NEUR200 Exam 4

Rhythms: We display biological _____ that are tied to the passage of time. (Sleep)

Rhythms

Circadian Rhythms (Sleep)

24-hour biological cycles influential in the regulation of sleep and other physical responses

Rhythyms: The exposure of light (Zeitgerber: time giver) _______________. (Sleep)

Readjusts people's biological clocks by affecting the activity of the hypothalamus

True or false: The hypothalamus is a circadian clock. (Sleep)

True

Hypothalamus: Suprachiasmatic Nucleus (SCN) (Sleep)

Influenced by light; controls the release of melatonin in the pineal gland, which makes us sleepy; light reaches the SCN directly in mammals (retinohypothalamic pathway)

Brain structures for arousal: Reticular information (Sleep)

(Ascending fibers) influence physiological arousal

Brain structures for arousal: Locus coeruleus (Sleep)

Located in the pons

Brain structures for arousal: Hypothalamus (Sleep)

Histamine; Orexin or hypocretin: Necessary to stay awake, inhibition of orexin can cause rats to fall asleep quickly

Brain structures for arousal: Narcolepsy (Sleep)

Lack hypothalamic cells that produce orexin

EEG and Sleep: Stage 1

Lasts 5 to 10 minutes, EEG theta waves

EEG and Sleep: Stage 2

Brief bursts of higher-frequency brain waves

EEG and Sleep: Stage 2 K-complex

Sharp waves; temporal inhibition of neuronal firing; they occur after a sudden interruption within the sleeper's environment, i.e. noise

EEG and Sleep: Stage 2 Sleep Spindles

Generated in the thalamus; Brief: 500 ms, inhibition, the greater number of sleep spindles in participants who napped, the more they were refreshed to performed on a learning task

EEG and Sleep: Stage 3 and 4

Slow-wave sleep; high-amplitude, low-frequency delta waves become prominent; synchronization of low-waves. Reduction of sensory input

EEG and Sleep: Stage 5 (REM sleep)

Rapid Eye Movement; high-frequency beta waves in some areas; most dreams occur during this stage (they also happen during stages 3 and 4)

Sleep Disorders: Insomnia

Chronic problems in getting adequate sleep

Sleep Disorders: Causes of Insomnia

Anxiety and tension, depression

Sleep Disorders: Narcolepsy

Irresistable onsets of sleep durign normal waking periods

Sleep Disorders: Causes of Narcolepsy

Lack hypothalamic cells that produce orexin; Huntington's disease

Sleep Disorders: Sleep apnea

Frequent, reflexive gasping for air (of a minute) that awakens a person

Sleep Disorders: Causes of Sleep apnea

Obesity, genetics, hormones, old-age deterioration of the brain mechanisms that regulate breathing

Sleep Disorders: Night terrors

Abrupt awakenings form NREM sleep accompanied by intense autonomic arousal and feelings of panic

Sleep Disorders: Nightmares

Anxiety-arousing dreams that lead to awakening

Sleep Disorder: Local phenomenon

You may have substanial inhibition in one brain area and not so much in another

Sleep Disorders: Sleepwalking

Motor cortex is awake

Sleep Disorders: REM behavior disorder

People who move around vigorously during their REM periods, acting out their dreams --> GABA deficiency

Sleep Disorders: Lucid Dreaming

Monitoring areas are awake (frontal)

Sleep Disorders: Sleep Paralysis

Waking up while you still cannot move

Fatal Familial Insomnia (FFI) (What happens if we don't sleep?)

Inherited rare disease, onset occurs when a critical amount of protein PrP is converted to protein PrPres; Greater amounts of PrPres than normal in thalamus --> degeneration of thalamus

Fatal Familial Insomnia (FFI) consequences (What happens if we don't sleep?)

Absense of sleep spindles and k-complexes; deep sleep is reduced, REM sleep can happen during waking state; weight loss, elevated sympathetic activation, hallucinations, epileptic seizures, coma, death

Energy Conservation: Sleep

Sleep conserves energy during inefficient times; automatic nervous system; analogous to hibernation

Sleep and memory

Memories that are more important will be consolidated better during sleep

Sleep and memory: EEG patterns during sleep

Resemble those that occur during learning

Sleep and memory: Sleep spindles

Increase in number after new learning

Sleep and memory: Adjustments

The brain makes adjustments when we learn new things; strengthening new synapses; weakening or removing old synapses that are not used anymore

Sleep and memory: Reactivation process

Associated with consolidation begins when a memory is formed, but it becomes strong during sleep

Working Memory: There may be ____ working memory systems

Two working memory (shorterm) systems, for spatial and object memory

Working Memory: The ____ and ___ visual pathways from the _____ and the ______ project to prefrontal cortical regions and support two kinds of short-term memory

Dorsal, ventral, parietal, temporal; The dorsal stream enables vision for action and the ventral stream, vision for perception

Processes in Short Term Memory and LTM: Encoding (from sensory system into Short Term Memory)

Visual objects: right prefrontal and right parahippocampal cortex; Words: left prefrontal and parahippocampal cortex

Processes in STM and Long Term Memory: Consolidation (into Long Term Memory)

Medial temporal lobe: After further processing that involves the hippocampus, the permanent memory storage may require the outermost layer of the cortex, layer I, which has few neuronal cell bodies but is packed with synapses; Engrams: What pathway (visual cortex for visual objects, auditory cortex for auditory objects)

Processes in STM and Long Term Memory: Retrieval

Requires attention (frontal areas). Retrieval from LTM makes the memories plastic again and they can be updated -- important for PTSD memory

Long-Term Explicit Memory: Episodic Memory

Memory of life experiences centered on the person herself

Long-Term Explicit Memory: Semantic Memory

Knowledge about the world -nonautobiographical knowledge-. I.e. ability to recognize family, friends, information learned in school...

Long-Term Explicit Memory: Neural Substrates

Temporal-frontal-lobes, ventral stream, temporal lobe: hippocampus and rhinal cortex mainly, acetylcholine, serotonin, and noradrenaline

Long-Term Memory and Hippocampus

Explicit memory, specifically episodic

Long-Term Memory and Hippocampus: Spatial Memory

Morris water maze; hippocampus as a spatial map -- place cells, grid cells found in nearby entorhinal cortex; London taxi drivers: hippocampus activates more when they answer to spatial questions

Long-Term Memory and Hippocampus: Contextual memory

The hippocampus brings together representations from various locations and reconstructs the context

Long-Term Implicit Memory: Fear conditioning, amygdala

Damage to the amygdala abolishes emotional memory but has little effect on other types of implicit or explicit memory

Long-Term Implicit Memory: Procedural learning, basal ganglia

People with Parkinson's disease may have problems with this type of memory

Procedural Memory and Basal Ganglia: Basal Ganglia

Stratium, Globus Pallidus, Substantia Nigra; gradual learning of habits; reinforcement-based teaching (trial and error); related to procedural memory; this type of learning is less flexible; you may need to use frontal cortex at the beginning, otherwise it takes a long time to learn

Procedural Memory and Basal Ganglia: Prefrontal Cortex

It is more flexible, switching respones

Long-Term Potentiation: Glutamate Receptors (AMPA and NDMA)

NDMA receptors are blocked by magnesium (positive ions); they open after depolarization

Long-Term Potentiation: Calcium

When calcium (together with sodium) enters through the NDMA channels, it will lead to the release of the protein CREB, that goes to the nucelus and alters genes (gene expression) that can last for months or years

Long-Term Potentiation: Brain-derived neurotrophic factor (BDNF)

These effects are modulated by the BDNF; repeated activation will lead to action protentials that back-propagate into dendrites and release BDNF; BDNF can increase NMDA activity

Amensia: Anterograde amensia

Disruption of memory for experiences after the onset of amnesia

Amensia: Retrograde amensia

Disrupt memory for things learned prior to the event that initiated the amnesia

Amensia: Time-dependent retrograde amnesia

Injury severity determines how far back in time the amnesia extends. People usually start remembering with the passage of time and they only end up with amnesia for a few seconds to minutes for events preceeding the injury

Amnesia: Henry Molaison (HM)

Removed his hippocampus to end his epilespy; he suffered from anterograde amnesia and retrograde amnesia; severe impairement of episodic memory (he could not describe any event that happened after the surgery); people with amensia are as impaired at imagining the future as they are describing the past; better implicit than explicit memory; intact working memory but as soon as he was distracted, the memory was gone within seconds (impaired long term memory); intact procedural memory

Attention definition

Narrowing or focusing awareness selectivity to a part of the sensory environment or to a class of stimuli

Consciousness definition

Synonymous at a primary level with awareness and at a secondary level with awareness of awareness (first person experience of the events that you are aware of)

Attention is primarily a _______ process that ___________.

Top-down process that selects information from a specific part of the sensory world, such as a point in space or an object

Consciousness is not so ____________.

Selective; it summarizes all information pertinent to the individual and its environment

Attention Networks: Alerting Network

Reticular Activating System --> Locus coeruleus (Noradrenaline) acts to prepare regions (alertness) especially in prefrontal and posterior parietal cortex for detecting stimuli rapidly

Attention Networks: Orienting Network

Acetylcholine; Prioritizes sensory input by selecting a sensory modality or a location in space

Attention Networks: Dorsal Attention System

Top-down visuospatial; right-lateralized (neglect syndrome)

Attention Networks Functions: Default mode network (Brain Networks)

Thinking about one's past thinking about the future, or mind wandering (i.e. mPFC, PCC, medial temporal areas)

Attention Networks Functions: Salience network (Brain Networks)

Most active when a behavioral change is needed. If the salience network is not functioning properly, the default network shows excessive activity, leading to lapses in attention (i.e. ACC, insula)

Attention Networks Functions: Dorsal attention system

Top-down visuospatial; right-lateralized (i.e. right IPS, FEF)

Synchrony: How does our brain choose important events from among all of the ongoing sensory information? (Attention)

The attentional system induces synchrony across a population of neurons that assess some sensory signal; importance of temporal positions of action potentials (i.e. several inputs to a given neuron arrive together)

Synchrony: Increasing activity

Increasing activity in the attention network increases brain synchrony globally; increasing activity in the default network may have the opposite effect -- loss of global syndrome

Attention: Meditation

Meditation reduces activity in the default mode network and increases in salience and central executive network connectivity; increased activity of anterior cingulate during meditation

Anatomical Areas: Broca's area (Language)

Inferior frontal gyrus (44 and 45 of Broadmann's map)

Anatomical Areas: Wernicke's area (Language)

Superior temporal gyrus (22 of Broadmann's map)

Anatomical Areas: Hesch'l's gyrus (other important areas for language)

Primary auditory cortex (41, 42)

Anatomical Areas: Premotor area 6 (other important areas for language)

Facial movements (mirror neurons), the dorsal part of the area 6 (SMA) is important for rhythmic mouth movments that articulate sounds

Anatomical Areas: Visual areas (other important areas for language)

Left fusiform cortex (important for reading)

Fluent Aphasias: Wernicke (Language Disorders)

Poor comprehension, paraphasias (the production of unintended syllables, words, or phrases during speech, i.e. "pike" instead of "pipe") and anomias; fluent speech and poor repetition

Fluent Aphasias: Transcortical (Language Disorders)

Extrasylvian regions (POT junction); poor comprehension, paraphasias and anomias; fluent speech and good repetition

Fluent Aphasias: Conduction aphasia (Language Disorders)

Disconnection of fibers that connect language comprehension and speech areas; they can understand language and they may speak fluently (speech sounds and movements are retained), but usually speech is impaired because it cannot be conducted from one region to the other; they may have problems with repetition

Fluent Aphasias: Anomic aphasia (Language Disorders)

May involve damage of pathways in frontal, temporal, and/or parietal lobes; amonia and occasional paraphasias ("spot" instead of "pot"); fluent speech

Nonfluent Aphasias: Broca (Language Disorders)

Speech is impaired, naming is impaired; repetition is limited (i.e. only single words); problems with complex syntax or grammar

Pure Aphasias: Agraphia (Language Disorders)

Writing (normal speech); several types of damage can lead to this problem (i.e. damage in the superior or middle frontal gyri, parietal lobe, sometimes occurs together with alexia)

Pure Aphasias: Alexia (Language Disorders)

Reading (normal speech)

Pure Aphasias: Anarthria (Language Disorders)

Incoordination of the musculature of the mouth

Review: Action Potential

Stimulation that reaches the treshold leads to a massive depolarization of the neuron (sodium channels open and allow sodium inside the membrane)

Review: Peak of Action Potential

Sodium channels close and beacuse potassium channels are still open (potassium ions exit the cell), polarization occurs and the membrane returns to its resting potential

Review: The refractory period

Right after the AP, the membrane is in a refractory period during which it resists the production of other APs; sodium channels are close, potassium exit the cell

Review: Propagation of the action potential

Positive charges (in the inside) depolarize the next area of the membrane, that reaches its treshold and opens its sodium channels; the action potential is regenerated at that point and so on

Review: Hemianopia or hemianopsia

Blindness of half visual field (right or left) because of damage in left or right V1

Review: Blindsight or cortical blindness

Sometimes people with anopsia or hemianopsia respond to the stimuli that they don't consciously see (specific characteristics of the stimulus such as a movement can help)

Review: Cortical color blindness

Damage of a V4 area; imagery and memory are affected too

Review: Visual agnosia

Inability to recognize visual information; geniculostriate and what (ventral) pathways

Review: Apperceptive (Object agnosias)

Inability to develop a percept (i.e. they cannot copy an object)

Review: Associative agnosia (Object agnosias)

Inability to recognize an object despite its apparent perception (i.e. they can copy an object, but cannot recognize it)

Review: Prosopagnosia (Visual agnosia)

Difficulty recognizing familiar faces; bilateral damage of fusiform area (right hemisphere is more important)

Review: Alexia or word blindess (Visual agnosia)

Inability to read; damage of left fusiform area affects word recognition (they can read letter-by-letter). They can use motion (tracing the letters) to read

Review: Simultagnosia (Ataxia)

Patients have problems to perceive more than one object at a time. This rare symptom can occur because of damage in different areas i.e. doral stream (it can occur in patients with Balint's syndrome -- spatial attention problem)

Review: Amusia, Heschl's gyrus (Auditory Disorders)

Impairement to make pitch discriminations; much larger Heschl's gyrus in musicians

Review: Auditory hallucinations (Auditory Disorders)

Spontaneous activity in the auditory regions

Review: Wernicke's aphasia (Auditory Disorders)

Disturbed word recognition, the extreme form being "word deafness", an inability to recognize words despite hearing of pure tones