Neurobiology of Learning, Memory, and Neurological Disorders

Flashcards covering the neurobiology of memory systems, synaptic plasticity (LTP/LTD), psychiatric disorders like schizophrenia and depression, and neurological conditions including stroke, Parkinson's, and Alzheimer's disease.

Anterograde amnesia

A condition characterized by difficulty in learning new information after the occurrence of brain damage.

Retrograde amnesia

A condition characterized by difficulty in recalling information or events that occurred prior to the onset of brain damage.

Declarative memory

Also known as explicit memory, these are things you know that you can tell or "declare" to others, including facts and life events.

Nondeclarative memory

Also known as implicit memory, these are tasks or skills you know that you show by doing, such as skill learning, priming, and conditioning.

Episodic memory

A division of declarative memory involving the recollection of specific details surrounding an episode or event in your life.

Semantic memory

A division of declarative memory involving general factual knowledge, such as knowing the capital of a country.

Priming

A type of nondeclarative learning where exposure to an initial stimulus influences a person's response to a subsequent stimulus without conscious intention.

Synaptogenesis

The cellular process of creating new synapses between neurons.

Habituation

A form of learning at the neural level involving a weakening of neural connections where a subject stops responding to a repeated stimulus.

Long-Term Potentiation (LTP)

A long-lasting strengthening of a neural synapse resulting from frequent stimulation.

NMDA receptor

An ionotropic glutamate receptor that acts as a coincidence detector, requiring both glutamate binding and membrane depolarization to remove a $Mg^{2+}$ block.

AMPA receptor

A chemically gated ionotropic receptor that, when activated by glutamate, allows $Na^+$ to enter and depolarize the membrane.

$$CaMKII$$

A protein kinase that autophosphorylates and plays a role in LTP by increasing the number of AMPA receptors on the postsynaptic membrane.

Long-Term Depression (LTD)

A process where low-frequency stimulation of synaptic inputs leads to a decrease in the strength of the synapse.

Positive symptoms (Schizophrenia)

Abnormal additions to behavior, such as delusions, hallucinations, and thought disorders.

Negative symptoms (Schizophrenia)

Abnormal absences in behavior, such as flattened affect, social withdrawal, and poverty of speech.

Dopamine hypothesis

The theory that schizophrenia is caused by overactivity in dopaminergic synapses, specifically between the VTA and the nucleus accumbens.

Monoamine hypothesis

The suggestion that depression is caused by low activity of one or more monoaminergic synapses, involving serotonin ($5-HT$) or norepinephrine ($NE$).

Therapeutic index

The ratio of the dose that causes toxicity in $50\%$ of the population to the dose that is effective in $50\%$ of the population.

Cushing's syndrome

A medical condition characterized by persistently elevated levels of cortisol, placing patients at a greater risk for depression.

Ischemia

A disruption of blood flow to a particular region of the brain, which is the primary cause of obstructive strokes.

Infarction

The area of the brain closest to an occluded blood vessel during a stroke where all cells die.

Penumbra

The region of cells surrounding an infarction that are potentially rescuable with treatment.

$tPA$ (tissue plasminogen activator)

A thrombolytic agent used to dissolve blood clots in stroke patients, which must be administered within $3$ hours of onset.

Lewy bodies

Abnormal circular structures found in the cytoplasm of surviving dopaminergic neurons in the substantia nigra of Parkinson's patients.

Amyloid plaques

Extracellular deposits consisting of a dense core of $A\beta$ (amyloid-beta) protein surrounded by degenerating axons and dendrites, common in Alzheimer's disease.

Status epilepticus

A life-threatening condition where a patient experiences recurrent tonic-clonic seizures for more than $30$ minutes without regaining consciousness.