Physio and Psychopharm Flashcards
Neuron (Nerve Cell)
Neuron (Nerve Cell) is a specalized cell that conducts info. in the nervous system & neurons can vary in size & shape.
Neurons consist of 3 parts:
- Dendrites (Branch Like): Recieve info from other cells & conduct it toward the cell body.
-
Cell Body (SOMA): Contains several structures including:
- Nucleus
- Mitochondria: Site where the cell perf. metabolic acitivites.
- Ribosomes: Site where cell synthesizes new protien molecules.
- Golgi Complex: System of membrane that prep neurotransmitters & other sub for secretion.
- Axon: Then transmit info. from the cell body to other cells by releasing neurotransmitters
- Synaptic Cleft: Goes into this area which is the gap btwn the axon terminal of the presynaptic cell & receptors on the dendrite of the post-synaptic cell.
Most neurons have a single axon that divides into numerous branches & many axons are connected by a Myelin Sheath: A fatty substance that acts as an insulator & speeds up the conduction of nerve impulses.
Neuron (Nerve Cell)
Neuron (Nerve Cell) is a specalized cell that conducts info. in the nervous system & neurons can vary in size & shape.
Neurons consist of 3 parts:
- Dendrites (Branch Like): Recieve info from other cells & conduct it toward the cell body.
-
Cell Body (SOMA): Contains several structures including:
- Nucleus
- Mitochondria: Site where the cell perf. metabolic acitivites.
- Ribosomes: Site where cell synthesizes new protien molecules.
- Golgi Complex: System of membrane that prep neurotransmitters & other sub for secretion.
- Axon: Then transmit info. from the cell body to other cells by releasing neurotransmitters
- Synaptic Cleft: Goes into this area which is the gap btwn the axon terminal of the presynaptic cell & receptors on the dendrite of the post-synaptic cell.
Most neurons have a single axon that divides into numerous branches & many axons are connected by a Myelin Sheath: A fatty substance that acts as an insulator & speeds up the conduction of nerve impulses.
Neuron (Action Potential)
The neuron (nerve cell) is a specialized cell that is directly involved in mental processes & behavior. Messages w/in a neuron are transmitted from a neuron’s dendrites to the end of its axon through an electrical process called conduction.
With sufficient stimulation from other cells, a cell becomes:
- Depolarized (the interior of the cell becomes less negative), which triggers an action potential- i.e. an electrical impulse that travels quickly through the cell.
Neuron (All-or-None Principle)
Predicts that an action potential will always be of the same magnitude regardless of the amount of stimulation received by a neuron as long as the minimal level of stimulation (the threshold) has been reached.
Neurotransmitters
Chemical substances that are released from axon terminals, diffuse across synapses, & excite or inhibits receptor sites on postsynaptic nerve cells.
Neurotransmitters Include:
- Acetylcholine (ACh)
- Dopamine (Catecholamine)
- Norepinepherine (Catecholamine)
- Epinepherine (Catecholamine)
- Serotonin (5-HT)
- Gamma-Amino Butyric Acid (GABA)
- Glutamate
- Endorphins
Acetylcholine
ACh is both excitatory and inhibitory and is involved in:
- voluntary movement: ACh causes muscles to contract, and myasthenia gravis is an autoimmune disorder that causes muscle weakness by destroying ACh receptors at neuromuscular junctions.
- parasympathetic arousal,
- attention
- memory: low levels of ACh in the entorhinal cortex and hippocampus have been linked to the early memory loss associated with Alzheimer’s disease.
- Too much assoc. w/Depression
- Too little (in Hippocampus) assoc w/Dementia (e.g. memory loss in Alzheimers disease)
Dopamine
Dopamine serves both excitatory and inhibitory functions. It contributes to:
- movement,
- personality,
- mood,
- sleep
-
Too Little:
- Parkinson’s Disease: A degeneration of dopamine producing cells in the substantia nigra & basal ganglia (Muscle rigidity & tremors) &
- Forms of Depression
-
Too Much linked to:
- Schizophrenia: According to Dopamine Hypothesis, schizophrenia is due to high levels of dopamine or hyperactivity of dopamine receptors.
- Tourtte’s Disorder: an excessive level in the caudate nucleus
*Cocaine, Amphetamines & other stimulant drugs elevate mood my increasing levels of dopamine in areas of the midbrain & limbic system that have been ID as part of the brains reward system.
*Alcohol increases dopamine levels & causes the pleasurable feelings related to alcohol use leading to reinforcing effects of alcohol additction.
Norepinepherine
Norepinephrine is an excitatory neurotransmitter and is involved in:
- arousal
- attention
- learning
- memory
- stress
- mood.
- Too Little: assoc. w/Depression (Catecholamine Hypothesis)
- Too Much: mania is due to excessive norepinephrine.
Epinephrine
Neurotransmitter involved in energy & glucose metabolism.
- Too little assoc. w/Depression
Serotonin (5-HT)
Neurotransmitter that has an inhibitory effect and plays a role in many functions including:
- arousal
- sleep
- sexual activity
- mood
- appetite
- pain.
-
Too Little:
- Depression
- increased risk for suicide
- Anxiety D/O’s (OCD)
- Bulimia (Antidepressant Rx that increases serotonin levels have been found useful to control binge & purge behaviors)
- Migraine headaches
-
Too much:
- Schizophrenia
- Autism spectrum disorder (ASD)
-
Anorexia: Assoc. w/an excess of serotonin which causes nervousness & anxiety. Food restriction helps lower serotonin levels which reduce thses unplesant feelings.
- Rx that increases serotonin are not useful for these indiv. but once they have reached normal weight Rx may help prevent weight loss.
*Evidence that low levels of serotonin are involved in cravings for alcohol in abusers.
Gamma Amino Butyric Acid (GABA)
GABA is a primary inhibitory neurotransmitter and is involved in:
- memory
- mood
- arousal
- sleep
- motor control
-
Too Little:
- insomnia
- seizures
- anxiety
- benzodiazepines reduce anxiety and induce sleep by amplifying the effects of GABA.
- Degeneration of GABA and ACh cells in the basal ganglia contributes to the motor symptoms of Huntington’s disease
- Affected by CNS Depressants
Glutamate
Glutamate is an excitatory neurotransmitter and contributes to:
- movement
- emotions
- learning
- memory: Long-term potentiation (LTP): Brain mechanism believed to be responsible for the formation of long-term memories.
Too much:
- Excessive levels can produce Excitotoxicity - which damages or destroys nerve cells & have been linked to stroke related brain damage, TBI, Huntington Disease & Alzhiemers Disease.
- Alcohol alters Glutamate levels in the brain & are related to memory impairment & alcohol related black outs; responsible for the harmful effects alcohol has on memory.
Endorphins
(Endogenous Morphines) Inhibitory neuromodulator that lowers the sensitivity of postsynaptic neurons & neurotransmitters.
Have analgesic properties & involved in:
- Pain Relief: Prevents release of substance P, involved in transmission of pain impulses.
- Feelings of pleasure & contentedness, emotions, sexual behaviors, memory & learning.
Central Nervous System (CNS)
Consists of the:
- Brain: Recieves & processes sensory info., initiates responses, stores memories, generates thoughts & emotions.
- Spinal Cord: Sends signals to & from brain; controls reflex activity
Spinal Cord (Quadriplegia & Paraplegia)
The spinal cord carries info. btwn:
- The brain & the peripheral nervous system,
- Coordinates activities of the left & right side of the body, and
- Controls simple reflexes that do not involve the brain.
Consists of 31 segments, which are divided into 5 groups. Each nerve consists of bundles of axons.
From the top of the spinal cord to the bottom, these are:
- Cervical
- Thoracic
- Lumbar
- Sacral
- Coccygeal.
Damage at different levels causes different types of paralysis:
- Quadriplegia: Occurs at the cervical level (loss of sensory & voluntary motor Fx in the arms & legs).
- Paraplegia: Occurs at the thoracic level (loss of functioning in the legs; below T1)
Brain
Cerebral Ventricles/Hydrocephalus
The ventricles are the 4 cavities of the brain that contain cerebrospinal fluid.
- Hydrocephalus: Blockage of the ventricles & a resulting build-up of fluid.
Hydrocephalus
The abnormal accumulation of cerebrospinal fluid in the ventricles (aka Water head), which results in increased intracranial pressure & can lead to brain damage.
Peripheral Nervous System (PNS)
Made up of nerves (Bundles of axons) that relay messages btwn the CNS & body’s sensory organs, muscles & gland.
Peripheral Nervous System (PNS):
-
Motor Neurons: CNS to muscles & glands
- Somatic Nervous System (SNS): Controls Voluntary movements.
-
Automatic Nervous Systerm (ANS): Controls involuntary responses.
- Sympathetic: “Fight or Flight”
- Parasympathetic: Resting
- Sensory Neurons: Sensory organs to CNS
Somatic Nervous System (SNS)
Consists of sensory nerves that carry information from the body’s skeletal muscles & sense receptors to the CNS & motor nerves that carry information from the CNS to the skeletal muscles.
- Governs activities that are ordinarily considered voluntary.
Autonomic Nervous System (ANS)
(Sympathetic & Parasympathetic Branch)
ANS controls the glands & muscles of the internal organs & regulates bodily processes that we ordinarily don’t consciously control such as digestion, respiration & HR.
Part of PNS & controls involuntary responses. It consists of 2 parts:
- Sympathetic Branch: Active during states of activity & energy output. Involved in the mediation of Flight or Fight (emergency) reactions. Activation of the sympathetic branch produces:
- increased heart rate,
- pupil dilation,
- increased blood sugar, and
- inhibition of the digestive processes
-
Parasympathetic Branch: Active during states of relaxation & energy conservation. Involved in the conservation of energy & relaxation (Para = Parachute come down/relax). Activation is associated with:
- slowing of heart rate,
- lowered blood pressure,
- contraction of pupils,
- reduction of sweat gland output, and
- increased activity of the digestive system.
- Hypnosis & meditation
The 5 Stages of Brain Development (CNS)
Developmemnt of the Brain involves 5 Stage:
- *Proliferation:* Production of cells inside neural tube when embryo is 2.5 weeks.
- *Migration:* Each cell moves (migrates) to it’s ultimate destination in the nervous system.
- *Differentiation:* (Grow axons & dendrites) Cells devel. the unique charachteristics of nerve cells.
- *Myelination:* The axons of some cells become surrounded (insulated) by glial cells.
- *Synaptogenesis:* Formation of synapses & depends on certain areas of brain, but most occur post natally. Appears to be influenced by both endogenous (genetic) & Exogenous (exp.) factors.
Neuroimaging Techniques
Make it possible to study both the structure & function of the living brain.
Structural Techniques:
- Computed tomography (CT):
- Magnetic resonance imaging (MRI): uses magnetic fields & radio waves to produce high quality 2/3D images of brain structures.
Functional Techniques: Provide info. on the functional activities of the brain.
- Positron-emission tomography (PET),
- Single proton emission computed tomography (SPECT)
- Functional magnetic resonance imaging (fMRI): Measure brain activity, by detecting changes in blood oxygenation & flow in response to neural activity.
3 Divisions of the Brain (Structures)
Structure of the Brain categorized into 3 divisions:
- Hindbrain: From an evolutionary perspective, the hindbrain is the oldest part of our brain & is located deep w/in our head & on top of our spinal cord. This is the 1st & most basic brain it controls most of our most basic Fx’s. There are 3 structures of the hindbrain:
- Medulla Oblongata: Helps control our heart rate, blood pressure & breathing. Located above the spinal cord.
- Pons: Located just above the medulla & it helps coordinate the hindbrain w/the midbrain & forebrain; also involved in facial expressions.
- Cerebellum: Located at the bottom rear of brain & looks like a little version of our whole brain (like mini me). Helps coordinate balance & fine muscle movements.
-
Midbrain: Located in the middle of ther brain, the midbrain does a lot, but primary Fx’s are to coordinate sensory info. w/simple movements. Any sensory inputs, all 5 senses. There are 2 structures:
- Substantia Nigra: Involved in motor activity & plays a role in the brains reward system. Reticular Formation: Control respiration, coughing, posture, locomotin, vomiting & REM sleep.
- Reticular Activating System (RAS): Controls wakefulness, arousal & consciousness.
-
Forebrain: The most important part of the brain & contains the newest structures in the brain. There are 3 structures:
- **Thalamus: The operator/switchboard of brain. Any sensory info. that comes into the body (sight, hearing, touch & taste) go thru the Thalamus 1st & sends the info. to the right parts of the brain to get processed (except for smell).
-
Hypothalamus: Size of a pea & the most important structure in the brain. Controls thirst, hunger, body temperature, sexual arousal & the endocrine system.
- Suprachiasmatic Nucleus (SCN)
-
Limbic System: aka the emotional control center of the brain bc it contains structures that control raw emotions. It is made up of 3 structures:
- Hippocampus: Involved in memory processing (not stored here), but it does helps put memories in the right parts of brain. Ex: Think of a librarian that does not store the info. of all the books in the library in her head, but can tell you where to find that info.
- Amygdala: Controls some memory processing, but for the most part handles basic emotions like anger & jealousy.
- Septum
Hindbrain
Hindbrain: From an evolutionary perspective, the hindbrain is the oldest part of the brain & is located deep w/in the head & on top of the spinal cord. This is the 1st & most basic brain it controls most of the most basic Fx’s. There are 3 structures of the hindbrain:
-
Medulla Oblongata: Helps regulate automatic responses & helps control our heart rate, blood pressure & breathing. Located above the spinal cord.
- Damage can be fatal (Ex: SIDS)
- Pons: Located just above the medulla & it helps coordinate the hindbrain w/the midbrain & forebrain; also involved in facial expressions.
-
Cerebellum: Located at the bottom rear of brain & looks like a little version of our whole brain (like mini me). Helps coordinate voluntary motor movements & is responsible for balance & posture & motor skills.
- Abnormalities have been linked to Autism, Schizophrenia &ADHD.
Medulla
Hindbrain: There are 3 structures of the hindbrain:
- Medulla Oblongata: Helps control flow of info. btwn the spinal cord & brain & regulates a number of vital Fx’s such as heart rate, blood pressure & regulate breathing. Located above the spinal cord. (Reflexes/Unconscious)
- Pons
- Cerebellum
Pons
Hindbrain: There are 3 structures of the hindbrain:
- Medulla Oblongata
- Pons: Located just above the medulla & it helps coordinate the hindbrain w/the midbrain & forebrain. Plays a role in integration of movement in right & left side of body, sleep & facial expressions.
- Cerebellum
Cerebellum and Ataxia
Hindbrain: There are 3 structures of the hindbrain:
- Medulla Oblongata
- Pons
- Cerebellum: A large structure on the dorsal aspect of the hindbrain.
- Located at the bottom rear of brain & looks like a little version of our whole brain (like mini me).
- It is involved in the extrapyramidal control of motor activities (e.g., timing & coordination of movements, balance, posture).
- STM, following rules & carry out plans
Damage can result in:
- Ataxia: Which is characterized by slurred speech, severe tremors, & a loss of balance
Midbrain
Midbrain: Located in the middle of ther brain, the midbrain does a lot, but primary Fx’s are to coordinate sensory info. w/simple movements. Any sensory inputs, all 5 senses. There are 2 structures:
- Substantia Nigra: Involved in motor activity & plays a role in the brains reward system. Reticular Formation: Control respiration, coughing, posture, locomotin, vomiting & REM sleep.
- Reticular Activating System (RAS): Controls wakefulness, arousal & consciousness.
Reticular Activating System
Midbrain: There are 2 structures:
- Substantia Nigra
-
Reticular Activating System (RAS): A network of nerve fibers involved in wakefulness, arousal, and consciousness.
- Damage = Disrupts sleep-wake cycles & can produce permanent coma like state of sleep.
-
Reticular Formation: Plays a role in arousal & consciousness & includes the:
- Ascending Reticular Activating System (ARAS): Which is involved in selective attention & arousal.
- Ex: A mother being awakened in the middle of the night by a babies cry but not other background noises.
Forebrain
Forebrain: The most important part of the brain & contains the newest structures in the brain. There are 3 structures:
- Thalamus: The operator/switchboard of brain. Any sensory info. that comes into the body (sight, hearing, touch & taste) go thru the Thalamus 1st & sends the info. to the right parts of the brain to get processed (except for smell).
-
Hypothalamus: Size of a pea & the most important structure in the brain. Controls thirst, hunger, body temperature, sexual arousal & the endocrine system.
- Suprachiasmatic Nucleus (SCN)
- Basal Ganglia: Involved in control of voluntary movement.
-
Limbic System: aka the emotional control center of the brain bc it contains structures that control raw emotions. It is made up of 3 structures:
- Hippocampus: Involved in memory processing (not stored here), but it does helps put memories in the right parts of brain. Ex: Think of a librarian that does not store the info. of all the books in the library in her head, but can tell you where to find that info.
- Amygdala: Controls some memory processing, but for the most part handles basic emotions like anger & jealousy.
- Septum
Hypothalamus and Suprachiasmatic Nucleus
Forebrain: There are 3 structures:
- Thalamus
- Hypothalamus: The hypothalamus consists of a cluster of nuclei (size of a walnut) that maintain the body’s homeostasis thru it’s influences on the autonomic nervous system & endocrine glands.
- Mediate metabolic processes, temperature, hunger & thirst & regulate emotional expression.
- Generates physiological reactions assoc. w/rage, fear 7 other stron emotions
- Control the release of hormones from the pituitary & other endocrine glands
-
Suprachiasmatic Nucleus (SCN): Which is located in the hypothalamus, is involved in regulation of the body’s circadian rhythms.
- Controls the release of melatonin
-
Suprachiasmatic Nucleus (SCN): Which is located in the hypothalamus, is involved in regulation of the body’s circadian rhythms.
- Basal Ganglia
- Limbic System: 3 Structures:
- Hippocampus
- Amygdala
- Septum
Thalamus and Wernicke-Korsakoff Syndrome
Forebrain: There are 3 structures:
- Thalamus: The thalamus is a “relay station” for all the sense except olfaction & is also involved in language & memory.
- The operator/switchboard of brain.
- Integrates any sensory info. that comes into the body (sight, hearing, touch & taste) go thru the Thalamus 1st & sends the info. to the right parts of the brain to get processed (except for smell).
- Plays a role in declarative memory, & damage to certain areas can produce severe memory impairment.
-
Hypothalamus:
- Suprachiasmatic Nucleus (SCN)
- Basal Ganglia
-
Limbic System: 3 Structures:
- Hippocampus
- Amygdala
- Septum
Wernicke-Korsakoff Syndrome: Due to a thiamine deficiency that is often the result o long-term alchololism, that causes atrophy of neurons in certain areas of the thalamus & the mammillary bodies of the hypothalamus & is usually the result of chronic alcoholism.
It beings w/Wernicke’s encephalopathy, which is characterized by mental confusion, abnormal eye movements, & ataxia; & is then followed by Korsakoff’s syndrome, which involves severe anterograde amnesia, retrograde amnesia, and confabulation
Basal Ganglia
The basal ganglia are subcortical structures (caudate nucleus, putamen, globus pallidus, & substantia nigra) that are involved in planning, organizing, & coordinating voluntary movements.
Damage may cause Akinesia (Reduced movement or paralysis) or Hyperkinesia (Excessive movement).
Basal ganglia pathology has been linked to:
- Huntington’s disease,
- Parkinson’s disease,
- Tourette’s Disorder,
- OCD, and
- ADHD
Amygdala and Kluver-Bucy Syndrome
Forebrain: There are 3 structures:
- Thalamus
- Hypothalamus
- Suprachiasmatic Nucleus (SCN)
- Basal Ganglia
- Limbic System: 3 Structures
- Hippocampus
- Amygdala: A substructure of the limbic system & is involved in the control of emotional activities, including the mediation of defensive-aggressive behaviors & the attachment of emotions to memories.
Bilateral lesions in the amygdala & temporal lobes of primates produces:
- Kluver-Bucy Syndrome: Which is characterized by emotional blunting, excessive hunger, reduced fear & aggression, increased docility & compulsive oral exploratory behaviors, altered dietary habits, hypersexuality, and “psychic blindness” (an inability to recognize the significance or meaning of events or objects)
Flashbulb Memory
Refers to a vivid recollection of an emotionally-charged event.
Attributed to activity in the limbic system & the amygdala which is part of the limbic system. It is believed to add the emotional component to our memories & active in the formation of flashbulb memories.
Hippocampus
Forebrain: There are 3 structures:
- Thalamus
- Hypothalamus
- Suprachiasmatic Nucleus (SCN)
- Basal Ganglia
- Limbic System: 3 Structures
-
Hippocampus: A limbic system structure that is important for visual, spatial & verbal info., explicit memory & the consolidation of declarative memories.
- Involved in converting shot-term declarative memories to long-term memories & temp. storage for new decalrative memories.
- Controls emotion & degeneration has been linked to depression
- Amygdala
- Septum
-
Hippocampus: A limbic system structure that is important for visual, spatial & verbal info., explicit memory & the consolidation of declarative memories.
A person w/damage (lesions) to the hippocampus & adjacent areas in the temporal lobe wil most likely demonstrate an inability to form long-term memories about facts & events.
Ex: H.M.’s epilepsy, he was unable to form new memories of facts & events.
Corpus Callosum
The right & left hemisphere are connected by several bundles of fibers, the largest of which is the corpus callosum.
If the corpus callosum is severed, the two hemispheres operate essentially as separate, independent brains.
Damage to one side = Opposite Side Response
Left Dominant Hemisphere:
- Language & Verbal Abilities
- Math
- Logical Thought/Analytical
- Positive Emotional States (Happiness)
Right non-Dominant Hemisphere:
- Visuo-Spatial abilities
- Face recognition
- Visual imagery
- Creative & holistic/intuitive Thinking
- Music
- Non-verbal Memory
- Negative Emotional States (Anger)
Contralateral Representation
For most sensory & motor Fx’s, the cortex exhibits contralateral representation, which means that the left hemisphere controls the functions of the right side of the body and vice-versa
Brain Lateralization/Split Brain Patients
Although the left and right hemispheres are both involved to some degree in most Fx’s, they tend to specialize.
Left (dominant) hemisphere:
- Dominates in verbal activities (spontaneous speaking and writing, word recognition, memory for words and numbers);
- analytical, logical thought; and
- positive emotional states.
The right (non-dominant) hemisphere:
- dominates in visual-spatial activities such as facial recognition, spatial interpretation and
- memory for shapes and in
- negative emotions.
The specialization of the two hemispheres is referred to as brain lateralization and was initially studied in split-brain patients, whose corpus callosums had been severed to control severe epilepsy.
- This had some unusual consequences. When a picture of an object was presented so that it was processed by the right hemisphere only, the CT could not use language to name or describe the object.
Damage to one side = Opposite Side Response
In about 95-99% or Right-handed ppl & 50-60% of Left-handed ppl, the left hemisphere is dominant for written & spoken language.
Exception: Olfactory signals from the right nostril go to the right hemisphere & vice vers w/ the left side.
Primary Functions of Each Lobe of the Cerebral Cortex
- Frontal Lobe: Mediates motor Fx, language production, personality & executive cognitive Fx’s, attention, planning.
- Parietal Lobe: Recieves tactile input & mediates visuospatial Fx, reading & calcualtion.
- Occipital Lobe: Responsible for vision & visual perception.
- Temporal Lobe: Responsible for auditory perception, language comprehension & memory,.
Frontal Lobe and Broca’s Area/Prefrontal Cortex
The frontal lobe occupies the major portion of the cortex & includes the primary motor cortex, supplementary motor area, premotor area, Broca’s area, & prefrontal cortex.
Prefrontal Cortex: Playsa role in emotion, memory, self-awareness, attention & higher-order cog. Fx’s (initiative, planning ability, abstract thinking) & other executive functions.
- Damage to the prefrontal cortex produces personality changes and deficits in higher-level cognitive abilities.
- Damage to Dorsolateral Area causes impaired judgement, planning, insight, org., inflexibility & perseverative responses. Indiv that has trouble learning from exp. will repeat the same response over & over.
- Damage to Orbitofrontal area causes Psudopsychopathy: which involves to emotional liability, distractibility, poor impule control, & impaired social insight.
- Damage to Mediofrontal Area produces Psudodepression: Which involves impaired spontaneity, reduced emptional reactions, & diminished motor behavior & verbal output.
Primary Motor Cortex: Part of the pyramidal motor system & different areas control muscle in different parts of the body & involved in execution of voluntary movement & damage includes impaired motor Fx in corresponding area of brain.
Broca’s Area: The major language area, & damage to Broca’s area produces Broca’s (expressive) aphasia: Involves deficits in the prod. of written & spoken lang. while comprehension remains relatively intact; ppl w/this D/O speak slowly & w/great difficulty & have ltd vocab.
- Often includes Anomia (Inability to ID familiar objects by name) & difficulty repeating phrases spoken by another person espescially phrases that contain many prepositions & conjunctions.
Parietal Lobe and Apraxia/Anosognosia/Gerstmann’s Syndrome
The parietal lobe contains the somatosensory cortex: which processes sensation related to touch, pressure, pain, temperature & propiocertion.
Depending on its location, damage to the parietal lobe can cause
-
apraxia (inability to perform skilled motor movements in the absence of impaired motor functioning),
- Ideomotor Apraxia: Involves an inability to mimic a simple motor action in response to a request.
- anosognosia (inability to recognize one’s own neurological symptoms or other disorder), or
- Gerstmann’s syndrome, which involves a combination of finger agnosia, right-left confusion, agraphia, and acalculia (May occur after a stroke or in assoc. w/damage to parietal lobe.
- Contralateral Neglect: Usually the result of damage to the right parietal lobe & involves neglect of the left side of the body & env.
- Tactile Agnosia: Involves an inability to recognize familiar objects by touch.
L-R confusion is ordinarily caused by lesions in the L Angular Gyrus which is located near the boundary btwn the L Parietal & Temporal Lobes.
- Finger Agnosia: Inability to distinguish btwn fingers on the hand.
- Agraphia: Deficiency in the ability to write
- Acalculia: Difficulty in learn/comprehend math.
Temporal Lobe and Wernicke’s Area
The temporal lobe contains the primary auditory cortex and Wernicke’s area.
Auditory Cortex: Responsible for auditory sensations, & perceptions.
- Damage can result in auditory agnosia, cortical deafness, impairments in long-term memory, and/or
Wernicke’s (receptive) aphasia: A major language area & deficits in comprehension & production of speech.
- Speech is rapid & seems effortless & has approp. syntax yet devoid of content & may include
- anomia (probs. w/repitition) &
- Paraphasia (Sub one word for another) & jumble words; unitelligible speech
- Wernicke’s = Word Choice Probs. (What?)
Certain areas of the temporal lobe are essential for the encoding, storage & retrival of long-term declarative memories.
- Damage to these areas, the Amygdala & Hippocampus produces anterograde & retrogrande amnesia.
- Electrical stimulation of certain areas elicits complex, vivid memories that had been previously forgotten.
Occipital Lobe and Visual Agnosia/Prosopagnosia
The occipital lobe contains the visual cortex.
Visual Cortex: Responsible for visual sensations & perceptions.
Damage to the occipital lobe can result in:
- Visual Agnosia (inability to recognize familiar objects),
- Achromatopsia: An inability to distinguish btwn different colors.
- Color Agnosia: An inability to pair particular colors w/specific object.
- word blindness, and/or
- scotomas (blind spots).
- Lesions at the junction of the occipital, temporal, and parietal lobes can produce Prosopagnosia (inability to recognize familiar faces)
Theories of Color Vision (Trichromatic and Opponent Process)
There are 2 theories of color vision:
Trichromatic theory: There are 3 types of color receptors that are each a receptor to a different primary color (red, blue, or green).
- All other colors are produced by variations in the activity of these 3 receptors.
Opponent-process theory: Postulates 3 bipolar receptors:
- red-green
- yellow-blue
- white-black.
According to this theory, some cells are excited by red & inhibited by green, & so on; & the overall pattern of stimulation of these cells produces the various colors that we perceive
Depth Perception/Retinal Disparity
Depth perception depends on a combination of binocular and monocular cues.
Retinal disparity is a binocular cue and refers to the fact that our two eyes see objects in the world from two different views; and the closer an object, the greater the disparity of the two images
Gate-Control Theory of Pain
According to the gate-control theory of pain, there are mechanisms (special cells) in the spinal cord that mediate (block) the perception of pain
Synesthesia
Synesthesia (“joining senses”) is a rare condition in which the stimulation of one sensory modality triggers a sensation in another sensory modality.
Ex: a person with synesthesia might hear a color or taste a shape
Psychophysical Laws (Weber’s Law, Fechner’s Law, and Stevens’s Power Law)
The psychosocial laws attempt to predict the relationship between perception & sensation.
- Weber’s Law: States that the just noticeable difference in stimulus intensity is a constant proportion of the initial stimulus intensity.
- Fechner’s Law: States that physical stimulus changes are logarithmically related to their psychological sensations.
- Steven’s Power Law: Proposes that the magnitude of a sensation is equal to the physical magnitude of the stimulus producing the sensation raised to a certain power (exponent) which varies, depending on the specific sensation being measured