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<p>Finding and consuming food and water are among the most critical functions for an animal's survival. Food seeking (e.g., exploration and approach) and consummatory (e.g., licking, chewing, swallowing) behaviors are usually highly controlled, resulting in stable food intake, body mass, and fat stores in humans and laboratory animals. These variables are thought to be governed by homeostatic control systems that closely regulate many aspects of feeding behavior. However, the homeostatic mechanisms underlying these processes are often disrupted in humans, resulting in either hyperphagia or hypophagia. Despite many decades of investigations into the regulatory circuits of animals and humans, the neural circuits that underlie voluntary feeding are unclear. There have been considerable advances into understanding how the brain is able to broadly regulate food consumption (e.g., the role of circulating hormones on food intake and body weight). As much work has focused on hypothalamic mechanisms, relatively little is known about how other neural systems contribute to specific aspects of food seeking and consumption. </p><p> The basal ganglia have been implicated in many aspects of motivated behavior including appetitive and consummatory processes. However, the precise role that basal ganglia pathways play in these motivated behaviors remain largely unknown. One reason for this is that the basal ganglia are functionally and anatomically heterogeneous, with distinct functional circuit elements being embedded within overlapping tissue. Until recently, tools permitting identification and manipulation of molecularly defined neuron populations were unavailable. </p><p> The following experiments were designed to assess the role of the basal ganglia in regulating appetitive and consummatory behavior in mice. The first experiment (Chapter 2) examines the relationship between neural activity in the substantia nigra¬, a¬ major output nucleus of the basal ganglia, and an animal's motivational state. Both dopaminergic and GABAergic neurons show bursts of action potentials in response to a cue that predicts a food reward in hungry mice. The magnitude of this burst response is bidirectionally modulated by the animal's motivational state. When mice are sated prior to testing, or when no pellets can be consumed, both motivational state and bidirectional modulation of the cue response are unchanging. </p><p> The second set of experiments (Chapter 3 and 4) utilizes a mouse model of hyperdopaminergia: Dopamine transporter knockout mice. These mice have persistently elevated synaptic dopamine. Consistent with a role of dopamine in motivation, hyperdopaminergic mice exhibit enhanced food seeking behavior that is dissociable from general hyperactivity. Lentiviral restoration of the dopamine transporter into either the dorsolateral striatum or the nucleus accumbens, but not the dorsomedial striatum, is sufficient to selectively reduce excessive food seeking. The dopamine transporter knockout model of hyperdopaminergia was then used to test the role of dopamine in consummatory processes, specifically, licking for sucrose solution. Hyperdopaminergic mice have higher rates of licking, which was due to increased perseveration of licking in a bout. By contrast, they have increased individual lick durations, and reduced inter-lick-intervals. During extinction, both knockout and control mice transiently increase variability in lick pattern generation while reducing licking rate. Yet they show very different behavioral patterns. Control mice gradually increase lick duration as well as variability in extinction. By contrast, dopamine transporter knockout mice exhibited more immediate (within 10 licks) adjustments--an immediate increase in lick duration variability, as well as more rapid extinction. These results suggest that the level of dopamine can modulate the persistence and pattern generation of a highly stereotyped consummatory behavior like licking, as well as new learning in response to changes in environmental feedback. </p><p> The final set of experiments was designed to test the relationship between consummatory behavior and the activity of GABAergic basal ganglia output neurons projecting from the substantia nigra pars reticulata to the superior colliculus, an area that has been implicated in regulating orofacial behavior. Electrophysiological recording from mice during voluntary drinking showed that activity of GABAergic output neurons of the substantia nigra pars reticulata reflect the microstructure of consummatory licking. These neurons exhibit oscillatory bursts of activity, which are usually in phase with the lick cycle, peaking near the time of tongue protrusion. Dopaminergic neurons, in contrast, did not reflect lick microstructure, but instead signaled the boundaries of a bout of licking. Neurons located in the lateral part of the superior colliculus, a region that receives direct input from GABAergic projection neurons in the substantia nigra pars reticulata, also reflected the microstructure of licking with rhythmic oscillations. These neurons, however, showed a generally opposing pattern of activity relative to the substantia nigra neurons, pausing their firing when the tongue is extended. To test whether perturbation of the nigrotectal pathway could influence licking behavior, channelrhodopsin-2 was selectively expressed in GABAergic neurons of the substantia nigra and the axon terminals within the superior colliculus were targeted with optic fibers. Activation of nigrotectal neurons disrupted licking in a frequency-dependent manner. Using optrode recordings, I demonstrate that nigrotectal activation inhibits neurons in the superior colliculus to disrupt the pattern of licking. </p><p> Taken together, these results demonstrate that the basal ganglia are involved in both appetitive and consummatory behaviors. The present data argue for a role of striatonigral dopamine in regulating general appetitive responding: persistence of food-seeking. Nigraltectal GABA neurons appear to be critical for consummatory orofacial motor output.</p> / Dissertation

The aim of this experiment was to test whether LIPX-induced decreases in body fat affect appetitive (foraging effort and food hoarding) or consummatory (food intake) ingestive behaviors and whether the effects of LIPX on these behaviors is in turn affected by changes in energy expenditure produced by varying the amount of work required to obtain food. This was accomplished by housing male Siberian hamsters (Phodopus sungorus) in a foraging/hoarding apparatus where food pellets (75 mg) could be earned by completing various wheel running requirements. Requiring a foraging effort (10 revolutions/pellet) abolished the normal compensation of WAT mass by the non-excised WAT pads that typically follows IWATx or EWATx. After foraging, food hoarding was increased more than food intake when hamsters were required to forage for food (10 revolutions/pellet). The magnitude of the LIPX-induced lipid deficit (IWATx > EWATx) did not correspond to a proportional change in either appetitive or consummatory ingestive behaviors.

The aim of this experiment was to test whether LIPX-induced decreases in body fat affect appetitive (foraging effort and food hoarding) or consummatory (food intake) ingestive behaviors and whether the effects of LIPX on these behaviors is in turn affected by changes in energy expenditure produced by varying the amount of work required to obtain food. This was accomplished by housing male Siberian hamsters (Phodopus sungorus) in a foraging/hoarding apparatus where food pellets (75 mg) could be earned by completing various wheel running requirements. Requiring a foraging effort (10 revolutions/pellet) abolished the normal compensation of WAT mass by the non-excised WAT pads that typically follows IWATx or EWATx. After foraging, food hoarding was increased more than food intake when hamsters were required to forage for food (10 revolutions/pellet). The magnitude of the LIPX-induced lipid deficit (IWATx > EWATx) did not correspond to a proportional change in either appetitive or consummatory ingestive behaviors.

Individuals experience different dimensional levels of motivation and apathy (i.e., the lack of motivation), which can reflect both state and trait contributions. Chronic apathy is common in a number of neurological and psychiatric disorders such as mild cognitive impairment, Parkinson’s disease, Alzheimer’s disease, depression, bipolar disorder, and schizophrenia. The primary aim of the current study was to create a new self-report measure that measures different domains of motivation/apathy with subscales and also take into account many other aspects that could affect motivation within the same scale, including energy level, anticipatory and consummatory pleasure, indecisiveness, and initial and sustained effort. A sample of undergraduate university students from the University of Central Florida (N = 327, 57% female) and Louisiana State University (N = 400, 82% female) completed and passed exclusion criteria from an online survey which included the initial Multifaceted Motivation Inventory (MMI), along with other existing measures. Following factor analysis and exclusion criteria, of the 38 activities included on the initial MMI, two factors of 10 activities each emerged for the final MMI scale. One reflected solitary activities while the other factor asked about social activities. The Cronbach’s alphas for the frequency in which activities were endorsed as having completed in the past year for each factor were acceptable at .69 and .70. Construct validity for the two factors was supported through significant relationships in the expected directions with external scales of depression, indecisiveness, apathy, and anticipatory and consummatory pleasure. Further research on the final MMI can help assess its psychometric ability to distinguish individual trait differences that contribute to a dimensional level of motivation/apathy.

Flat affect (i.e., diminished expressivity) and self-reported anhedonia (i.e., lack of pleasure) are associated with many psychiatric disorders. There is a need to examine the relationship between specific anhedonia subtypes and flat affect in a non-clinical sample. Forty-seven undergraduate students (59% male; mean age 20.37; SD = 4.74) completed self-report questionnaires assessing four subtypes of anhedonia - consummatory/anticipatory by social/non-social. Participants then viewed 15 randomly-presented pictures (five neutral, ten negative) from the International Affective Pictures System while facial muscle activity (electromyography; EMG) was recorded. Male participants reporting a greater level of anhedonia, particularly consummatory social anhedonia, showed greater EMG activity change in the corrugator supercilii muscle to negative pictures, as compared with neutral pictures. Females showed the opposite pattern: more consummatory social anhedonia related to less EMG activity change in the corrugator muscle. In summary, consummatory social anhedonia in particular showed a strong relationship with facial expressivity that interacted with sex. In the presence of more consummatory social anhedonia, males show more negative facial reactions to negative stimuli while females show a more flattened affect. These findings may help explain discrepancies in existing research examining anhedonia and flat affect in clinical populations and have implications for etiology and treatments.

During the past few decades, obesity has risen significantly in the United States with recent estimates showing that 65% of Americans are overweight and 30% are obese. This increase is a major cause for concern because obesity is linked to many secondary health consequences that include type II diabetes, heart disease, and cancer. Current approaches to the obesity problem primarily have focused on controls of food intake and have been largely unsuccessful. Food, however, almost always has to be acquired (foraging) and frequently is stored for later consumption (hoarding). Therefore, a more comprehensive approach that includes studying the underlying mechanisms in human foraging and food hoarding behaviors could provide an additional target for pharmaceutical or behavioral manipulations in the treatment and possibly prevention of obesity. Neuropeptide Y (NPY) is a particular peptide that provides a potent orexigenic drive to alter foraging, food hoarding (appetitive ingestive behaviors) and food intake (consummatory ingestive behaviors) in variety of species. NPY is predominantly produced in the arcuate nucleus of the hypothalamus (ARC) and has extensive efferent projections throughout the brain. Two target nuclei of ARC-NPY, the paraventricular nucleus of the hypothalamus (PVH) and perifornical area (PFA), have been shown to mediate the effect of NPY on food intake in laboratory rats and mice, but nothing is known about the effect of ARC-NPY on foraging and food hoarding. In addition, the action of specific NPY receptor subtypes within these two nuclei for these behaviors is unknown. Even though ARC-NPY is one of the main sources of input into the PVH and PFA, it is not known if this NPY fiber projection mediates alterations in appetitive and consummatory ingestive behaviors. Therefore, the purpose of this dissertation is to test 1) if NPY within the PVH or PFA controls appetitive, as well as, consummatory ingestive behaviors, 2) if NPY Y1 receptors within the PVH or PFA differentially control appetitive or consummatory ingestive behaviors, and 3) if NPY from the ARC is necessary for the control of appetitive and consummatory ingestive behaviors.

In certain species, puberty is thought to be a period of susceptibility to various stressors, resulting in pathological behavioral and physiological changes subsequent to exposure during this period. However, juvenile male golden hamsters appear to be fairly resilient to pubertal stress, as compared to adult hamsters and many other species. In these experiments, repeatedly stressed juvenile male hamsters were found to be avoidant of aggressive adult male social stimuli, but did not display anxious behavior outside of a social context. In addition, several long-term changes in neural activity were associated with social stress during early puberty. The medial preoptic area and medial preoptic nucleus, and ventral tegmental area showed decreased neural activity in subjugated juveniles than in naïve individuals. Since these brain areas are involved in the expression of motivated behaviors, specifically sexual behavior, and reward pathways, we next investigated sexual behavior in virgin juveniles. When placed in a confined space with receptive females, consummatory behavior in subjugated juveniles was similar to those observed in naive juveniles. Appetitive aspects of sexual behavior were also tested in a Y-maze to allow subjects to choose whether to approach a social stimulus. When given a choice between a sexually receptive and non-receptive female social stimulus, socially stressed individuals showed anxiety related behaviors and did not show a preference. However, naïve hamsters preferred the non-receptive female. Interestingly, this effect was less significant in naïve animals tested during late puberty and early adulthood, and a preference for sexually receptive females was not observed. In addition, stressed hamsters tested with harnessed females at mid-puberty were slower to approach females, indicating altered motivation to approach adult conspecifics. This research is unique in that it is the first to suggest the disconnect between the development of consummatory and appetitive aspects of sexual behavior. Together, these data examine the effects of stress on the development of pubertal social behaviors. / text

La schizophrénie (SZ), maladie psychiatrique invalidante, est caractérisée par des symptômes positifs, négatifs, cognitifs, désorganisés, affectifs et moteurs. De par l’absence de résultats positifs dans la prise en charge des symptômes négatifs, nous avons décidé de nous intéresser à l’apathie dans la SZ. Elle se définit par une baisse des comportements dirigés vers un but ayant une origine cognitive, émotionnelle ou comportementale. Notre objectif est d’apporter un éclaircissement sur le concept d’apathie en s’intéressant aux liens entre apathie, anhédonie et BIS/BAS. Le protocole 1 porte sur la validation de la Lille Apathy Rating Scale (LARS), outil multidimensionnel de l’apathie validée dans la maladie de Parkinson, dans la SZ, auprès de 112 patients. Le protocole 2 (étude transversale) s’intéresse aux liens entre apathie, plaisir consommé, anticipatoire, sociale et BIS/BAS, auprès de 112 patients. Enfin, le protocole 3 (étude longitudinale d’un an) porte sur l’évolution de l’apathie et explore les déterminants émotionnels et comportementaux qui pourraient la prédire, auprès de 61 patients. Nos résultats ont mis en évidence une LARS à quatre facteurs avec de bonnes qualités psychométriques dans la SZ. Le facteur 1 est associé au BAS, à l’anhédonie sociale et anticipatoire. Le facteur 2 corrèle avec le BIS et l’anhédonie sociale. Trente-six pourcent des patients ont une apathie trait. Enfin, seul leplaisir anticipatoire prédit le facteur 4. L’apathie nécessite donc pour sa compréhension une approche multidimensionnelle. L’anhédonie et le BIS/BAS ne peuvent expliquer à eux seuls l’apathie émotionnelle et comportementale. D’autres pistes méritent donc d’être explorées. / Schizophrenia (SZ) is a chronic psychiatric disease characterized by positive, negative, cognitive, disorganized, emotional and motor symptoms. The lack of positive results in the treatment of negative symptoms led us to be interested in apathy. Apathy is defined as a multidimensional psychopathological state (cognitive, emotional, and behavioral) manifesting as a reduction of voluntary behaviors directed toward one goal. Our aim is to provide a clarification of the concept of apathy by focusing on the relationship between apathy, anhedonia and BIS/BAS. The first study deals with the validation of the Lille Apathy Rating Scale (LARS), which is a multidimensional tool of apathy validated in Parkinson’s disease, in 112 SZ patients. The second study (cross-sectional study) focuses on the link between apathy, consummatory and anticipatory pleasure, social pleasure and BIS/BAS, in 112 SZ patients. Finally, the third study (one year longitudinal study) deals with the evolution of apathy and explores the emotional and behavioral derminants that could predict it. Ours results have shown that the LARS is structured in four factors and has good psychometric properties in SZ. The factor 1 is associated to the BAS and the social and anticipatory anhedonia. The factor 2 is linked to the BIS and the social anhedonia. Thirty-six percent of the patients have an apathy trait. Finally, only anticipatory pleasure predicts the factor 4. Therefore, apathy requires for its understanding a multidimensional approach.Anhedonia and the BIS/BAS cannot by themselves explain the emotional and the behavioral apathy. Consequently, others lines of research need to be explored.

Made available in DSpace on 2016-04-29T13:18:02Z (GMT). No. of bitstreams: 1 Gustavo Teixeira.pdf: 502529 bytes, checksum: 0badfa331efd29c54624e82d8098ac77 (MD5) Previous issue date: 2006-11-24 / The present study researched the effects of the reinforcement history under DRL or FR schedules upon the response under FI schedule and the possible implications of the consummatory response in these schedules. Twelve university students from different courses, except from the Psychology school, took part in this research. The subjects were set in 4 groups and submitted to six sessions with 40 reinforcements each. Members of 2 groups were initially exposed to a FR 40 and the members of the other two groups to a DRL 20-sec. Later on, all participants were exposed to three sessions of FI 10- sec. One consummatory response was made a requirement in the six sessions only for the participants of one of the two groups exposed to a FR 40 and for the participants of one of the two groups exposed to DRL 20- sec. The subjects presenting a history of reinforcement under FR (with or without a consummatory response) showed a high rate response standard and relatively constant during the third session exposed to FR 40. All the participants, except one, kept a performance at a high rate of responses when exposed to a FI schedule. Nevertheless, two participants of the FR 40 Group with consummatory response showed a trend to decreasing the response rate throughout the FI exposition sessions, suggesting that the consummatory response may have contributed to the reduction of the response rates. The participants presenting a history of reinforcement in DRL (with and without consummatory response) showed response standard at low and constant rate during the third session of exposition to DRL 20-sec. These participants kept having a performance at low rate of responses when exposed to FI, however the response rate increased remarkably. For those participants members of the Group with no consummatory response, suggesting that the consummatory response may have contributed to the increase of the response rate for the groups with DRL history. Concerning the effects of the history, observing the final performance in FI 10-sec. from the participants with a history of reinforcement under FR and from the participants with a history of reinforcement under DRL, one can see that the general response rate was higher for those participants with a history of FR than for those with a reinforcement history under DRL. These results suggest that the participants behavior along the third session under FI 10-sec. was under the control of the current contingencies and showed effects of the reinforcement history / O presente estudo investigou efeitos da história de reforço em esquemas de DRL ou FR sobre o responder em esquema de FI e possíveis implicações da resposta de consumação nesses esquemas. Participaram desta pesquisa 12 estudantes universitários de diversos cursos, com exceção do curso de Psicologia. Os participantes foram distribuídos em 4 grupos, submetidos a seis sessões com 40 reforços cada. Os participantes de dois grupos foram expostos inicialmente a FR 40 e os participantes dos outros dois grupos a DRL 20 seg. Subseqüentemente, todos os participantes foram expostos a três sessões de FI 10 seg. Houve a exigência de uma resposta de consumação nas seis sessões somente para os participantes de um dos grupos exposto a FR 40 e um dos grupos exposto a DRL 20 seg. Os participantes com história de reforço em FR (com e sem resposta de consumação) apresentaram um padrão de responder em taxa alta e relativamente constante durante a terceira sessão de exposição a FR 40. Com exceção de um, todos os outros participantes continuaram com um desempenho em taxa alta de respostas quando expostos a FI. No entanto, dois participantes do Grupo FR 40 com consumação apresentaram tendência de diminuição das taxas de respostas ao longo das sessões de exposição a FI, sugerindo que a resposta de consumação pode ter contribuído para a diminuição das taxas de respostas destes participantes. Os participantes com história de reforço em DRL (com e sem resposta de consumação) apresentaram um padrão de responder em taxa baixa e constante durante a terceira sessão de exposição a DRL 20 seg. Estes participantes continuaram com um desempenho em taxa baixa de respostas quando expostos a FI, entretanto, a taxa de respostas aumentou acentuadamente. Para os participantes do Grupo com resposta de consumação o aumento na taxa de respostas, quando expostos a FI, foi ainda mais acentuado do que para os participantes do Grupo sem resposta de consumação, sugerindo que a resposta de consumação pode ter contribuído para o aumento das taxas de respostas para os grupos com história em DRL. Em relação aos efeitos de história, ao observar o desempenho final em FI 10 seg dos participantes com história de reforço em FR e dos participantes com história de reforço em DRL, verifica-se que a taxa geral de respostas foi mais alta para os participantes com história de FR que para aqueles com história de reforço em DRL. Estes resultados sugerem que o comportamento dos participantes na terceira sessão sob FI10 seg estava sob controle das contingências atuais e mostrava efeitos da história de reforço