The Vertebrate Brain

The Vertebrate Brain

1. is regionally specialised

2. Forebrain

   • Diencephalon
     • Hypothalamus
       • regulates homeostasis and basic survival behaviors such as
         • feeding
         • fighting
         • fleeing
         • reproducing
       • regulates the biological clock
         • regulates cicardian rhythms such as the sleep/wake cycle
         • most mammals have a pair of suprachiasmatic nuclei (SCN) in the hypothalamus which act as a biological clock
           • Biological clocks generally require external cues to remain synchronised with environmental cycles
     • Thalamus
       • the main input centre for sensory information to the cerebrum
       • the main output centre for motor information leaving the cerebrum
     • Epithalamus
       • pineal gland
         • secretes melatonin
   • Cerebrum/telencephalon
     • the structure which varies most across species
     • has two hemispheres the right and the left
       • each hemisphere consists of a cerebral cortex (grey matter) overlaying white matter and basal nuclei
     • in humans the cerebral cortex is the largest and most complex part of the brain
       • it controls voluntary movement and cognitive functions
     • the basal nuclei are important centres for planning and learning movement sequences
       • diseases of the basal ganlia include
         • Parkinson's
         • Huntington's
         • Tourette syndrome
     • lateralisation of cortical function
       • corpus callosum
         • a thick band of axons provides communication between the right and left hemispheres
         • split brain occurs if corpus callosum is removed
       • left hemisphere
         • is more adept at language, maths, logic and processing of serial sequences
       • right hemisphere
         • is stronger at pattern recognition, nonverbal thinking and emotional processing
       • the differences in hemisphere function are called lateralisation
     • the right half of the cerebral cortex controls the left side fo the body and vice versa
     • each side of the cerebral cortex has four lobes:
       • frontal
       • temporal
       • occipital
       • parietal
       • each lobe contains primary sensory areas and association areas where information is integrated

3. The Brainstem

   • Hindbrain
     • pons
       • regulates the breathing centres in the meulla
     • medulla oblongata
       • contains centres that control several functions including
         • breathing
         • cardiovascular activity
         • swallowing
         • vomiting
         • digestion
     • cerebellum
       • is important for
         • movement coordination
         • balance
         • error checking during motor, perceptual and cognitive functions
       • is involved in learning and remembering motor skills
       • part of hind brain but not of Brainstem
   • Midbrain
     • contains centres for receipt and integration of sensory information
   • coordinates and conducts information between brain centres
   • Arousal and sleep
     • controled by both the cerebrum and the brainstem
     • in the core of the brainstem there is a network of neurons called the reticular formation
       • this regulates the amount and type of information that reaches the cerebral cortex and affects alertness
       • the hormone melatonin is released by the pineal gland
         • this plays a role in the sleep cycles of birds and mammals
     • sleep is essential and may play and role in the consolidation of learning and memory
       • dolphins sleep with one brain hemisphere at a time
         • this means they are able to swim while they're "asleep"

4. the limbic system

   • where emotions are generated and experienced
     • this takes place in other parts of the brain as well including various sensory areas
   • is a ring of structures around the brainstem inculding
     • the amygdala
       • located in the temporal lobe
         • helps store an emotional experience as an emotional memory
     • the hippocampus
     • parts of the thalamus

5. the outermost layer of the cerebral cortex has a different arrangement in bird and mammals

   • in mammals the cerebral cortex has a convoluted surface called the neo cortex
     • this was previously thought to be required for cognition
       • cognition is the perception and reasoning that form knowledge
       • however it has recently been shown that birds also demonstrate cognition even though they do not have a neocortex

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