BEI

• Three major divisions of the brain

  • Hindbrain
  • Midbrain
  • Forebrain
• Forebrain


  • Prosencephalon ("forward-brain")
  • Diencephalon ("between-brain")
  • Telencephalon ("end-brain")
• Midbrain


  • Tectum
  • Superior colliculus
  • Inferior colliculus
  • Tegmentum
  • Substantia nigra
• Hindbrain


  • Medulla
  • Pons
  • Cerebellum
• Hindbrain structures, the midbrain and other central structures of the brain combine and make up the brain stem

  
• Medulla


  Located just above the spinal cord and could be regarded as an enlarged extension of the spinal cord
• Medulla


  • Responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing and sneezing
  • Damage can be fatal (e.g., large doses of opiates can suppress activity of the medulla)
  • Cranial nerves allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs to the organs
• Cranial nerve nuclei


  Clusters of neurons in the CNS for nerves V through XII are in the medulla and pons, nerves I through IV are in the midbrain and forebrain

  
• Cranial nerves


  Integrate sensory information, regulate motor output, or both

  
• Cranial nerves


  • CN VII (Facial) - taste from the anterior two thirds of the tongue and controls facial expressions, crying, salivation, and dilation of the head's blood vessels
  • CN II (Optic) - vision
  • CN III (Oculomotor), IV (Troclear), and VI (Abducens) - control eye movement

  
• Pons

  • Lies on each side of the medulla (ventral and anterior)
  • Location where axons from each half of the brain cross to the opposite side of the spinal cord
  • Along with the medulla, contains the reticular formation and raphe system

  
• Reticular formation

  • Descending portion is one of several brain areas that control the motor areas of the spinal cord
  • Ascending portion sends output to much of the cerebral cortex, selectively increasing arousal and attention (e.g., waking/sleeping, discriminating between relevant and irrelevant background stimuli)

  
• Raphe system


  • Sends axons to much of the forebrain, modifying the brain's readiness to respond to stimuli
  • Release serotonin to rest of brain
  • Vigilance and levels of alertness, Circadian rhythms in animals
• Cerebellum


  • Helps regulate motor movement, balance and coordination
  • Is also important for shifting attention between auditory and visual stimuli
  • Damage: clumsy, lose balance, trouble shifting attention between auditory and visual stimuli, difficulty with timing (e.g., which rhythm is faster)
• Tectum


  • Roof of the midbrain
• Superior colliculus


  • Processes visual sensory information
• Inferior colliculus


  • Processes auditory sensory information
• Tegmentum


  • Intermediate level of the midbrain containing nuclei for cranial nerves (III & IV), parts of the reticular formation, and extensions of the pathways between the forebrain and the spinal cord or hindbrain

  
• Substantia nigra


  • Gives rise to the dopamine containing pathway facilitating readiness for movement
• Forebrain


  The most anterior and prominent part of the mammalian brain and consists of two cerebral hemispheres

  
• Forebrain


  • Outer cortex
  • Subcortical regions

  
• Cerebral cortex


  Outer portion of the forebrain
• Each side of the cerebral cortex receives sensory information and controls motor movement from the opposite (contralateral) side of the body
• Subcortical regions of the forebrain

  • Thalamus
  • Basal Ganglia
• Thalamus


  Relay station from the sensory organs and main source of input to the cortex, except for olfactory information which progresses from the olfactory receptors to the olfactory bulb and then directly to the cerebral cortex
• Basal Ganglia


  Important for certain aspects of movement
• Limbic system


  • Olfactory bulb
  • Hypothalamus
  • Hippocampus
  • Amygdala
  • Cingulate gyrus of the cerebral cortex
• Limbic system


  Associated with motivation, emotion, drives and aggression
• Hypothalamus


  • Small area near the base of the brain
  • Conveys messages to the pituitary gland to alter the release of hormones
  • Associated with behaviours such as eating, drinking, sexual behaviour and other motivated behaviours
• Diencephalon


  Thalamus and the hypothalamus together
• Pituitary gland


  • Hormone producing gland (endocrine gland) found at the base of the hypothalamus
  • Contains neurons, blood vessels and connective tissue
  • Respond to message from hypothalamus
  • Synthesises and release hormones into bloodstream, which carries them to other organs
• Basal ganglia


  • Comprised of the caudate nucleus, the putamen, and the globus pallidus
  • Associated with planning of motor movement, and aspects of memory and emotional expression
  • Have subdivisions that exchange information with different parts of cerebral cortex especially the frontal areas
  • Deteriorates in patients with Parkinson's disease and Huntingtons's disease leading to impaired movement, depression, deficits in memory, reasoning, and attention
• Basal forebrain


  • Comprised of several structures that lie on the ventral surface of the forebrain
  • Contains the nucleus basalis
  • Receives input from the hypothalamus and basal ganglia
  • Sends axons that release acetylcholine to the cerebral cortex
  • Key part of the brains system for arousal, wakefulness, and attention
  • Deterioration in patients with Parkinson's and Hungtinton's have impairments of attention and intellect
• Hippocampus


  • A large structure located between the thalamus and cerebral cortex, toward the posterior portion of the forebrain
  • Critical for storing certain types of memory
• Central canal


  A fluid-filled channel in the center of the spinal cord
• Ventricles


  Four fluid-filled cavities within the brain containing cerebrospinal fluid

  
• Meninges


  • Membranes that surround the brain and spinal cord
  • Swelling of blood vessels in meninges causes migraine headache (meninges has pain receptors although the brain does not)
• Subarachnoid spaces


  Narrow spaces between brain and meninges
• Cerebrospinal fluid


  • A clear fluid found in the brain and spinal cord
  • Produced by choroid plexus
  • Provides "cushioning" for the brain
  • Reservoir of hormones and nutrition for the brain and spinal cord
  • Obstruction leads to hydrocephalus

  
• Cerebral cortex


  • The most prominent part of the mammalian brain and consists of the cellular layers on the outer surface of the cerebral hemispheres
  • Divided into two halves
  • Joined by two bundles of axons called the corpus callosum and the anterior commissure
  • Cells within certain column share similar properties (e.g., respond to touch on left hand)
  • More highly developed in humans than other species