Passive exposure to speech sounds induces long-term memory representations in the auditory cortex of adult rats

Experience-induced changes in the functioning of the auditory cortex are prominent in early life, especially during a critical period. Although auditory perceptual learning takes place automatically during this critical period, it is thought to require active training in later life. Previous studies demonstrated rapid changes in single-cell responses of anesthetized adult animals while exposed to sounds presented in a statistical learning paradigm. However, whether passive exposure to sounds can form long-term memory representations remains to be demonstrated. To investigate this issue, we first exposed adult rats to human speech sounds for 3 consecutive days, 12 h/d. Two groups of rats exposed to either spectrotemporal or tonal changes in speech sounds served as controls for each other. Then, electrophysiological brain responses from the auditory cortex were recorded to the same stimuli. In both the exposure and test phase statistical learning paradigm, was applied. The exposure effect was found for the spectrotemporal sounds, but not for the tonal sounds. Only the animals exposed to spectrotemporal sounds differentiated subtle changes in these stimuli as indexed by the mismatch negativity response. The results point to the occurrence of long-term memory traces for the speech sounds due to passive exposure in adult animals.Peer reviewe

Ohjaajien käsityksiä sosiaalipedagogiseen hevostoimintaan osallistuvan hyvinvointiin vaikuttavista tekijöistä ja hevosen roolista asiakastyössä

Sosiaalipedagoginen hevostoiminta on määritelty työtavaksi, jonka tavoitteena on sosiaalisen kasvun ja hyvinvoinnin tukeminen hevosen kanssa tapahtuvassa yhteisöllisessä toiminnassa. Tavoitteenamme oli tutkia hevostoiminnan ohjaajien käsityksiä siitä, mitkä tekijät toiminnassa lisäävät osallistujan hyvinvointia ja mikä on hevosen rooli asiakastyössä. Tutkimuksemme viitekehyksenä on kestävän hyvinvoinnin teoria, johon peilaten analysoimme ohjaajien käsityksiä ihmisen ja hevosen välisestä yhteistoiminnasta. Tutkimusaineistomme koostui hevostoimintaohjaajien vuosina 2021–2022 täyttämistä laatukäsikirjadokumenteista (n=67), joista analysoimme kahden avoimen kysymyksen vastauksia laadullisella sisällönanalyysillä teoriaohjaavasti. Ohjaajien käsitysten mukaan hevostoiminnan vaikuttavat tekijät liittyvät merkityksellisiin vuorovaikutussuhteisiin, läsnäoloon, toimijuuteen sekä elämisen perustarpeiden merkityksen osoittamiseen. Ohjaajien käsitysten mukaan hevosen rooli on tukea niin ohjaajaa kuin asiakasta vuorovaikutteisessa työskentelyssä. Tutkimuksen perusteella hevoselle annetaan emotionaalisen työn tekijän rooli, mikä edellyttää työn luonteen pohdintaa myös siitä näkökulmasta, miten hevonen toiminnan kokee. Jatkotutkimuksissa tulisi tarkastella monilajisen vuorovaikutuksen etuja, haittoja ja edellytyksiä sekä sopivia tutkimusmenetelmiä vaikutusten arvioimiseksi niin ihmisen kuin eläimen näkökulmasta.Social-educational horse activity is defined as a working orientation to support social growth and well-being in community education with horses. The study aimed to explore the instructors’ perceptions about what factors increase the participant’s well-being and what the horse’s role is. The theoretical framework is the theory of sustainable well-being. Our research data consisted of quality manuals (n=67) completed by the instructors in 2021–2022, of which we analyzed two open questions with qualitative theory-driven content analysis.According to our results, the influencing factors of social-educational horse activity are related to meaningful interactions, presence, agency, and demonstrating the importance of basic living needs. The horse’s role is to support the instructor andthe client in interactive work. Based on our results, the horse is assigned a position of emotional labour, which requires consideration of the nature of the work from the horse’s perspective. Further studies could examine the advantages, disadvantages, and prerequisites of multi-species interaction and appropriate research methods for assessing impacts from both human and animal perspectives

Ohjaajien käsityksiä sosiaalipedagogiseen hevostoimintaan osallistuvan hyvinvointiin vaikuttavista tekijöistä ja hevosen roolista asiakastyössä

Sosiaalipedagoginen hevostoiminta on määritelty työtavaksi, jonka tavoitteena on sosiaalisen kasvun ja hyvinvoinnin tukeminen hevosen kanssa tapahtuvassa yhteisöllisessä toiminnassa. Tavoitteenamme oli tutkia hevostoiminnan ohjaajien käsityksiä siitä, mitkä tekijät toiminnassa lisäävät osallistujan hyvinvointia ja mikä on hevosen rooli asiakastyössä. Tutkimuksemme viitekehyksenä on kestävän hyvinvoinnin teoria, johon peilaten analysoimme ohjaajien käsityksiä ihmisen ja hevosen välisestä yhteistoiminnasta. Tutkimusaineistomme koostui hevostoimintaohjaajien vuosina 2021–2022 täyttämistä laatukäsikirjadokumenteista (n=67), joista analysoimme kahden avoimen kysymyksen vastauksia laadullisella sisällönanalyysillä teoriaohjaavasti. Ohjaajien käsitysten mukaan hevostoiminnan vaikuttavat tekijät liittyvät merkityksellisiin vuorovaikutussuhteisiin, läsnäoloon, toimijuuteen sekä elämisen perustarpeiden merkityksen osoittamiseen. Ohjaajien käsitysten mukaan hevosen rooli on tukea niin ohjaajaa kuin asiakasta vuorovaikutteisessa työskentelyssä. Tutkimuksen perusteella hevoselle annetaan emotionaalisen työn tekijän rooli, mikä edellyttää työn luonteen pohdintaa myös siitä näkökulmasta, miten hevonen toiminnan kokee. Jatkotutkimuksissa tulisi tarkastella monilajisen vuorovaikutuksen etuja, haittoja ja edellytyksiä sekä sopivia tutkimusmenetelmiä vaikutusten arvioimiseksi niin ihmisen kuin eläimen näkökulmasta

Memory-Based Mismatch Response to Frequency Changes in Rats

Any occasional changes in the acoustic environment are of potential importance for survival. In humans, the preattentive detection of such changes generates the mismatch negativity (MMN) component of event-related brain potentials. MMN is elicited to rare changes (‘deviants’) in a series of otherwise regularly repeating stimuli (‘standards’). Deviant stimuli are detected on the basis of a neural comparison process between the input from the current stimulus and the sensory memory trace of the standard stimuli. It is, however, unclear to what extent animals show a similar comparison process in response to auditory changes. To resolve this issue, epidural potentials were recorded above the primary auditory cortex of urethane-anesthetized rats. In an oddball condition, tone frequency was used to differentiate deviants interspersed randomly among a standard tone. Mismatch responses were observed at 60–100 ms after stimulus onset for frequency increases of 5% and 12.5% but not for similarly descending deviants. The response diminished when the silent inter-stimulus interval was increased from 375 ms to 600 ms for +5% deviants and from 600 ms to 1000 ms for +12.5% deviants. In comparison to the oddball condition the response also diminished in a control condition in which no repetitive standards were presented (equiprobable condition). These findings suggest that the rat mismatch response is similar to the human MMN and indicate that anesthetized rats provide a valuable model for studies of central auditory processing

Electrophysiological evidence of memory-based detection of auditory regularity violations in anesthetized mice

In humans, automatic change detection is reflected by an electrical brain response called mismatch negativity (MMN). Mismatch response is also elicited in mice, but it is unclear to what extent it is functionally similar to human MMN. We investigated this possible similarity by recording local field potentials from the auditory cortex of anesthetized mice. First, we tested whether the response to stimulus changes reflected the detection of regularity violations or adaptation to standard stimuli. Responses obtained from an oddball condition, where occasional changes in frequency were presented amongst of a standard sound, were compared to responses obtained from a control condition, where no regularities existed. To test whether the differential response to the deviant sounds in the oddball condition is dependent on sensory memory, responses from the oddball condition using 375 ms and 600 ms inter-stimulus intervals (ISI) were compared. We found a differential response to deviant sounds which was larger with the shorter than the longer ISI. Furthermore, the oddball deviant sound elicited larger response than the same sound in the control condition. These results demonstrate that the mismatch response in mice reflects detection of regularity violations and sensory memory function, as the human MMN.peerReviewe

Artificial theta stimulation impairs encoding of contextual fear memory.

Several experiments have demonstrated an intimate relationship between hippocampal theta rhythm (4-12 Hz) and memory. Lesioning the medial septum or fimbria-fornix, a fiber track connecting the hippocampus and the medial septum, abolishes the theta rhythm and results in a severe impairment in declarative memory. To assess whether there is a causal relationship between hippocampal theta and memory formation we investigated whether restoration of hippocampal theta by electrical stimulation during the encoding phase also restores fimbria-fornix lesion induced memory deficit in rats in the fear conditioning paradigm. Male Wistar rats underwent sham or fimbria-fornix lesion operation. Stimulation electrodes were implanted in the ventral hippocampal commissure and recording electrodes in the septal hippocampus. Artificial theta stimulation of 8 Hz was delivered during 3-min free exploration of the test cage in half of the rats before aversive conditioning with three foot shocks during 2 min. Memory was assessed by total freezing time in the same environment 24 h and 28 h after fear conditioning, and in an intervening test session in a different context. As expected, fimbria-fornix lesion impaired fear memory and dramatically attenuated hippocampal theta power. Artificial theta stimulation produced continuous theta oscillations that were almost similar to endogenous theta rhythm in amplitude and frequency. However, contrary to our predictions, artificial theta stimulation impaired conditioned fear response in both sham and fimbria-fornix lesioned animals. These data suggest that restoration of theta oscillation per se is not sufficient to support memory encoding after fimbria-fornix lesion and that universal theta oscillation in the hippocampus with a fixed frequency may actually impair memory

Electrophysiological evidence of memory-based detection of auditory regularity violations in anesthetized mice

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Auditory cortical and hippocampal-system mismatch responses to duration deviants in urethane-anesthetized rats

Any change in the invariant aspects of the auditory environment is of potential importance. The human brain preattentively or automatically detects such changes. The mismatch negativity (MMN) of event-related potentials (ERPs) reflects this initial stage of auditory change detection. The origin of MMN is held to be cortical. The hippocampus is associated with a later generated P3a of ERPs reflecting involuntarily attention switches towards auditory changes that are high in magnitude. The evidence for this cortico-hippocampal dichotomy is scarce, however. To shed further light on this issue, auditory cortical and hippocampal-system (CA1, dentate gyrus, subiculum) local-field potentials were recorded in urethane-anesthetized rats. A rare tone in duration (deviant) was interspersed with a repeated tone (standard). Two standard-to-standard (SSI) and standard-to-deviant (SDI) intervals (200 ms vs. 500 ms) were applied in different combinations to vary the observability of responses resembling MMN (mismatch responses). Mismatch responses were observed at 51.5–89 ms with the 500-ms SSI coupled with the 200-ms SDI but not with the three remaining combinations. Most importantly, the responses appeared in both the auditory-cortical and hippocampal locations. The findings suggest that the hippocampus may play a role in (cortical) manifestation of MMN.peerReviewe