topic 1: localisation of function in the brain

• human nervous system: conducts stimuli from the sensory receptors to the brain and spinal cord and conducts impulses back to other body parts
• central nervous system: is the processing centre of the body and consists of the brain and spinal cord
• peripheral nervous system: consists of neurons associated with sensory input (afferent) and motor input (efferent) and connects CNS to the rest of the body
• motor system: regulate voluntary and involuntary and and subconscious activities, sends neural signals from CNS to smooth muscle, cardiac muscle and glands
• sensory system: portion of the brain responsible for processing input from the environment
• brain: contains 100 billion neurons transmitting signals to and from parts of the body as well as regulation of voluntary and involuntary actions
• spinal cord: carries nerve signals from brain to rest of body, commands muscles to move, receives sensor input from body and processes/transmits info to the brain
• somatic nervous system: voluntary control of body movement via the use of skeletal muscles
• autonomic system: regulates involuntary physiological processes including heart rate, blood pressure, respiration, digestion and sexual arousal
• sympathetic nervous system: responsible for the body's fight, flight or freeze response when the body is preparing for action
• parasympathetic nervous system: responsible for the body's rest and digest response when the body is relaxed, resting or feeding
• spinal cord

  • part of the CNS
  • its tightly padded column of nerve tissue runs down from the brain stem through the central column of the spine
  • it is crucial for our daily activities
  • it receives sensory input from the body and transmits that info to the brain
  • it carries nerve signals from the brain to the body, commanding the muscles we use to move
• monosynaptic reflexes:

  • the simplest reflex loops that involve only 1 synaptic connection between 2 neural cells in the spinal cord
  • a sensory neuron receives environmental input and sends a message to a motor neuron that stimulates appropriate muscles in response
  • this action is involuntary
• polysynaptic reflexes:

  • 1 or more interneurons connect afferent and efferent signals
  • for examples the withdrawal reflex is a spinal reflex to protect the body and causes the stimulation of sensory, relay and motor neurons
  • this action can be inhibited by conscious control (can choose to touch a hot pan but cannot control the knee jerk)
• corpus callosum: the band of neural fibres that connect the right and left cerebral hemispheres
• outer layer of cerebrum (left and right hemispheres separated by corpus callosum) that receives environmental info, controls responses, voluntary movement, and higher order thinking
• primary motor cortex is located at the rear of each frontal lobe and is responsible for movement of skeletal muscles
• the primary somatosensory cortex is located at the front of each parietal lobe and processes sensations like touch, pressure, temperature and pain
• parietal lobe: touch, non-verbal thought, spatial orientation
• the primary visual cortex is located in the occipital lobe and processes info from eyes
• the primary auditory cortex is located in the upper part of the temporal lobe and receives sound from ears
• temporal lobe: hearing, language, visual recognition
• frontal lobe: abstract thought, social skills, planning
• thalamus:

  • located above bran stem between the cerebral cortex and the midbrain
  • relays motor and sensory signals to cerebral cortex
• basal ganglia:

  • a set of structures involved in the control of movement, gathering and channelling info from the frontal, parietal and temporal lobes
  • tis causes voluntary movement by operating a complex feedback loop that channels info from various regions of the brain to the motor cortex
  • it also blocks movement that may not suit the end goal of the movement (eg. hear bang and move away from sound - temporal to basal ganglia)
• primary motor cortex:

  • located at the rear of frontal lobe
  • responsible for movement of the body's skeletal muscle and activates the neural impulses that execute voluntary movement
  • voluntary movement is contralateral organisation - left PMC is responsible for movement on the right side
• cerebellum:

  • located in the hindbrain
  • stores sequences of movements that have been previously learnt
  • coordinates and integrates info about movement from other brain areas to make it smooth, well-sequenced and "effortless"
  • communicates with PMC by sending signals through a dense nerve bundle that consists of a large number of axons
• basal ganglia links to Parkinson's Disease
• broca's area:

  • located in left frontal lobe and is the motor region for language production
  • coordinates movements of lips, tongue and vocal cords in readiness for speech
  • comprehends grammar
  • Broca's aphasia - difficulty speaking, using correct grammar and articulating words
• wernicke's area:

  • located in left temporal lobe and is a sensory region for language production
  • stores receptor codes to interpret meaning of langage
  • grammatical accuracy
  • wernicke's aphasia - cannot communicate - no comprehension or ability to produce grammatical sentences
• geschwind's territory:

  • located in parietal lobe and connects language regions of broca's and wernicke's areas by a bundle of nerve fibres
  • helps explain how we input words we hear/read and produce speech
  • platform for abstract thought
• limbic system:

  • located in the midbrain
  • implicated in memory (hippocampus), emotion (amygdala), behaviour and motivation (thalamus/hypothalamus)
  • 2 major structures in emotion regulation are amygdala and hippocampus
  • thalamus and hypothalamus control hormone production and regulation of hunger, flight/fight, reprodution
• hippocampus:

  • involved in the regulation and expression of emotion
  • implicated in memory
  • emotional stimuli activates the hippocampus and recalls info relevant to the situation
• amygdala:

  • located in temporal lobes
  • involved in activation of certain emotions, particularly fear
  • specialised - right amygdala particularly perceives negative emotion
  • implicated in learning - classical conditioning of learned fear responses
• prefrontal cortex:

  • located at the front of the temporal lobe
  • associated with and connects brain regions involved in emotional processing and production
  • regulates and modifies emotion
  • also implicated in executive functions and decision making
• transmitting neural info between neurons:

  • 2 types of synapses involved in communication between neurons
  • excitatory (causes neuron to fire)
  • inhibitory (inhibits neuron to fire)
• presynaptic neuron - a neuron that transmits info to another neuron
• postsynaptic neuron - a neuron that receives info from another neuron
• action potential - when an axon of a neuron fires, the terminal buttons of the excitatory synapses release a neurotransmitter that excites the postsynaptic neurons or causes it to reach its action potential
• Glutamate (Green light):

  • an excitatory neurotransmitter that causes the neuron to fire
  • it can excite almost every neuron in the brain and the rest of the nervous system
  • important role in learning and memory