Psychology test 1 (Biological Psychology)

The Nervous System

The system that produces and relays messages between the brain, spinal cord, and a network of neurons

Central nervous system (CNS)

• part of the nervous system make up of the brain and spinal chord

• Carries sensory information up spinal cod to brain via sensory neurons

• Carries motor messages to the PNS via motor neurons

Peripheral Nervous System (PNS)

• made up of all the nerves outside of the brain and spinal cord

• PNS carries sensory information to the CNS from the body

• PNS carries motor messages from the brain to organs and muscles

Key function of the CNS

1. Input- to receive information

2. Processing- to integrate/interpret that information based on past experiences

3. Output- guide actions

Key function of the PNS

• made up of out muscles, organs and glands

• Consists of all the neurons outside of the CNS

• Relay information to the CNS

• Carry motor information from the CNS to the muscles and organs via the spinal cord

Parts of the Peripheral Nervous System

Somatic and Autonomic NS

Somatic nervous system

• nerves that control voluntary movement through its control of skeletal muscles

• Receives motor messages from CNS and transports to skeletal muscles in specific body regions

Autonomic nervous system (ANS)

• contains nerves that are connected to the CNS and the involuntary muscles that control activity level of internal organs/glands

• By relaying messages between the CNS and the internal systems, ANS controls the body’s internal activities that are essential to survival (heart rate, digestion etc.)

Function and division of the somatic NS

Sensory (function)

• transmits sensory information from the body to the CNS via the spinal cord

Motor (function)

• sends motor commands from the CNS to skeletal muscles, glands, or organ as for voluntary movement

Divisions of the ANS

Sympathetic and Parasympathetic

Sympathetic nervous system

• regular;ages the glands and internal organ function

• Physically prepare body during heightened arousal (flight or fight response)

Parasympathetic nervous system

• calms the body after ring under control of the SNS

• Controls the rest and digest response

• Returns body to normal function (homeostasis)

Neurons

• neurons are specialised cells located in the CNS and PNS

• Cells that receive, transmit, process information

• Billions of these cells, each with synaptic connections to more neurons

• These connections allow for messages to be passed along throughout the

Diagram of a neuron

Features of a Neuron

Cell body (soma)

Dendrites

Axon

Axon terminals

Myelin sheath

Cell body (Soma)

• contains a nucleus that controls the activities of the neuron

• Contains nucleus, and processes information received by dendrites

Dendrites

• extensions of cell body that receive neurotransmitters from pre-synaptic neurons and covert them into electrical chemical impulses that are conducted towards cell body

• Branch like structures that receive signals from other neurons

Axon

• long projection of neuron that conduct electrical nerve impulses and carries away from cell body

• Long fibre that transmites electrical signals away from cell body

Axon terminals

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

• end structure that release neurotransmitters to communicate with other neurons

Myelin sheath

• fatty covering axon that acts as insulator, protecting from stimuli that could interfere with transmission.

• Also assist with speed of electrical impulses

Neurogenesis: The process of growing Neurons

1. Producing new neurons

• the creation of new neurons from neural stem cells

1. Growing New Branches

• development of new dendrite or axon terminal branches

1. Establishing connections

• forming connections between existing neurons to create neural circuits

sensory neaurons

• Transmit information from sensory receptors to CNS

• Receives sensory information from the sense organs/environment and carry the sensory messages to the spinal cord and brain (CNS)

Motor Neurons

• Carry through signals from CNS to muscles and glands

• communicates information from the CNS to muscles, allowing movement.

Interneurons

• connect and integrate information between other neurons within the CNS

• act as the connection between sensory neurons and motor neurons. Activated when sensory neurons receive intense sensory information. Coordinates the reflex arc.

Sensory (differences)

• carry nerve impulses from receptor to CNS

• Have long dendrites and short axons

Motor (Differences)

• Carry nerve impulses from CNS to an effector gland (muscle or gland)

• Short dendrites and long axons

Interneurons (Differences)

• Found completely in CNS

• Provide link within CNS between sensory neurons and neurons

• Short dendrites, long or short axons

How can neurons be categorised

Neurons can be categorised by number of processes (sending/receiving( extending from the cell body)

Unipolar, Bịpolar and multipolar neurons

Unipolar

• neurons have one axon

Bipolar

• neurons have axon and one dendrite, extending from cell body toward opposite poles

Multipolar

• neurons have multiple dendrite and a single axon

Neural networks

Neurons form neural networks when axons of one neuron link up with dendrites of another neuron

efficiency of neural transmissions is influenced by

1. Number of neurons connected and

2. How often the pathway is used

Neural transmission

Neural transmission is an electro-chemical process

Nerve impulses

• Neurons form neural networks when axons form one neuron link with dendrites from another neuron

• Nerve impulse is message (electrochemical signal) that travels along fibre nerve

• Transmitted very quickly, making possible for body towards respond to change

• Described as electrochemical change because involved change in electrochemical signal, within neuron and neurotransmitters are chemical component of signal

• Aka action potential, travels in one direction, from dendrites along axon

The electro-chemical signal (4 steps)

1- resting state

2- depolarisation

3- action potential

4- Depolarisation

Resting state

• neuron maintains negative charge inside, relative to outside

Depolarisation

• stimulus causes sodium channels to open, positive ions flow in

Action potential

• If threshold is reaches, electrical signal travels down axon

Depolarisation

• Potassium channels open, restoring negative internal charge

Synaptic gap

• tiny space between neurons where chemical communication occurs

Neurotransmitters

• chemical messengers released by presynaptic neuron to transmit signals

Receptors

Specialised proteins on postynaptic neuron that bind to specific neurotransmitters

What happens at the synapse? Step 1

1. Axon terminals connect with receptors on neighbouring dendrites

Synapse Step 2

2. When hit with electrical impulse (action potential), axon terminals of the sending neuron release neurotransmitters

Synapse step 3

3. Neurotransmitters travel across tiny gap called synapse and attach to receptor sites on the target dendrite of the recieving neuron

Synapse step 4

4. Attached neurotransmitters generate action potential in recieving neurons Short dendrites (neural impulse has been transmitted)

Synapse step 5

5. Most of neurotransmitters return to their original axon terminal a “re-uptake” process.

Synapse step 6

6. Other neurotransmitters are broken down by enzymes and need to be replenished

• we replenish neurotransmitters through the food we eat, exercise and sleep

• Neurotransmitters and their receptors are affected by drugs, toxins, and emotional states

What happens at synapse simplified

1. Release: neurotransmitters are released into synaptic gap

2. Binding: Neurotransmitters bind to receptors

3. Signal: Postsynaptic neuron is excited or inhibited (depending on the emotion etc)

4. Removal: excess neurotransmitters are removed

Role of neurotransmitter

Acts as chemical messengers.                

Allow neurons to communicate by relaying information between them across synapse

Electrochemical signal

Electrical nerve impulses are ‘electro’ component                                                             Neurotransmitters are ‘chemical’ component

Direction of transmission

One way.                                                                

Travels from dendrites down to axon.               

Once reached the axon terminals, causes the release of neurotransmitters

role of synapses

Synapse allows neural transmission to occur by converting electrical nerve impulses from one neuron into chemical signal and then back again into electrical

Acetylcholine: The memory Messenger

Key role

• Acetylcholine crucial for memory and learning

• Plays role in muscle movement

Deficiency impact

• low levels relate to memory problems

• Associated with diseases like alzheimers

Boosting levels

• diet and certain medications raise acetylcholine

• May improve cognitive function

Dopamine: Pleasure, Motivation & more

1. Reward system: centra to brain’s reward system, reinforces pleasurable behaviours (doesn’t always mean good)

2. Motivation driver: drives motivation, focus, and productivity. Optimal levels enhance performance

3. Imbalances: Too little or too much can cause disorders, includes Parkinson’s and schizophrenia.

Serotonin: Mood, Sleep and Digestion

1. Mood regulation: Serotonin stabilises mood, promotes feelings of well-being and happiness

2. Sleep cycle: regular;ages sleep patterns, healthy levels promote restful sleep

3. Digestive health: serotonin influences digestion, imbalances can impact gut function

GABA: The Calmer

• GABA inhibits nerve transmission

• Reduces anxiety and promotes relaxation

Glutamate” The exciter

• Glutamate excites neurons

• Vital for learning and memory

GABA & Glutamate Balancing act

• proper brain function depends on balance between GABA and Glutamate

Adrenaline & Noradrenaline: Fight or Flight

1. Adrenaline: surges during stress, boosts energy and awareness

2. Noradrenaline: sharpens focus, prepares body for action

3. Survival mechanism: Activate fight-or-flight response, ensures quick reaction to danger

Neurotransmitters in disease: What happens when things go wrong?

1. Depression: serotonin and dopamine imbalances, causing depression

2. Parkinson’s: dopamine deficiency leads to motor impairments

3. Anxiety: GABA imbalances, increase anxiety

4. Schizophrenia: Excess dopamine triggers schizophrenia symptoms

The Brain

• weighs between 1.3-1.5kg

• Most water 78%, Fat 10%, Protein 8%

• Made up of 100 billion neurons

• Each neuron can make up to 100 connections (total 100 trillion connections)

• Vital organ and command centre of body

• Responsible for all mental processes

• Regulates survival processes such as breathing, digestion sleep, blood circulation

Grey matter

• brain outer converting

• information is stored (Cerebral cortex)

White matter

• brain needs neural pathways that connect the different parts of grey matter as well as other inner structures

Forebrain, Midbrain, Hindbrain

Hindbrain

• located at rear base of skull that controls the most basic biological needs for life

• Primitive part of the brain

• Region of the developing vertebrate brain that is composed of the medulla oblongata, the pons and the cerebellum

Hindbrain- structures

Pons

Medulla oblongata

Cerebellum

Pons: above medulla

• regularlates sleep, arousal and respiration

• Relays information between cerebellum and cerebrum

Medulla oblongata: middle of the spinal cord

• controls involuntary actions such as breathing, heart rate

• Also controls reflexes; like swallowing and coughing

Cerebellum

• aka little brain

• Regulation and coordination of movement- allows us to make accurate and fluid movements

• Also involved in learning- storage of lọng term procedural memories

Midbrain

• connects hindbrain and forebrain and controls arousl levels, attention and consciousness

• Role is to be brains sensory switchboard, involves receiving and processing sensory information (reticular formation), attention and consciousness

• Receives messages from our senses, sends these to higher brain regions tha deal with these senses

• Also responsible for auditory and visually processing and eye movement

Midbrain- Reticular formation

• through centre of midbrain runs network of thick nerves called reticular formation

• Job is to screen information so only relevant information gets passed to higher brain, Prevents overload

• Reticular activating system (RAS), increases or decreases brain arousal, controlling our level of alertness

forebrain

• most highly developed and largest part of the brain.

• Affects how we think, feel and

• Cerebral cortex consists of the cerebral hemispheres, which account for two this of the brain’s total mass

• Part of lambic system (group of structures in your brain that regulated emotions, behaviour, motivation, and memory

Forebrain structures

Thalamus

Hypothalamus

Cerebral cortex

Thalamus

• structure beneath cortex, known as body’s communication centre

• Processes incoming sensory information and transmits to other parts of brain

Hypothalamus

• small structure that controls basic survival actions

• Sleep, regulation of body temp., hunger and thirst, and expression of emotions

Cerebral cortex

• outer layer

• Responsible for receiving information from environment, controlling responses and high order thinking involve in memory, language and emotions

Limbic system

• forebrain consists of the cerebrum, thalamus and hypothalamus (part of limbic system)

• 2 main structures:

• Amygdala: controls fear and aggression

• Hippocampus: memory formation

CEREBRAL CORTEX

• responsible for higher brain function, such as perception, conscious thought, voluntary movement

• 2 hemispheres (left and right), each with sensory and motor functions in the same place

• Each hemisphere is further divided into four lobes

Left (Logic) and Right (Creative) Hemispheres

• Connected by corpus callous’s

• Each hemisphere is dominant in control o specific tasks (Hemispheric specialisation)

• Hemispheric specialisation means each hemisphere has greater control over certain functions (but both are involved in almost all functions, just each is Dominant)

• Hemispheres have contralateral control of body (ears left hemisphere controls right, right controls left)

Corpus callosum

• It’s a set of neural fibres that connect two brain hemispheres

• Each hemisphere has central fissure that runs from top of each hemisphere , and sides, separating front of cerebral cortex from rear.

• Corpus callosum is part of the mind that allows communication between two hemispheres of the brain. its responsible for transmitting neural messages between both the right and left hemispheres

Lobes of the cerebral cortex

Frontal lobes

Temporal lobes

Occipital lobes

Parietal lobes

Frontal Lobes

• voluntary movement

• Planning and decision making

• Problem solving

• Organise information

• Recognition of emotions

• Speech production

• Impulses control

Temporal lobes

• understanding speech

• Interprets auditory information

• Processing sense of smell

• Facial recognition

• Partial responsibility for recognition of emotions

• Involved in long-term memory formation

Occipital lobes

• visual perception and processing

• Interpreting visual information

• Involved in facial recognition

• Depth perception

Parietal Lobes

• processing sensory information

• Spatial awareness

• Proprioception

• Integrating sensory information

Localisation of functions

• Localisation of function refers to the idea that certain functions have certain localisation or areas within the brain

• Supported by brain imaging and case studies (phineas gage)

7 localised areas we focus on

• Broca’s area

• Wernickes area

• Pre-frontal cortex

• Primary motor cortex

• Primary sensor cortex

• Primary auditory cortex

• Primary visual cortex

Broca’s area

Location: Adjacent to the primary motor cortex in the left frontal lobe

Function: Controls the fine muscles responsible for clear and articulate speech.

Impairment when damaged: hinders ability to produce articulate speech

Wernickie’s area

Location: Adjacent to the primary auditory cortex in the left temporal lobe

Function: Responsible for the understanding of language and the production of meaningful speech.

Impairment when damaged: hinders ability to understand language and make meaningful speech

Pre-frontal cortex

• front layer os the frontal lobe that coordinates executive functions, such as predicting consequences of behaviour, recognise and regulate emotions

Primary motor cortex

• strip running through the frontal lobes that control voluntary movement of the body.

• Different zones Whithorn cortex correspond to various part of the body, with size of zone representing the importance of body part

Primary sensory cortex (somatosensory)

• strip running through parietal lobed that register and processes sensory information

Primary auditory cortex

• area within both temporal lobes that register and processes auditory information that is received from the ears

Primary visual cortex

• area within the occipital lobes that register and process visual information that is received from the eyes

Pre-frontal cortex (More detail)

• part of the brain behind forehead

• One of last parts to mature

• Area is responsible for skills like planning, prioritising,and making god decisions

Primary motor cortex (more detail)

• upper motor neurons in cerebral cortex reside in several adjacent and highly interconnected areas in the frontal lobe

• Which all together mediate planning and initiation if complex temporal sequences of voluntary movements

Primary sensory cortex (more detail)

• central processing of tactile and nociceptive stimuli take place in primary somatosensory cortex

• Fine-touch and proprioception inputs reach these cortical areas through dorsal column-medial lemniscus pathway, and information regarding pain, temperature, and touch reach this cortical areas through the lateral and ventral spinothalamic tracts

• Simultaneously received information from other cortical regions and sub cortical areas that modify the output response from this region, similar to operation of primary motor cortex

Primary auditory cortex (more detail)

• areas are regions of the cerebral cortex, located bilaterally in the temporal lobes

• Primary auditory is positioned in the temporal lobe and associated with auditory areas

• Primary auditory area acts as the principal location that receives sounds from peripheral auditory structures and is integral to being the process of complex sound interpretation as well as the conscious perception of noise

Primary visual cortex (more detail)

• region of cerebral cortex

• Responsible for processing visual data

• Situated posterior in occipital lobe

• Begins from eyes, travels through lateral geniculate nucleus until reaches visual cortex.