Section IV: Cognitive Neuroscience

Chapter 19: Consciousness

A patient is diagnosed as having a brain infarct and presents primarily with contralateral hemiparesis and dysarthria. Which of the following regions is affected by the infarct?

A. Medial thalamic nuclei

B. Lateral thalamic nuclei

C. Dorsomedial thalamus

D. Ventromedial thalamus

E. Medial hypothalamus

B. The lateral region of the thalamus and the posterior limb of the internal capsule are supplied by choroidal branches of the internal carotid artery. Infarct of this artery most frequently results in contralateral hemiparesis and dysarthria. Although lesions associated with this artery may affect only motor functions, they may also cause loss of pain, touch, and sometimes visual functions. The other choices given in this question are not associated with this constellation of deficits.

A middle-aged woman, who is suffering from a rare autosomal recessive condition that results in calcification and degeneration of specific regions of the forebrain, is seen by a psychiatrist. The patient is given a battery of tests and is found to be unable to recognize fear in pictures presented to her. Nor is she able to draw a picture depicting fear; however, she is capable of drawing pictures depicting other emotions. A magnetic resonance imaging (MRI) scan indicates significant atrophy of tissue in a specific region of the brain. Which of the regions indicated below is the most likely target of this rare autosomal recessive condition?

A. Mammillary bodies

B. Septal area

C. Amygdala

D. Cingulate gyrus

E. Lateral hypothalamus

C. Studies conducted on fear conditioning in rats have demonstrated that the amygdala plays a very important role in this process. Rare evidence obtained from patients has shown that individuals suffering from a rare autosomal recessive condition called Urbach-Wiethe disease, in which there is bilateral atrophy of the portion of the temporal lobe that includes the amygdala, have no sense of the emotion of fear. They are unable to recognize it and are not capable of depicting it in a drawing. Other regions listed in this question have not been linked to the emotion of fear.

A 65-year-old man suddenly finds himself unable to recognize the speech of individuals and the sounds of animals, whistles, or bells, but is still able to discriminate tones and hear sounds. On an MRI, a lesion was detected in which of the following regions?

A. Inferior parietal cortex

B. Superior parietal cortex

C. Inferior temporal cortex

D. Superior temporal cortex

E. Medial geniculate nucleus

D. Failure to recognize complex sounds such as those of animals, individuals, bells, or whistles can occur with a lesion of the superior temporal cortex, while the ability to discriminate tones and hear sounds is preserved. A lesion of the inferior parietal cortex would result in other forms of agnosia such as finger agnosia (Gerstmann syndrome); a lesion of the superior parietal cortex results in a syndrome called sensory neglect; a lesion of the inferior temporal cortex typically results in a failure to recognize faces called prosopagnosia; and a lesion of the medial geniculate nucleus is rare in man, but if it were to occur, the effect would presumably be to affect hearing directly, especially discrimination of tones. There is no evidence that such a lesion would produce an auditory agnosia.

A patient is described as being socially disinhibited and displaying severe impairments in judgment, foresight, and insight. An MRI reveals the presence of a brain lesion. Where is the likely locus of this lesion?

A. Premotor cortex

B. Superior parietal lobule

C. Prefrontal cortex

D. Hippocampal formation

E. Amygdala

C. Damage to the prefrontal cortex results in social disinhibition and impairment of judgment, insight, and foresight. The patient may retain basic cognitive functions; however, the patient may display behaviors that are inappropriate without feeling any regret or guilt about such responses. Other regions presented as alternative choices in this question do not display these forms of dysfunctional responses. For example, lesions of the superior parietal and premotor cortices are more closely associated with apraxia, lesions of the hippocampal formation with short-term memory disorders, and lesions of the amygdala with the loss of fear responses and changes in aggressive behavior.

Chapter 20: Learning & Memory

Short-term working memory mainly involves which brain region(s)?

A. Only the prefrontal cortex (PFC)

B. Only the posterior parietal cortex and temporal cortex

C. Only the hippocampus

D. The PFC, posterior parietal cortex, and temporal cortex

E. All regions of the frontal, parietal, and temporal lobes

D. A combination of human functional imaging studies and research in rodents has demonstrated that short-term working memory involves specific regions in the prefrontal cortex, posterior parietal cortex, and temporal cortex.

The hippocampus is required for the formation of new _________ memories.

A. semantic, episodic, and spatial

B. explicit and implicit

C. declarative and nondeclarative

D. procedural and spatial

E. short-term working

A. Human studies (eg, patient H.M. and others) have demonstrated that the hippocampus is required for semantic and episodic (together with declarative or explicit) and spatial memory. Encoding of implicit/nondeclarative and short-term memory involves other brain regions.

The majority of long-term explicit memories are thought to be stored in many

A. structures of the medial temporal lobe (MTL).

B. regions of the hippocampus.

C. parts of the basal ganglia.

D. domains of the cerebellum.

E. areas of the cerebral cortex.

E. Although encoding and formation of new declarative/explicit memories require the hippocampus, studies in rodents suggest that memories are transferred from the hippocampus to the cerebral cortex following encoding and learning over a period of days to weeks to months. Human studies also suggest that some episodic memories, especially autobiographical memories, are either stored in the hippocampus or require the hippocampus for retrieval.

Long-term potentiation (LTP) is thought to be a neuronal mechanism involved in

A. sensory memory.

B. short-term working memory.

C. long-term memory.

D. only hippocampal-dependent memory.

E. all types of memory: sensory, short-term, and long-term.

C. Sensory memory involves very short-lived enhancement of synaptic transmission, whereas short-term working memory involves increased circuit activity, most likely via reverberating circuits in the prefrontal cortex. Neither sensory nor short-term working memory involves long-term synaptic changes, including biochemical changes. So only hippocampal-dependent memory (declarative and spatial memory) is thought to require LTP. That said, it is anticipated that other types of long-term memory such as nondeclarative, procedural, and motor memory will likely involve similar LTP and/or long-term depression mechanisms.

Sleep has been proposed as an ideal period for system consolidation because during sleep there is _____________ the transmission or transfer of information from hippocampus to neocortex.

A. little use of adenosine triphosphate (ATP) by other regions of the brain, so more ATP will be available for

B. no incoming sensory activity; hence, there is no interference with

C. detoxification of free radicals and toxic proteins that improves

D. a decrease in rogue brain waves that might complicate and confound

E. an increase in a specific brain wave that enhances

B. Although all of these ideas have been proposed, are plausible, and are not mutually exclusive, the theory that many neuroscientists are most keen on at the moment is that during sleep there is reduced incoming sensory activity to the hippocampus, and thus synaptic and systems consolidation can proceed without interference.

Chapter 21: Language

A 64-year-old woman presents with a reduction in fluency of speech with a serious deficiency in naming of objects and repetition of words when requested to do so. The patient’s writing is poor, and she also displays a hemiparesis. Comprehension of speech appears to be preserved. A magnetic resonance imaging (MRI) scan and overall neurologic examination reveal that the patient has a lesion. Which of the following regions is likely to contain the lesion?

A. Medial convexity of the premotor cortex

B. Frontal operculum and convexity

C. Supramarginal gyrus

D. Angular gyrus

E. Inferior parietal lobule

B. A lesion of the operculum and convexity of the frontal lobe (which lies rostral to the precentral gyrus of the left side of the cortex and is called the Broca area) results in aphasia. This form of aphasia is characterized by nonfluency in speech, as well as difficulty in word naming and repetition of words, while comprehension of speech is preserved. Frequently, such lesions extend beyond this region and include wide parts of the precentral gyrus, thus resulting in hemiparesis of the right side of the body. A lesion of the medial convexity of the premotor cortex would result in loss of motor functions mainly of the lower limb; lesions of the supramarginal gyrus or angular gyrus produce forms of aphasia in which fluency is preserved; and a lesion of the inferior parietal lobule might also produce a form of aphasia where fluency is preserved or a Gerstmann syndrome.

A 67-year-old woman is brought to a local hospital following complaints by her family because of recent difficulties that the patient has experienced in communicating with others. In particular, the patient has great difficulty in comprehending words and understanding simple commands. A neurologic examination confirms that the patient experiences difficulties in language comprehension, and an MRI reveals a cortical lesion. Which of the following regions was observed to be the locus of the lesion?

A. Medial convexity of the premotor cortex

B. Frontal operculum and convexity

C. Medial aspect of occipital cortex

D. Posterior aspect of superior temporal lobe

E. Superior (posterior) parietal lobule

D. A lesion of the posterior aspect of the superior temporal cortex, known as Wernicke area, results in a reduction in fluency in speech, and this form of aphasia is sometimes referred to as receptive aphasia. A lesion of the medial convexity of the premotor cortex would produce apraxic movement disorders; a lesion of the lateral convexity of the precentral gyrus would produce a limb paralysis; a lesion of the medial aspect of the occipital cortex would produce visual deficits; and a lesion of the superior parietal lobule could produce a form of apraxia.

A 75-year-old man, who is right handed, was told in the past by his internist that he has an irregular heartbeat. The patient decides that he does not wish to learn anything further about this condition, so he does not return to this physician, and it remains untreated. One morning, he awakes to find that his face droops on the right side and that he cannot move his right arm or right leg. When he tries to call an ambulance for help, he has a great deal of difficulty communicating with the operator because his speech is slurred, nonfluent, and missing some pronouns. The call is traced by the police; an ambulance arrives at his house and takes him to an emergency room. A neurologist is called to see the patient in the emergency room. When he listens to the patient’s heart, he detects an irregular heartbeat. It is very difficult to understand his speech because it is halting, with a tendency to repeat the same phrases over and over. He has difficulty repeating specific sentences given to him by the neurologist, but he is able to follow simple commands such as, “Touch your right ear with your left hand.” His mouth droops on the right when he attempts to smile, but his forehead remains symmetric when he wrinkles it. He cannot move his right arm at all, but he is able to wiggle his right leg a little bit. Which of the following language problems does this patient have?

A. Dysarthria

B. Wernicke aphasia

C. Broca aphasia

D. Alexia

E. Pure word deafness

C. The language problem is an example of Broca aphasia, a deficit seen with lesions of the Broca area and manifested by defects in the motor aspect of speech, leaving the patient’s speech halting and nonfluent. People with Broca aphasia tend to repeat certain phrases, as well as leave out pronouns. Because the language centers are usually located on the dominant side of the brain (the left side for a right-handed person), this lesion must be on the left side of the patient’s brain. Wernicke aphasia is a problem with the sensory aspect of speech, where the patient can speak fluently, but the speech sounds like gibberish. The area of disruption in this type of aphasia is usually in Wernicke area, a region of the posterior superior temporal lobe. Dysarthria is slurred speech that makes grammatical sense. Alexia is the inability to read. Pure word deafness is a type of sensory aphasia whereby language, reading, and writing are only mildly disturbed, but auditory comprehension of words is very abnormal. This arises from lesions of the posterior temporal lobe.

Chapter 22: Emotion

A car accident victim continues to exhibit a normal lack of fear of intrinsically fearful entities such as snakes and leopards but has lost fear for images that one learns are dangerous, such as guns and fearful facial expressions. Normal semantic and episodic memories of non–fear-associated items remain intact and continue to be learned. The lesion is likely to be located where?

A. Hippocampus

B. Amygdala

C. Insula

D. Ventromedial prefrontal cortex

E. Dorsolateral prefrontal cortex

B. The amygdala is specifically involved with memories of fearful items associated with dangerous or punishing contexts from the past. Damage to the hippocampus would interfere with the acquisition of all new memories. Damage to the insula does not eliminate emotional learning but interferes with visceral consciousness and empathy. Prefrontal damage interferes with all emotional judgement, not just emotional learning.

After a stroke, a 57-year-old man suddenly develops a gambling addiction and loses most of his savings at a casino. He also exhibits what is called utilization behavior, the tendency to use objects that do not belong to him, such as grabbing coins from someone else’s pile at the casino and inserting them in the slot machine. Where is the lesion likely to be?

A. Hippocampus

B. Amygdala

C. Thalamus

D. Ventromedial prefrontal cortex

E. Dorsolateral prefrontal cortex

D. Damage to ventromedial prefrontal cortex, as in the case of Phineas Gage, results in poor social judgement, risk taking, and utilization behavior. Damage to the hippocampus interferes with the acquisition of new memories. Thalamic damage results in deficits in sensory processing, motor control, and attention. Damage to the dorsolateral prefrontal cortex would interfere with working memory tasks.

Two patients present at a neurology clinic with mirror image brain lesions. One patient has become high risk taking and manic, while the other is lethargic and depressed. The manic/depressed mirror lesions are where?

A. Left/right ventromedial prefrontal cortex

B. Right/left ventromedial prefrontal cortex

C. Left/right dorsolateral prefrontal cortex

D. Right/left dorsolateral prefrontal cortex

E. Left/right amygdala

B. The left prefrontal cortex, ventromedial prefrontal cortex more than dorsolateral, is biased to approach, while the right is biased toward withdrawal. Damage to the left side biases activity toward right side–mediated withdrawal, whereas damage to the right biases toward left-mediated approach and manic activity. Amygdala damage compromises fear learning.

Chapter 23: Circadian Rhythms & Sleep

When did circadian rhythms originate?

A. Soon after the origin of life

B. After the dinosaur extinction at the end of the Cretaceous

C. After the Permian extinction 250 million years ago

D. At the onset of the Cambrian explosion about 530 million years ago

E. At the transition from prokaryotes to eukaryotes

A. Soon after the origin of life is the correct answer.

How does entrainment differ from synchronization?

A. Entrainment works by always setting the circadian clock when the amount of light exceeds a certain threshold.

B. Entrainment works by always setting the circadian clock when the amount of light falls below a certain threshold.

C. Entrainment allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

D. Synchronization allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

E. Entrainment and synchronization are 2 names for the same thing.

C. Entrainment allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

What is the primary, central pacemaker brain area in mammals?

A. The striatum

B. The SCN of the hypothalamus

C. The nucleus interpositus of the cerebellum

D. The lateral geniculate nucleus of the thalamus

E. The superior colliculus deep layers

B. The suprachiasmatic nucleus of the hypothalamus is the central pacemaker brain area in mammals.

What is the retinal output to the SCN?

A. Magnocellular retinal ganglion cells

B. Kinocellular retinal ganglion cells

C. Motion-selective retinal ganglion cells

D. Intrinsically photoreceptive retinal ganglion cells

E. Starburst amacrine cells

D. Intrinsically photoreceptive retinal ganglion cells compose the retinal output to the suprachiasmatic nucleus.

Which gene is involved in circadian clocks?

A. Per2

B. Clock2

C. Sync1

D. Sync2

E. Per-cyc1

A. Per2 is the gene involved in circadian clocks.

Which of the following is a common circadian rhythm disorder?

A. Seasonal affective disorder

B. Metabolic asynchronicity

C. Overactive immune responses

D. Sleep problems

E. Poor night vision

D. Sleep problems are the most common circadian rhythm disorder.

The retinal projection to the suprachiasmatic nucleus that mediates circadian rhythms is mediated by what types of retinal neurons?

A. Magnocellular cells.

B. Parvocellular cells.

C. A special class of amacrine cells.

D. Intrinsically photosentive melanopsin ganglion cells.

E. Photoreceptors with axons that project to the brain.

7.  D. The retinal contains a class of ganglion cells called intrinsically photosensitive that contain their own photopigment and react directly to light (although they may also be driven by photoreceptors through bipolar cells, like other ganglion cells). These project to the suprachiasmatic nucleus via the retino-hypothalanic tract. Neither photoreceptors, amacrine cells, or other ganglion cell classes are involved in this projection.