64. the aging brain over time, as healthcare and nutrition improve, humans live longer: average life span in the US was only ~50 in 1900, and is ~80 now. sadly, this means more of us are encountering the cognitive impairments that come with age, including alzheimer's and other dementias.

63. genetic mechanisms in neurodegenerative diseases of the nervous system the late-onset degenerative diseases fall into 2 categories: - sporadic, i.e. unknown etiology (majority of alzheimer's and parkinson's cases) - inherited (huntington's, spinocerebellar ataxia, several muscular atrophies)

62. disorders affecting social cognition: autism spectrum disorder neurodevelopmental disorders can affect perception, general cognition, or, as in autism, social cognition. autism has 2 defining features: - impaired social communication - stereotyped behaviors with highly restricted interests

61. disorders of mood and anxiety some stats: - 19% of people have major depression at some point in their lives, 8.3% each year - bipolar disorder (depression plus at least one episode of mania) affects ~1% of people - 28.5% of people have an anxiety disorder at some point in their lives

60. disorders of thought and volition in schizophrenia schizophrenia symptoms fall in 3 clusters: - cognitive (impairment of executive function, memory, fluency, and emotional processing) - deficit (loss of motivation, poverty of thought) - psychotic (hallucinations, delusions, disordered thought)

59. disorders of conscious and unconscious mental processes depending on context, "cognition" can either mean "all information processing in the brain" or "higher-level processes that underlie conscious experience". cognitive therapy, which operates on thoughts, aligns more with the latter.

58. seizures and epilepsy we can't carry out invasive experimental studies in human brains, so a lot of what we know was learned from stroke or injury–trying to tell from functional deficits what a missing brain area did. seizures provide similar data, but for when a brain area is hyperactive.

57. diseases of the peripheral nerve and motor unit motor unit disorders are categorized by part affected: - motor neuron cell body (motor neuron diseases) - motor neuron axon (peripheral neuropathies) - neuromuscular junction (disorders of the neuromuscular junction) - muscle fibers (myopathies)

56. decision-making and consciousness we consider a behavior "cognitive" if it exhibits: - contingency (inputs do not necessitate particular outcomes) - freedom from immediacy (there's some kind of time course) decisions, defined here as provisional commitments to action, are cognitive.

55. language animals communicate, but none come close to what we do with language: provide information, express emotion, comment on past and future, tell stories, and more, all by age 3! "phonemes" are basic units of sound ("c" in "cat"). "morphemes" are basic units of meaning ("un" in "undo").

54. the hippocampus and the neural basis of explicit memory storage working memory relies on ongoing activity in PFC–distractions are destructive. long-term explicit memory is implemented as changes to synaptic structure in cortex. hippocampus is needed, but how exactly that loop works is unclear.

53. cellular mechanisms of implicit memory storage and the biological basis of Individuality long-term implicit memory storage happens in: - neocortex (priming) - striatum (skills, habits) - amygdala (threat conditioning) - cerebellum (motor skills) - reflex pathways (habituation, sensitization)

52. learning and memory learning is a change in behavior from acquiring knowledge. memory is processes by which knowledge is encoded, stored, and retrieved. there are different kinds of memory, classified by time course and information type. memory errors give us clues about how the system works.

51. sexual differentiation of the nervous system humans have 23 chromosomal pairs. 22 of these ("autosomes") are the same between the sexes, while the 23rd pair ("sex chromosomes") differs: XX for females, XY for males. XX → female and XY → male genotypes are conserved across most mammals.

50. repairing the damaged brain developmental neuroscience has recently suggested new approaches to 2 clinical applications we thought were impossible: - regrowth of axons and reformation of synapses in CNS after injury - regeneration of neurons after they're killed by damage or disease

49. experience and the refinement of synaptic connections neural circuitry in mammals is first roughly formed by genetics, then refined by experience. the second stage in humans is extra long. this means we're pretty helpless at birth, but our brains are custom-fit to our bodies and environment.

48. formation and elimination of synapses when axons get to where they're going, they form synapses. this is the last step before the brain can start to process information! 3 parts to synapse formation: - initial partnering - growing pre- and postsynaptic sites - maturation and rearrangement

47. the growth and guidance of axons neurons are born, migrate to their homes, ~then grow axons and dendrites to connect up with each other! some axons are extremely long, and they have to grow in the right direction past a bunch of distractors before reaching their correct synaptic targets.

46. differentiation and survival of nerve cells in the neural tube, ectoderm cells first become CNS stem cells ("neuroepithelial cells"), then progenitor cells ("radial glial cells"). these have their cell bodies near the tube's hollow ventricle, and long fibers extending towards the pial surface.

45. patterning the nervous system neural development falls into 3 epochs: - generation and differentiation of neurons and glia - genetically-guided migration and wiring up - experience-guided refinement of circuits this chapter is about the epoch 1 and the >1000 cell types in the mammalian brain.

44. sleep and wakefulness a "polysomnogram" is used to measure a night of sleep. it is built out of: - electroencephalogram (EEG) for brain activity - electro-oculogram (EOG) for eye movement - electromyogram (EMG) for muscle tone in sleep disorder studies, respiration will often be tracked too.

43. motivation, reward, and addictive states sometimes we (and animals!) see a snack and really want to eat it. other times we don't care. the stimulus is the same, so the difference is in motivation. motivation is influenced by both internal (physiological and cognitive) and external variables.

42. emotion emotion is complicated to define or organize, but we can talk about its valence (pleasantness) and intensity (arousal level). emotions correlate with physiological responses, but we don't know which way the causation goes there. humans are uniquely able to describe their emotions.

41. the hypothalamus: autonomic, hormonal, and behavioral control of survival the hypothalamus acts on 3 systems: - the autonomic nervous system, to regulate unconscious functions like heart rate - the neuroendocrine system, to release hormones - neural pathways that mediate motivated behavior

40. the brain stem brains of primitive vertebrates (reptiles, amphibians, fish) have tiny forebrains, mostly for olfaction, but they still move, eat, sleep, reproduce, and react to emergencies. physically and functionally, the brain stem exists between the spinal cord and the rest of the brain.

39. brain-machine interfaces <3 brain-machine interfaces, devices that measure or alter activity at the ~neuron level, typically do some of the following things: - restore sensory capability - restore motor capability - regulate pathological neural activity - restore brain processing capability

38. the basal ganglia we used to think the basal ganglia were only for motor control, but we now know they play a role in cognition, motivation, and emotion too. based on connectivity to other brain areas, we suspect they select among incompatible behaviors, and mediate reinforcement learning.

37. the cerebellum cerebellum constitutes only 10% of the volume of the brain but has more than 50% of its neurons. cerebellar cortex is made of highly regular repeating units. different regions get input from brain and spinal cord, and project back to the brain. it is involved in motor control.

36. posture posture control has 2 goals: - balance (prevent falling) - orientation (position body parts with respect to each other and the world) they often work together, but not always: soccer goalies sacrifice balance to orient to the ball; bus riders disregard orientation to maintain balance.

35. the control of gaze eyes are basically spheres that sit in a socket ("orbit") and rotate. 6 extraocular muscles accomplish this, in 3 agonist / antagonist pairs (for yaw, pitch, and roll). the muscles originate in a few different places, but on the eyeball side, they all attach at the sclera.