Psychology Concise Notes PDF

Peripheral Somatosensation          **Somatosensation** includes 5 main ones - position sense, vibration, touch, pain, temperature. \-      Position + vibration + touch = **mechanoreceptors**, pain = **nociceptors**, temperature = **thermoreceptors**.  ·       One of [differences] between two typ...

Peripheral Somatosensation          **Somatosensation** includes 5 main ones - position sense, vibration, touch, pain, temperature. \-      Position + vibration + touch = **mechanoreceptors**, pain = **nociceptors**, temperature = **thermoreceptors**.  ·       One of [differences] between two types is [how big their axons] are -- position/vibration/touch receptors have large diameter axons. Have thick myelin sheath. Fast. ·       Rest have small diameter axons. Slower. \-      Touch is both. Fine touch travels in fast neurons, less precise info travels in slower ones.           Many receptors found in the skin such as mechanoreceptors, one type close to skin, another type lower. Also some in deep tissue, deep in muscle that detects stretch. One sin muscle important for position, while ones in skin are imp for vibration/touch.  \-      Pain and temperature receptors end in uncovered terminals, don't have big structures like mechanoreceptors.  \-      Receptors send info down **afferent** axons          **Muscle Stretch Reflex**          Reflexes have 2 parts -- **afferent** (stimulus) and **efferent** (response). \-      The **muscle stretch reflex** causes a muscle to contact after it's stretched, as a protective response.  ·       Ex. ***Knee jerk response*** -- involuntary response of leg kicking out. The hammer hits the tendon right below the knee cap, which hooks onto the lower leg bone on one end, and a large group of upper muscles on the other. Muscles are called **muscle spindles**.  ·       **Somatosensory neurons** (afferent) in muscle spindles form excitatory synapse in spinal cord with another neuron in the spinal cord, which sends axon out back to same muscle that was stretched, and excite skeletal muscle cells to contract -- **lower motor neurons**(efferent). ·       Muscle on underside of leg are inhibited when the topside of leg is excited. Necessary for reflex to occur.  **         Gray and White Matter** \-      **Gray matter** contains most of the neuron somas.  \-      White matter contains **myelinated axons**.  ·       In spinal cord, grey is on inside and white matter on outside.  ·       For brain, different. White on inside and grey on outside. Axons go down tracts of white matter.  **         Upper Motor Neurons** \-      LMNs control muscles of limbs and trunk, while LMNs that pass through cranial nerves control muscles of head and neck. \-      [UMNs control the LMNs]. Found in the ***cerebral cortex***, and synapse on LMNs in the brainstem or spinal cord. \-      Can divide them into tracts depending if they go to brainstem, or spinal cord. ·       UMN starts in cerebral cortex, axon travels down through brainstem, and where it meets the spinal cord most of these axons cross and travel down other side until they reach LMN. This collection of axons is called the **corticospinal tract**.  ·       If it goes to brainstem, called **corticobulbar tract**          **Upper motor signs:** \-      **Hyperreflexia** -- increase in the muscle stretch reflexes.  ·       Cause is unclear, but when muscle spindle receptors are activated, without periodic stimulation of LMNs by UMNs, they become hypersensitive and you get bigger reflex. \-      **Clonus** -- rhythmic contractions of antagonist muscle.  ·       Ex. Foot goes involuntarily up and down. Cause is ***hyperflexia***, because if doctor pulls on foot activates muscle stretch reflex, so triggers [antagonist muscles]. \-      **Hypertonia** -- increased tone of skeletal muscles.  \-      **Extensor Plantar Response** -- if you take a hard object and scrape along bottom of foot, normal response is flexor -- toes will come down on the object. But with extensor, toes extend up.  **         Somatosensory Tracts** \-      **Somatosensory information** travels in different pathways. In general, 2 big categories:  ·       1) position sense, vibration sense, and fine touch  ·       2) pain, temperature, gross touch \-      Deliver info to spinal cord.  \-      Spinal cord carries info to the brain in one of the tracts. Crosses other side immediately, then goes to cerebrum.  \-      It is why injury to one side of brain often results in damage to other side                                                                                         Overview of the Functions of the **Cerebral Cortex** \-      **Frontal lobe** -- motor, prefrontal, Broca's area,  **Parietal lobe** -- somatosensory cortex, spatial manipulation, **Occipital lobe** -- vision, "striate cortex", **Temporal cortex** -- sound, Wernicke's area          [Cerebellum] \-      Coordinates movement: **motor plan** info is sent to cerebellum, also receives **position sense** information (ex. Muscle stretch fibres), and sends feedback to the cerebellum and motor areas of motor cortex.  \-      Middle of cerebellum coordinates middle body movement and walking, while the sides are involved in movements of the limbs -- arms and legs. Also speech and movement of eyes.           [Brainstem] \-      Connects all parts of the brain together, including the cranial nerves.  \-      Midbrain, pons, medulla.  \-      Neuron somas scattered throughout brainstem is the **reticular formation** -- big role in autonomic functions, and controlling things like respiration, digestion, and lower/higher functions.  \-      **Long tracts** -- collections of axons connecting cerebrum and brainstem.  ·       2 long tracts that are important: **motor** (UMNs), and **somatosensory**.           **Cranial nerves** -- most of cranial nerves are attached to the brainstem, doing many things. 12 pairs. All sorts of functions.           [Subcortical Cerebrum]          Subcortical cerebral nuclei that are located deep part of the cerebrum  \-      **Internal capsule --** contains many important pathways, including the corticospinal tract \-      **Corpus collosum --** connects right and left cerebral hemispheres.  \-      **Basal ganglia** -- major role in motor functions, don't have UMNs but help motor areas to perform proper movements. Also cognition + emotion.  \-      **Thalamus** -- Sensory functions, because all senses have pathways that travel to the thalamus. Also higher functions of brain such as cognition and emotion. \-      **Hypothalamus** -- controls the pituitary gland, the master gland that controls all other glands in body.  **          Neurotransmitter Anatomy** \-      **Glutamate** -- most common excitatory neurotransmitter.  ·       **Reticular activating system** (required for **consciousness**) has diffuse projection of glutamate to the cerebral cortex.  \-      **GABA** (brain) and **Glycine** (spinal cord) -- most common inhibitory NTs \-      **Acetylcholine** -- nuclei in frontal lobe that releases it to cerebral cortex, called the Basilis and septal nuclei.  ·       Released for LMNs, and the autonomic nervous system.  \-      **Histamine** -- hypothalamus sends it \-      **Norepinephrine** -- area in pons called the **locus ceruleus** that releases it.  ·       Also ANS, but less so than Ach.  \-      **Serotonin** -- raphe nuclei in midbrain/medulla release it.  \-      **Dopamine** -- VTA and substantia nigra          [Lesion Studies and Experimental Ablation]          Deliberately making brain lesions in order to observe changes on animal's behavior. Not done with humans! \-      **Tissue removal**: surgical removal, surgical aspiration (sucking out brain tissue), or nerve cuts.  \-      **Radiofrequency lesions** -- used to destroy tissue on surface of brain and deep inside brain. Wire is inserted into brain to determine the area. Then pass high freq current which heats up and destroys tissue. Can vary current to change size, but destroys cells and axons.  \-      **Neurochemical lesions** -- excitotoxic lesions, cause influx of calcium that it kills the neuron and excites it to death. ·       One example is **kainic acid**. Destroys cell bodies but doesn't influence axons passing by. ·       Also **oxidopamine** (6-hydroxydopamine) selectively destroys dopamine and NE neurons. Can model Parkinson's Disease. \-      **Cortical cooling** (Cryogenic blockade)- involves cooling down neurons until they stop firing.  ·       ***Cryoloop*** -- surgically implanted between skull and brain. Most important part is it's temporary/reversible, unlike other techniques.  **         Modern Ways of Studying the Brain** \-      Brain structure ·       **CAT scans (CT scan), MRI** ·       **EEG** -- external, can't tell us about activity of individual/groups of neurons. Can only look at sum total. Can tell us about seizures, sleep stage, cognitive tasks.  ·       **MEG** (aka SQUIDS) -- better resolution than EEG, but more rare because requires a large machine and special room to shield it.  \-      Can we combine brain structure and function? Yes! ·       **fMRI** -- same image from MRI but can look at which structures are active (can see **BLOOD FLOW**) ·       **PET scans** -- can't give us detail of structure, but can combine them with CAT scans and MRIs. Inject glucose into cells and see what areas of brain are more active at given point in time.           **Behaviour and Genetics**          Temperament, Heredity, and Genes \-      Differences between children -- **temperament**, not same as personality. It's their characteristic emotional reactivity, their sociability. Temperament seems to be established before babies are exposed to environment. And persistent as person ages. ·       Talking about **heredity** -- passing traits from parents/ancestors to offspring through genes. \-      **Personality**, unlike psychological characteristics/abnormalities is believed to be **constant** over a person's lifetime.           **Twin Studies and Adoption Studies**          Classical twin study -- compare monozygotic + dizygotic each raised in same household  \-      **Monozygotic (identical)** vs. **dizygotic twins (fraternal)** ·       Monozygotic -- egg splits into 2 after fertilization. Share 100% of genes ·       Dizygotic -- develop from 2 separately fertilized eggs. Share 50% of genes, like regular siblings.  ·       Share same environment in womb, and also share same parents. So both can be said to share 100% environment.  ·       Regular siblings don't share 100%, similar, but can vary depending on parenting/age.            Ex. What causes schizophrenia?  \-      ***Nature*** -- genetic component or ***Nurture*** -- environmental component? \-      Monozygotic twins vs. dizygotic twins -- can hold environment constant.  \-      If schizophrenia was caused by [genes], expect to see different rates in identical vs. fraternal twins.  ·       Higher in identical twins. \-      But if [environmental], ***similar rates*** of disorder in both sets of twins.  ·       Wouldn't matter if they were identical vs. fraternal.  ·       Problems with twin studies: identical twins treated more similarly than fraternal twins are.           **Adoption studies** -- adopted child is compared to biological family and their adopted family. If no relation between individual and biological parents, but there is relation between individual and adoptive parents, then can assume environment was a factor. If opposite, then genetic factor. \-      Problems: incomplete info about biological families. Also adoption isn't random, adoptive family sometimes matched to biological family.           Identical twins adopted by different family -- genetically similar, different environments. But families who adopt are usually similar.           **Heritability** \-      Variability of traits can be attributed to differences in genes.  \-      Assume we say heritability of intelligence is 50%. NOT saying that intelligence is 50% genetic, saying that the difference in intelligence is 50% attributable by genes.   ·       Ex. Control boys environment 100%, but IQ not the same. Difference couldn't be attributed to environment, so we'd say their IQ difs heritable because environment was 100% same. So h\^2 = 99%. Close to 100%.  ·       Alternatively you can say 4 identical quadruplets (genetically identical), but completely different environments. Since variability can't be due to genes, must be environmentally-caused so H^2^ = 0%.            **Gene-Environment Interaction** \-      Nature vs. nurture. ·       Ex. Attractive baby and hideous baby. As a result, attractive baby receives more attention and is more sociable and well-adjusted. But say both have genes that predispose for depression, that are triggered by environment. Beautiful baby's genes are not activated, while ugly baby's genes are making proteins all the time since his life is tougher.  ·       Another example is **phenylketonia**, caused by mutations to a gene that encodes a liver enzyme phenylalanine hydroxylase. But because enzyme is missing amino acid phenylalanine, it doesn't get converted into tyrosine. Build-up of phenylalanine can cause brain problems.  ·       During infant screening, placed on phenylalanine-free diet, and most grow up without major problems.  **         Regulatory Genes** \-       (Watson & Crick) **Central dogma** of genetics. DNA codes for RNA, which code for 1 of 20 amino acids, and eventually become building blocks of proteins, which affects our behavior.  \-      We can now look at genes that may contribute to a trait, and compare and contrast. ·       Ex. Vast majority of our genes, 95% don't code for proteins, but regulate how proteins are coded. \-      Called **epigenetics** -- changes to gene expression other than to gene. Ex. Addition of methyl groups to the gene, which make it more difficult for TFs to come in and activate gene.  **         Adaptive Value of Behavioral Traits** \-      Function of behavior -- **homeostasis**. Behavior is coordinated internal and external response of organisms to their environment, aka **adaptation**. \-      **Ethology** focuses on the observation of animal behaviours, call these **overt** behaviours (not necessarily obvious, just means observable).  ·       Innate, learned, and complex behaviours.           **[Innate behavioural traits]** -- genetically programmed behavior.  \-      **Inherited** -- innate behaviours are encoded by DNA \-      **Intrinsic** -- present even if you're raised in isolation. Ex. Pooping, peeing, etc. \-      **Stereotypic** -- performed the same way each time.  \-      **Inflexible** -- [not modifiable] by experience. \-      **Consummate** -- fully developed right away, at first performance. Not influenced by experience.  ·       Ex. Nausea in women during pregnancy helps them avoid toxic foods in critical period of development. Thought of as programmed. \-      3 main types: **reflexes** (ex. Knee-jerk response), **orientation** (ex. Kinesis, our change in speed, or taxis, movement towards/away from stimulus), and **fixed-action pattern** (performed without interruption). \-      **Learned** behavioural traits  ·       Non-inherited -- acquired only through observation/experience ·       Extrinsic -- absent when animals are raised in isolation, ex. social skills ·       Permutable -- changeable ·       Adaptable -- capable of being modified in response to changing conditions ·       Progressive -- improvement or refined practice over time \-      **Complex** behavior -- can be a spectrum, most behaviours are between the two.  ·       Ex. ability of insects to fly, starts off as innate but through learning become more efficient.           **Motivation and Attitudes**          Physiological Concept of Positive and Negative Feedback \-      Positive, increase production of product. \-      Negative, works to decrease product. \-      Negative feedback is put into place to inhibit production of product. **         Instincts, Arousal, Needs, Drives: Drive-Reduction and Cognitive Theories**