NEUR2020 midsem

tutorials and lectures weeks 1-6 for now

what is the primary goal of neuroscience?

to understand how the nervous system produces behaviour, cognition, and emotion

what are the two major divisions of the nervous system?

central nervous system (CNS) peripheral nervous system (PNS)

what structures make up the CNS?

brain and spinal cord

what is the role of the PNS?

to transmit information between the body and the CNS

what are the two branches of the PNS?

somatic nervous system autonomic nervous system

what does the somatic nervous system control?

voluntary movement and sensory communication

what does the autonomic nervous system regulate?

involuntary physiological processes such as heart rate and digestion

what are the two divisions of the autonomic nervous system>

sympathetic and parasympathetic systems

what is the function of sympathetic nervous system?

prepares the body for action (fight of flight)

whats the function of the parasympathetic nervous system?

restores and conserves energy (rest and digest)

what is a neuron?

a specialised cell that transmits information using electrical and chemical signals

what are the main parts of neuron?

dendrites, soma (cell body), axon, and terminal buttons

what is the function of dendrites?

receive incoming information from other neurons

what is the function of the axons?

conduct electrical impulses away from the cell body

what is the myelin sheath?

a fatty insulating layer that speeds neural transmission

why is myelination imprtant?

it increases the speed and efficiency of signal conduction

what occurs at the synapse?

communication between neurons via neurotransmitters

what are neurotransmitters?

chemical messengers that transmit signals across the synaptic gap

difference between electrical and chemical signalling in neurons?

eletrical signals travel within neurons chemical signals transmit between neurons

what is an action potential?

a rapid eletrical change that propagates along the axon

what principle governs action potentials?

the all or none law

what is the all or none law?

a neuron either fires completely or not at all

how is information intensity encoded if action potentials are all or none?

by the frequency of firing, not the size of the signal

what is resting potential?

the stable negative charge of a neuron when not firing

what causes depolarisation?

influx of positively charged ions (eg sodium)

what is repolarisation?

return of the membrane toward resting potential after firing

why is the refractory period important?

it limits firing rate and ensures signals travel in one direction

what role to glial cells play?

support, protect, and maintain neurons

why are glial cells essential despite not transmitting signals?

they regulate the neural environment, provide nutrients, and aid repair

what is localisation of function?

the idea that specific brain regions perform specialised tasks

what is neuroplasticity?

the brain's ability to change structurally and functionally with experience

why is neuroplasticity important for learning?

it allows neural circuits to reorganise and strengthen with use

how does experience shape the brain?

repeated activation strengthens synaptic connections

what is the relationship between structure and function in neuroscience?

brain structure enables specific physiological and psychological functions

what does structure refer to in neuroscience?

the morphology or physical form of brain tissue

what type of method reveals brain structure?

imaging such as CT scans show anatomy (eg tumours)

what does function refer to in neurosciene?

acitivity occurring within the brain

what type of method reveals brain function?

techniques like EEG that measure neural activity

difference between structural and functional methods?

structural shows what the brain looks like; functional shows what the brain is doing

what does superior mean anatomically?

above

what does inferior mean anatomically?

below

what does rostral mean?

toward the head

what does caudal mean?

toward the tail

what does contralateral mean?

on the opposite side of the body

what does ipsilateral mean?

on the same side of the body

what does bilateral mean?

on the same side of the body

what does unilateral mean?

on one side only

what does proximal mean?

close to the main body mass

what does distal mean?

far from the main body mass

prefixes such as sub-, hypo-, and infra- indicate what spatial meaning?

below

terms like tract, lemniscus, funiculus, and fasciculus refer to what?

fibre bundles or neural pathways in the CNS

what is spatial resolution?

how precisely a method can localise a structure in space

what characterises low spatial resolution?

localisation only to large regions (centimetre scale)

what characterises high spatial resolution?

precise localisation down to milimetres or micrometres

what is temporal resolution?

how precisely a method can measure timing of neural events

what characterises low temporal resolution?

timing measured in seconds

what characterises high temporal resolution?

timing measured in milliseconds or microseconds

why is there often a trade-off between spatial and temporal resolution?

methods that mesure precises location often cannot measure rapid timing, and vice versa

what is correlation?

a reliable relationship between two variables

why does correlation not imply causation?

the relationship may be due to coincidence or a third variable

what three conditions are required to infer causation?

a reliable relationship, cause precedes effect, removing the cause removes the effect

why is observing brain activity alone insufficient to claim causation?

activity may correlate with behaviour without producing it

how can causation be inferred in neuroscience?

by stimulating or disrupting a brain region and observing behavioural change

what does PET mesure?

metabolic activity using radioactive tracers taken up by active brain areas

why is PET considered invasive?

it requires injection or inhalation of radioactive substances

what is a limitation of PET?

radioactivity exposure and limited repeat use

what does fMRI measure?

changes in oxygenated blood flow associated with neural activity

what is the BOLD signal?

'blood oxgyen level dependent' signal indicating active regions

major advantage of fMRI?

high spatial resolution and non-invasive whole-brain imaging

major limitation of fMRI?

poor temporal resolution

what is transcranial magnetic stimulation (TMS)?

a method using magnetic pulses to disrupt neural activity

why is TMS useful for research?

allows causal inference by creating a virtual lesion

what does MEG measure?

magnetic fields produced by neural activity

key strength of MEG?

excellent temporal resolution

key weakness of MEG?

poorer spatial localisation

what is stereotaxic surgery?

a technique that precisely places recording or stimulating devices in the brain

what are lesion methods?

techniques that remove or disable brain tissue to study resulting behaviour

why do lesion studies provide casual information?

they show which functions are lost when a region is damaged

what is a limitation of lesion research?

damage is rarely perfectly localised and may affect neighbouring tissue

what is acquired brain injury?

damage occuring after birth (eg stroke, TBI, substance effects)

why must researchers interpret brain injury cautiously?

lesions may be incomplete or extend beyond the intended structure

what is psychophysics?

the measurement of psychological responses to physical stimuli

what is a detection threshold?

the faintest stimulus a person can detect

what is a discrimination threshold?

the smallest detectable difference between stimuli

what does signal detection theory analyse?

the ability to distinguish signal from noise in perception

why are behavioural measures important in brain imaging studies?

they verify whether participants are actually performing the task being measure

what is the peripheral nervous system? pns

it transmits information to and from the CNS. located outside the skull and spine. contains ganglia and nerves

what is the ganglia?

clusters of cell bodies in the PNS

what are nerves?

clusters of axons in the PNS

what is the autonomic nervous system? ans

it regulates the body's internal state. it afferents from internal organs to CNS and efferents from CNS to internal organs involuntary. to efferents to internal organs - to cardiac muscle and glands two types of efferent nerves

what are the two types of efferent nerves?

sympathetic and parasympathetic

what does the sympathetic nerves do?

stimulates and organises energy in threatening situations fight or flight responses stimulates organs to release hormones to wind things up increases blood flow and respiration suppress non-essentials mobilises energy

what does the parasympathetic nerves do?

conserves energy rest and digest stimulate digestion and restorative functions

what does the somatic nervous system do? sns

afferent nerves (sensory to CNS) efferent nerves (motor from CNS) for voluntary movements exteroceptive sense organs information to enable interaction with the world

what does efferent nerves do?

motor commands from CNS skeletal muscle facilitate body's interaction with the world

what is efferent?

conducted or conducting outwards or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied).

what is afferent?

conducting or conducted inwards or towards something (for nerves, the central nervous system; for blood vessels, the organ supplied).

afferent vs efferent

Feature Afferent (Sensory)Efferent (Motor)DirectionToward the CNS Away from the CNSFunction Receives sensory stimuli Produces motor responsePathwayPeripheral receptors to CNS CNS to muscles/glands Memory Aid Afferent = Arrive Efferent = Exit

what physically protects the brain?

skull menenges (Dura Mater, Arachnoid meninx, Pia mater meninx) cerebrospinal fluid (CSF)

what chemically protects the brain?

blood brain barrier -- tightly packed cells along the blood vessel walls of the CNS prevent entry of many large molecules