PSYC 388 FINAL EXAM 2025 NEWEST
ACTUAL EXAM QUESTIONS AND
CORRECT VERIFIED ANSWERS | A+
GRADE
The direct projection from the retina to the
suprachiasmatic nucleus is called the____________
Correct Answer The retinohypothalamic tract
In the mouse circadian clock, activation of retinal
photoreceptors by light causes release of which
neurotransmitter in the suprachiasmatic nucleus? Correct
Answer glutamate
The neurotransmitter, glutamate, that is released in the
SCN in response to light, has what effect on SCN
neurons? Correct Answer Glutamate is the photic
neurotransmitter for shifting the SCN clock and mediates
the SCN's response to light (conveys light input to SCN)
Photic input pathway summary Correct Answer
Melanopsin-containing RGC send axons that make up the
optic nerve.
Some of these axons diverge at the optic chiasm and form
the RHT.
RHT axon terminals release glutamate and a peptide.
Glutamate depolarizes SCN neurons > influxing calcium >
activating second messenger cascades which eventually
activate Per1gene.
,This shifts the clock gene cycle, producing behavioural
shifts.
(ipGRCs stimulated by light > release glutamate and
PACAP in SCN, depolarizing its neurons > activates
intracellular 2nd messengers > stimulates Per1
transcription in SCN clock cells > circadian cycle is reset).
Lesions to which of the following structures consistently
block phase shifts induced by exercise in Syrian
hamsters? Correct Answer SCN
A neurotoxin that kills 5HT (serotonin) neurons in the
mouse brain has what effect on circadian rhythms Correct
Answer Mice affected by the neurotoxin 5,7-DHT which
kills 5HT cells, failed to entrain to daily exercise
schedules, BUT their free running rhythms did appear
modulated
Neurons in the intergeniculate leaflet (IGL) are activated
by what type of stimulus, and are important for
entrainment to what kind of time cues? Correct Answer
IGL neurons project to the SCN and release neuropeptide
Y (NPY), GABA, and enkephalin.
NPY neurons are activated by exercise, releasing NPY
into the SCN which can cause it to shift
Non-photic input summary Correct Answer Exercise and
some arousal procedures can shift or entrain hamster
circadian rhythms, but stressful arousal does not.
, Stressful arousal activates cells in the dorsal raphe >
projects to IGL inhibiting NPY neurons > preventing the
activation needed to release NPY into the SCN and shift.
Non-stressful arousal causes 5HT release in the SCN and
IGL > this may inhibit GABA interneuron in the IGL >
which normally inhibits the IGL NPY neurons > this
permits the NPY neurons to become active releasing NPY
into the SCN inducing a phase shift.
In hamsters, the phase shifting effect of exercise in the
usual sleep period can be mimicked by injection of which
neurochemical into the SCN? Correct Answer
Neuropeptide Y - NPY
Do neurons in the dorsal and median raphe project directly
or indirectly to the SCN pacemaker? Correct Answer
Median raphe projects directly to the SCN.
The dorsal raphe projects to the IGL, which then projects
to the SCN.
Does melatonin induce phase shifts in mammals, and if
so, is the phase response curve similar to the PRC for
light, for exercise, or for neither? Correct Answer PRCs
have been demonstrated to respond to melatonin, but
these are not PRCs corresponding to light, behavioural
exercise, or arousal
Which of the following is a possible mechanism for 'radio
broadcasting' of circadian signals from an SCN graft?
Correct Answer Neurons can transmit signals via
synapses or via releasing signaling molecules that diffuse
ACTUAL EXAM QUESTIONS AND
CORRECT VERIFIED ANSWERS | A+
GRADE
The direct projection from the retina to the
suprachiasmatic nucleus is called the____________
Correct Answer The retinohypothalamic tract
In the mouse circadian clock, activation of retinal
photoreceptors by light causes release of which
neurotransmitter in the suprachiasmatic nucleus? Correct
Answer glutamate
The neurotransmitter, glutamate, that is released in the
SCN in response to light, has what effect on SCN
neurons? Correct Answer Glutamate is the photic
neurotransmitter for shifting the SCN clock and mediates
the SCN's response to light (conveys light input to SCN)
Photic input pathway summary Correct Answer
Melanopsin-containing RGC send axons that make up the
optic nerve.
Some of these axons diverge at the optic chiasm and form
the RHT.
RHT axon terminals release glutamate and a peptide.
Glutamate depolarizes SCN neurons > influxing calcium >
activating second messenger cascades which eventually
activate Per1gene.
,This shifts the clock gene cycle, producing behavioural
shifts.
(ipGRCs stimulated by light > release glutamate and
PACAP in SCN, depolarizing its neurons > activates
intracellular 2nd messengers > stimulates Per1
transcription in SCN clock cells > circadian cycle is reset).
Lesions to which of the following structures consistently
block phase shifts induced by exercise in Syrian
hamsters? Correct Answer SCN
A neurotoxin that kills 5HT (serotonin) neurons in the
mouse brain has what effect on circadian rhythms Correct
Answer Mice affected by the neurotoxin 5,7-DHT which
kills 5HT cells, failed to entrain to daily exercise
schedules, BUT their free running rhythms did appear
modulated
Neurons in the intergeniculate leaflet (IGL) are activated
by what type of stimulus, and are important for
entrainment to what kind of time cues? Correct Answer
IGL neurons project to the SCN and release neuropeptide
Y (NPY), GABA, and enkephalin.
NPY neurons are activated by exercise, releasing NPY
into the SCN which can cause it to shift
Non-photic input summary Correct Answer Exercise and
some arousal procedures can shift or entrain hamster
circadian rhythms, but stressful arousal does not.
, Stressful arousal activates cells in the dorsal raphe >
projects to IGL inhibiting NPY neurons > preventing the
activation needed to release NPY into the SCN and shift.
Non-stressful arousal causes 5HT release in the SCN and
IGL > this may inhibit GABA interneuron in the IGL >
which normally inhibits the IGL NPY neurons > this
permits the NPY neurons to become active releasing NPY
into the SCN inducing a phase shift.
In hamsters, the phase shifting effect of exercise in the
usual sleep period can be mimicked by injection of which
neurochemical into the SCN? Correct Answer
Neuropeptide Y - NPY
Do neurons in the dorsal and median raphe project directly
or indirectly to the SCN pacemaker? Correct Answer
Median raphe projects directly to the SCN.
The dorsal raphe projects to the IGL, which then projects
to the SCN.
Does melatonin induce phase shifts in mammals, and if
so, is the phase response curve similar to the PRC for
light, for exercise, or for neither? Correct Answer PRCs
have been demonstrated to respond to melatonin, but
these are not PRCs corresponding to light, behavioural
exercise, or arousal
Which of the following is a possible mechanism for 'radio
broadcasting' of circadian signals from an SCN graft?
Correct Answer Neurons can transmit signals via
synapses or via releasing signaling molecules that diffuse
