NSCI 110 1st Edition Lecture 19 Outline of Last Lecture I Excessive amounts of glutamate overstimulates a neuron and may lead to excitotoxicity a Increased and prolonged depolarization of membrane results in apoptosis b Excess of cytochrome c released by mitochondria II There is an initial period of biological recovery followed by more psychological responses a Premorbid state followed by glial cell assistance b Eventually learning and compensatory mechanisms take over III There are numerous cellular mechanisms that follow the recovery period a Astrocytic aid involved in nerve growth factors and restoration of nutrients b Denervation hypersensitivity c Synaptogenesis d Cortical reorganization IV Through neuropsychological assessment the extent of brain and cognitive damage may be assessed a Cognitive status b Behavioral compensation Outline of Current Lecture I There are a variety of ways to assess degrees of wakefulness a Glasgow coma scale measures eye opening motor response verbal response b A person in a vegetative state may exhibit signs of wakefulness without awareness i Persistent vegetative state II Our perceptions of the visual world are based on environment internal state and experience III Anatomy of the human eye allows photons of light to be converted into action potentials a Optic disk is our blind spot b Light is bent when traveling from the air to the aqueous environment in the eye CurrentLecture Assessing levels of awareness after waking up from an unconscious state o Glasgow coma scale measures difference indexes of wakefulness Eye opening motor responses verbal responses Scale from 3 15 points E M V o Vegetative state wakefulness without awareness These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Long periods of wakefulness not necessarily correlated to rhythms circadian Eyes rove and may appear to track briefly Sudden sounds or light may elicit orienting by the colliculi but still not conscious awareness by the hypothalamus Limbs spastic show withdrawal to pain grasping reflex Facial grimacing or perhaps groaning to pain Gag reflexes chewing motions but not adequate enough for nutrition by spoon feeding Careful observations fail to detect consistent responses indicating conscious awareness Meaningful emotional responses are not elicited by appropriate stimuli or related to any external stimuli No learned or consistently meaningful responses and no mimicry If this condition is for more than a month it is said to be in a persistent vegetative state VISION PART ONE SEEING FORM AND COLOR Perception of the visual world is dependent on context our environmental conditions and culture o Experience and internal state aroused angry ect also influence visual perception o Not based on reality because the brain processes stimuli differently Basic anatomy of the human eye o Pupil Shape is dependent upon species evolutionary history animals who hunt in plains have more elongated lateral pupils o Conjuctiva Layer that is close to blood vessels Conjunctivitis pink eye o Extraocular muscles are controlled by cranial nerves III IV and VI Control movements of the eye o Sclera White of the eye o Iris Muscle that regulates how much light enters the eye regulates the size of the pupil Has a texture that differs directly around the pupil vs more distantly surrounding the pupil Color influences how much light is absorbed and reflected People who live in lots of sunlight tend to have darker colored irises Review functional groupings of the cranial nerves o Extrinsic eye muscles allow voluntary control of gaze CN III IV VI o Intrinsic eye muscles exhibit parasympathetic and sympathetic activity CN III has parasympathetic nerve fibers that contact the circular sphincter muscle of the iris Sympathetic fibers originate in the thoracic portion of the spinal cord and contact radial muscles of the iris to cause pupil dilation Dorsal view of the right eye looking from the top down o Optic nerve travels medially and meets the other optic nerve at the optic chiasm o Macula lutea is the 6mm spot with high acuity vision Contains the fovea no rods almost all cones highest visual acuity o Optic disk is the point of exit for ganglion cell axons that make up the optic nerve No rods or cones no visual perception here responsible for blind spot o Light is bent most by the fact that it is travelling from air to an aqueous substance o Blood vessels may observed through the pupil Eye tissue comes from the brain embryologically In diabetes these blood vessels are damaged areas of the eye are degenerated and vision is lost