Biological Bases of Behavior Flashcards

A patient presents with fluent but nonsensical speech, often referred to as 'word salad,' and has significant difficulty understanding spoken language. However, their ability to produce speech rhythm and melody is intact. Damage to which of the following brain regions is the MOST likely cause of this presentation?

Answer: Wernicke's area

This clinical picture describes Wernicke's aphasia (receptive aphasia), which is characterized by impaired language comprehension and fluent but meaningless speech. This condition is associated with damage to Wernicke's area, typically located in the posterior part of the superior temporal gyrus in the left hemisphere. Broca's area damage results in non-fluent, effortful speech (expressive aphasia). The primary motor cortex is involved in executing voluntary movements, and the angular gyrus is more associated with reading and writing.

The hypothalamic-pituitary-adrenal (HPA) axis is a critical neuroendocrine system involved in the body's reaction to stress. Which of the following represents the correct sequence of hormone release in this axis?

Answer: CRH from the hypothalamus -> ACTH from the pituitary -> Cortisol from the adrenal cortex

The activation of the HPA axis begins when the hypothalamus secretes corticotropin-releasing hormone (CRH). CRH then travels to the anterior pituitary gland, stimulating it to release adrenocorticotropic hormone (ACTH). Finally, ACTH circulates in the bloodstream to the adrenal cortex, which triggers the release of cortisol, the primary stress hormone.

An action potential, the electrical signal that travels down a neuron's axon, is an 'all-or-nothing' event. The rapid depolarization phase, where the inside of the neuron becomes positively charged, is primarily caused by the influx of which ions?

Answer: Sodium (Na+)

The rising phase, or depolarization, of an action potential is caused by the rapid opening of voltage-gated sodium (Na+) channels. This allows a massive influx of positively charged sodium ions into the neuron, causing the membrane potential to shoot up from its negative resting state to a positive value. The subsequent outflow of potassium (K+) ions is responsible for the repolarization phase.

Long-term potentiation (LTP) is widely considered a crucial cellular mechanism for learning and memory. It refers to a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously. The induction of LTP is heavily dependent on the activation of which type of receptor?

Answer: NMDA receptors

Long-term potentiation (LTP) is a persistent strengthening of synapses that underlies learning and memory. The induction of LTP at many synapses, particularly in the hippocampus, is critically dependent on the NMDA (N-methyl-D-aspartate) receptor, which is a type of glutamate receptor. This receptor acts as a coincidence detector, opening to allow calcium influx only when it is stimulated by glutamate and the postsynaptic membrane is already depolarized, thus strengthening the synaptic connection.

A client is prescribed a benzodiazepine for severe anxiety. This class of drug primarily achieves its anxiolytic effect by acting as a positive allosteric modulator for which neurotransmitter system?

Answer: GABA

Benzodiazepines exert their sedative, anxiolytic, and anticonvulsant effects by binding to the GABA-A receptor complex. They are not direct agonists but are positive allosteric modulators, meaning they enhance the effect of the endogenous neurotransmitter, gamma-aminobutyric acid (GABA). By increasing the affinity of GABA for its receptor, benzodiazepines enhance the inhibitory effects of GABA, leading to a calming of the nervous system.

A psychologist is reviewing a brain scan of a patient who has difficulty with executive functions, such as planning, problem-solving, and inhibiting inappropriate responses. These cognitive deficits are MOST likely associated with damage to which lobe of the cerebral cortex?

Answer: Frontal lobe

The frontal lobe, and particularly the prefrontal cortex within it, is responsible for higher-level cognitive processes known as executive functions. These include planning, working memory, decision-making, social judgment, and impulse control. Damage to this area can lead to significant personality changes and difficulties in organizing and regulating behavior.