Neuro Quiz 5 Content

Homeostasis

the process by which an animal maintains a stable internal environment, essential for survival (caloric intake, fluid intake, body temp, blood oxygen levels).

Allostasis

Temporary maintenance of internal physiological conditions outside the normal range to respond to an immediate threat to survive (a fever can help fight off an infection).

Negative feedback loop of homeostasis

Environmental change (in environment) → sensor (nerves) → control center (brain) → effector (muscles) → response (behavior) → negative feedback helps return the body back to normal.

Sensory cells

specialized cells in the brain and bodythat detect internal changes in homeostatic factors

Control centers

Sensory signals are integrated in neural control centers, usually located in the hypothalamus or brainstem.

Sensing temperature

Peripheral nerve endings with thermosensitive channels send information to the spinal cord than into the brain.

Preoptic Area (POA)

regulates sleep/wake cycles, core body temperature, fluid balance, and reproductive behaviors.

Satiety Signals (anorexigenic)

(fullness)

Amylin

CCK

PYY

Leptin

• from the organs and intestines

Hunger signals (orexigenic)

Ghrelin (sounds like gremines and you know not to feed them even though they’re hungry)

• from the stomach

Vagus nerve

Stretching of the stomach muscles causes sensory fibers to fire. Tells the brain if the body feels full or hungry.

Hormonal signals and hunger

Amylin spikes right after a meal

Ghrelin peaks right before a meal

Leptin in the blood

Fat cells that respond more gradually, increasing over the course of the day as meals are consumed, LONG TERM FULLNESS.

Circumventricular organs

specialized, highly vascularized midline brain structures surrounding the third and fourth ventricles that lack a typical blood-brain barrier, hormones can easily pass through, with hunger (POMC - fullness & AgRP - hunger)

Chronobiology

The study of biological clocks and biological rhythms within an organism (humans run on a 24h endogenous/entrainable cycle).

the suprachiasmatic nucleus (SCN)

a tiny, bilateral structure in the hypothalamus, acting as the primary internal clock for hormones, respiratory, and sleep cycles.

Lesions in the SCN

Mice will begin to lose their 24-hour clock, and their arrhythmic activity will be set off. If there is a fetal transplant and the SCN tissue restores, so will the 24-hour sleep cycle.

The SNC and light.

Blue light (specifically) activates intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina, which help the brain signal that it is daytime. Warmer tones will help calm the brain down. If there are leasions, brain will not be impacted by tones.

Sleep and hormones

Heavy:

• VLPO

Light:

• TMN

• Rn

• LC

• PPT/LDT

Awake and hormones

Heavy:

• TMN

• Rn

• LC

• PPT/LDT

Light:

• VLPO

Narcolepsy

Feeling excessivley sleeping at inopportune times throughout the day (will fall asleep at any point in time, even if someone is holding their head up)

Symptoms:

• Sleep paralysis

• visual and auditory hallucinations

• reduction or loss of muscle tone

• excessive daytime sleepiness

Typically, nighttime sleep is very disrupted with multiple awakenings during the night. ACTUALLY SLEEP QUALITY IS HORRIBLE!!!!!

During naps, brain will go stright to REM sleep, skipping NREM sleep.

Social jetlag

Occurs when an individual aligns their sleep/wake cycle with their social life (e.g., falling asleep at 10 on weekdays and 2 on weekends). This can impact the quality of sleep and will cause problems in paying attention, can also have physical and mental impacts

Learning

refers to the acquiaition of new information or skills

Memory

the process by which that information is stored and later retrieved.

Sensory memory

seconds

Short-term memory

minutes

Intermediate-term memory

hours to days

Long-term memory

Hours to a lifetime

Haptic sensory registers

touch

Iconic sensory registars

visual

Echoic sensory receptors

auditory

Time course of memories

Environmental input → sensory registers → short-term storage → output response or consolidation (synaptic plasticity and then gets stored into long-term storage).

Explicit/declarative memory

Conscious → semantic memory (facts) or episodic memory (events in life)

Implicit/procedural memory

Unconscious memories (muscle memory of how to ride a bike).

Stratum and memory

procedural memory

Amygdala and memory

Emotion association

Hippocampus and memory

episodic memory (patient H.M.)

Epilepsy and memory

Temporal love _____ is the most common form. Uncontrolled neuronal firing.

• memory impairment due to whatever caused the ____. Could be caused by drugs or head injuries.

Alzheimer’s disease

The most common form of dementia.

• Gradual loss of memory and cognitive abilities, such as planning and decision making.

• Dramatic deterioration of episodic memory followed by a loss of executive functions.

• The brain starts to shrink and neurons start to die.

Normal mice vs those with AD

Normal mice spent more time than not in the area where they remembered the platform being, vs those with AD spend the same amount of time in the target area and non tartget area, showing that they have no memory of where the platform was during the training trials

Non-associative learning

Uses a single stimulus either once or multiple times with no reward or punishment.

• habitutation

• sensitization

Habituation

Uses a single stimulus multiple times, and response to a stimulus decreases with repeated exposure (moving next to a highway and having to get used to the loud noise of the highway, eventually it will be just like background noise)

Sensitization

RESPONSE TO A STIMULUS INCREASES WITH REPEATED EXPOSURE (stimulus must be intense and/or unpleasant). e.g., a friend’s alarm going off in the morning and it keeps going off after a period of time, and it starts to get annoying asf. We can see this with sea slugs (aplysia)

Associative learning

A relationship between two stimuli is learned by presenting stimuli close together in time

• Classical conditioning

• Operant conditioning

Classical conditioning

An involuntary response becomes associated with a stimulus. → Dr. Ivan Pavlov and the classical conditioning of dogs. Fear conditioning, office episode with the candy.

Operant conditioning

The association of a voluntary behavior with a punishment or reward. Relies on the basal ganglia (associated with the reward pathway)

Episodic memory

REMEMBER PATIENT H.M. → relies on the hippocampus

Place cells

hippocampal neurons that prederentially fire in response to an animal being in a particular location

hippocampal trisynaptic loop.

the primary excitatory pathway of the hippocampus, crucial for learning and episodic memory.