Unit 1 Flashcards
Anatomical and Functional Organisation of the Nervous System
What is the definition of Psychobiology?
Aims to understand the biological basis of behaviour: it seeks to explain behaviour in terms of biological mechanisms
What is all behavior?
a reflection of activity in the nervous system
Is the brain the center of behavior? Why?
No. Behavior and interactions with the environment can also affect the brain
How do the brain, behavior and the environment relate to each other?
it is a circular system
-> environment provides input, brain processes the input and produces output, which in turn influences environment
What is the black box?
the analogy used to describe how the nervous system works
What influences the blackbox and what happens then?
Causal Elements influence the Black Box: Genes and Environment
The Brain (Neurochemistry & Neurocircuitry)
Brain creates Behaviors
What are the different levels of psychobiological analysis?
- study large brains and see how they relate to behavior
- how groups of neurons relate to behavior
- how individual neurons relate to behavior
Who was René Descartes and what did he believe regarding psychobiology?
A philosopher with important theories in the study of psychobiology
-> believed behavior occurs automatically and involuntary (everything is reflexive)
Is there behavior which doesn’t require the mind?
Yes, they are called reflexes
What is Cartesian dualism? Who invented it?
Réne Descartes
mind and body do somehow interact (even tho he saw mind and body as separate entities)
Who disproved Descartes theory that the mind sends “animal spirits” down hollow tubes in oder to move muscles and tendons?
Luigi Galvani
What did Luigi Galvani discover?
the electrical nature of neural conduction (stimulating frogs nerve caused contractions of muscle - EVEN when detached to body)
How do nerves work?
by sending electrical impulses
Does the brain produce movement in muscles?
no, the neurons do
-> muscle contractions are produced by the nerves and muscles themselves
How does the brain ‘produce’ movement?
by initiating a chain of commands, in the form of electrical nerve impulses
Who was Johannes Purkinje and what was he first to describe?
a nerve cell in detail
- discovered large nerve cells in the cerebellum
What are the large cells in the cerebellum called and what are they important for?
Purkinje cells -> important for balance and movement
What did Theodor Schwann describe?
the myelin sheath wrapped around neurons
How can we imagine a myelin sheat in real life?
like the plastic tube around the metal in an electrical cable
What view did Joseph Gall present of the brain?
a view in which different areas are responsible for different functions
-> brain like a muscle, the more we use certain brain areas, the bigger it will get
-> would be measurable in skull (seen or felt)
What is the reading of bumps on the head called?
phrenology
What is cerebral localization?
The view that different brain areas are specialized for specific functions
What did John Baptiste Bouillaud consider the frontal lobes of the brain to be?
responsible for higher order mental functions (intelligence, inhibition, planning etc.)
Which case supported the concept of cerebral localization? What happened to him?
the rail worker Phineas Gage
- an iron rod projected through his skull, destroying part of his frontal lobe
-> before accident: hard-working, after accident: unreliable, heavy drinker, gambler
Does the frontal lobe influence our behavior?
yes
What did the neuroscientist Korbinian Brodmann divide the cerebral context in?
52 discrete areas, supporting the idea of cerebral localization
How did Brodmann divide the cerebral cortex into areas?
the areas were delineated based on cytoarchitecture - meaning the cells in each area had a similar cellular structure
What is the significance of the cellular structure in Brodmann areas?
the whole cortex is organized into layers of cells, and the thickness of these layers varies around the cortex
-> helping define different Brodmann areas
Do Brodmann areas correspond to specific functions? What is an example?
yes, most of them correspond with specific functions
e.g.: Brodmann Area 4: motor cortex, responsible for motor control
Who developed the silver staining technique and what is it?
Camillo Golgi
-> allowed the identification of single neurons among other body cells
What did Santiago Ramon and Cajal discover based on Golgi’s staining technique?
that neurons are discrete, unitary entities, rather then branches of a continuous network
What are synapses?
small gaps or junctions between neurons where they interact and communicate with each other
Who first identified and described synapses?
Charles Scott Sherrington
How do neurons communicate across synapses?
mostly by sending and receiving neurotransmitters
What are neurotransmitter and what is one of the first one that was discovered?
neurotransmitters are chemical substances
-> first one: acetylcholine
Who understood the advanced functions of the cerebral cortex and how?
Wilder Penfield, by removing malfunctioning brain tissue on epilepsy patients before neurosurgery
-> applied light electrical stimulation to different parts of the cortex to see which are healthy and which needed removing
What did the stimulation of the primary somatosensory cortex produce?
a tingling sensation in specific parts of the body
What did the stimulation of the temporal lobe cause some of Penfields patients?
to hear music, familiar voices or relive familiar events
What does invasive stimulation provide in Penfields work?
information on the functional organization of the cerebral cortex
What are some functions of the frontal lobe, precentral gyrus, central sulcus, postcentral gyrus, parietal lobe, occipital lobe, temporal lobe and where are they located?
- frontal lobe: planning of movements, recent memory, some aspects of emotion (front of brain)
- precentral gyrus: primary motor cortex (in back of front brain)
- central sulcus: middle of brain
- postcentral gyrus: primary somatosensory cortex (Middle to back of brain)
- parietal lobe: body sensations (upper back of brain)
- occipital lobe: vision (lower back of brain)
- temporal lobe: hearing, advanced visual processing (lower fore-middle brain)
What is the Frontal lobe for?
Planning of movements, recent memory, some aspects of emotions
What is the Precentral gyrus?
primary motor cortex
What is the Postcentral gyrus?
primary somatosensory cortex
What is the Parietal lobe for?
body sensations
What is the Occipital lobe for?
vision
What is the Temporal lobe for?
hearing, advanced visual processing
What was the case of patient HM about, Brenda Milner reported? What did the patient experience due to the removals?
patient had untreatable epilepsy and focus of his seizures was localized to medial temporal lobe of cortex
-> removed both medial temporal lobes and the hippocampus (to reduce seizures)
-> experienced anterograde amnesia (unable to form new memories)
Which process does the hippocampus play a role in?
the memory process
What did Hubel & Wiesel’s experiments on monkeys and cats showed?
that neurons in the visual cortex respond to different patterns of light projected on the retina
What do simple and complex cells best respond to?
simple cells: to stationary light in a particular orientation (e.g.: vertical line)
complex cells: to light in a specific orientation, that has a particular direction of movement (e.g.: vertical bar moving from left to right across the retina)
What does the responding of cells according to Hubel & Wiesel’s experiments show?
that neurons in the cerebral cortex respond to some patterns of stimulation of receptors but not others
What 2 things is the brain mainly made of?
Neurones and Glia
What changed the way we think about consciousness and free will?
Benjamin Libet’s recordings of the brain activity where participants had to make a random hand movement and hat to remember the time they made the conscious decision to move the hand
What were the findings of Benjamin Libet’s brain activity recording experiment?
the electrical brain activity was found in the form of a readiness potential (RP) 300 ms earlier than the perceived conscious decision
-> preceded by unconscious processes in the brain
What is the readiness potential (RP)?
a measure of neural activity that occurs in the brain before a conscious decision is made
Which part of the brain plays an important role in addiction?
nuecleus accumbens
What are the cells of the human body divided into? What are examples?
systems that perform particular functions
e.g.: urinary system = kidneys, ureters, bladder and urethra
e.g.: cardiovascular system = heart, blood vessels and blood
What does the nervous system consist of?
neurones and support cells called glia
What does the nervous system control?
everything we do: walking, changes in HR, breathing, complex problem solving, etc.
What is the main function of the nervous system?
to use information regarding the body’s internal and external environments, and produce response in muscles, organs and glands (that are beneficial to the individual)
What are the 3 steps of the Nervous System?
- NS RECEIVES INFORMATION from receptors (throughout whole body)
- The NS integrates internal and external information in order to COORDINATE SOME KIND OF RESPONSE
- PRODUCE A RESPONSE on effectors throughout whole body (muscles, organs or glands)
What does ‘cortex’ mean?
outer layer (for example of the brain)
What is the Neurone?
the basic, functional unit of the nervous system
-> the building block of the nervous system (like bricks that add up to create a house)
What is the estimated amount of neurons, the nervous system contains?
22 to 100+ billion :)
What is the fundamental function of the neurone?
- receive and process impulses from sensory receptors and other neurons
- send impulses to the next neurons in the chain of communication
What are the effector organs?
muscles, organs & glands
What other type of cell does the nervous system consist of?
glia (also called neuroglia, or glial cells)
Does Glia play a direct role in communication throughout the nervous system?
no, they work as support cells to aid functioning of neurons
Are there other cells present in the nervous system besides glia and neurons?
yes, but they are not unique to the nervous system
What are neurones and who do they share characteristics with?
a type of cell
-> share characteristics with other cells in the human body (e.g.: cell body filled with cytoplasm and organelles)
What is the structure of neurones adapted to?
to carry out their main function - producing neural impulses, stimulate other neurones and be stimulated by other neurones
How is neural communication achieved?
via electro-chemical signals
-> neurons receives stimulation from another neurones when a chemical neurotransmitter is sent and received across a tiny junction
called SYNAPSE
Why does any message the neurones receive must be transmitted along the entire length of the neuron?
they receive stimulation at one end and stimulate targets at the other end
Where is the signal transmitted along by the electrical impulse?
along the neurons axon
How does the neuron A communicate with the neuron B?
by releasing neurotransmitters into the synapses
What is the chain of electro-chemical communication throughout the nervous system?
the biological basis of encoding and transmission of information throughout the whole body
Which 3 main components does a neuron have?
soma (cell body), dendrites and axon
What does the cell body of a neuron contain? What are the functions of these organelles?
contains the nucleus and mitochondria
nucleus: contains cells genetic information
mitochondria: performs metabolic activities, providing the neurons with energy to function
What are the variable number of branches emerging from the cell body called?
Dendrites
What do Dendrites receive?
stimulation across a synapse from other neurones
-> branching structure allows to receive stimulation from many neurones
-> electrical impulse is transmitted away from the cell body along the axon
What is the axon?
a long projection that emerges from the cell body
What are many neurones axons covered in?
a lipoprotein material called myelin
-> insulates the axon to increase the efficiency of the neural impulse
What is myelin produced by and what happens without the myelin sheat?
produced by type of glia (oligodendrocytes) in brain and spinal cord and Schwann cells when found elsewhere in the NS
-> without myelin sheat neural impulse would be slower and weaker - require more energy
What can we find at the end of the axons?
axon terminals (presynaptic terminals)
-> form synapses with the dendrites to other neurones
What are the 2 types of Neurones?
afferent and efferent
- afferent: send sensory impulses from around the body towards the brain and spinal cord
- efferent: send impulses in the opposite direction, from brain and spinal cord to muscles, organs and glands
What are the terms afferent and efferent also used to describe?
the direction of neuronal communication anywhere in the nervous system
- afferent: towards a structure
- efferent: away from a structure
What does it mean for a neuron to ‘send information’ around the nervous system?
one neurone can send a message to another, telling it to fire (excitation) or not to fire (inhibition)
How does the sending information of neurones translate into sensation and behavior?
a receptor can send a message to the brain that the body is receiving stimulation or a neuron can send message to muscle gland or organ, telling it to produce some kind of action
How does the nervous system communicate more complex ‘information’ such as during problem solving?
input from one neurons alone is not enough to make the following neurone fire
- neurones receive stimulation from many neurones, as well as repeated stimulation from the same neurones
- furthermore, some of these inputs are excitatory while others may be inhibitory
is a neurone just a communicator of a simple message?
No, it is an integrator of information from multiple inputs
-> works as decision maker, deciding wether to fir or not based on inputs received
What can we compare the nervous system to?
a computer
How does brain activity results in complex behavior?
neurones work in concert with each other in complex neural networks
- communicating messages by sending repeated neural impulses (even time between impulses can hold information)
What is an example of stimulation resulting in complex behavior?
stimulating the primary motor cortex (precentral gyrus) of monkeys:
impulses of 50ms: produces muscle twitching
impulses of 500ms: elicit complex movements
What are the 2 subdivisions of the Nervous System?
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
What is the CNS composed of?
the brain and the spinal cord
-> lies within the cranium and spinal column
What is responsible for processing sensory stimulation detected around the body in order to produce a response in the CNS?
the brain
What does the spinal cord contain?
bundles of sensory neurones that carry somatosensory information from body to the brain
-> as well as bundles of motor neurones that descend from the brain
What is the spinal cord also responsible for?
producing some reflexive behaviors with little influence from the brain
How is the CNS protected?
by different structures
-> both, brain and spinal cord are surrounded by three-layer system
What does the protective three-layer system of the CNS contain?
the meninges (dura, mater, arachnoid and Pia mater)
-> space between meninges: filled with cerebrospinal fluid
-> blood-brain-barrier
What is the blood-brain-barrier?
cells that compose blood vessels in the brain and spinal cord are very tightly packed together
-> prevents harmful toxins passing from bloodstream into the brain and spinal cord
What does the PNS consist of?
A dense network of nerves outside the cranium and spinal column throughout whole body
-> cells more exposed than CNS cell
-> more vulnerable to trauma and toxins
Are the CNS and PNS connected?
yes, even though described as separate subdivisions of NS
-> motor neurones that innervate muscles and organs throughout the body have cell bodies within spinal cord
What is the difference between a neurone and a nerve?
neurone is a single cell
nerve is bundle of axons (like multiwire cable)
What is a bundle of axons called in the PNS and what is it called in the CNS?
in the PNS: nerve
in the CNS: a tract
what do individual neurones that compose nerves and tracts tend to share and follow?
share common connections, follow the same course and have a common function
What are Neuronal cell bodies?
clustered together in groups throughout the nervous system
What is a group of neuronal cell bodies called in the CNS?
nucleus (not the nucleus of a cell!)
What is a group of neuronal cell bodies in the PNS called?
ganglion
What can the PNS be divided into?
the somatic nervous system (SNS) and the autonomic nervous system (ANS)
What is the SNS involved in?
voluntary control of movement, detecting sensory stimulation around the body and communication of these sensations to CNS
How does the Somatic Nervous System (SNS) receive and process sensory information and control muscles in the body and head?
- receives sensory information from the body (below the neck) through spinal nerves
- sensory nerves communicate this information while motor nerves control movement
- in head and neck, SNS receives sensory input and controls muscles via cranial nerves rather than spinal nerves
What does the ANS regulate?
the internal organs, smooth muscle and hormone glands of the body
-> maintains homeostasis
How is Homeostasis achieved in the ANS?
by regulating cardiovascular (heart and blood vessels), respiratory, digestive, hormonal and thermal biological mechanisms
-> regulation is INVOLUNTARY and not controlled by conscious decision making
How does the ANS regulate the internal state of the body?
via nerves
-> not the same as the spinal and cranial nerves of the SNS although they do depart from the spinal cord with SNS nerves
What is the difference in organization of the somatic and autonomic nerves?
- SNS motor neurones simply leave the CNS (e.g.: spinal cord) and connect directly with a target muscle (e.g.: bicep)
- ANS neurones make multiple connections before arriving at their target (e.g.: heart)
What is the autonomic and second neurone in the two-part connection of autonomic nerves?
autonomic neurone: preganglionic neurone
second neurone: postganglionic neurone
What do the preganglionic and postganglionic neurone each do?
- preganglionic: departs from spinal cord and connects with postganglionic neurone
- postganglionic neurone: connects with and innervates the target (e.g.: heart)
The ANS can be divided into 2 more system. Which ones?
Sympathetic and Parasympathetic nervous system
What is the origin of sympathetic preganglionic neurones?
originate from the middle segments (lumbar and thoracic) of the spinal cord
How do sympathetic neurones connect to organs?
They connect with a chain of ganglia on either side of the spinal cord called the sympathetic chain, which contains postganglionic neuron cell bodies that innervate various organs and glands
What distinguishes the pathway of parasympathetic preganglionic neurones?
Parasympathetic preganglionic neurons originate from the brain (brainstem) and sacral spinal cord and travel longer distances to synapse with postganglionic neurons located close to or on the target organs
What neurotransmitters do sympathetic and parasympathetic systems use?
- Sympathetic preganglionic neurons release acetylcholine; postganglionic neurons release noradrenaline (except sweat glands, which release acetylcholine).
- Both parasympathetic preganglionic and postganglionic neurons release acetylcholine.
What effects do sympathetic and parasympathetic nervous systems have on the body?
opposite effects
When is the sympathetic system activated?
during stressful situations
-> preparing body for fight or flight responses
-> increases blood flow to the muscles and stimulates release of adrenaline to increase heart rate etc.
When is the parasympathetic system activated?
relaxes the body and aids recuperation with the aim of increasing the body’s supply of stored energy
-> reduces heart rate and increases salivation, gastric and intestinal motility
Which systems are most organs under autonomic control innervated by?
both, sympathetic and parasympathetic systems
-> they are both active at the same time, have antagonistic effects on organ activity
What determines whether an organ’s activity increases or decreases?
An organ’s activity depends on the balance of sympathetic and parasympathetic stimulation; more of one type will increase activity while the other decreases it
What system does the field of psychology follow?
a system of reference axes to correctly identify and describe different parts of the nervous system
Which 3 terms do we use to describe locations as the nervous system is three dimensional?
up-down, left-right, forwards-backwards
What do the reference axes provide?
prefixes that we can attach to anatomical labels that helps us quickly identify what part of the nervous system we are talking about
What is the neuraxis in the context of the nervous system?
an imaginary line through the CNS, extending from the lower end of the spinal cord to the front of the brain, used to describe locations and directions in the nervous system
What are the key directional terms associated with the neuraxis?
- Rostral (anterior): Front end of the neuraxis
- Caudal (posterior): Lower end of the neuraxis
- Dorsal: Top of the head and back of the body
- Ventral: Front of the body
What are the key directional terms referring to the brain?
- The front is the rostral or anterior end
- The back is the caudal or posterior end
- The top is the dorsal or superior surface
- The bottom is the ventral or inferior surface
What does lateral and medial refer to in the neuraxis?
lateral: away from the neuraxis
medial: towards the neuraxis
What does lateral and medial refer to in the brain?
lateral: the left and right outer sides of the brain
medial: the inner parts of the brain
What do the terms Ipsilateral and contralateral describe?
how different parts of the nervous system relate to each other and the direction of information flow
What does Ipsilateral and contralateral refer to?
Ipsilateral: structures on the same side of the body
contralateral: structures on opposite sides of the body
What is the transverse (or coronal) plane in brain anatomy?
The transverse or coronal plane separates the brain into rostral (front) and caudal (back) sections, allowing for a view of the structures from front to back
How do the sagittal and horizontal planes divide the brain?
- Sagittal plane: Separates the brain into left and right halves.
- Horizontal plane: Divides the brain into dorsal (top) and ventral (bottom) parts
How does the Central Nervous System (CNS) begin developing prenatally?
The CNS starts as a hollow neural tube. The upper end of the tube forms three swellings, which later develop into the brain’s three main divisions: forebrain, midbrain, and hindbrain
What does the remaining part of the neural tube develop into?
The rest of the neural tube eventually forms the spinal cord
What structures are part of the Forebrain (Prosencephalon)?
Telencephalon: Cerebral hemispheres
Diencephalon: Thalamus, hypothalamus & others
What structures are part of the Hindbrain (Rhombencephalon)?
Metencephalon: Pons, cerebellum
Myelencephalon: Medulla
What structures are part of the Midbrain (Mesencephalon)?
Tectum
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