Publications by authors named "Gregory B Bissonette"

Recent computational models of sign tracking (ST) and goal tracking (GT) have accounted for observations that dopamine (DA) is not necessary for all forms of learning and have provided a set of predictions to further their validity. Among these, a central prediction is that manipulating the intertrial interval (ITI) during autoshaping should change the relative ST-GT proportion as well as DA phasic responses. Here, we tested these predictions and found that lengthening the ITI increased ST, i.

View Article and Find Full Text PDF

The nucleus accumbens core (NAc) is important for integrating and providing information to downstream areas about the timing and value of anticipated reward. Although NAc is one of the first brain regions to be affected by drugs of abuse, we still do not know how neural correlates related to reward expectancy are affected by previous cocaine self-administration. To address this issue, we recorded from single neurons in the NAc of rats that had previously self-administered cocaine or sucrose (control).

View Article and Find Full Text PDF

Dorsal lateral striatum (DLS) is a highly associative structure that encodes relationships among environmental stimuli, behavioral responses, and predicted outcomes. DLS is known to be disrupted after chronic drug abuse; however, it remains unclear what neural signals in DLS are altered. Current theory suggests that drug use enhances stimulus-response processing at the expense of response-outcome encoding, but this has mostly been tested in simple behavioral tasks.

View Article and Find Full Text PDF

The ability to properly adjust behavioral responses to cues in a changing environment is crucial for survival. Activity in the medial Prefrontal Cortex (mPFC) is thought to both represent rules to guide behavior as well as detect and resolve conflicts between rules in changing contingencies. However, while lesion and pharmacological studies have supported a crucial role for mPFC in this type of set-shifting, an understanding of how mPFC represents current rules or detects and resolves conflict between different rules is unclear.

View Article and Find Full Text PDF

Many brain areas are activated by the possibility and receipt of reward. Are all of these brain areas reporting the same information about reward? Or are these signals related to other functions that accompany reward-guided learning and decision-making? Through carefully controlled behavioral studies, it has been shown that reward-related activity can represent reward expectations related to future outcomes, errors in those expectations, motivation, and signals related to goal- and habit-driven behaviors. These dissociations have been accomplished by manipulating the predictability of positively and negatively valued events.

View Article and Find Full Text PDF

Cognitive flexibility is a hallmark of prefrontal cortical (PFC) function yet little is known about downstream area involvement. The medial dorsal striatum (mDS) receives major projections from the PFC and is uniquely situated to perform the integration of responses with rule information. In this study, we use a novel rule shifting task in rats that mirrors non-human primate and human studies in its temporal precision and counterbalanced responses.

View Article and Find Full Text PDF

Background: Cerebral cortical gamma-aminobutyric acidergic interneuron dysfunction is hypothesized to lead to cognitive deficits comorbid with human neuropsychiatric disorders, including schizophrenia, autism, and epilepsy. We have previously shown that mice that harbor mutations in the Plaur gene, which is associated with schizophrenia, have deficits in frontal cortical parvalbumin-expressing interneurons. Plaur mice have impaired reversal learning, similar to deficits observed in patients with schizophrenia.

View Article and Find Full Text PDF

Decision-making is motivated by the possibility of obtaining reward and/or avoiding punishment. Though many have investigated behavior associated with appetitive or aversive outcomes, few have examined behaviors that rely on both. Fewer still have addressed questions related to how anticipated appetitive and aversive outcomes interact to alter neural signals related to expected value, motivation, and salience.

View Article and Find Full Text PDF

Alterations of inhibitory GABAergic neurons are implicated in multiple psychiatric and neurological disorders, including schizophrenia, autism and epilepsy. In particular, interneuron deficits in prefrontal areas, along with presumed decreased inhibition, have been reported in several human patients. The majority of forebrain GABAergic interneurons arise from a single subcortical source before migrating to their final regional destination.

View Article and Find Full Text PDF

Background: The development of addiction is thought to reflect a transition from goal-directed to stimulus-response driven behavior, functions attributed to ventral (VS) and dorsal striatum (DS), respectively. In line with this theory, neuroadaptations that occur during prolonged drug use progress from VS to DS. Here we ask if VS dysfunction alone, independent of drug use, can affect neural selectivity in DS.

View Article and Find Full Text PDF

Neurons in the ventral striatum (VS) fire to cues that predict differently valued rewards. It is unclear whether this activity represents the value associated with the expected reward or the level of motivation induced by reward anticipation. To distinguish between the two, we trained rats on a task in which we varied value independently from motivation by manipulating the size of the reward expected on correct trials and the threat of punishment expected upon errors.

View Article and Find Full Text PDF

Impaired attentional set-shifting and inflexible decision-making are problems frequently observed during normal aging and in several psychiatric disorders. To understand the neuropathophysiology of underlying inflexible behavior, animal models of attentional set-shifting have been developed to mimic tasks such as the Wisconsin Card Sorting Task (WCST), which tap into a number of cognitive functions including stimulus-response encoding, working memory, attention, error detection, and conflict resolution. Here, we review many of these tasks in several different species and speculate on how prefrontal cortex and anterior cingulate cortex might contribute to normal performance during set-shifting.

View Article and Find Full Text PDF

Background: Neural activity in basolateral amygdala has recently been shown to reflect surprise or attention as predicted by the Pearce-Kaye-Hall model (PKH)--an influential model of associative learning. Theoretically, a PKH attentional signal originates in prediction errors of the kind associated with phasic firing of dopamine neurons. This requirement for prediction errors, coupled with projections from the midbrain dopamine system into basolateral amygdala, suggests that the PKH signal in amygdala may depend on dopaminergic input.

View Article and Find Full Text PDF

The ability to learn a rule to guide behavior is crucial for cognition and executive function. However, in a constantly changing environment, flexibility in terms of learning and changing rules is paramount. Research suggests there may be common underlying causes for the similar rule learning impairments observed in many psychiatric disorders.

View Article and Find Full Text PDF

Schizophrenia is a complex developmental disorder that presents challenges to modern neuroscience in terms of discovering etiology and aiding in effective treatment of afflicted humans. One approach is to divide the constellation of symptoms of human neuropsychiatric disorders into discrete units for study. Multiple animal models are used to study brain ontogeny, response to psychoactive compounds, substrates of defined behaviors.

View Article and Find Full Text PDF

Many psychiatric and neurological disorders present persistent neuroanatomical abnormalities in multiple brain regions that may reflect a common origin for a developmental disturbance. In mammals, many of the local GABAergic inhibitory interneurons arise from a single subcortical source. Perturbations in the ontogeny of the GABAergic interneurons may be reflected in the adult by interneuron deficits in both frontal cerebral cortical and striatal regions.

View Article and Find Full Text PDF

Disrupted ontogeny of forebrain inhibitory interneurons leads to neurological disorders, including epilepsy. Adult mice lacking the urokinase plasminogen activator receptor (Plaur) have decreased numbers of neocortical GABAergic interneurons and spontaneous seizures, attributed to a reduction of hepatocyte growth factor/scatter factor (HGF/SF). We report that by increasing endogenous HGF/SF concentration in the postnatal Plaur null mouse brain maintains the interneuron populations in the adult, reverses the seizure behavior and stabilizes the spontaneous electroencephalogram activity.

View Article and Find Full Text PDF

Many neuropsychiatric diseases are associated with cognitive rigidity linked to prefrontal dysfunction. For example, schizophrenia and Parkinson's disease are associated with performance deficits on the Wisconsin Card Sorting Test, which evaluates attentional set shifting. Although the genetic underpinnings of these disorders can be reproduced in mice, there are few models for testing the functional consequences.

View Article and Find Full Text PDF

Animals prefer an immediate over a delayed reward, just as they prefer a large over a small reward. Exposure to psychostimulants causes long-lasting changes in structures critical for this behavior and might disrupt normal time-discounting performance. To test this hypothesis, we exposed rats to cocaine daily for 2 weeks (30 mg/kg, i.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_sessionqsartne70mt6ceal6t7c58n36gduj3nq): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once