Brain and Behaviour Flashcards
What is the aim of psychobiology?
Psychobiology aims to understand the biological basis of behaviour. There are two schools of thought:
-> Dualist (Mind is different from matter)
-> Materialist (Mind is what brains do)
What are the different biological systems that are studied in psychobiology?
Biological systems studied in psychobiology:
-> Immune System
-> Endocrine System (the body’s internal state, growth, development, reproduction)
-> Nervous System (coordinates response to stimuli + biological basis of cognitive functions
What is the evolutionary history of the nervous system?
Evolutionary history of the nervous system:
-All animals have nervous systems, except sponges
-Electrochemically-active cells specialised to communicate with eachother (chemical change in one cell causes chemical change of another)
-Simplest forms of NS are uncentralised
-Simple organisms have centralised NS with seperate CNS + PNS systems
-Vertebrate NS are more complex, and CNS + PNS systems more seperated
Organisation of the nervous system
-CNS is split into the brain and spinal cord
-PNS is made up of somatic (voluntary control of skeletal muscles) systems and autonomic systems (involuntary control of muscles and glands)
-The autonomic system is made up of the sympathetic (fight/flight) and parasympathetic (rest/maintenance)
Spinal Cord link between PNS and CNS
-Sensory signals from body enter CNS via spinal cord
-Motor signals to body leave CNS via spinal cord
Outline the monosynaptic reflex arc (eg knee-jerk reflex)
Monosynaptic Reflex Arc:
1. Specific sense organs in muscle fibres (called muscle spindles) activates sensory neurone
2. Axons enter spinal cord (via dorsol root), connecting directly with motor neurones which send their axons out (via central root)
3. This therefore activates the same muscles from which signals originated (causing it to contract)
What are monosynaptic reflexes?
Monosynaptic reflex resist skeletal muscle stretching, enabling smooth and stable movement
-> These can have additional synaptic connections
What is the polysynaptic reflex arc?
Polysynaptic reflex arc:
-Sensory and motor neurones connected via one or more interneurons
-Sensory and effector in different locations
-More flexible arrangement
-Can show simple forms of learning
What are central pattern generators?
Central pattern generators:
-Spinal cord neurones generate complex movement patterns
-Cannot voluntarily initiate movements - only in response to stimulation
Monosynaptic and Polysynaptic synapse functions
-Monosynaptic synapse = Functionally, only one synapse links between sensory and motor neurones
-Polysynaptic synapse = Functionally, multiple synapses between neurones (bi-synaptic and tri-synaptic)
‘What does it take for an organism to ‘behave’?
1 -> Information from the environment is registered
2-> Resulting in an internal change (‘transform’ or ‘process’ the info)
3->Generate an appropriate response
What does an ‘uncentralised’ nervous system mean, as found in the simplest forms of nervous systems?
Uncentralised nervous systems = no ‘nerve centre’ that controls the activity of large numbers of other neurons and the actions of distant body parts
Vertebrate nervous systems
-More complex than simple
-Structurally = CNS and PNS more seperated
-Hierarchically organised with brain specialised to organise and communicate between neurones as well as control the action of distant body parts
Autonomic nervous system input (resulting in involuntary control)
Autonomic NS receives input from CNS only whereas Somatic nervous system receives input from both sense organs and CNS
3 basic processes of the nervous system
Sensory signals detected
Signals interpreted
Motor signals sent to muscles and glands
Why are monosynaptic reflex arcs important?
Monosynaptic reflex arcs are important because it resists or dampens stretching of skeletal muscles, providing smooth and stable movements.
Differentiate monosynaptic and polysynaptic reflex arcs
Monosynaptic reflex arc activates the same muscle the signal is originated from, whereas polysynaptic reflex arc has the receptor and effector in different places
CNS anatomy
Anatomically, CNS is a delimited nervous tissue that is compromised of functionally specialised neurons interconnected by axon tracts (neuropil)
What are ganglia in the nervous systen?
Ganglia are groups of brain cells or nerves that are closely related and work together as part of the nervous system
->Also known as the relay stations in the PNS
->CNS is subdivided into ganglia
Define the uncentralisation of nervous systems, as found in simpler organisms
Uncentralised nervous systems = recieves sensory input and output only locally, without central intergration -> this is achieved by direct interconnection of sensory neurons and effector neurons
Determination of the cell becoming active
The combined input of the signal integration at relay stations determines if the cell becomes active
Location of which precisely localised information is sent
Neurons transmitting precisely localised information send axons to the top of the spinal cord (medulla)
What is sensory adaption?
Sensory adaption = refers to neurons getting used to a specific stimulus -> this means that a constant stimulus would not be felt (only changing stimuli)
Transmission of poorly localised information
Neurons transmitting poorly localised information (eg temperature and pain) synapse immediately with other neurons upon entering the spinal cord
What are relay stations?
Relay stations = where all signals are integrated -> the combined input of the signal integration determines if the cell becomes active
->A lot of information processing takes place before a signals has reached the brain
What structures do the hindbrain consist of?
The hindbrain consists of the medulla, pons and cerebellum
Hindbrain - function
->Medulla and Pons = where the spinal cord enters the brain (functions: contains several nuclei/clusters of cell bodies, connected to the autonomic nervous system)
->Cerebellum: not part of the brain stem (function = balance and motor learning)
Midbrain location
Midbrain is above the pons
Midbrain function
Function of the midbrain = includes combination of information from different sense modalities; direction of attention
Function of the forebrain (Diencephalon)
Forebrain function = main relay station for incoming sensory signals
->Recieves downward-going input from higher areas, modulating the relay of sensory signals
What does the brainstem consist of?
Brainstem = medulla, pons and midbrain -> not the cerebellum
Thalamus location
Thalamus: massive structure ontop of the midbrain, deep in the centre of the brain
Function of the thalamus
Thalamus = directly connected to the pituitary gland (master gland of the ES, controls activity of all other glands)
->Gateway to ES: NS can influence ES via hypothalamus - pituitary connection
Hypothalamus location and function
-> Small structure infront of and below thalamus
->Directly connected to the pituitary gland (master gland of ES)
->Gateway to ES: NS influences ES via H-P connection
Forebrain - Telencephalon
Forebrain:
->From the diencephalon, incoming signals go up to the cerebrum
->Divided into two highly similar hemispheres
->Each hemisphere is covered in cerebral cortex
->Grey and white matter
->Each hemispheres recieves input from and sends output to the opposite site of the body
Cerebral cortex
The cerebral cortex is a thin layer of neurons covering each hemisphere
->Contains groups of sub-corticol nuclei (tight clusters of neuron cell bodies)
Grey matter in the brain
Grey matter in the brain = Neuron cell bodies are located here
->Cortex and sub-corticol nuclei
White matter in the brain
White matter = myelinated axons of neurons
Central hemisphere
->Group of nuclei surrounding the thalamus
->Involves in motor control processes
->Consists of globus pallidus, putamen caudate
->Putamen and caudate often referred to as corpus striatum (‘striped body’)
->Amygdala closely connected to this system, therefore sometimes described as being part of the basal ganglia (but usually described in the context of the limbic system)
Basal Ganglia
Basal ganglia:
->Multiple interconnected cortical and sub-corticol areas, playing a crucial role in memory and emotion
->Sub-corticol: Almost complete circle formed by fornix and hippocampus, ending in mammillary body and amygdale
->Corticol: Cingulate cortex directly above corpus callosum (evolutionary older, more primitive than rest of the cortex)
->Connected to the hypothalamus (septum) and olfactory system
Structures found within limbic system
Structures found within limbic system:
-Cerebral cortex
-Corpus callosum
-Gyri
-Sulci
-Longitudinal fissure
-Cerebral lobes (occipital, temporal, partial, frontal)
What is the function of the limbic system?
Function of the limbic system: memory formation and emotional control
How is sensory input processed in the left and right side of the brain?
Sensory input from the right side of the body (or the right visual field) is processed in the left side of the brain
->And vice versa
Where is motor output to the right side of the body generated?
Motor output to the right side of the body is generated in the left half of the brain (and vice versa)
What determines how a signal is interpreted?
How a signal is interpreted depends entirely on its location
What is meant by ‘topographic representation’?
Topographic representation = in each sensory area, signals arrive at a position correponding to the position of the receptor cell
Types of topographic representation mapping
Tomoggraphic mapping:
->Somatographic (signals recieved from nearby areas eg hand and arm)
->Retinographic (visual signals frmo neighbouring retional positions arrive at neighbouring positions in the primary visual cortex)
->Tonotopic map (auditory signals from adjacent areas of the cochlea arrive at adjacent areas in the primary auditory cortex
Note: multiple, differing maps for each sense modality
Why do complex organisms need a nervous system?
Complex organisms need a nervous system because; cells are not in direct contact with outisde world, cells live in different environments, cells are specialised
What are the two biological systems responsible for coordinating cell activity?
The endocrine system and nervous system are responsible for cell activity/
->Endocrine = hormones, slow
->Nervous = impulses, rapid
What are neural impulses?
Neural impulses = basis for constant and rapid communication between cells (constant and rapid control and adjustment of ongoing cell activities)
What are the general functions of neurons?
General functions of neurons include;
->Generation and transmission of electrical impulses (modifies activity of target cells, allows selective control of target structures)
->Electrical activity modulated by integrated input from other cells (input adjusts output, integrations of signals from various sources)
Special requirements of neurons
Special requirements of neurons;
->Cannot store energy, so glucose and oxygen must be constantly supplied -> without this supply, neurons stop working
->Cannot divide (neurogenesis occurs during pregnangy) but neuron death normal
What are Glia cells?
Glia cells;
->Provide protected environments for neurons to survive
->Develops from neural stem cells
->As many glia as there are neurons in the brain
What are the different types of glia cells?
Glia cell types;
->Astrocytes
->Microglia
->Oligodendroglia
What are astrocytes?
Astrocytes;
->Star-shaped
->Physical and nutritional support for neurons (transports nutrients from blood vessels to neurons, waste products moved away from neurons, hold neurons in place)
->Takes part in neural signalling
What are microglia?
Microglia;
->Small
->Mobile for defensive function (produces chemical that aid repair of damaged neurons - digests dead neurons via phagocytosis)
What are oligdendroglia?
Oligdendroglia;
->Large, flat branches wrapping themselves around axons
->Consists of myelin sheath which insulates the axon
Why is it good that membranes are not impermeable?
If membranes were impermeable, electrical potential would remain static
Function of protein channels within the membrane
Protein channels within the membrane allow ions to enter/leave the cell, allowing for depolarisation therefore generating action potentials
When does a membrane depolarise, and when does a membrane hyperpolarise?
->Ion specific channels open either by chance or in response to stimulation
->The membrane depolarises when positive ions enter/negative ions leave
->The membrane hyperpolarises when positive ions leave/negative ions enter
Electrotonic transmission (soma and dendrites)
Electrotonic transmission;
->Electrical and concentration gradients sweep ions along membranes
->Passive and graded (initial magnitude dependant on how many ions enter)
What initiates an action potential?
An action potential is initiated;
->Ion channels open in response to electrical changes in the membrane
->Sodium channels open, sodium ions enter and the membrane is depolarised
->Membrane potential must reach threshold value
Threshold potential & The Hodgkin-Huxley Cycle
->If membrane potential at axon hillick remains below -50mV => resting potential returns
->If membrane potential at axon hillick rises above -50mV => action potential generated
What are the electrochemical processes occuring during an action potential?
Electrochemical processes during an action potential;
1-> Enough positive ions arrived that threshold reached (complete depolarisation)
2-> Na channels close
3-> K channels open, K ions leave, membrane repolarises
4-> Membrane briefly hyperpolarised when fewer K ions inside than outside cell
Why does an action potential not travel backwards?
An action potential does not travel backwards because the membrane is more difficult to depolarise after hyperpolarisation
-The membrane in front of AP still at resting potential
What are the properties of an action potential?S
Properties of an action potential;
->Does not decay during transmission
->Always strong enough to depolarise next area of membrane ahead of it
->All-or-nothing principle
->Cannot be produced continuously
->Fast
What is saltatory conduction?
Saltatory Conduction;
->Myelinated sensory and motor neurons, resulting in faster transmission
->Myelin prevents inflow and outflow of ions
->Electrical charges transported inside axons without the need to produce an action potential
->Nodes of ranvier (action potential jumps across these)
Qualitative and Quantitative coding of neuronal information
Qualitative = determined by place in the brain where signal is recieved
Qualitative = represented in a neuron’s firing rate -> a strong input wiill cause neurons to send signals out more quickly
