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Memory refers to the retention of learned information or experiences in the brain. It is known that interference of certain brain functions immediately after training or memory reactivation can cause memory loss (i.e. amnesia). The post-training process is called consolidation and the post reactivation process is called reconsolidation. However, it remains unclear as to: (1) whether appetitive, goal-directed memories undergo reconsolidation, (2) whether overtrained memories undergo reconsolidation, (3) what the nature of amnesia is (i.e. whether it represents storage or retrieval impairment), (4) how to test the nature of amnesia, and (5) whether the brain uses the same mechanism for a new learning and from a second learning. This thesis, composed of five manuscripts, aims to answer these questions. In the first manuscript, the model of incentive learning of appetitive outcomes in instrumental conditioning was used. Protein synthesis inhibitor (PSI) was infused into lateral and basal amygdala (LBA) after the new incentive learning and after the reactivation of the memory. The results show that appetitive memories in controlling goal-directed behaviors underwent consolidation and reconsolidation in the LBA. In the second manuscript, rats were overtrained with auditory fear conditioning and received intra-LBA PSI infusions after memory reactivation. The results show that only old, but not recent, overtrained auditory fear memories underwent reconsolidation. This suggests overtraining sets a boundary condition on memory reconsolidation. Further results showed dorsal hippocampus and intra-LBA NR2B-subunit containing N-methyl-D-aspartic acid receptors (NMDAr) were involved in this boundary condition. In the third manuscript, the unresolved debate about the nature of amnesia was reviewed from a historical perspective and the suggestions on reconciling this issue are proposed. In the fourth manuscript, a new approach was used to test the nature of amnesia in contextual fear conditioning. Because NMDAr blockade impairs a new learning but not a second learning, it is predicted that if a memory is not stored then the second learning should be impaired by NMDAr blockade. The results suggest amnesia of contextual fear memory caused by intra-dorsal hippocampus (dH) PSI infusion represents a storage impairment which gives a different result from extinction induced irretrievability. In the fifth manuscript , the aim is to identify the brain mechanism for the second learning as the previous manuscript suggests it is different from the first learning mechanism. The results show that the first, but not the second learning required voltage-dependent calcium channels and activation in dH. The second learning was impaired by intra-dH or ventral hippocampus (vH) inactivation only when the protein synthesis in the other portion of hippocampus was blocked after training. This suggests while the first learning by default requires dH, the second learning can be acquired through a functional dH or vH. In summary, this thesis extends memory research from consolidating a new learning to characterizing the reconsolidation of appetitive and overtrained memory to consolidating a second learning which will lead to a more complete description of memory process.

The purpose of this paper was to characterize and compare pressure patterns in the skate boot of elite and recreational players during the forward crossover turn. In-skate pressure patterns of eight elite varsity level hockey players (mean +/- SD: height (m) = 1.80 +/- 0.07, weight (kg) = 87 +/- 0.06) and eight recreational hockey players (mean +/- SD: height = 1.76 (m) +/- 0.06, weight (kg) = 82 +/- 0.07) were measured using fifteen piezo-resistive sensors per foot during the forward crossover skating stride. Each participant performed three trials in both the clock-wise (CW) and counter clock-wise (CCW) directions. For each trial the pressure profiles of three strides were cut and averaged according to ability groups and turn directions. The results showed that the elite skaters performed the skill quicker than the recreational skaters (6.85 (sec) +/- 0.114 vs 7.62 (sec) +/- 0.125), respectively (p < 0.01). Other significant differences (p < 0.05) were found in peak pressures on the plantar, medial and lateral surfaces between groups. No significant differences were found when turn directions were compared. These results show that recreational skaters differ from elite skaters by displaying higher peak pressures on the plantar surface and lower peak pressures on the lateral and medial surfaces. Also, pressures on the plantar, medial and lateral surfaces appeared to be higher on the inside foot when compared to pressures on the outside foot for both groups.

This study describes the biomechanics of the foot during an ice hockey tight tum.Pressure data were collected with flexible piezo-resistive sensors from 15 anatomicalpoints on both left and right feet. Participants inc1uded 8 elite (86.82 Kg +/- 6.48Kg,179.69 cm +/-6.74cm) and 8 recreationallevel (82.10Kg, +/-7.49Kg, 175.63cm +/-6.37cm) hockey players, with the elite players being members ofthe McGill varsity teamand the recreational players participating in recreational organized hockey of 10wercaliber. The data from three to four tums for both left and right tight tums were collectedand normalized, with statistical measures taken for blade contact/tum initiation, peakpressure and peak pressure at push off. Two way ANOV As showed numerous areas ofstatistical significance (p ≤ 0.05) between the elite and recreational participants. Thetracking of center of pressure was also investigated leading to sorne speculations ofadvanced techniques for the successful execution of a tight tum. / Cette étude décrit les pressions du pied en dedans du patin pendant un viragebrisque. Des collections de données de pression ont été collectionnées avecdes détecteurs piezo résistifs à 15 endroits anatomiques sur les deux pieds. Les groupescomprenaient 8 joueurs de hockey élites (86.82 Kg +/- 6.48Kg, 179.69 cm +/-6.74cm) et8 joueurs de hockey de niveau récréatif(82.10Kg, +/- 7.49Kg, 175.63cm +/- 6.37cm).Les joueurs élites étaient tous membres de l'équipe de première catégorie de l'Universitéde McGill et les joueurs récréatifs participaient tous dans des ligues de hockey organiséesmais d'un niveau plus bas. Les données de trois à quatre virages sur le côté droit et côtégauche ont été collectionnées et normalisées. Les variables retirées de cette analysecomprenaient le contact de lame/initiation de virage, pression maximale et « peak pushoff ». Une analyse statistique (2 way ANOV A) a démontrée plusieurs différences (p ≤ 0.05) entre les sujets élites et les joueurs récréatifs. Le centre de pression a été tracé etétudié. Cette analyse a servi comme source de réflexion sur les techniques avancées pourexécution idéale d'un virage brisque.

The study examined the peak pressures and pressure patterns in the skate boot of hockey players during the backward cross-over stride. Fifteen flexible piezo-resistive pressure sensors (1.2 x 1.1 x 0.2cm thick) were placed on the plantar, dorsal, medial, and lateral surfaces of each foot for eight varsity level hockey players (mean +/- SD: height (m) = 1.80 +/- 0.07, weight (kg) = 87 +/- 0.06) and eight recreational hockey players (mean +/- SD: height = 1.76 (m) +/- 0.06, weight (kg) = 82 +/- 0.07). The strides were cut and the data was processed according to ability group and cross-over direction. The results demonstrated significant differences between groups in average speed, and in peak pressures on the medial and lateral surfaces of the foot (p≤0.05). The results also indicated a significant difference on the plantar surface of the foot when comparing cross-over directions (p≤0.05).

Purpose. This study quantified fit of ice hockey skate boots by measuring the pressure (MP) at the foot/ankle-to-boot interface using three skate sizes. The relationship between perceived pressure (PP), perceived comfort (PC) and measured pressures (MP) also were documented. Methods . 18 male subjects participated. Thirty piezo-resistive sensors recorded MPs from seven areas with the foot/ankle in various positions. A Visual Analogue Scale was used for subjective assessment of PP and PC. Results. Overall fit MP was estimated at 34.2 KPa though significant mixed interactions (p<0.05) occurred between areas, foot/ankle positions and sizes. MP correlations with PP, PC, and foot/ankle dimensions were low though a strong inverse relationship was identified between PP and PC (r = -0.63). Conclusions. The technology and protocol adopted was effective in discriminating "fit" between regional pressure differences as well as responsive to foot/ankle positions. Further examination of other footwear products and different populations is feasible and warranted.

Music depends on the perception and production of complex temporal patterns, or rhythms, as a vital part of its power to communicate. These experiments investigated the neuroanatomical substrate of rhythm perception and production in patients with focal cerebral lesions, and in neuroimaging studies with normals. The hypotheses focused on the role of the primary and secondary auditory cortex, as well as the cerebellum and other motor-related areas. / Experiment I. To estimate the extent of removals in the region of auditory cortex in neurosurgical patients, a 3D probabilistic map of Heschl's gyrus (HG) was developed from magnetic resonance imaging (NW scans of normals. The map was coregistered with patent MRIs, revealing that most removals involved only anterior secondary auditory cortical regions, with relatively little encroachment onto primary auditory cortex. Additionally, this experiment compared the volumes of HG between hemispheres and found a consistent L > R asymmetry in the volume of cortical white matter, which could contribute directly to the preferential left-hemisphere processing of speech. / Experiment II. Using a paradigm contrasting reproduction of auditory and visual rhythms, four groups of patients were tested: those with right or left anterior temporal-lobe removals (RT-a, LT-a) and those with similar removals which also included HG (RT-A, LT-A). RT-A patients were impaired on auditory but not visual rhythms, particularly when accurate reproduction of stimulus durations was required. In contrast, LT-a, RT-a and LT-a patients were not impaired. These results demonstrated a role for the right anterior secondary auditory cortical regions in the retention of auditory temporal information. / Experiment III. The rhythm reproduction paradigm was adapted for a positron emission tomography (PET) activation study in normals. These data confirmed the participation of secondary auditory regions in the retention of auditory temporal information. They also demonstrated a supra-modal contribution of the lateral cerebellar cortices, vermis and basal ganglia to the task, pointing to a distributed system of neural structures involved in the production of a timed motor response from external stimuli. / The results are discussed in relation to possible interhemispheric differences in auditory temporal processing as well as the role of the cerebellum in motor and perceptual timing.

The present studies used the classical method of serial transections of the neuraxis to examine the neural mechanisms of injury-produced pain and morphine analgesia in the formalin test. The results showed that the behavioral response that follows formalin injection is complete within the brainstem, whereas telencephalic structures are critical for morphine to produce analgesia. In contrast, when the tail flick test, a model of noninjurious pain was used, both the behavioral response, and analgesia, were intact in the brainstem transected rat, in keeping with the current model of analgesia for this test. Brain areas classically associated with pain processing were not sufficient for morphine to produce analgesia in the formalin test. Instead, the amygdala, part of the emotion-mediating limbic system, was critical. It is argued that the formalin test may be a model of "dissociative" analgesia, in which reduction of the negative affective consequences of the pain plays a major role.