the neuron.

Myelin Sheath

1. Insulates the axon

2. Allows for rapid movement of the action potential along the axon

Dendrites

Extensions of the cell body

Receive neurotransmitters from pre-synaptic neurons

Converts them into electrical nerve impulses that are conducted towards the cell body.

Axon

The long projection of a neuron that conducts electrical nerve impulses and carries them away from the cell body.

Axon Terminal

the enlarged end points of axon branches that store neurotransmitters and release them into the synaptic cleft.

Role of Neurotransmitters

• Are molecules found within the NS that act as chemical messages.

• Neurotransmitters allow neurons to communicate by relaying information between them across the synapse, as well as from neurons to glands and muscle cells.

Steps of Neural Transmission

1. electrical impulses travel to the axon terminal in the pre-synaptic neurons

2. the action potential causes neurotransmitters to be released from vesicles in the axon terminal

3. neurotransmitters diffuse across the synaptic cleft

4. neurotransmitters bind to receptor sites on the dendrites of the post-synaptic neuron

5. dendrites convert neurotransmitters into electrical nerve impulses which travel to the cell body

Electro-chemical Signal

• an electrical nerve impulse (action potential) whcih travels through the neuron

  • neurotransmitters travel between the synapse of communicating neurons. 

• The electrical nerves impulses are the electro component, and the neurotransmitters are the chemical component of the signal.

Direction of Transmission

1. from the dendrites to the cell body, then along the axon to the axon terminal

2. it causes the release of neurotransmitters into the synaptic cleft

3. myelin increases the transmission speed of the nerve impulses trough the axons

The Role of the Synapse

The synapse allows neural transmission to occur by converting the electrical nerve impulse from one neuron into a chemical signal and then back again into an electrical nerve impulse in another neuron.

The Brain

Receives, processes and interprets sensory information, integrates the information and coordinates a response

3 Regions of the Brain

Hindbrain, Midbrain, Forebrain

Hindbrain

Base of the brain and is responsible for lower-brain functions that occur with no conscious effort

• controls basic autonomic functions e.g heart rate, breathing, sleep

• coordinates voluntary muscle movements, balance, posture, and reflexes

Consists of pons, medulla, and cerebellum

Pons

a group of nerve that connect the cerebral cortex with the medulla

• assists in transfer of neural messages between various parts of the brain & spinal cord

• involved in dreaming, sleeping, arousal, coordination of some muscle movements

Medulla

lowest part of the brain connects the brain and spinal cord

• relays information between brain and spinal cord

• regulates involuntarily bodily functions, communicates with autonomic NS

Cerebellum

‘Little Brain’ - wrinkly similar to the outer layer of the brain

• helps coordinate voluntary movement and balance by relaying motor information to and from the cerebral cortex

• receives information from spinal cord, sensory neurons and brain to adjust posture and coordination

• fine motor skills are controlled

Midbrain

Connects the hindbrain and forebrain, below the cerebral cortex at the top of the hindbrain

• processes information related to hearing, vision, movement, pain, sleep, arousal

• helps keep us awake and alert

Consists of reticular formation

Reticular Formation

network of neurons that coordinates the function of vital brain systems

• extends through SC to Midbrain

• directs and filters information

• arouses cortex to alertness

• regulates autonomic NS function and sleep-wake cycle

The Forebrain

located above the midbrain towards the top of the brain

• most developed and complex region

• responsible for emotions, motivations, sensations, perceptions, learning, memory, and reasoning

Consists of; hypothalamus, thalamus, cerebrum

Hypothalamus

Below the thalamus

• maintains homeostasis

• regulates endocrine system and the release of hormones

• influences basic biological needs e.g hunger, thirst

• controls ‘internal clock’ and sleep-wake cycle

Thalamus

2 egg-shaped structures joined together

• relay system for sensory messages

• conducts motor signals - brain stem to cortex

• coordinates shift in consciousness

• works with RF to focus attention

Cerebrum

the largest & most developed part of the brain

• top of the forebrain

• responsible for most conscious actions

• cerebral cortex: the outer layer which is responsible for higher cognitive functions, voluntary movements, emotions and personality

Lobes of the Brain

frontal, parietal, temporal, occipital

Left and Right Hemispheres

Left Hemisphere - analytics, logic, ideas, facts, maths

Right Hemisphere - creativity, intuition, arts, creation, feeling , imagination

They have contralateral control of the body

Specialised Functions of the Left Hemispheres

Receives sensations from the right side of the body and controls voluntary movements of the right side & is responsible for language and analytical function

Left Hemisphere - Language Functions

Broca’s and Wernicke’s Area

• Speaking, writing, reading, and understanding language

Left Hemisphere - Analytical Functions

• Breaks down information to process sequentially (ordering)

• focuses on small details

• logical and sequencing used in maths

• judging time and rhythm

Specialised Functions of the Right Hemisphere

Receives sensations from the left side, controls voluntary movements of the left side, is responsible for non-verbal & information processing

Right Hemisphere - Information Processing

Processes information simultaneously and holistically

• assembles pieces of information into a coherent image, by identifying patterns and general connections

Right Hemisphere - Non-verbal communications

• Uses non-verbal responses to answer questions e.g pointing or nodding

• understands context

• understands sarcasm, jokes and irony

• dominant in detecting and expressing emotion non-verbally

• Spatial Skills

  • recognising patters, faces, melodies; puzzles, reading maps

Corpus Callosum

Tract of nerve fibres connecting left & right hemispheres

• deep in the centre of the brain

Functions: physically connects the hemispheres, transmits informations registered in one to the other, exchanges and integrates information

Cerebral Cortex

Outer layer of the brain

• most developed structure

• contains 70% of NS neurons

• wrinkled to increase surface area, therefore more neurons and neural connections

• ultimate control and processing centre

Functions:

• initiates, plans and controls voluntary movements

• receive, process and integrate sensory information

Cerebral Cortex Example

Choosing a new blanket for bed

1. coordinate voluntary movement to touch the blanket

2. receive and process sensory information from hand about the texture

3. apply cognitive though process to visualise the blanket on the bed

4. decide if the colour will match decor

5. process sensory information to decide if it will be warm enough

Frontal Lobe

Largest of the lobes

• Consists of:

  • Pre-frontal Cortex

  • primary motor cortex

  • broca’s area

Frontal Lobe - Pre-frontal cortex

• forward part of the frontal lobes

• responsible fro advanced cognitive and executive functions

• contributes to personality, intelligence, social skills

• cognitive processes e.g decision making

• responsibility to predict outcomes

• emotion control and impulse control

Frontal Lobe - Primary Motor Cortex

• controls voluntary movement - directs skeletal movement

Frontal Lobe - Broca’s Area

• formulates the structure of sentences & analysis grammar

• control the production of speech

Parietal Lobe

• Controls bodily (somatic) sensations

• receive and integrates information

• determines the location of the body and objects

• Consists of:

  • primary somatosensory cortex

Parietal Lobe - Primary Somatosensory Cortex

neurons at the front of the lobe

• registers and processes sensations detected by the body

Temporal Lobes

Involved in hearing, language skills, social understanding

• consists of:

  • Primary Auditory Cortex

  • Wernicke’s Area

Temporal Lobes - Primary Auditory Cortex

Registers & processes auditory information

• right temporal lobe - non-verbal sounds

• left temporal lobe - verbal sounds

Temporal Lobe - Wernicke’s Area

Controls comprehension and identifies words as sounds

Occipital Lobe

Registers and processes visual information

• Consists of:

  • Primary visual cortex

Occipital Lobe - Primary Visual Lobe

• information is transmitted from retinas

• has specialised neurons to respond to specific visual ques

Phineas Gage

An explosive detonated prior to his expectations, resulting a in a 42 inch long 1.2 in wide metal rode to be blown into his skull, into the frontal lobe

He surprisingly had no pain, no loss of consciousness, normal pulse, breathing and, vision

But long term effects were major personality changes, reasoning and capacity to understand and follow social norms was diminished. He became vulgar and an irresponsible vagent

Roger Sperry

The role of the corpus callosum using split-brain experiments

• Deduced that the two hemispheres worked independently and when the corpus callosum was severed the connected between the two was lost

• Done to originally treat epilepsy

• The information received from the optic nerves of each eye was still processed contra-laterally

• If the word/image was flashed to the right of the dot the participant could say what they saw but not if the word/image was on the left

  • but the image/word shown on the left was able to be drawn with the participants left hand as the left hand is controlled by the right side (creative) an the word/image flashed on the left is processed by the right

Walter Freeman

Role of the pre-frontal cortex using frontal lobotomy

• He believed that mental issues sprung from self-awareness and overactive emotions, so by severing the connection between the thalamus and pre-frontal cortex would eliminate excessive emotion

• done under local anaesthesia do the patient can provide feedback and feelings

• The knife inserted cut the nerve fibres that connect the thalamus and pre-frontal cortex

• his goal was to reduce patient agitation - but in most cases apathy, decreased concentration, and emotional numbness was produced

Electroencephalograph (EEG)

External Recording - records the movement of electricity across the scalp

• indicates neuronal activity, the changed in activity indicate underlying functions

• ADVANTAGES: cheap, transportable, silent, no radiation, non-invasive

• DISADVANTAGES: low spatial and temporal resolution, poor cortex measures, can’t locate specific areas

Computed Tomography (CT)

Still Imaging - series of x-ray images, 2D slices, can show th extent of a lesion and contrast dye can be used

• ADVANTAGES: better than 1 x-ray, quicker than MRI, metal doesn’t matter, can be reconstructed to make 3D, good spatial resolution

• DISADVANTAGES: higher radiation levels, cost, doesn’t show functions, poor temporal resolution

Magnetic Resonance Imaging (MRI)

Still Imaging - magnet causes hydrogen in H2O in cells to orient in a single direction, pulse of radiation waves causes atoms to spin at a certain frequency and direction

• ADVANTAGES: no ionising fields, good spatial resolution, goods contrast between white and grey matter

• DISADVANTAGES: strong magnetic field, poor temporal resolution, cost, size of machine

Functional Magnetic Resonance Imaging (fMRI)

Dynamic Imaging - shows the function of NS and diagnose metabolic disorders

• sensors detect a change in oxygen in an area of heightened neural activity

• if high neural activity haemoglobin has less O2 as it is being used

• Haemoglobin w/oxygen reacts different in a magnetic field than haemoglobin w/ out

• ADVANTAGES: satisfactory temporal and spatial resolution, no ionising radiation

• DISADVANTAGES: strong magnetic field