Lecture 2 Flashcards
what does the brain do?
the brain takes information from the outside world, performs computations/ processes the information and produces effects/ outputs and behaviours
the whole nervous system can be thought of as performing this input-computation-output function as can different brain circuits and even cells
peripheral nervous sytem
- inputs and outputs of the nervous system
- somatic = external environment
- autonomic = internal environment
- enteric = gut
sensory neurones take info from environment to CNS
motor neurones take info from CNS to environment
somatic nervous system (component of peripheral)
- first neurone we have seen has 2 ends - input, output and soma
SENSORY NEURONE = input from skin (touch sensation)
the soma is in dorsal route ganglion, output goes to spinal cord
signal passes up spinal cord to brain or for reflexes goes through spinal cord onto motor neurone
MOTOR NEURONE = gets input from brain or spinal cord (reflexes) and outputs to muscle
dermatomes and myotomes
dermatomes = sensation
myotomes = movement
- spinal cord injury effects related to which muscles denervated
- lower sacral = only problems with incontinence
the spinal afferents that accompany the autonomic nerves are responsible for initiating visceral sensation such as pain
outputs = parasympathetic and sympathetic nervous system
parasympathetic nerves travel along vagus nerve
sympathetic down spinal cord with cell bodies in sympathetic ganglia
they have opposing actions
overall information flow through the brain
overall: inputs from senses - outputs to muscles or organs
in each region: inputs from upstream and downstream regions
what brain region does depends on the nature of the inputs and outputs and how the info is integrated in that brain area
medulla
takes input from periphery and forebrain and regulates autonomic functions like breathing and heart-rate
damage can be fatal
pons
takes input from periphery and forebrain and functions like arousal and control of sleep
sends info to rest of nervous system
midbrain
lots of different nuclei with diverse functions e.g. substantia nigra and VTA- dopamine neurone cell bodies, which send dopamine signals into forebrain (basal ganglia)
superior colliculus - orientates behaviour
cerebellum
- layered structure
- involved in refining movements
- e.g. balance and procedural memory
- organised structure “laminar”
inputs are from cerebral cortex and spinal cord via pons to thalamus
outputs are from cerebellar nuclei, from which brain stem goes to thalamus
computations: modifies descending motor commands to make them adaptive and accurate
balance, procedural memory, motor learning and cognitive functions
diencephalon
major structures: thalamus and hypothalamus
like rest of the brain all these structure are bilateral (have two of them) except the pineal gland
it makes melatonin and involved in circadian rhythms
thalamus
- info hub
- relays ascending and descending info from widespread brain areas
- different thalamic nuclei connect to specific parts of cortex
- suggests different functional specialisations
hypothalamus
- regulates several homeostatic processes such as feeding and drinking
- links brain to endocrine system (hormones)
cerebrum
- cerebral cortex
- sub-cortical structures (hippocampus, basal ganglia, amygdala, olfactory bulb)
- corpus callous carries information between the two hemispheres
basal ganglia
inputs: cortex, hippocampus, VTA/ substantia nigra
outputs: thalamus and onto cortex, VTA/ substantia nigra
computations: co-ordinating movements via dorsal striatum
motivated behaviour via ventral striatum
amygdala
inputs: cortex, hippocampus, thalamus, hypothalamus, brainstem
outputs: cortex, basal ganglia, hypothalamus and brainstem
computations: emotional learning especially fear conditioning
