The Brain and Neurones

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The Brain and Neurones

• Psychopharmacology

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The Human Brain

• Complex
• 1.4 kg in weight
• Pre frontal cortex
• 2 of body weight
• 20 of oxygen
• 15 of our cardiac input
• 10 of all energy

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The Blood Brain barrier

• Brain protection system
• The BBB is both
• A physical barrier that restricts the entrance of
  potentially harmful substances
• A system of cellular transport mechanisms that
  controls the entrance of essential nutrients

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Forebrain

• Cerebrum and Cerebral cortex
• Left and Right Hemispheres
• Left Hemisphere- dominant hemisphere
• Production of language
• Mathematical ability
• Problem solving

• Right Hemisphere
• - Creativity
• - Spatial ability

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Frontal Lobe

• Located at the front of both cerebral hemispheres
• Primary motor cortex
• Pre motor cortex
• Brocas Area
• Complex Functioning personality, judgement,
  insight, reasoning, problem solving, abstract
  thinking and working memory

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Parietal Lobe

• Located behind frontal lobe
• Somatosensory cortex
• Spatial orientation, perception and comprehension
  of language function recognising objects by touch
• Links visual and somatosensory information
  together
• Neglect

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Temporal Lobes

• Located et each side of the brain
• Involved in receiving and processing auditory
  information, higher order visual information ,
  complex aspects of memory and language
• Wernickes area

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Occipital Lobe

• Visual processing area
• Corpus Callosum

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Diencephalon

• Thalamus
• Filter for sensory information
• Control of mood states
• Body movement
• Hypothalamus
• Central control
• Regulate autonomic, emotional, endocrine and
  somatic function
• Stress

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Hindbrain

• Cerebellum
• Equilibrium
• Muscle tone
• Postural control
• Coordination of muscle movement
• Pons
• Relay station

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Hindbrain

• Medulla Oblongata
• Skeletal muscles
• Balance
• Coordination
• Inner ear sound impulses
• Heart rate, vomiting, sneezing
• Reticular formation
• Arousal
• Circadian rhythm
• respiration

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• Basal ganglia
• Muslce tone
• Posture
• Movement
• Substantia Nigra

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The Limbic System

• Amygdala
• Mood
• Hippocampus
• Memory

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Neurones

• The structural unit of the brain
• Cell body
• Axon
• Dendrites
• Synapse

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Electrical Transmission

• The Information that flows in the neurone
• Approximately 10 billion neurons are responsible
  for receiving, organising and transmitting
  information in the central nervous system
• Ions in the intracellular fluid (inside the
  cell) have a negative charge
• Ions in extracellular fluid (outside the cell)
  have a positive charge attracting positively
  charged cells (cations)
• Potential difference between the inside and
  the outside of the cell

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• Ions are sodium, potassium, calcium and chloride
• voltage gated
• Resting Potential vs. Action potential

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Chemical Neurotransmission

• The flow of neurotransmitter across the synapse
• Neurotransmitter
• Made in the pre synaptic neurone
• Stored inactively in synaptic vesicles
• Released from the synaptic vesicles into the
  synapse
• Binds to receptors
• Binds to reuptake transporters to be taken back
  into the neurone
• Is degraded by specific enzymes

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Neurotransmitters

• Acetylcholine (ACh)
• Norepinephrine (NE)( also known as noradrenaline)
• Dopamine(D)
• Serotonin (5HT)
• Glutamate
• Gamma-aminobutyric acid (GABA)

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Neurotransmitters

• There are two kinds of neurotransmitters
  INHIBITORY and EXCITATORY.
• stimulate the brain
• calm the brain

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Acetylcholine (ACh)

• Cholinergic pathways
• thought to be involved in cognition (esp.
  memory) and our sleep/wake cycle
• parasympathetic nervous system regulating
  bodily functions such as heart rate, digestion,
  secretion of saliva and bladder function
• Alzheimers disease and myathesia gravis
  (weakness of skeletal muscles)
• Anti-cholinergic effects

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Norepinephrine (NE)

• attention, alertness and arousal
• NE levels fluctuate with sleep and wakefulness
  and changes in attention and vigilance
• mood, affective states and anxiety
• antidepressant

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Dopamine(D)

• complex movement and cognition
• Emotional responses such as euphoria or pleasure
  (seen in amphetamine/cocaine use).
• Significant role in motor control
• EPSEs

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Serotonin (5HT)

• Great influences on behaviour.
• Low serotonin activity is associated with
  aggression, suicide, impulsive eating and
  dis-inhibited sexual behaviour
• modulating general activity levels of the CNS,
  particularly the onset of sleep
• depression and anxiety disorders
• delusions, hallucinations (LSD)
• negative symptoms of schizophrenia

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Glutamate

• Glutamate is found in all cells of the body
• control the opening of ion channels that allow
  calcium to pass into nerve cells producing
  impulses
• Blocking of glutamate receptors produces ( eg. By
  PCP) schizophrenic like symptoms
• Over exposure of neurons to glutamate cause cell
  death seen in stroke and Huntingtons disease
  (PN).

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Gamma-aminobutyric acid (GABA)

• Inhibitory and its pathways are only found within
  the CNS.
• control excitatory neurotransmitters in the brain
  and controlling spinal and cerebral reflexes.
• anxiety disorders
• decreased GABA can lead to seizure activity
• Benzodiazepines and barbiturates sedative
  medication act on GABA