Beyond Emotions: Oscillations of the Amygdala and Their Implications for Electrical Neuromodulation

The amygdala is a structure involved in emotions, fear, learning and memory and is highly interconnected with other brain regions, for example the motor cortex and the basal ganglia that are often targets of treatments involving electrical stimulation. Deep brain stimulation of the basal ganglia is successfully used to treat movement disorders, but can carry along non-motor side effects. The origin of these non-motor side effects is not fully understood yet, but might be altered oscillatory communication between specific motor areas and the amygdala. Oscillations in various frequency bands have been detected in the amygdala during cognitive and emotional tasks, which can couple with oscillations in cortical regions or the hippocampus. However, data on oscillatory coupling between the amygdala and motor areas are still lacking. This review provides a summary of oscillation frequencies measured in the amygdala and their possible functional relevance in different species, followed by evidence for connectivity between the amygdala and motor areas, such as the basal ganglia and the motor cortex. We hypothesize that the amygdala could communicate with motor areas through coherence of low frequency bands in the theta-alpha range. Furthermore, we discuss a potential role of the amygdala in therapeutic approaches based on electrical stimulation

Fornix deep brain stimulation induced long-term spatial memory independent of hippocampal neurogenesis

Deep brain stimulation (DBS) is an established symptomatic treatment modality for movement disorders and constitutes an emerging therapeutic approach for the treatment of memory impairment. In line with this, fornix DBS has shown to ameliorate cognitive decline associated with dementia. Nonetheless, mechanisms mediating clinical effects in demented patients or patients with other neurological disorders are largely unknown. There is evidence that DBS is able to modulate neurophysiological activity in targeted brain regions. We therefore hypothesized that DBS might be able to influence cognitive function via activity-dependent regulation of hippocampal neurogenesis. Using stimulation parameters, which were validated to restore memory loss in a previous behavioral study, we here assessed long-term effects of fornix DBS. To do so, we injected the thymidine analog, 5-bromo-2'-deoxyuridine (BrdU), after DBS and perfused the animals 6.5 weeks later. A week prior to perfusion, memory performance was assessed in the water maze. We found that acute stimulation of the fornix improved spatial memory performance in the water maze when the probe trial was performed 1 h after the last training session. However, no evidence for stimulation-induced neurogenesis was found in fornix DBS rats when compared to sham. Our results suggest that fornix DBS improves memory functions independent of hippocampal neurogenesis, possibly through other mechanisms such as synaptic plasticity and acute neurotransmitter release

Rat ultrasonic vocalizations as social reinforcers—Implications for a multilevel model of the cognitive representation of action and rats’ social world

Rats are social animals. For example, rats exhibit mutual-reward preferences, preferring choice alternatives that yield a reward to themselves as well as to a conspecific, over alternatives that yield a reward only to themselves. We have recently hypothesized that such mutual-reward preferences might be the result of reinforcing properties of ultrasonic vocalizations (USVs) emitted by the conspecifics. USVs in rats serve as situation-dependent socio-affective signals with important communicative functions. To test this possibility, here, we trained rats to enter one of two compartments in a T-maze setting. Entering either compartment yielded identical food rewards as well as playback of pre-recorded USVs either in the 50-kHz range, which we expected to be appetitive or therefore a potential positive reinforcer, or in the 22-kHz range predicted to be aversive and therefore a potential negative reinforcer. In three separate experimental conditions, rats chose between compartments yielding either 50-kHz USVs versus a non-ultrasonic control stimulus (condition 1), 22-kHz USVs versus a non-ultrasonic control stimulus (condition 2), or 50-kHz versus 22-kHz USVs (condition 3). Results show that rats exhibit a transient preference for the 50-kHz USV playback over non-ultrasonic control stimuli, as well as an initial avoidance of 22-kHz USV relative to non-ultrasonic control stimuli on trend-level. As rats progressed within session through trials, and across sessions, these preferences diminished, in line with previous findings. These results support our hypothesis that USVs have transiently motivating reinforcing properties, putatively acquired through association processes, but also highlight that these motivating properties are context-dependent and modulatory, and might not act as primary reinforcers when presented in isolation. We conclude this article with a second part on a multilevel cognitive theory of rats’ action and action learning. The “cascade” approach assumes that rats’ cognitive representations of action may be multilevel. A basic physical level of action may be invested with higher levels of action that integrate emotional, motivational, and social significance. Learning in an experiment consists in the cognitive formation of multilevel action representations. Social action and interaction in particular are proposed to be cognitively modeled as multilevel. Our results have implications for understanding the structure of social cognition, and social learning, in animals and humans

A Usability Study of Friendlyreader Webb

Syftet med mitt examensarbete är att undersöka användbarheten i FriendlyReader Web. Programmet är en e-tjänst som underlättar förståelse och överblick av digital materialet som textdokument, PDF m.m. Användbarheten har att testas genom att mäta ögonrörelser på 10 dyslektiker och 20 icke-dyslektiker. Vid ögonrörelsemätningar fick användarna utföra tre olika uppgifter i FriendlyReader Web. Användarna fick också ta fram en egen gränssnittprofil. Användarna har även att intervjuas med hjälp av ”Tänka-högt-protokoll” och detta skede efter ögonrörelsemätningarna. Här fick användare se sina egna ögonrörelser på en dator och kommentera detta. Till sist fick användarna svara på ett Webbformulär om hur de upplevde användbarheten i FriendlyReader Web. Sedan jämfördes båda gruppernas ögonrörelser för att se om det fanns några olik- och/eller likheter. Det viktigaste resultatet som kom fram i studien var att användarna tycker att FriendlyReader Web har ett enkelt gränssnitt och att gränssnittet fungera bra