Biological Basis of Behaviour Flashcards
Nervous System
Central Nervous System (CNS)
- Brain
- Spinal cord
- Optic nerve
- Retina
Peripheral Nervous System (PNS)
- Cranial nerves
- Spinal nerves
- Autonomic nervous system (sympathetic, parasympathetic, enteric)
- Somatic Nervous System
The Brain
Neurons (nerve cells)
- Basic unit of the nervous system—> composed of a cell body, dendrite, and axon
Glial cells (glia)
- Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain
- A.K.A neuroglia
- There are four different types of glial cells
Parts of the neuron
Soma (cell body)
- Has one or more dendrites attached to it and typically one axon
- Its main function is to synthesize macromolecules and integrate electrical signals
Dendrites
- Tapered extensions of cell body
- Purpose is to collect information from other neurons
Axon
- Single and cylindrical
- Can be myelinated or unmyelinated
- Purpose is to conduct information to other neurons
Axon Terminals (presynaptic terminals/synaptic boutons)
- Vesicle-filled apposition to part of another neuron
- Transmits information to other neurons
The Axon Terminal
Synaptic Vesicle
- Spherical sack containing neurotransmitters
Neurotransmitter
- The chemical released from the presynaptic axon terminal that serves as the basis for communication between neurons
Synapse
- An intercellular site where fast, highly localized transmission of chemical and electrical signals occur
- Includes presynaptic/postsynaptic terminals, and synaptic cleft
Synaptic Cleft
- A gap into which neurotransmitters are released from the axon terminal
Types of neurons
Unipolar neuron
- Has a cell body that extends in a branch that becomes an axons going in two different directions
- Has dendrites on one end and axon terminals on the other end
Bipolar neuron
- Has one dendrite and one axon
Multipolar neuron
- Has one axon and many dendrites
The Neural Impulse
Resting Potential
- Difference in electrical charge (-70mv) across the neuronal membrane when the neuron is not being stimulated or inhibited
Depolarization
- The reduction of a membrane’s resting potential so that it becomes less negative
Action Potential
- Electrical impulse that travels down the axon, triggering the release of neurotransmitters
Repolarization
- Na+ channels close, K+ channels open and the efflux of K+ goes down the electro-chemical gradient
Hyperpolarization
- “Overshoot” of repolarization
Refractory Period
- The time during which another action potential is impossible; limits the maximal firing rate of the neuron
- Absolute and relative
Unconventional Neurotransmitters
Anandamide
- Binds to the same receptors as THC (tetrahydrocannabinol), the active ingredient in cannabis leaves
- Comes from Sanskrit word for “joy, delight, bliss”
- Occurs in PNS and CNS
- Likely plays a role in eating, memory, motivation, and sleep
Neuropeptides
Endorphins
- A naturally occurring (endogenous) analgesic (ie. painkiller)
- Inhibits the communication of pain signals to the spinal cord
- Insensitivity to pain (oversupply)
- Hypersensitivity to pain (undersupply)
Endocrine System
- Series of glands that produce chemical substances known as hormones
- Hormones: slow chemical messenger released into the blood by endocrine glands
- Interacts with nervous system
Neuroplasticity
Nervous system morphs/evolves over the course of a lifetime; has the ability to adapt to new stimuli and experiences
Plasticity
Neuroplasticity in early development
1. Growth of axons and dendrites
2. Synaptogenesis (formation of new synapses); the more synapses that the presynaptic terminal can interact with, the more likely it is to get its message across
3. Pruning
- the removal of extra synapses to increase the efficiency of the neural network
4. Myelination
- the insulation of the axons with a myelin sheath
Neuroplasticity and learning
Long-term potentiation of synapses
- A long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously
- Potentiation: the increase in strength of nerve impulses along pathways that have been used previously
Structural changes
- Axonal growth
- Dendric branching/growth
Neuroplasticity following injury
- Brain regions can sometimes take over functions previously performed by others
- Researchers are searching for treatments to promote healing and prevent damage
- Stem cell: a cell (usually originating in embryos) which has the capacity to differentiate into a specialized cell—> potential to offer treatments for certain medical conditions
- Neurogenesis: creation of new neurons in the adult brain
Meninges
Three protective membranes that cover the brain and the spinal cord
- Dura mater—> Arachnoid mater—> Pia mater
Cerebral Ventricles
Pockets in the brain that contain cerebrospinal fluid (CSF), which provide nutrients and cushion against injury
can also be found in the subarachnoid space
Franz Joseph Gall
- Believed that all functions arise from the brain
- Mind and body are NOT separate entities—> brain consists of functional regions
The Cerebral Cortex
Cortex
- Outermost part of the forebrain
- Responsible for analyze sensory processing and “higher” brain functions
Cerebral Hemispheres
- Two halves of the cerebral cortex
- Each of them serve distinct and highly integrated functions
Corpus Callosum
- Large band of fibers connecting the two cerebral hemispheres
Frontal Lobe
- Performs functions that coordinate other brain areas, motor planning, language, and memory
- Primary Motor Cortex: part of the frontal lobe responsible for bodily movement
Receiving signals
Postsynaptic potential (PSP)
- a voltage change at a receptor site on a postsynaptic cell membrane
Excitatory PSP
- a positive (+) voltage shift that increases the likelihood that the postsynaptic neuron will fire action potentials (because it gets closer to the -55mV threshold)
Inhibitory PSP
- a negative (-) voltage shift that decreases the likelihood that the postsynaptic neuron will fire action potentials (because it gets further from the -55mV threshold)
Reuptake
- reabsorption of neurotransmitters from the synaptic cleft by the presynaptic membrane
The Temporal Lobe
- Processes auditory information, language, and autobiographical memory
- Wernicke’s area: part of the temporal lobe involved in understanding speech
- If damaged, it could cause speech impairments
The Occipital Lobe
- Back part of the cerebral cortex specialized for vision
The Basal Ganglia
- A group of nuclei (cluster of neurons) located beneath the cerebral cortex
- Involved in goal-directed motor control
- Contains dopamine neurons and is closely associated with reward and motivation
The Limbic System
- Loosely connected network of structures located roughly along the border between the cerebral cortex and deeper subcortical areas
- Plays a role in olfaction (smell), motivation, memory, and emotion
The Thalamus
- Gateway from the sense organs to the primary sensory cortex
- All sensory information (except smell) is relayed through the thalamus
The Hypothalamus
- Regulates the pituitary gland and is responsible for maintaining a constant internal state (homeostasis)
- “The four F’s” —-> feeding, fighting, flight, fornication
- Body temp
- Hunger/thirst
- Sleep
- Emotional behaviours
The Hippocampus
- Plays a role in spatial memory and may be necessary for the formation of new memories
