neurochemistry
In our laboratory we pursue a mechanistic neurobiological understanding of the phenomenon of motivated memory. Specifically, we study the effects of neuromodulatory neurotransmitter systems on memory formation in the human brain, with a particular interest in the reward-driven neuromodulation of episodic memory formation that is likely to involve the dopaminergic system.
Dopamine
Our current projects build on our previous experimental work using the motivated memory event-related fMRI paradigm described in Adcock et al., Neuron 2006. This study demonstrates interactions between the ventral tegmental area (VTA) and hippocampus in humans and makes the important connection between these interactions and memory formation. Anticipatory coupling of VTA and hippocampus appears to prepare the hippocampus to record experience: a candidate neural mechanism for motivation to learn.
Direct dopaminergic projections are known to connect the VTA to the hippocampus, and the prior presence of dopamine in hippocampal synapses has been shown to decrease the threshold for cellular changes thought to underlie lasting memories. For these reasons, we hypothesize that this anticipatory functional coupling of VTA and hippocampus reflects the release of dopamine from the VTA into the hippocampus, leading to the enhancement of episodic memory. Thus we are beginning studies aimed at tying both the behavioral and brain activation phenomena to dopamine. Specifically, we are using pharmacological manipulations of the dopaminergic system to determine dopamine’s role in reward-driven memory enhancement.
This work has implications for both healthy individuals and clinical populations with disorders associated with hippocampal dysfunction, such as Alzheimer’s dementia and schizophrenia.
Oxytocin
Our interest in the modulation of memory extends beyond dopamine, with another active area of research focusing on oxytocin. Oxytocin is a neuromodulatory peptide essential for normal social behavior in mammals, perhaps through its effects on reward and attention circuitry in the brain. In rodents, oxytocin is required for social memory: when oxytocin receptors are blocked, social memories appear not to form. In humans, oxytocin appears to influence the salience of both social and nonsocial information. Our lab is examining the role of oxytocin in social and nonsocial attention, reward, and memory.
Interested in learning more? Please contact Betsy Johnson (johnsonbetsy_at_neuro.duke.edu).
In our laboratory we pursue a mechanistic neurobiological understanding of the phenomenon of motivated memory. Specifically, we study the effects of neuromodulatory neurotransmitter systems on memory formation in the human brain, with a particular interest in the reward-driven neuromodulation of episodic memory formation that is likely to involve the dopaminergic system.
Dopamine
Our current projects build on our previous experimental work using the motivated memory event-related fMRI paradigm described in Adcock et al., Neuron 2006. This study demonstrates interactions between the ventral tegmental area (VTA) and hippocampus in humans and makes the important connection between these interactions and memory formation. Anticipatory coupling of VTA and hippocampus appears to prepare the hippocampus to record experience: a candidate neural mechanism for motivation to learn.
Direct dopaminergic projections are known to connect the VTA to the hippocampus, and the prior presence of dopamine in hippocampal synapses has been shown to decrease the threshold for cellular changes thought to underlie lasting memories. For these reasons, we hypothesize that this anticipatory functional coupling of VTA and hippocampus reflects the release of dopamine from the VTA into the hippocampus, leading to the enhancement of episodic memory. Thus we are beginning studies aimed at tying both the behavioral and brain activation phenomena to dopamine. Specifically, we are using pharmacological manipulations of the dopaminergic system to determine dopamine’s role in reward-driven memory enhancement.
This work has implications for both healthy individuals and clinical populations with disorders associated with hippocampal dysfunction, such as Alzheimer’s dementia and schizophrenia.
Oxytocin
Our interest in the modulation of memory extends beyond dopamine, with another active area of research focusing on oxytocin. Oxytocin is a neuromodulatory peptide essential for normal social behavior in mammals, perhaps through its effects on reward and attention circuitry in the brain. In rodents, oxytocin is required for social memory: when oxytocin receptors are blocked, social memories appear not to form. In humans, oxytocin appears to influence the salience of both social and nonsocial information. Our lab is examining the role of oxytocin in social and nonsocial attention, reward, and memory.
Interested in learning more? Please contact Betsy Johnson (johnsonbetsy_at_neuro.duke.edu).