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Epigenetics: Molecules in your cells that can either increase or decrease the gene transcription process and essentially turn your genes on or off Exposure to prenatal stress can result in: Increase in stress response, anxiety, impaired memory, hyperactivity, increased risk of...

Epigenetics: Molecules in your cells that can either increase or decrease the gene transcription process and essentially turn your genes on or off Exposure to prenatal stress can result in: Increase in stress response, anxiety, impaired memory, hyperactivity, increased risk of schizophrenia Exposure to prenatal malnutrition can result in: Increased risk of depression and impaired cognitive functioning Exposure to prenatal environmental toxins can result in: Cigarettes = difficulty in regulating emotions, attentional issues, excitability and irritability Air pollution = difficulty in inhibitory control and poorer academic achievement Postnatal experiences: If a rat had a mother that lacked grooming and licking then there would be changes in gene expression which can result in higher stress responses but if the rat was then later fostered by another mother who did groom and lick then the gene expression can be reversed. Cannabis exposure during adolescence changes gene expression resulting in altered dopamine levels (reduced rewards, motivation and cognition) First trimester: forms 16 days after conception Neural plate (foundation of CNS) Neural plate folds into neural tube, neural tube closes at 6-7 weeks after conception ○ Movement and sense of touch start to develop Second trimester: Myelination of peripheral nerves being Brainstem matures (controls blood pressure, heart rate, and breathing) ○ Sense of taste and hearing start to develop Fetus tastes every thing you taste You want to expose fetus to wide variety of tastes to reduce the chances of a picky eater or allergies Third trimester: Brain triples in weight due to rapid development of neurons, cerebellum develops and sleep cycles develop Cerebral cortex being to function at birth Spina bifida: Birth defect in which neural tube does not fully close due to lack of folic acid Early childhood: Brain forms an estimated 1000 new neural connections every second  This period of proliferation is followed by a period of synaptic pruning, this occurs in sensory pathways first, then the language area and then higher cognitive function areas ○ Language = need to talk to child a lot 5-10 months old second language exposure ○ Memory = hippocampus fully developed at 3-4 years old (no ability to form a memory prior to this) ○ Amygdala = emotional response, fully developed White matter = myelin (fat) Myelination increases sharply from birth - 2 years of age, before leveling off for the rest of childhood without sex differences present ○ Increases sharply again during adolescence Adolescence: Pruning process (back to front of brain) Gray matter volume (amount of neuron cell bodies and dendrites) decreases from back to front during adolescence as a result of synaptic pruning Dual process of proliferation (increasing neural connections) and synaptic pruning (removing neural connections to increase officiency) during adolescence is delayed in male brains by about 2-3 years and continues into early adulthood ○ Delayed 3-4 years in ADHD White matter volume (amount of myelin on neurons) increases sharply during adolescence in many brain regions Early adulthood: Fully mature and functional brain in you are: ○ 22-25 years old and female with no ADHD ○ 25-30 years old and male with no ADHD Can enjoy your fully mature and functional brain for: ○ 10-15 years if male (degeneration being in early 40s) ○ 25-30 years if female ( estrogen is neuroprotective so degeneration beings after menopause) Vision: Cornea: ○ Outer surface of the eye, helps to refract light Pupil ○ Hole in the center of iris that allows light to enter eye Iris ○ Controls the diameter of the pupil (how much light is allowed into eye) Color of iris depends on how much melanin you have in iris (more melanin the darker the iris) Lens ○ Helps to refract light to be focused on retina  Retina ○ Receives light from lens, converts electromagnetic waves to neural signals Fovea ○ Small depression in retina where cones are highly concentrated and visual acuity is high Blind spot ○ Spot on retina where the optic nerve begins, contains no photoreceptor cells Cells of the Retina: Rod cells ○ Photoreceptor cells concentrated on outer edge of retina ○ Used for peripheral vision and night vision ○ Approximately 90 million per eye Cone cells ○ Photoreceptor cells concentrated in fovea ○ used for color vision ○ Approximately 4.5 million per eye Bipolar cells ○ Trasmit signal from photoreceptor cells to ganglion cells ○ Allow cone cells to interact to process color vision Ganglion cells ○ Receive signal from bipolar cells ○ Axons create the optic nerve Young & Helmholtz: Each cone subtype processes a section of the visible light spectrum Cones work independently Hering: Color vision is result of three cone cell subtypes interacting (combination of inhibitory and excitatory signaling) to process visible light spectrum Cones interact Color blindness / deficiency About 1 in 12 males have some form of color blindness (mutation X chromosome) red - green color blindness is most common followed by blue - yellow and total color blindness Retinal dispartiy and binocular depth perception: Due to different physical positions of two eyes, each eye receives slightly different visual information Brain is able to use different visual information to process depth perception ○ Can produce visual illusions The visual projection pathway: Right visual field projects to your left primary cortex and vice versa  Optic chiasm ○ Where optic nerves intersect and visual field information separates on way to primary visual cortex Lateral geniculate nucleus ○ Optic nerves end here ○ Send visual information to primary visual cortex via optic radiation nerves Hubel and Wiesel: Discovered visual cortex cells Called simple cells that respond strongest to lines of specific orientations Helps to determine borders of objects Detection of an object’s boundaries and features Visual cortex: Feature detection of an object ○ Ventral visual stream = process of the “what” information about the object ○ Dorsal visual stream = process of the “when” information about the object Visual perception disorders: Object agnosia ○ Impaired ability to recognize objects due to damage to ventral visual stream Prosopagnosia ○ Impaired ability to recognize familiar faces due to damage to fusiform gyrus (part of ventral visual stream) Color agnosia ○ Impaired ability to perceive colors possibly due to damage of dorsal visual stream Movement agnosia ○ Impaired ability to recognize movement due to damage to dorsal visual stream Visual neglect ○ Ignoring information in visual field on the side opposite of injury to posterior parietal cortex ○ Deficit in attention but not perception Outer ear: Pinna ○ Outer part of ear ○ Captures and slight amplifies sound Ear canal ○ Transmits sound to ear drum Middle ear: Ear drum ○ Vibration caused by sound waves transmits sound energy to ossicles  Ossicles ○ Three tiny bones connecting eardrum to cochlea ○ Vibration of eardrum caused them to move / transmit vibration signal to cochlea Hammer (malleus) = attached to eardrum Anvil (incus) = attaches hammer to stirrup Stirrup (staples) = attached to cochlea Inner ear: Cochlea ○ Where sound - analyzing structures are located Auditory nerve ○ Transmits sound information to auditory cortex Cochlea: Filled with fluid that carries sound waves across the organ of corti ○ Organ of corti = four rows of hair cells (cilia), the receptors of auditory stimuli Vibration from auditory stimuli pushes hair cells over and causes theme to fire and send signals down auditory nerve Smell: Odor molecules activate olfactory hairs on receptor cells Receptor cells sends signal to olfactory bulb Olfactory bulb projects olfactory tract to olfactory cortex Strong smells signals to our hippocampus and amygdala (memory and emotion) Taste: 5 tastes ○ Sweet ○ Sour ○ Bitter ○ Satly ○ Savory (umami) = evenly distributed across the tongue Temporoparietal Junction: Integrates external sensory information (visual and auditory) with internal sensory info (somatosensation) to provide a sense of being within your body Right TPJ dysfunction can produce out-of-body (dissasociation) experiences ○ Also involved in empathy and sympathy Left TPJ contains Wenicke;s area (language comprehension) ○ Involved in theory of mind (understanding thoughts, beliefs and intention of others) Emotional theory of mind (ventromedial prefrontal cortex) ○ Putting yourself in someone elses “emotional shoes” ○ Sociopaths do not have a high emotional theory of mind  Child abuse = no longer have emotional theory of mind = can inflict pain on other and feel nothing Psychedelics: LSD ○ Serotonin and dopamine agonist ○ Modulates sensory processing in the thalamus ○ Activated amygdala and medial prefrontal cortex Involved in emotion regulation Ecstasy ○ Serotonin and dopamine agonist ○ Produces visual and auditory hallucinations at high doses Mescaline (peyote) ○ Serotonin, dopamine, and norepinephrine agonist ○ Produces only visual hallucinations Psilocybin (mushrooms) ○ Serotonin and dopamine agonist ○ Produces only visual hallucinations Ketamine (special K) ○ serotonin , dopamine and norepinephrine agonist ○ Produces visual and auditory hallucinations Hallucinations ○ Can be visual, auditory, olfactory, tactile or gustatory ○ Caused by non-sensory activation of thalamus and or sensory cortical area Same thing happens when you dream ○ Can be due to: Schizophrenia Parkinsons Alzheimers Migraines Brain tumors Epilepsy Nicotine: Activates nicotinic acetylcholine receptors on neurons in the ventral tegmental area (VTA), causing them to increase dopamine release in brain's reward path ○ Causes increased release of natural opioids, which activate neurons in the nucleus accumbens that produces reward sensation (“liking” ○ Dopamine activation of neurons in the nucleus accumbens produces motivation to consume substance again (“wanting”) Misconception that dopamine makes you feel good : THIS IS NOT TRUE  Activation of nicotinic acetylcholine receptors also causes increase of acetylcholine in the prefrontal cortex ○ Increased focused attention ○ Increased attention orientation / stimulus detection Also increases norepinephrine release in the brain which activates sympathetic nervous system (increased arousal and stimulation) THC: Primary psychoactive component of cannabis Agonist of cannabinoid receptor (CB1) in the brain Activation of CB1 receptors in neurons result in: ○ Increased release of dopamine in reward pathway, leads to increased release of natural opioids in the nucleus accumbens (produces high) ○ Decreased release of excitatory NTS (glutamate, noradrenaline, serotonin, acetylcholine) in many brain areas ○ Decreased release of inhibitory NTS GABA in several brain regions (Nucleus accumbens, hippocampus, hypothalamus