EEG records synchronous firing of pyramidal neurons in cortex (many combined dipoles). EEG measures combined activity of ~10 million neurons Basic EEG (‘brainwaves’)

Why do we sleep? Why can’t we simply run continuously? What parts of the brain are active when sleeping…why do we forget once we’ve woken? Why can some people fxn on fewer hours of sleep and others require more? Sleep questions

Sleep is complex and electrically active  Deep NREM sleep: body repair, build bone, muscle Rodents deprived of sleep live 3 weeks instead of normal 2-3 years Your ability to remember dreams partly depends on what phase of sleeping you were in Sleep physiology and function

A set of interconnected brain areas that fxn in motivation, emotion, and memory Limbic association cortex

 Involves both cortical and subcortical regions  “Feeling and reacting brain” vs. thinking brain of frontal cortex.  Fear, anger, pleasure and sexual drive  Reward and punishment centers exist Limbic system

Receives signals right from thalamus when experiencing fearful stimuli (emotional stimuli) Amygdala is associated with hippocampus, learning. Limbic system: amygdala

 Short-term memory – stored for a few minutes and can contain only a few items or concepts (like a phone number). Items can get ‘bumped’ from STM.  Long-term memory – lasts years or more – generally stored in cortex. Includes factual info about the world, and personal events. Memory

Hippocampus Short-term memory is converted to long- term memory using signals involving the hippocampus Hippocampus is an area where new neurons can be produced.

Newly acquired information Usually permanently lost Rapid retrieval Inability to retrieve “Forgetting”“Remembering” Searching and readout Short-term memory stores (Practice) Consolidation Long-term memory stores Slower retrieval, except for thoroughly ingrained memories, which are rapidly retrieved Usually only transiently unable to access stores Storage in temporal lobes, limbic system, cerebellum How we remember

 In Alzheimer’s disease, abnormal proteins cause damage to neurons (amyloid beta, tau)  The hippocampus is the first to be affected Alzheimer’s disease

Idea that areas of the brain distinctly focus on one sense has been discarded There is a lot of ‘cross-talk’ between the senses (i.e. what you see influences what you hear and so on) Our brain is not really a ‘swiss army knife’ Then Now

Figure 5.28 Page 173 Cervical cord Thoracic cord Lumbar cord Sacral cord Cervical nerves Thoracic nerves Lumbar nerves Sacral nerves Coccygeal nerve Cauda equina

Dermatome - a patch of skin innervated by the same spinal nerve

Spinal cord Spinal nerve Vertebra Meninges layers

Nerve- a bundle of peripheral axons. Spinal nerves contain afferent and efferent fibers.

Cell body of efferent neuron Cell body of afferent neuron From receptors To effectors Interneuron Dorsal root ganglion Ventral root

Stimulus Biceps (flexor) contracts Hand withdrawn Triceps (extensor) relaxes Ascending pathway to brain Response Reflex arc Receptor Afferent pathway Integrating center Efferent pathway Effector organs Integrating center (spinal cord) Thermal pain receptor in finger Efferent pathway Effector organs Afferent Pathway